mm-34 === Subject: Yes, a long time ago.The business cycles has a varying period and amplitude. Also cycles are notalways that clear when you get 'double dips' and the such like.>> Has anybody ever studied business cycle data with FFT-based spectral> techniques? === Subject: I think that the idea would then be to simply examine the spectral function and see if it obeys a power law. Has that ever been observed in the data?Power law dependence would mean that it is aperiodic, that basis function expansions are a waste of time (not counting wavelets) and that active control wouldn't work. Passive control might still work, (ie. setting interest rates to neutral and forgetting about them) but I wouldn't bet on that either. I'm not up on the math, but a few years ago there was a breakthrough in aerodynamics, where engineers realized when a fighter jet went into a tumble (chaotic trajectory) the pilot was causing it by fighting the stick. If he let go of the stick, the plane would spontaneously come out of the tumble.A sloppy person might be inclined to simply try the same solution for stabilizing the business cycle, but that would be a bad idea. It might be that there is no stable limit cycle in the available range of parameters except the one where all activity stops dead.This would be the same as if the time constant for recovery were so long that everybody starved before the economy came back. In the absence of actual state equations for the process model, I think you'd have to assume that this is the way things are and that the business cycle is the best solution allowed by the system.> Yes, a long time ago.The business cycles has a varying period and amplitude. Also cycles> are not always that clear when you get 'double dips' and the such> like. === Subject: power law ... would you mind to give a little bitmore than you already said?I think that the idea would then be to simply examine the spectral function> and see if it obeys a power law. Has that ever been observed in the data?Power law dependence would mean that it is aperiodic, that basis function> expansions are a waste of time (not counting wavelets) and that active> control wouldn't work.Passive control might still work, (ie. setting interest rates to neutral> and forgetting about them) but I wouldn't bet on that either. I'm not up> on the math, but a few years ago there was a breakthrough in aerodynamics,> where engineers realized when a fighter jet went into a tumble (chaotic> trajectory) the pilot was causing it by fighting the stick. If he let go> of the stick, the plane would spontaneously come out of the tumble.A sloppy person might be inclined to simply try the same solution for> stabilizing the business cycle, but that would be a bad idea. It might be> that there is no stable limit cycle in the available range of parameters> except the one where all activity stops dead.This would be the same as if the time constant for recovery were so long> that everybody starved before the economy came back. In the absence of> actual state equations for the process model, I think you'd have to assume> that this is the way things are and that the business cycle is the best> solution allowed by the system.> Yes, a long time ago.>> The business cycles has a varying period and amplitude. Also cycles> are not always that clear when you get 'double dips' and the such> like. === Subject: If you do not insist in FFT you may find a lot on timeseries analysis + econometrics (i never had the patientsto work through J. Hamilton) and even in TA it is used.The problem - as Rod says - is data are disturbed andnot clearly follow one rule (you need 'windowing').A concurrent approach is to set up a process model andestimate parameters from market data. Your FFT willbe translated to characteristic functions (take careto get not lost in mathematical physics). For the timevarying aspect you may dig for wavelets + econometrics.A third may be adaptive low pass filter (being slow iprefer that). Anyway you need lots of data. And maythink about ARMA / GARCH according to your intention.Just my 2 Euro cents ...Yes, a long time ago.The business cycles has a varying period and amplitude. Also cycles are not> always that clear when you get 'double dips' and the such like.>> Has anybody ever studied business cycle data with FFT-based spectral> techniques? === Subject: understand what I am missing. The problem is as follows: The Feige-Fiat-Shamir identification scheme is modified s.t.: - Peggy sends each of y_1,...,y_k individually, where every y_i =r*(s_i)^(b_i) - The verification in Step 4 is replaced with checking (y_i)^2 *(v_i)^(b_i) = r^2 mod n. As before, there are t rounds of the above protocol, so we can usethe notation y_(i,j) for the y_i of round j, and similarily, b_(i,j)is the b_i round of j. Of course, Victor can find out k-1 of the s_i's if t=1, and canfind out all of the s_i's if t > 1 by a judicious choice of theb_(i,j)'s, but we assume Victor is not interested in doing so, so thateach b_(i,j) is random with equal probability of being 1 or 0, andthen the b_(i,j)'s are independent of each other. In this case, what is the probability that Eve, who is recordingall the t rounds between Peggy and Victor, can obtain s_1? This is my line of thinking: The probablity we can obtain s_1 is based on two things: 1. b_1 = 1, i.e. y_1 = r*s_1 2. b_k = 0, i.e, k != 1 i.e some y_i = r P(1) = 1/2 P(2) = (2^(k-1)-1)/(2^(k-1)) P(pass in a single round) = P(1) * P(2) = (1/2) - (1/2^k) P(pass in t rounds) = P(1-fail in t rounds) = 1-(1-((1/2) -(1/2^k))) = 1-((1/2) + 1/2^k)^t This logic is somehow flawed. I have the posted solution of 1 -2^(-t) - 2^(t-kt) + 2^(-kt) without a good explination, which variesfrom my answer by one term. Can anyone help me find the error inhere? -Chu === Subject: >> But how do we know (from theoretical considerations) that the batteries > aren't using up their chemical energy fighting each other to keep a current> from flowing???They aren't. The space charge in the diode is doing that. There is a static field caused by the accumlation of charge that creates the space charge. Basically you form a capacitor in the diode. === Subject: > There are instances in physics where we encounter transcendental> equations of the form:exp(-constant*x) = x-r1where r1 is a constantHas anyone encountered real-life cases of:exp(-constant*x) = (x-r1)*(x-r2)where r1 and r2 are real numbers?> Well, I don't think that's exactly the kind of example you would liketo get, but once I had an experince almost like the one you mentioned.I work on the planning of the expansion of electric systems and I wastrying to adjust, by the least square method, a curve that representedthe marginal cost C of a thermal plant as a function of it's factor ofutilization, f. Through simulation programs I got a table relating thevalues of C to several values of f. The curve I found was divided into2 branches, the fist comprehending the interval [0.2 , k] and theother the interval [k, 0.96]. In the first branch the curve was givenby a 3rd degree polynomial and in the second by a negativeexponencial. Since the curve was supposed to be differentiable, at thepoint k we had an equation almost like yours.I used an Excel spreadsheet to find the the value of k, the values ofthe coefficients of the polynomial the constants of the exponentialcurve.Artur === Subject: > I bet you already knew that cos pi = -1 and such. But I was shocked to find,> just now, that there appears to be a _vegetable_ in the domain of cos x.> (Yes, you read that correctly. Obviously this is a silly pseudo-mathematical> post, but then you could tell that from the thread's title.)What is that vegetable? What is the value of cos x there?(I guess I should wait for other people to try to answer first. But this is> far too silly to be drawn out that way, and so I've given the answers below.)DavidThe vegetable is lettuce.According to my dictionary:cos lettuce = romaineYou're wrong, lettuce is NOT in the domain of cos. It would be if itwas cos(lettuce) = romaine, which is not the case.Amanda === Subject: >>I have never reviewed material for exams when I took the>course.>> I like to say that a test which can be studied for is not worth> giving (or taking).Been to a medical doctor lately? I'm glad mine studied for their exams.What is the graduate with the lowest GPA in a Medical School class> called?Doctor.What do you call the person with the least achievement to graduatefrom Stanford Chem with a Ph.D.?Doctor Schwartz> A license to practice medicine isn't meaningful until the doctor does> years of clinical work supervised by nurses (re green lieutenants and> seargents) and senior doctors. An MD is not a license to practice medicine. What you are trying todiscuss above is called a Residency. After MD, before license. Without it, you don't see patients unsupervised. === Subject: > An MD is not a license to practice medicine. What you are trying to> discuss above is called a Residency. After MD, before license. > Without it, you don't see patients unsupervised.Here's something not to do:When lying on the emergency room table and the ER Dr. is stitching up your hand (where there are a LOT of nerve endings)and he tries to distract you from the fact that the pain-killing shot hasn't really taken effect, by making small talkwith you, by saying:So, what do you do for a living?DO NOT SAY I'm a math prof.Because odds are that Calculus almost kept the poor bastardout of med school and he may inform you of that fact whilehe continues to ram that needle in and out of your hand.Indeed, sewing may become throwing stitches. Case in point, my ER Dr. put stitches through my thumbnail.In one side and up through the other. I'd have paid extranot to have that done. What the heck was wrong with adhesivetape. Or duct tape. I didn't give him his stupid C-, but Isure took the hit for it. The ONLY saving grace of the entire experience was that it wasn't a groin injury. === Subject: What are your credentials Niles? Are you only capable of whining andbitching? === Subject: > Anyone know why Grad Schools will not accept your application unless> you have a Bachelor's? Is it not possible to have the required> knowledge and no degree? Is it so very hard to verify that one's claim> of knowledge.>> some reasons:>> 1. it invalidates the whole college education schtick.> 2. lack of institutional admissions exams.> 3. the general population lacks the discipline to pull off such> thing as self-education.>> now to address your latter question.>> it wouln't be very hard to verify knowledge, but it is politically> incorrect and somewhat costly and time-consuming.Which is why grad schools can't be bothered unless you indicate that you are> special. You don't get special consideration unless you're a special> person.well, it seems that our advise seeker is reporting that the typicalgraduate programme does NOT offer such special consideration, even tospecial persons.> Jon Miller === Subject: Suppose we take the chess rules and add a new one:A1: You have the option of moving two pieces simultaneously, as long as each move considered separately was legal in 'single move' chess. The two pieces can't land on the same square, obviously.So you can't move a pawn, then the bishop behind itwhich was previously blocked by the moved pawn. Or,if your king is checked, you move your king,and move another piece to kill the check.I'm just wondering how drastic would a change be?Would a typical chess game have half the number ofturns for each player? Would the games be faster?Would there be some opening trick that white can playthat will always guarantee a win in a few turns?Now, if we were to look at the entire decision treefor double-move chess, it would be bigger thansingle-move chess, because double-move chess wouldhave all the moves of single-move chess too.But now, let's look at the decision tree for thosedouble-move chess games where two pieces were alwaysmoved if legal to do so. Would the tree be roughlytwice as wide but half as deep as the single-movechess decision tree?I know silly questions... just curious to know theanswer. === Subject: > Suppose we take the chess rules and add a new one:A1: You have the option of moving two pieces simultaneously,> as long as each move considered separately was legal in> 'single move' chess. The two pieces can't land on the> same square, obviously.http://homepages.stayfree.co.uk/gpj/gvc.htmand scroll down to Two-Move Chess.Marco-- === Subject: > Suppose we take the chess rules and add a new one:A1: You have the option of moving two pieces simultaneously,> as long as each move considered separately was legal in> 'single move' chess. The two pieces can't land on the> same square, obviously.> So you can't move a pawn, then the bishop behind it> which was previously blocked by the moved pawn. Or,> if your king is checked, you move your king,> and move another piece to kill the check.> I'm just wondering how drastic would a change be?> Would a typical chess game have half the number of> turns for each player? Would the games be faster?Would there be some opening trick that white can play> that will always guarantee a win in a few turns?> It would probably go much faster. One thing that might help is to give white one move, then black gets 2 and they alternate 2 moves from there on.Two moves in a row is such a huge advantage that in Monster Chess (white gets Ke1, Pc2d2e2f2 and two moves per turn, black gets the normal setup and one move per turn) is pretty much a forced win for white.--Harold BuckI used to rock and roll all night, and party every day. Then it was every other day. . . . -Homer J. Simpson === Subject: InHarold Buck typed:> Two moves in a row is such a huge advantage that in MonsterChess> (white gets Ke1, Pc2d2e2f2 and two moves per turn, black getsthe> normal setup and one move per turn) is pretty much a forced winfor> white.On the contrary, with careful play, Black should win. It isn'teasy, and if you never seen it before, Black is very hard toplay, but nevertheless it's better for Black.-- Ken BlakePlease reply to the newsgroup === Subject: > In> Harold Buck typed:Two moves in a row is such a huge advantage that in Monster> Chess> (white gets Ke1, Pc2d2e2f2 and two moves per turn, black gets> the> normal setup and one move per turn) is pretty much a forced win> for> white.> On the contrary, with careful play, Black should win. It isn't> easy, and if you never seen it before, Black is very hard to> play, but nevertheless it's better for Black.Really? I thought I'd read that it was hugely in white's favor. In any case, the fact that it's even playable shows how important those extra moves are.--Harold BuckI used to rock and roll all night, and party every day. Then it was every other day. . . . -Homer J. Simpson === Subject: InHarold Buck typed:> In>> Harold Buck typed:>> Two moves in a row is such a huge advantage that in Monster>> Chess>> (white gets Ke1, Pc2d2e2f2 and two moves per turn, blackgets>> the>> normal setup and one move per turn) is pretty much a forcedwin for>> white.>> On the contrary, with careful play, Black should win. It isn't>> easy, and if you never seen it before, Black is very hard to>> play, but nevertheless it's better for Black.> Really? I thought I'd read that it was hugely in white's favor.In any> case, the fact that it's even playable shows how importantthose extra> moves are.Yes, I agree.-- Ken BlakePlease reply to the newsgroup === Subject: >> Find the natural numbers k, as many as possible, so that all the> solutions of the scalar equation x'' = x^k can be extended> infinitely far?Do you mean you want there to be a solution x(t) with a domain ofthe form (a, infty) ?> d(x^(k+1))/dt = (k+1)(x^k)x'> = (k+1)(x'')(x')> = ((k+1)/2)(d((x')^2)/dt)This tells you that x^(k+1) - (k+1)/2 (x')^2 is a constant, C. Thus dx/dt = sqrt( 2/(k+1) x^(k+1) - C ). You can solve this byseparation of variables: t will be an antiderivative of1 / sqrt( 2/(k+1) x^(k+1) - C ). More accurately, if (a0, b0) and (a1, b1) are two points on thegraph of x(t), then a1 - a0 = int_b0^b1 dx / sqrt( 2/(k+1) x^(k+1) - C ). Since you want the domain to extend to infinity, you need theintegral to grow unbounded as b1 increases. But your integrand isbig-O of x^{-(k+1)/2}, and so the integral stays bounded if(k+1)/2 > 1, i.e. if k > 1.For k=1, of course, all solutions can be defined across the whole line.dave === Subject: >> Find the natural numbers k, as many as possible, so that all the> solutions of the scalar equation x'' = x^k can be extended> infinitely far?>> d(x^(k+1))/dt = (k+1)(x^k)x'> = (k+1)(x'')(x')> = ((k+1)/2)(d((x')^2)/dt)>> How could I do this?>> --What do you mean by extended infinitely far?Lurch === Subject: > Also, can we have things such as e^(quat) or ln(quat) where quat is a>> quaternion? Has anybody ever figured out how to do this? Also, what>> about using lie algebras which work on quaternions?>Any quaternion q can be written a+bu, where a,b are real and u^2 = -1.>So the set of {x+yu:x,y real} for this fixed u is isomorphic>to the complex numbers. Compute e^q and ln(q) in it just as in the>complex numbers.>>Generalizing functions of two variables is where problems come, if you>use two quaternions that don't commute.>>-- >G. A. Edgar http://www.math.ohio-state.edu/~edgar/This proves that representing quaternions as 3x3 matrices is notexact, since they can at most have 2 eigenvalues, whereas 3x3 matricesusually obey a cubic. === Subject: >Problem (Calculus of variations)> b> />minimise s= | (1+u^2)^0.5 dx for u(x)> /> a>>where s>0 and b>a, subject toDid you mean to write u > 0?>> b> /> |u dx - c = 0 c>0> /> a>>and b> / du> | --- dx - m = 0 m>0> / dx> a>when m = 0, the solution is trivial, namely u=constant. >>I am interested in the case m>0.>You can use the standard variation formula to show that the value ofthe functional for any non-constant u(x) can be decreased by changingu near two points where the value of u differs, in such a way as toleave the integral of u equal to c (and leaving the end points fixed).This shows that, in general, there is no continuous minimizingfunction. A generalized solution is a function u(x) that equalsc/(b-a) everywhere except at x = b, where the value is chosen tosatisfy the last condition.John Mitchell === Subject: >I have a partial difference equation whose sum over>> a certain range can be used to count prime numbers.>>2) Presumably you are going to justify why that's true at some point>Who cares if Mr. Harris can justify it? Are you really interested in hisexplanation? The interesting questions about his formula are: (1) Over whatrange does the method work? and (2) Is it faster than other methods on thisrange? Simple experiments should answer both questions. rich === Subject: >I have a partial difference equation whose sum over> a certain range can be used to count prime numbers.>>2) Presumably you are going to justify why that's true at some point>>Who cares if Mr. Harris can justify it? Are you really interested in his> explanation? The interesting questions about his formula are: (1) Over what> range does the method work? and (2) Is it faster than other methods on this> range? Simple experiments should answer both questions. richI care. Sufficiently many people whose opinions I respect havedecided it will count primes, in a manner similar to Legendre's method. Iwould like to see James, who has consistently denied it has anything to dowith Legendre (in fact for a while he even refused to admit Legendre'sformula could be used to count primes, so how he knew it was different fromhis is a mystery), prove he understands what's going on and can justifyhis claims that it is an all new and powerful method that no one else 'inthe history of mankind' has discovered. And just proving a range in which it works is a start. Unlike all the rest of his maths that he's shown recently, I think he may well have something here. I just don't see that it is new, exciting, or useful. He has also in the currently running debate on his crankhood repeatedlysaid he wants a point by point critique by a mathematician, withoutinsults, so that he can rebut them all. So there were some observations by someone who's not a number theorist. Ifanyone who does number theory seriously wants to point out where he or Iam misunderstanding something (which possibly I am too) please tell me.As it is the thread currently gives the lie to James assertion that hewould respond to any fair criticisms. I'm not remotely interested in insulting him, or debating his mentalhealth; it seems counterproductive. I am interested in people learning more mathematics, and that includes me. === Subject: >Dear Group Members,>>I ran into a problem where I would need to solve for a system (specifically>2) of quadratic equations. My search on the net lead me to systems of>polynomial equations. Unfortunately my math knowledge does not yet allow me>Could anyone please point me to a text that could be understood by a>interested technician?>>For completeness I formulate my problem, and what I know so far:>>1)The equations:>transpose (x-a) * A * (x-a) = r0>transpose (x-b) * B * (x-b) = r1>>where x is the (column) matrix of unknowns, a and b are column matrices and>A,B are symmetric matrices. r0 and r1 are scalars.>>2) I know about how to transform the quadratic forms into their>eigensystems, but then still can see no systematic way of how I could>eliminate one of the unknowns.>>3) I guess the order of my (specific) problem is at most of degree 4.>>Any pointers appreciated.>>Roland>>BTW.: Of course I would be interested how to solve for more than two>equations too.>>First expand both equations and rewrite them as M1 v = v1, M2 v = v2, where in x has dimension n, v has dimension equal to all quadratic, plus all linear, plus one constant, terms.Now if M1 is invertable, M2 (M1^-1) v1 = v2. So it is possible you have no solution at all. === Subject: > (x,y)--> sqrt{x^2+y^2} cos (arctg y/x) if x=/=0> comes from thinking about (r,t)-->r cos(t)> it isn't lineartime to review polar coordinates === Subject: Mystery remains as journal withdraws paperJOHN WHITFIELD[LONDON]A mathematics journal has withdrawn a paper that claimed to crack one of thediscipline's great mysteries after reviewing and accepting the work andpublishing it online.On 18 November, Nonlinear Analysis published a paper by Elin Oxenhielm - apostgraduate student in mathematics at the University of Stockholm, Sweden -sixteenth problem, one of a set of challenges laid out by GermanIf a solution were validated, mathematicians agree, it would be asignificant step towards a complete solution to the problem. Oxenhielmpredicts just that: We could find one in a year or so, if we're lucky, shesays.The work was described in a 24 November press release from Oxenhielm andcovered in several media outlets including the BBC. But the paperimmediately came under fire from mathematicians. It's completelyinadequate - I can't imagine who would have thought it was a proof, saysJohn Mather of Princeton University, New Jersey.Critics include Oxenhielm's supervisor, Yishao Zhou, who put a statement onher website saying: The paper is incomplete and contains serious mistakes.research. Solving any one of them is almost guaranteed to make amathematician's name, and by 2000 all but three had been solved.The sixteenth, the problem of the topology of algebraic curves and surfaces,deals with the territory where geometry meets algebra. Its second partinvolves showing that the number of periodic solutions to a differentialequation is finite.Such periodic solutions are also known as limit cycles - stable, oscillatingtrajectories to which a system will return if perturbed. Limit cycles arecommon in nature, and a proof of the second part could lead to a betterunderstanding of heartbeats, animal movements and the kind of runawayvibrations that can shake a structure to bits.Oxenhielm formulated her proof using 'describing functions' - which canpredict roughly the presence of limit cycles in nonlinear equations.A few minutes' scrutiny is enough to show that her reasoning is false, saysmathematician Grigori Rozenblioum of Chalmers University of Technology inGothenburg, Sweden. The approximate solutions studied by Oxenhielm cannotprovide the exact answers demanded in a proof, he says, and some of herequations contain exact terms where approximate ones should be used.The work should never have been published, Rozenblioum says: It'simpossible to understand the behaviour of the journal, which is one of theleaders in its field.Nonlinear Analysis pulled the paper on 4 December. Publication has beenhalted until a thorough investigation into the matter has been handled,says editor-in-chief V. Lakshmikantham, a mathematician at the FloridaInstitute of Technology in Melbourne.Originally approved by one reviewer, the paper has now been sent to two moremathematicians for further round of review, along with a defence byOxenhielm, who says that the critics do not understand her methods.She refuses to comment further. Nonlinear Analysis' editors have evaluatedthe paper, they accepted it for publication and they have the copyright ofits contents - and thus they are responsible for its correctness, she toldNorwegian newspaper Aftenposten.-------------------------------------------------- ------------------------------ === Subject: > [The author] refuses to comment further. Nonlinear Analysis'> editors have evaluated the paper, they accepted it for publication> and they have the copyright of its contents - and thus they are> responsible for its correctness, she told Norwegian newspaper> Aftenposten.Remarkable. Watch out, James. Another eminently .siggable quotefactory.But can she maintain this standard?-- Run mathematicians, RUN!!! I'm coming for you. It may take a fewmonths, but I'll get [computer verification of my proof] and then yourlives will be ended as you previously knew it. -- JSH meets PVS === Subject: >That is the theorem...but the converse is:>>If a triangle is inscribed in a semicircle with the angle opposite to the>hypoteneuse as 90 then the hypoteneuse is the diameter...>>How would you prove that ? I tried it many times and I get stuck>Well that is why I put a question mark at my statement of theconverse. I wondered if you asked what you meant to ask. Here is whatyou asked in the original post:>How do you prove the converse of this theorem?>If a right triangle is inscribed in a semicircle then the hypoteneuse is the>diameter of the circleSo you meant to ask how to prove this theorem, not its converse.--Lynn === Subject: >> Dear Nutjob,>> Stay out of alt atheism with your insane claims.>> There I said something else to you. What's my full legal name?>> 100,000 witnesses is a well founded claim, just examine the evidence>> someone to guess the names, its all in google.>You are the one making the claim you can tell a persons name by what they>said to you.>Your answer is meaningless.> 6 witnesses admit I'm the Truman, all in google. I've got evidence and>> witnesses, you're just a heathen.>Sadly people like you need help but probably don't qualify under 5150H&S.>However I bet that if you live in California you are familiar with the>section.> He lives in Townsville, Queensland. A population of about 140,000> people, businesses, and major tourism. Strangely though, he seems> unable to find employment, or a woman.>> That should tell you something. Under 5150 if you are a danger to yourself or others or can't take care ofyourself you can be committed for 72 hours. A doctor can over ride this. Itis a good and powerful law that will probably be overturned one day becauseof it's abuse. I once had some cops that wanted me to commit a woman becauseshe didn't agree with her boy friend. The cops (I used to be one) were notsmart enough to know they could do it.This guy is sick and I should not have responded to him.He is plonked. === Subject: > is a good and powerful law that will probably be overturned one day because> of it's abuse. I once had some cops that wanted me to commit a woman because> she didn't agree with her boy friend. The cops (I used to be one) were not> smart enough to know they could do it.at least you admit you're not smart and corrupt>> This guy is sick and I should not have responded to him.> He is plonked.You can't silence the truth, but you can PLONK it!after he actually contacted his famiily in townsville, i assume because theyconfirmed my storythis was his last post in aus.tv If what you say is true, wouldn't I be able to confirm what you say by 'hearing' your thoughts or watching a broadcast of your life on television? I have satellite cable, why can't I get the Herc show? My brother in law and his wife life in Townsville, and, amazingly enough, they can't seem to find this show on their television either. Nor have they ever heard of you or your demented claims. My partner's sister who lives in Rockhampton seems surprisingly unfamiliar with The 24 / 7 Herc Show!, starring everyone's favouriteWhy not use the imprison without charge law on all applicants to skepticcompanies? They're all insane right, cut out the middle man of formalapplicaitons, test procedure, just put up a big million dollar prize andsend all the names and addresses to the mental lock up! Pigs are soentrenched with the skeptic companies already wave a INC at a pigand you can lock up any unemployed person you want.Noone examining my claim of 3 extraordinary posts on the 1 day, just groupabuse from 5 newsgroups I've spent numerous months at each not one person to giveme any benefit of doubt for a few minutes investigation into my claim, doesthe 3 question test have an answer, are replies to herc's authors guessable?Very well, if YOU wont cooperate with fellow man then you can't be ruled with religion,you will be ruled with force like you are now under a real nutcase Bush who floodsmy life with noise from a spy satellite, believe me you would have preferred the former.HercEVIDENCEB Rust 3 attacks metal http://tinyurl.com/nd56E Rich Shewmaker 1 rich showmaker James Randi http://tinyurl.com/nd52H See You In Hell My Friend. 2 It all depends http://tinyurl.com/nd53predictions that paranormal will be demonstrated on 02 02.http://tinyurl.com/yo1b one year beforehttp://tinyurl.com/nw1r one day before-----------------------------Then I have 100,000 witnesses that I'm paranormal, here they admitthat I am the TRUEmanhttp://tinyurl.com/iky5 http://tinyurl.com/iky8 http://tinyurl.com/iky9http://tinyurl.com/iky4 http://tinyurl.com/rv5f http://tinyurl.com/v1yfHey Trueman...love the show. YOU ARE the Truman I heard him.Very spooky! We're sick of you You rule Truman.>Is the truman is living in Townsville? I've been hearing stuff, yeah.and watch here live in Google as I predict back in 2000 Jim Carrey's next romance costarLaurie Holden with http://tinyurl.com/fuf8 she looks exactly like Laurie Holden of the x-fileswith bright green eyes.Just like any Truman could have predicted, Majestic hey? Adam and Eve === Subject: Let X be compact Hausdorff, let {A_i} be a collection of closed connectedsubsets of X that is simply ordered by proper inclusion. Prove Y ={intersection of A_i over all i} is non-empty and connected.How can I prove this?The way I want to start is to suppose U,V are disjoint non-empty opensubsets of X. Then I want to analyze A_i - (U union V) over all i....canI get anywhere with this? How can I complete the proof?Steven === Subject: = some K1,..Kn with K1 /../ Kn subset UNow assume some open disjoint U,V with /C subset U/Vand use the exercise. I don't think Hausdorff is needed./ = cap = intersection---- === Subject: >Let X be compact Hausdorff, let {A_i} be a collection of closed connected>subsets of X that is simply ordered by proper inclusion. Prove Y {intersection of A_i over all i} is non-empty and connected.>How can I prove this?>The way I want to start is to suppose U,V are disjoint non-empty open>subsets of X. Then I want to analyze A_i - (U union V) over all i....can>I get anywhere with this? How can I complete the proof?Suppose that U union V contain the intersection of the A_i. Show thatit must contain some A_i. Compactness is helpful.--Dan Grubb === Subject: > Let X be compact Hausdorff, let {A_i} be a collection of closed connected> subsets of X that is simply ordered by proper inclusion. Prove Y {intersection of A_i over all i} is non-empty and connected.How can I prove this?The way I want to start is to suppose U,V are disjoint non-empty open> subsets of X. Then I want to analyze A_i - (U union V) over all i....can> I get anywhere with this? How can I complete the proof?Consider this: let U be an open subset of X such that cap A_i subsetU. Prove that A_i subset U for some i (hence, for all sufficientlylarge i--in the sense of the order). Why? Because if not, A_i capU^c is nonempty, compact and has the finite intersection property,hence has empty intersection.--Ron Bruck === Subject: Suppose that the random variables X_i are independent and P(X_i = 2^k) =2^(-k) for all k >= 1.Show that (X_1 + X_2 + ... + X_n)/(n*log(n)) converges in probability tolog(2).Prove or disprove that limsup (X_1 + ... + X_n)/(n*log(n)) = infinitywith probability 1.Can anyone prove this problem?Sincerely,Rob === Subject: >> Suppose that the random variables X_i are independent and P(X_i = 2^k) 2^(-k) for all k >= 1.>> Show that (X_1 + X_2 + ... + X_n)/(n*log(n)) converges in probability to> log(2).> Prove or disprove that limsup (X_1 + ... + X_n)/(n*log(n)) = infinity> with probability 1.>> Can anyone prove this problem?Well, Feller can.For the first part, see Feller's An Introduction to ProbabilityTheory and Its Applications: Volume 1. In my 3rd edition (1968),it's in section X.4 starting on p. 251.Feller also gave a very complete answer to the second problem in a1946 paper (A limit theorem for random variables with infinitemoments. Amer J. Math. 68, 257-262), but that result is much moregeneral than you need.You should be able to prove/disprove the second part fairly directlyusing Borel-Cantelli. Think about the events {X_n > n log n}. Dothey occur infinitely or finitely often? If the former, you should beable to easily show that the limsup is infinite. If the latter, youcan't quite prove that the limsup is finite, but you can get close.If you replace n log n with something smaller such that the events*still* happen only finitely often, you ought to be able to do it.Does that help?-- Kevin === Subject: >> Suppose that the random variables X_i are independent and P(X_i = 2^k) 2^(-k) for all k >= 1.>> Show that (X_1 + X_2 + ... + X_n)/(n*log(n)) converges in probabilityto> log(2).> Prove or disprove that limsup (X_1 + ... + X_n)/(n*log(n)) = infinity> with probability 1.>> Can anyone prove this problem?>> Well, Feller can.>> For the first part, see Feller's An Introduction to Probability> Theory and Its Applications: Volume 1. In my 3rd edition (1968),> it's in section X.4 starting on p. 251.>Where can I see your 3rd edition? What is your textbook called?(more text below)> Feller also gave a very complete answer to the second problem in a> 1946 paper (A limit theorem for random variables with infinite> moments. Amer J. Math. 68, 257-262), but that result is much more> general than you need.>> You should be able to prove/disprove the second part fairly directly> using Borel-Cantelli. Think about the events {X_n > n log n}. Do> they occur infinitely or finitely often? If the former, you should be> able to easily show that the limsup is infinite. If the latter, you> can't quite prove that the limsup is finite, but you can get close.> If you replace n log n with something smaller such that the events> *still* happen only finitely often, you ought to be able to do it.>I don't see how you would do this. How about this approach :What we want to show is P(limsup (X_1 + X_2 + .... + X_n)/nlog(n) =infinity) = 1where log is base e. (correct?)Now, is the following proposition true?For any sequence of independent random variables {Z_k}, ifSummation (from k = 1 to infinity) of P( |Z_k| > epsilon) = infinity forall epsilon > 0,then Z_k converges almost surely to infinity. (Maybe I can prove this withborel-cantelli lemma of independent events?)If true, then I'd like to use Markov's inequality, by saying thatP((X_1 + X_2 + .... + X_n)/nlog(n) > epsilon) <= (1/epsilon) * E((X_1 +X_2 + .... + X_n)/nlog(n))) or some variationof markov's inequality, and then sum up these values to possibly getinfinity and our proof would be done.If this doesn't work, how can I view the events {X_n > nlog(n)}? I agreethis would be helpful. I don't see how I can tellif they occur infinitely often. Furthermore, if this were true, how wouldthis imply that the limsup is infinite? And which Borel-Cantelli lemmawould you use?(a bit lost)> Does that help?>> -- > Kevin === Subject: >> For the first part, see Feller's An Introduction to Probability>> Theory and Its Applications: Volume 1. In my 3rd edition (1968),>> it's in section X.4 starting on p. 251.>> Where can I see your 3rd edition? What is your textbook called?> (more text below)Sorry, I meant my 3rd edition copy of Feller's An Introduction toProbability Theory and Its Applications: Volume 1.> Now, is the following proposition true?>> For any sequence of independent random variables {Z_k}, if> Summation (from k = 1 to infinity) of P( |Z_k| > epsilon) = infinity for> all epsilon > 0,> then Z_k converges almost surely to infinity. (Maybe I can prove this with> borel-cantelli lemma of independent events?)No, it's not true. Constant random variables (i.e., randomvariables that are always equal to a specific constant) areindependent of anything, so any deterministic sequence is a sequenceof independent random variables, too, but your proposition fails forZ_k=-k (where the limit is -infinity instead of infinity) or Z_k=k fork even and =0 for k odd (where there is no limit).It *is* true that a sequence of nonnegative, independent randomvariables {Z_k} satisfying sum_{k=1}^infinity P(Z_k > epsilon) = infinityfor all epsilon > 0 will have limsup Z_k = infinity, and this can beproved by Borel-Cantelli. (Note that we have added the hypothesis ofnonnegativity and changed the conclusion to specify the limsup ratherthan the limit.)> If true, then I'd like to use Markov's inequality, by saying that> P((X_1 + X_2 + .... + X_n)/nlog(n) > epsilon) <= (1/epsilon) * E((X_1 +> X_2 + .... + X_n)/nlog(n))) or some variation> of markov's inequality, and then sum up these values to possibly get> infinity and our proof would be done.The problem is that the inequality goes the wrong way. To apply theabove result, you need to show that the sum of the probabilities isinfinite, but the inequality will only let you conclude that this sumis less than or equal to something, and that won't help.> If this doesn't work, how can I view the events {X_n > nlog(n)}? I agree> this would be helpful.Well, if n=6, say, then nlog(n) is about 10.75. So, how would you goabout calculating P(X_n > nlog(n)) = P(X_6 > 10.75)? You should beable to generalize this to an arbitrary n.> I don't see how I can tell if they occur infinitely often.> Furthermore, if this were true, how would this imply that the limsup> is infinite?Well, okay, I spoke too glibly. It still wouldn't be *quite* enough,but it would tell you that, infinitely often (i.e., whenever X_n >nlog(n)), you'd have to have: (X_1 + ... + X_n)/nlog(n) > X_1/nlog(n) > 1Now, if you could do the same thing with {X_n > a n log(n)} for everya > 0 (instead of just for a=1), *then* that would be enough. Do yousee why?> And which Borel-Cantelli lemma would you use?Which do you have? The two I know about are the one that applies whenthe sum of the probabilities is infinite and the other that applieswhen the sum of the probabilities is finite. So, once you'vedetermined whether the sum of the probabilities is infinite or finite,you'll know.-- Kevin === Subject: > If this doesn't work, how can I view the events {X_n > nlog(n)}? I agree> this would be helpful. I don't see how I can tell> if they occur infinitely often. Furthermore, if this were true, how would> this imply that the limsup is infinite? And which Borel-Cantelli lemma> would you use?> Consider the events A_n = {X_n > a n log n} where a is a constant.These are independent events. Show that sum P(A_n) = infty(for any choice of a). === Subject: > If this doesn't work, how can I view the events {X_n > nlog(n)}? Iagree> this would be helpful. I don't see how I can tell> if they occur infinitely often. Furthermore, if this were true, howwould> this imply that the limsup is infinite? And which Borel-Cantelli lemma> would you use?>> Consider the events A_n = {X_n > a n log n} where a is a constant.>My apologies. These are discrete random variables. Now it appears that sum P(A_n) = infty, as I plug numbers into my calculator, but I need tocome> These are independent events. Show that sum P(A_n) = infty> (for any choice of a).>>Cancel-Lock: sha1:fo+GBypctlzmhtte3qiDdDA9jI4 === Subject: > My apologies. These are discrete random variables. Now it appears> that sum P(A_n) = infty, as I plug numbers into my calculator, but> I need to come up with a rigorous proof of this.Yes, and calculators can be deceiving. Rumour has it that log(log(n))goes to infinity as n does, but just try proving that with acalculator.-- Kevin === Subject: > If this doesn't work, how can I view the events {X_n > nlog(n)}? Iagree> this would be helpful. I don't see how I can tell> if they occur infinitely often. Furthermore, if this were true, howwould> this imply that the limsup is infinite? And which Borel-Cantelli lemma> would you use?>> Consider the events A_n = {X_n > a n log n} where a is a constant.>This is where my problem is....how do I calculate P(A_n)? I understandthey are independent events and then by Borel-Cantelli I am golden.But all I have is that P(X_i = 2^k) = 2^(-k)...how can I calculateP(X_n > an*log(n))?I really think this must be a stupid question I am asking but I am justforgetting somethingfrom my elementary probability...isn't P(X_i = 2^k) = 2^(-k) my densityfunction?Then do I just integrate from -infinity to an*log(n)? but I must change thedensityfunction to P(x) = 2^{-log(x)/log(2)} since I need a density function forP(X_i = x), not P(X_i = 2^k)...I think I am just getting more and more confused...> These are independent events. Show that sum P(A_n) = infty> (for any choice of a).>> === Subject: : : > : Anyway, my point had nothing to do with path categories specificallyThis almost looks like a mis-attribution; despite the fact that my nameis the last one occurring before it, the above line was written by the otherarguer, as was the following one: : > : it was entirely about your refusal to accept the general phenomenon that : > : different ways of looking at the same mathematical objects can lead to : > : better insights about those objects. : > : > All I can say to that, frankly, is that you are starting to deserve : > insults at the same level at which you are dishing them out. : : What insult?This insult: your refusal to accept the general phenomenon that different ways of looking at the same mathematical objects can lead to better insights about those objects.I have NOT so refused and I am not so refusing now.Or, as I said it better the first time, : > I DO NOT refuse to accept the general phenomenon that : > different ways of looking at the same mathematical objects can : > lead to better insights about those objects. ... : > In projective geometry, points : > and lines are REALLY dual. : Perhaps your understanding of projective duality is different from mine.Duality is one thing. The fact that it actually occurs in projectivegeometry is another. But it does NOT occur (not between points and linesanyway) in affine geometry. It is a DIFFERENCE between affine and projective geometries that points&lines ARE dual in projective geometry, but ARE NOT dualin affine geometry.Unfortunately (terminology-wise), it is also the case that for any givenaffine plane, there are some fairly simple things you can do to it toturn it into a projective one. This transition is SO small and simple thatsometimes people are tempted to say that the affine plane that you startedwith, and the projective one that you get to (from applying this simple transformationto it), are THEMselves dual to each other. But THAT is a BAD use of dual.Or at least a distracting one, in the context of the more real duality,which is between the projective plane's points and the projective plane's lines. : In my understanding, the dual of a configuration of points and lines : consists of the same objects, but the objects that were points now get : called lines and the objects that were lines now get called points.You can always perform this rename/exchange but you canNOT always CALLit the dual. In projective geometry, points and lines ARE dual, whichmeans that that re-calling works in the relevant sense. But where itdoesn't work, there simply IS NO duality. : A projective geometry is a system of objects with incidence relations : satisfying certain axioms and when you rename the objects they still : satisfy the appropriate axioms.Right, i.e., when you exchange points with lines, the same statements all keepthe same truth-values. AFTER that happens, THEN you can say that points andlies are dual, withIN that axiomatic framework. But affine geometry is governedby DIFFERENT axioms and under THEM, you canNOT perform this renaming withoutchanging truth-values. : The only difference is in the human : terminology for the objects, not in their mathematical behavior or : identity.There is no difference in projective geometry, yes; thatby definition is why you CALL it projective. But we were talkingabout the affine case. : To get back to an earlier point, one possible way of forming objects : satisfying the set of projective geometry axioms is to have points that : are just points (atomic from the point of view of the geometry) while : the lines are sets of points and the point-line incidence relation is : set membership. Projective duality tells us that we could instead view : the lines as being atoms, and the points as being sets of lines through : them, with incidence again being equivalent to set membership.Of course. : As someone who has personally gained insight into geometry problems by : applying projective duality,Oh, SHUT UP!The AFFINE plane IS NOT PROJECTIVE and DOES NOT EXHIBIT projective duality!In order to apply projective duality, you would FIRST need to APPLY SOMETRANSFORMATION TO the affine plane so that the result WOULD IN FACT BEprojective! ONLY AFTER that do you get to exploit duality! : despite duality's inability to change the : underlying mathematical objects involved, I find your claim You will : not gain any insight into the nature of a point by thinking about it as : an infinite collection of lines to be counterfactual and strange.No, you don't.I was talking about the affine case.In the projective case, obviously, points and lines are dual.AND I SAID THAT. : Why are you trying to tell me not to apply a technique that I know from : personal experience has worked?SHUT the up, bitch.THAT is, AGAIN, the sort of insult up with which I need not put.-- --- It's difficult ... you need to be united to have any strength, but internal issues have to be addressed. --- E. Ray Lewis, on liberalism in America === Subject: > : Why are you trying to tell me not to apply a technique that I know from > : personal experience has worked?SHUT the up, bitch.> THAT is, AGAIN, the sort of insult up with which I need not put.You keep using that word insult. I do not think it means what you think it means.I also do not think you are making a positive contribution to this newsgroup.*plonk*-- David Eppstein http://www.ics.uci.edu/~eppstein/Univ. of California, Irvine, School of Information & Computer Science === Subject: David Eppstein insultingly asks, : > : Why do you want to blinker us?I politely replied, : > I don't. : Give it a break George. Go back to the hell that spawned you, mitch. : You know what you are doing.Of course I do, but you don't, so whyare you presuming to pontificate about it? : > The general thrust of this thread is about : > representation theorems, not blinkering. : : Now who is lying?You are, fool. I FOUNDED this thread.I POSTED several messages in it about representation theorems. : You bring ridiculous concepts like burden of proof concerning metaphysical : positions like foundationalismWHERE? QUOTE ME OR SHUT THE * * UP, BITCH. : to mathematical discussionsI STARTED this discussion, IDIOT.IF I WANT to discuss foundations, THEN I CAN DO THAT,both on sci.logic and sci.math,AND THERE ISN'T * * that *YOU* can do about it. : and aren't honest about : it to the people with whom you are in discussion.About what, specifically, am I being dishonest?Will you please QUOTE SOMETHING I SAID and then EXPLAINwhy it is false? THEN you will become entitled to say whatyou just said. UNTIL you can do that, you are perfectly welcometo eat and die. === Subject: > David Eppstein insultingly asks,>> : > : Why do you want to blinker us?>> I politely replied,>> : > I don't.>> : Give it a break George.>> Go back to the hell that spawned you, mitch.>> : You know what you are doing.>> Of course I do, but you don't, so why> are you presuming to pontificate about it?>I'm not. If after having changed the topic in this thread you had redirected itunder sci.logic alone (as you have repeatedly stated that you do because you do notwant to be on math threads) I would have left my simple lol response withoutfurther comment, if even that.But you are in the business of a separate debate having nothing to do withmathematics proper. My presumption comes from a year of experience with your postson sci.logic. It is inappropriate to engage people with a specific disinterest inthe background motivation for your questions (forcing ontological commitment),blinker them, and then claim that is not what you are doing.As for the hell that spawned me--it was a course on intermediate logic in aphilosophy department. I received an 'A' and a recommendation for graduate school.As for why I have been on sci.logic... that is because it is an appropriateunmoderated newsgroup for posting ideas about the foundations of mathematics (giventhe general disinterest in these matters among mathematicians as you yourself havenoted).Look George. I am sorry for coming down on you like I did. But, there is adifference between opinions concerning foundations and formal philosophicproposals. Likewise, there is a difference between a discussion and aninterrogation.:-)mitchHell hath no bounds,Nor is circumscribed in any one self place.For where we are is hell,And where hell is,There must we ever be.And to conclude,When all the world dissolvesAnd every creature shall be purified,All places shall be hell that is not heaven. --Mephistopheles The Tragedy of Doctor Faustus by Christopher MarloweIt is, perhaps, true. Ignorance is bliss. One thing I find admirable about peopleof faith is that they begin with the principle that they cannot know the essentialtruths of the universe and then use that as a foundation for ethical guidance. === Subject: : > : > : You know what you are doing.I replied, > Of course I do, but you don't, so why > are you presuming to pontificate about it? : I'm not.Yes, you are. I will QUOTE you doing so, in a second. : If after having changed the topic in this thread you had redirected it : under sci.logic alone (as you have repeatedly stated that you do because you do not : want to be on math threads) I would have left my simple lol response without : further comment, if even that.This is idiotic. I already had an exchange with Tim Chow where I EXPLAINED WHYthis thread is still on sci.math. And you OF ALL PEOPLE are NOT qualified tojudge what does or doesn't belong on sci. math. : But you are in the business of a separate debate having nothing to do with : mathematics proper.That is an idiotic lie and MORE OF the same pontification-from-ignoranceabout what I am doing that you just falsely alleged about yourself that youdon't engage in. This debate is not separate from math. It does MATTERwhat you think about concreteness and it does MATTER what pedagogicallyuseful prototypical categories might be. : My presumptionWhat EXACTLY are you presuming?Do you mean presumption as in presuming a logical premise,or presumption as in daring to DO something you are notentitled to do? : comes from a year of experience with your posts on sci.logic.Which, tragically, has taught you nothing. : It is inappropriate to engage people with a specific disinterest in : the background motivation for your questionsA motivation which you are personally both intellectually andpsychologically completely UNABLE to compute : (forcing ontological commitment),and that was a really ty guess at it, since I am NOT trying toforce any kind of ontological commitment. I already posteda reply to James Dolan in which I completely agreed with himthat this was about noticing that tons of viewpoints are ontologicallyrelevant, whether anyone wants them to be or not, and that far fromcommitting to some of them, we were rather about recognizingisomorphisms and representation-theorems that would allow us tothink in terms of 1 representative viewpoint. In this thread,I am about electing representatives, NOT ontological commitment.But more to the point,They can ALWAYS JUST IGNORE IT. I ADVERTISED that I was gear-shiftingthe discussion. I did not lure anybody into this under false pretenses,or engage anyone against their will. Insinuations and pontificationsto the effect that I *have* done that are just bull and shouldbe flushed ALONG with the fool who was fool enough (or hateful enough)to assert them. : blinker them,I have not blinkered anybody.I can't help it if Dave Eppstein thinks you can have a vertical linein an affine geometry (I suppose next he will be telling us thatyou can have an origin). I can't help it if the fact that there areeasy transformations from affine to projective geometry has himwrongly speaking of a point/line duality in the affine case, when infact such only obtains in the projective case. I am NOT blinkeringanybody. If you are going to publicly claim that I am then you are justgoing to make yourself part of the problem. : and then claim that is not what you are doing.Well, I RE-claim, IT'S NOT. : As for the hell that spawned me--it was a course on intermediate logic in a : philosophy department.Just because you got it THEN doesn't mean you get it NOW.In your own opinion, you have grown up a lot since then, andyou now feel free to embrace perspectives that were NOT taught inTHAT course. Not that that course would even be EXPECTED to givea about philosophy of math in ANY case. : I received an 'A' and a recommendation for graduate school.Well, that makes two of us. : Look George. I am sorry for coming down on you like I did.You would do well to just never apologize to me again, period.It won't matter. : But, there is a difference between opinions concerning foundations : and formal philosophic proposals.Yeah, but since I'm the one with the philosophy degree here, maybe youshould ASK me instead of TELLING me what that difference is. : Likewise, there is a difference between a discussion and an interrogation.No, not likewise, not at all.And interrogation is going to remain appropriate as long as youkeep trying to evade basic questions. I mean, you don'tsee *me* whining about getting interrogated. === Subject: Download a free beta version of my new proof checking software, DC Proof 1.0athttp://www.dcproof.com/(for MS Windows 95 and later)It is a learning aid to teach the fundamentals of logic and proof. Afterentering a premise or assumption, the user can select rules of inference forLogic, Set Theory and Number Theory from easy-to-use, drop-down menus. Itshould be impossible to write an invalid proof in this system! Feedback isimmediate with each new line.A tutorial with examples and exercises demonstrating the main features of DCProof is included along with the user manual. (Click the Help** Button.)DC Proof is interesting from both pedagogical and theoretical perspectives.The axioms for set theory, for example, are a simplified version of thestandard ZF model. Yet they are robust enough to avoid the knowncontradictions of naive set theory, and, I believe, to develop much ofmodern-day mathematical theory.Please let me know what you think of my new system.Dan ChristensenToronto, Canada === Subject: > Download a free beta version of my new proof checking software, DC Proof1.0> at>> http://www.dcproof.com/>> (for MS Windows 95 and later)>> It is a learning aid to teach the fundamentals of logic and proof. After> entering a premise or assumption, the user can select rules of inferencefor> Logic, Set Theory and Number Theory from easy-to-use, drop-down menus. It> should be impossible to write an invalid proof in this system! Feedback is> immediate with each new line.>> A tutorial with examples and exercises demonstrating the main features ofDC> Proof is included along with the user manual. (Click the Help** Button.)>> DC Proof is interesting from both pedagogical and theoreticalperspectives.> The axioms for set theory, for example, are a simplified version of the> standard ZF model. Yet they are robust enough to avoid the known> contradictions of naive set theory, and, I believe, to develop much of> modern-day mathematical theory.>> Please let me know what you think of my new system.>> Dan Christensen>> Toronto, CanadaNeither the Help menu nor the Help** button produced any help. Here is whatgot installed...C:Program FilesDC Proofasycfilt.dllC:Program FilesDC Proofcomcat.dllC:Program FilesDC ProofCOMDLG32.OCXC:Program FilesDC ProofDC Proof.chmC:Program FilesDC ProofDC Proof.exeC:Program FilesDC ProofDefaultDir.binC:Program FilesDC Proofe.gifC:Program FilesDC Proofhhctrl.ocxC:Program FilesDC Proofmsvbvm60.dllC:Program FilesDC Proofoleaut32.dllC:Program FilesDC Proofolepro32.dllC:Program FilesDC ProofRecentFiles.binC:Program FilesDC ProofRICHTX32.OCXC:Program FilesDC Proofstdole2.tlbC:Program FilesDC Proofunins000.datC:Program FilesDC Proofunins000.exe-- Clive Toothhttp://www.clivetooth.dk === Subject: >> Download a free beta version of my new proof checking software, DC Proof> 1.0> at>> http://www.dcproof.com/>> (for MS Windows 95 and later)>> It is a learning aid to teach the fundamentals of logic and proof.After> entering a premise or assumption, the user can select rules of inference> for> Logic, Set Theory and Number Theory from easy-to-use, drop-down menus.It> should be impossible to write an invalid proof in this system! Feedbackis> immediate with each new line.>> A tutorial with examples and exercises demonstrating the main featuresof> DC> Proof is included along with the user manual. (Click the Help** Button.)>> DC Proof is interesting from both pedagogical and theoretical> perspectives.> The axioms for set theory, for example, are a simplified version of the> standard ZF model. Yet they are robust enough to avoid the known> contradictions of naive set theory, and, I believe, to develop much of> modern-day mathematical theory.>> Please let me know what you think of my new system.>> Dan Christensen>> Toronto, Canada>> Neither the Help menu nor the Help** button produced any help. Here iswhat> got installed...>> C:Program FilesDC Proofasycfilt.dll> C:Program FilesDC Proofcomcat.dll> C:Program FilesDC ProofCOMDLG32.OCX> C:Program FilesDC ProofDC Proof.chm> C:Program FilesDC ProofDC Proof.exe> C:Program FilesDC ProofDefaultDir.bin> C:Program FilesDC Proofe.gif> C:Program FilesDC Proofhhctrl.ocx> C:Program FilesDC Proofmsvbvm60.dll> C:Program FilesDC Proofoleaut32.dll> C:Program FilesDC Proofolepro32.dll> C:Program FilesDC ProofRecentFiles.bin> C:Program FilesDC ProofRICHTX32.OCX> C:Program FilesDC Proofstdole2.tlb> C:Program FilesDC Proofunins000.dat> C:Program FilesDC Proofunins000.exe>> -- > Clive Tooth> http://www.clivetooth.dk>>Somehow the HTML Help viewer isn't being made available to my program as itis downloaded. I will investigate and report back.In the mean time, the download is temporarily not available. Sorry for theinconvenience.Dan === Subject: >> Download a free beta version of my new proof checking software, DC Proof> 1.0> at>> http://www.dcproof.com/>> (for MS Windows 95 and later)>> It is a learning aid to teach the fundamentals of logic and proof.After> entering a premise or assumption, the user can select rules of inference> for> Logic, Set Theory and Number Theory from easy-to-use, drop-down menus.It> should be impossible to write an invalid proof in this system! Feedbackis> immediate with each new line.>> A tutorial with examples and exercises demonstrating the main featuresof> DC> Proof is included along with the user manual. (Click the Help** Button.)>> DC Proof is interesting from both pedagogical and theoretical> perspectives.> The axioms for set theory, for example, are a simplified version of the> standard ZF model. Yet they are robust enough to avoid the known> contradictions of naive set theory, and, I believe, to develop much of> modern-day mathematical theory.>> Please let me know what you think of my new system.>> Dan Christensen>> Toronto, Canada>> Neither the Help menu nor the Help** button produced any help. Here iswhat> got installed...>> C:Program FilesDC Proofasycfilt.dll> C:Program FilesDC Proofcomcat.dll> C:Program FilesDC ProofCOMDLG32.OCX> C:Program FilesDC ProofDC Proof.chm> C:Program FilesDC ProofDC Proof.exe> C:Program FilesDC ProofDefaultDir.bin> C:Program FilesDC Proofe.gif> C:Program FilesDC Proofhhctrl.ocx> C:Program FilesDC Proofmsvbvm60.dll> C:Program FilesDC Proofoleaut32.dll> C:Program FilesDC Proofolepro32.dll> C:Program FilesDC ProofRecentFiles.bin> C:Program FilesDC ProofRICHTX32.OCX> C:Program FilesDC Proofstdole2.tlb> C:Program FilesDC Proofunins000.dat> C:Program FilesDC Proofunins000.exe>> -- > Clive Tooth> http://www.clivetooth.dk>Clive,Perhaps you do not have the Windows HTML Help viewer. For the latest versionof it, go tohttp://msdn.microsoft.com/library/default.asp?url=/library/ en-us/htmlhelp/html/ hwHTMLHelpFrequentlyAskedQuestions.aspClick on Downloads. Read the notes carefully. Different versions ofWindows may require different solutions.If this does not seem applicaple, see the FAQ's at this link. Please let meknow if you continue to have problems.Dan === Subject: > Clive,Perhaps you do not have the Windows HTML Help viewer. For the latest version> of it, go tohttp://msdn.microsoft.com/library/default.asp?url=/library/ en-us/htmlhelp/html/ hwHTMLHelpFrequentlyAskedQuestions.aspClick on Downloads. Read the notes carefully. Different versions of> Windows may require different solutions.If this does not seem applicaple, see the FAQ's at this link. Please let me> know if you continue to have problems.DanHaven't had a look at the software yet, but you've usually got to writethe path to the required help file in the registry.... Does this registryentry exist?Bruce. === Subject: within my diploma thesis I read chapter 2 in the bookNumberTheory in Function Fields from Michael Rosen. I followedthe advice to translate some results for $Z$ into the context of thepolynomial ring $A=F_{p}[x]$. I did this also for the following function:Let $m=p_{1}^{e_{1}} cdot p_{2}^{e_{2}} cdot ldots cdotp_{t}^{e_{t}}$ where $p_{i}$ prime. Then define $g(m)=1$ if $m=1$and $g(m)=max(e_{1},e_{2},ldots,e_{t})$ if $m>1$. If one calculatesthe average value of $g$, one gets 1.705221, the constant of Niven.I translated the function to the ring $A$ in the following way: Let$f=P_{1}^{e_{1}} cdot P_{2}^{e_{2}} cdot ldots cdotP_{t}^{e_{t}}$ where $P_{i}$ irreducible polynomials in A. Then I defined$g(f)=1$ if$deg(f)=0$ or $deg(f)=1$ and $g(f)=max(e_{1},e_{2},ldots,e_{t})$ if$deg(f)>1$. I calculated $frac{1}{p^{n}} cdot sumlimits g(f)$(summing over all monic $f$ of degree $n$) for different $p$ andincreasing $n$. I got a lot of numerical values, which led me to thefollowing statement: $lim_{n to infty} frac{1}{p^{n}} cdot sumlimitsg(f) = 1 +frac{1}{p-1}$. Now I`d like to know if one of you out there knowsthis result and if so, could tell me, where I can find it. I`dlike to compare my prove to the known one.Yours sincerlyStefan Wagenbrenner === Subject: >I've never posted before, but as it is, it's 4:48am and for some>>stupid reason, I've been trying to solve a double integral for almost>>3 hours now.>>It's just personal now (not sure of notation here so i'm going to>>display it twice):>>/ 1 / arccos y>>| | exp (sin(x)) dx dy>>/ 0 / 0>>or>>integrate relative to y {0..1}>>integrate relative to x {0..arccos(y)}>>the equation: exp(sin(x)) dx dy>>My trusty calculator can give me an answer, but for some reason>>(fatigue for example) I can't figure out how to come up with the>>answer.>>any help?>Change the order of integration: x from 0 to pi/2 and y from 0 to cos x.>>KPThat's the wrong area, y goes from cos x to 1, which still leaves aproblem.--Lynn === Subject: No, y goes from 0 to cos x. If 0 < =x <= arccos y, then upon takingcosines (a decreasing function when 0 <= x <= pi/2) 1 >= cos x >= y or y<= cos x <= 1. This is NOT the same as cos x <= y <= 1!cos x <= 1 is assured in the real domain. leaving y <= cos x. The outerlimits in the original integral imply y >= 0, so we end up with 0 <= y<= cos x.--OL === Subject: >No, y goes from 0 to cos x. If 0 < =x <= arccos y, then upon taking>cosines (a decreasing function when 0 <= x <= pi/2) 1 >= cos x >= y or y><= cos x <= 1. This is NOT the same as cos x <= y <= 1!>>cos x <= 1 is assured in the real domain. leaving y <= cos x. The outer>limits in the original integral imply y >= 0, so we end up with 0 <= y><= cos x.>>--OLOops, you're correct of course. Guess I was a little hasty on thekeyboard.--Lynn === Subject: : (What I presented was an incidence matrix for the trivial affine plane because : it was easy to cut-and-paste from recent material I had written. Like a good : mathematician, George visualized the affine geometry from the presentation. My : words explaining otherwise made no difference.)That is a lie about what actually happened, not that any of you should care.If in fact the incidence matrix posted was the incidence matrix for the smallestaffine plane, then no words EVER COULD POSSIBLY explain otherwise, for thesole and simple reason that the TRUTH is NOT otherwise. If mitch wanted tosay something about this matrix OVER AND ABOVE, IN ADDITION TO (as OPPOSED tootherwise than) its being the one for this little plane, well, I read it,and it is NOT the case that it made no difference to me. It is, however,the case that what he was saying about it was ridiculous.-- --- It's difficult ... you need to be united to have any strength, but internal issues have to be addressed. --- E. Ray Lewis, on liberalism in America === Subject: > .... > the axis are the eigenvector of B, and the 'diameters' are> d^2= 1/ eigenvalue> ( is it correct? I think it is)> .... Not quite. You've missed a factor of 2 or 4. The semi-axis (_half_ the diameter you're looking at) is 1/sqrt(eigenvalue). There's a handy little reference written by a statistician, giving lots of facts about such things: M.G. Kendall, A course in the what you want. Ken Pledger. === Subject: >and sorry for the silly q., but i'm not a mathematician >>preamble( I hope this is correct)>let > A[a11 a12 0;>a21 a22 0;>0 0 -1]>>A is an ellipse>a11 x^2 + a22 y^2 +2 a12 x y =1 >if, let > B[a11 a12 ;>a21 a22]>>- B is symmetric>- B is positive definite>>the axis are the eigenvector of B, and the 'diameters' are>d^2= 1/ eigenvalue>( is it correct? I think it is)>>I wish to know if I can generalize in Rn ;>>A= [a11 .... a1n 0;> ..... >an1 an2 ... ann 0;>0 0 0 .... 0 -1]>>B= [a11 .... a1n ;>....>an1 an2 ... ann]>What about the eigenvalues and eigenvector of B?>>Are they related to the axes of the ' hyperellipsoid', like in R2 ??>Yes. You can see this by using an eigenbasis of B as a coordinatesystem. In that (orthonormal) coordinate system, the equation ise1*x1^2 + e2*x2^2 + ... + en*xn^2, where e1, e2, etc. are theeigenvalues and x1, x2, etc. are the coordinates (with respect to theeigenbasis). This describes an ellipsoid with the coordinatedirections as axes and with diameters as you indicated.John Mitchell === Subject: > and sorry for the silly q., but i'm not a mathematicianpreamble( I hope this is correct)> let> A [a11 a12 0;> a21 a22 0;> 0 0 -1]A is an ellipse> a11 x^2 + a22 y^2 +2 a12 x y =1> if, let> B [a11 a12 ;> a21 a22]- B is symmetric> - B is positive definitethe axis are the eigenvector of B, and the 'diameters' are> d^2= 1/ eigenvalue> ( is it correct? I think it is)Yes.I wish to know if I can generalize in Rn ;A= [a11 .... a1n 0;> .....> an1 an2 ... ann 0;> 0 0 0 .... 0 -1]B= [a11 .... a1n ;> ....> an1 an2 ... ann]> What about the eigenvalues and eigenvector of B?Are they related to the axes of the ' hyperellipsoid', like in R2 ??You can use exactly the same formulas. Perhaps you may want to look up theterm quadratic form over R. This has to do with the so-called spectraltheorems.-- Phyics is much too hard for physicists. === Subject: > One thing I don't get, is a big picture of how well I'm> doing. My investment dollars are spread across multiple> IRA/401K/SEP/Roth accounts, as well as six different> non-retirement accounts at 2 brokers. (don't ask -- this> can't currently be changed). Anyway, aggregating the> data from these various sources is easy, analysing the> data, in aggregate, is *not*.>The software 'KBH Investor Accounting' outputs a year- to-date gain ofrealized and un-realized positions combined together...for each date ofportfolio activity. It calls this a mark-to-market accounting. Theapplication also shows a year-to-date portfolio percentagegain relative the net of deposits and withdrawals...and it calls this aprofit margin. Finally, the application shows a year-to-date portfoliopercentage gain relative to a time-weighted net of deposits and withdrawalsand it calls this a time-weighted profit margin. Note that this last featureis an annualization or an IRR within the yearly period.Obviously, a consolidated accounting should be input. I would recommend aconsolidated accounting for the taxable portfolio and a consolidatedaccounting for the tax-deferred portfolio.Here is a user link to the application:http://pages.prodigy.net/halsteadinvest/kbh.htm === Subject: This may be better placed in one of the investing newsgroups,> but I find that most of the posters there can't handle basic> arithmetic, let alone what I'm trying to do.... You could find it worth while to follow some of the links from Ken Pledger. === Subject: http://online.itp.ucsb.edu/online/cmb02/caldwell/ http://qedcorp.com/APS/EmergentGravity.pdfhttp://qedcorp.com/ APS/StarGate1.movCaldwell does not seem to realize that the attractive dark matter can also bea zero point energy /zpf effect in addition to the repulsive dark energy ondifferent scales.Latest data is dark energy/dark matter split is 0.7 to 0.3 in spatially flat sumOmega = 1 of FRW cosmology metric with uncertainty 0.04. Ordinarymatter (stars, planets, radiation, dust clouds etc are inside that 0.04 uncertainty).My key new idea here is that dark matter detectors will not click with thethat is on mass shell in terms of quantum field theory Feynman propagators, whizzingaround in space like neutrinos passing through our bodies. That is wrong IMHO.Dark matter is, like dark energy a virtual, i.e. off mass shell exotic vacuum effectwith w = (pressure)/(energy density) = -1 because the total local zero point stress-energy densityvacuum Diff(4) symmetry group tensor istuv(Vacuum) = (String Tension)/zpf(x)guv(Curved Space-Time)where/zpf (x) = Lp*^-2[Lp*^3/2|Vacuum Coherence(x)|^2 - 1]Lp*^2 = hG*/c^3hc/Lp*^2 = String TensionG* is the variable scale-dependent effective gravity coupling coefficient.Something likeG*/G(Newton) = e^ ?The NON-EXOTIC i.e. non-gravitating vacuum region of space-time is when/zpf = 0When Vacuum Coherence = 0, like in the inside of a vibrating string of pure energy (Brian Greene NOVA Elegant Universe)we have a strongly attractive dark energy core /zpf(core) = -1/Lp*^2 that, for example, explains the self-cohesiveness of thespatially extended electron, which is a micro-geon Kerr-Newman ring singularity of size ~ e^2/mc^2 ~ 1 fermi surrounded bya virtual plasma of electron-positron pairs and virtual photon extending out to ~ h/mc ~ 10^-11 cm. This whole spatially extendedcomplex looks more and more like a Bohmian hidden variable point enormous space-warping since G*m^2/hc ~ 1 where m ~ 10^-27 gms.realism is consistent with J.P. Vigier's idea for a non-nuclear release of atomic energy from tight atomic states like the experiments in Beograd, Serbia were looking for. === Subject: http://online.itp.ucsb.edu/online/cmb02/caldwell/> http://qedcorp.com/APS/EmergentGravity.pdfhttp://qedcorp.com/ APS/StarGate1.movCaldwell does not seem to realize that the attractive dark matter can > also be> a zero point energy /zpf effect in addition to the repulsive dark energy on> different scales.Latest data is dark energy/dark matter split is 0.7 to 0.3 in spatially > flat sum> Omega = 1 of FRW cosmology metric with uncertainty 0.04. Ordinary> matter (stars, planets, radiation, dust clouds etc are inside that 0.04 > uncertainty).> My key new idea here is that dark matter detectors will not click > with the> that is on mass shell in terms of quantum field theory Feynman > propagators, whizzing> around in space like neutrinos passing through our bodies. That is wrong > IMHO.> Dark matter is, like dark energy a virtual, i.e. off mass shell > exotic vacuum effect> with w = (pressure)/(energy density) = -1 because the total local zero > point stress-energy density> vacuum Diff(4) symmetry group tensor istuv(Vacuum) = (String Tension)/zpf(x)guv(Curved Space-Time)where/zpf (x) = Lp*^-2[Lp*^3/2|Vacuum Coherence(x)|^2 - 1]Lp*^2 = hG*/c^3hc/Lp*^2 = String TensionG* is the variable scale-dependent effective gravity coupling coefficient.Something likeG*/G(Newton) = e^ ?The NON-EXOTIC i.e. non-gravitating vacuum region of space-time is when/zpf = 0When Vacuum Coherence = 0, like in the inside of a vibrating string of > pure energy (Brian Greene NOVA Elegant Universe)> we have a strongly attractive dark energy core /zpf(core) = -1/Lp*^2 > that, for example, explains the self-cohesiveness of the> spatially extended electron, which is a micro-geon Kerr-Newman ring > singularity of size ~ e^2/mc^2 ~ 1 fermi surrounded by> a virtual plasma of electron-positron pairs and virtual photon extending > out to ~ h/mc ~ 10^-11 cm. This whole spatially extended> complex looks more and more like a Bohmian hidden variable point > enormous space-warping since G*m^2/hc ~ 1 where m ~ 10^-27 gms.realism is consistent with J.P. Vigier's idea for a non-nuclear release > of atomic energy from tight atomic states like the experiments in > Beograd, Serbia were looking for.I love it when Sarfatti uses IMHO. It means just the opposite. === Subject: Here is the question:> Find the distance between the lines L(1) = (1, 1, 1) + s (1, 2, 3) and L(2) = (0, 1, 1) + t (1, -1, -1). I would really appreciate a full solution because many people have> given me tips on another message board and I have been unable to solve> this. I know that is not the style of this newsgroup but I would really> appreciate it as I have an exam tomorrow morning and I am sure a> question almost identical to this will be on it.ZackUsing vector notation , with P*Q as dot product of vectors P and Q > and P^Q as cross product of P and Q (see below), let A = (1,1,1), > U = (1,2,3), B = (0,1,1), V = (1,-1,1-) then U is parallel to line > L(1) and V is parallel to line L(2) so that C = (A^B) is > perpendicular to both lines.Then (A - B)*C/sqrt(C*C) is the projection of A-B parallel to C ( > and therefore perpendicular to both lines) and is its absolute value > is desired perpendicular distance between the lines.> Note, dot product is given by > (a,b,c)*(c,d,e) = ac + bd + cf > and cross product by> (a,b,c)^(d,e,f) = (bf - ce, cd - af, ae - bd)Urq.It has always seemed to me that this kind of problem can be solved witha lot less machinery and a lot more clarity by simply considering thedistance (squared) between a point on line L(1) and a point on L(2): f(s,t) = || (1+s,1+2s,1+3s) - (t,1-t,1-t)||^2 = (1+s-t)^2 + (2s+t)^2 + (3s+t)^2.This function is a minimum when its partial derivatives are both zero. (And it does take a minimum, because f is convex and --> +infty as s^2+ t^2 --> +infty.)That leads to simultaneous equations 2(1+s-t) + 4(2s+t) + 2(3s+t) = 0 i.e. 28s + 8t = -2, -2(1+s-t) + 2(2s+t) + 2(3s+t) = 0, i.e. 8s + 6t = 2.These are easily solved to give unique solution s = -7/26, t = 9/13(hence, there is a unique pair of closest points). We have f(-7/26, 9/13) = 1/26,and therefore the distance between the lines is 1/sqrt(26).I would MUCH prefer that students be able to use a seat-of-the-pants,common-sense method like this instead of the cookbook procedure taughtin section 8.2 of chapter 4, on page 167.Besides, your solution fails as soon as you go to R^4.--Ron Bruck === Subject: > Here is the question:>> Find the distance between the lines > L(1) = (1, 1, 1) + s (1, 2, 3) and L(2) = (0, 1, 1) + t (1, -1, -1). > I would really appreciate a full solution because many people have>> given me tips on another message board and I have been unable to solve>> this. I know that is not the style of this newsgroup but I would really>> appreciate it as I have an exam tomorrow morning and I am sure a>> question almost identical to this will be on it.> Zack>>Using vector notation , with P*Q as dot product of vectors P and Q >and P^Q as cross product of P and Q (see below), let A = (1,1,1), >U = (1,2,3), B = (0,1,1), V = (1,-1,1-) then U is parallel to line >L(1) and V is parallel to line L(2) so that C = (A^B) is >perpendicular to both lines.>Of course, you mean C = U^V, not A^B.--Lynn === Subject: > Here is the question:>> Find the distance between the lines > L(1) = (1, 1, 1) + s (1, 2, 3) and L(2) = (0, 1, 1) + t (1, -1, -1). > I would really appreciate a full solution because many people have>> given me tips on another message board and I have been unable to solve>> this. I know that is not the style of this newsgroup but I would really>> appreciate it as I have an exam tomorrow morning and I am sure a>> question almost identical to this will be on it.> Zack>>Using vector notation , with P*Q as dot product of vectors P and Q >and P^Q as cross product of P and Q (see below), let A = (1,1,1), >U = (1,2,3), B = (0,1,1), V = (1,-1,1-) then U is parallel to line >L(1) and V is parallel to line L(2) so that C = (A^B) is >perpendicular to both lines.>Of course, you mean C = U^V, not A^B.--LynnRight! Proof reading is such a bore! === Subject: > Huh? How in the world does it suggest that? None of the replies> have agreed with you... I felt there might be a bit of defensive feeling behind some of theposts. Is the geometrical approach the best one for anyone who justwants to study functions? Then as a technique analytical continuationis only practical with the aid of a computer program. If cuts areallowed I can treat some algebraic functions (I do not claim all)without using it. === Subject: >The fact that my original post has to date attracted 19 replies>suggests that there are others who do not see Riemann surfaces as an>entirely finished subject. >> Huh? How in the world does it suggest that? None of the replies>> have agreed with you...>> I felt there might be a bit of defensive feeling behind some of the>posts. Huh?>Is the geometrical approach the best one for anyone who just>wants to study functions? Huh? What does this have to do with anything that's beendiscussed here? The question was whether there arenecessarily arbitrary choices involved in constructing theRiemann surface for a function...>Then as a technique analytical continuation>is only practical with the aid of a computer program. Huh????????>If cuts are>allowed I can treat some algebraic functions (I do not claim all)>without using it.Huh? Nobody's said anything about cuts not being allowed.The question was [see above].************************David C. Ullrich === Subject: large n (say n > 100 digits). Since n is that large, it's not veryefficient to store the lookup table.I know it's not easy to find a polynomial that works. I am lookingfor a deterministic algorithm (likely to be recursive) probably withsome finite lookup table storage. Would studying the distributionof primes help? As I know given a particular prime, it is possible tofind the next m primes -- is that true?>> in which I need to map an integer identity (ID) to a> prime number.>> I want h( ): Z_n -> Z-m (m > n) s.t. for every integers in> Z_n, I can easily find a prime in Z_m that is distinct from> the image of another integer.>> i.e. h(ID_i)=h(ID_j) ID_i = ID_j.>> Please note that I don't want a lookup table for the mapping ---> that's what I meant efficient.>> What's not efficient about table lookup?>> Do you want to do this for one particular n? or do you want something> that works for all n?>> If the latter, you're looking for a simple (efficient) formula> f(a) that returns a different prime for each positive integer a.> You're unlikely to find anything to your liking. Certainly there> is no polynomial that works.>> If n < 40 then you can use Euler's polynomial, n^2 + n + 41 or> something like that.>> -- === Subject: > large n (say n > 100 digits).Whoa! You want a function that gives you more than 10^100 primes? and only primes? You're dreaming. > As I know given a particular prime, it is possible to> find the next m primes -- is that true?Yes, but only by testing each number after your prime until you find m more. Suppose you know some 100-digit prime, p, and you want to find the next 10 primes. Well, roughly one number in each 230 is prime up there, so, to be on the safe side, maybe you want to look at p + k for k from 1 to 5000. Now you can sieve out a lot of those k by deleting multiples of 2, of 3, of 5, etc, and then subject the remaining numbers to primality tests. Exactly how much sieving to do, I'll leave to the experts (who may know a better approach than what I'm outlining, but I don't see how one can do fantastically better).-- === Subject: > If I have 2 - sqrt(12)i how do I find the polar form?>> So far I've worked out that r = 4 and the argument is 5pi/6.>> The next step I'm not sure about. Do I put it in the form r(cos(theta) +> isin(theta))? Making it 4(cos(5pi/6) + isin(5pi/6))? Then what do I do?>> BTW - what is the correct notation on here for angle theta?>> TIA> You've done it perfectlySorry I should have elaborated. How do I get it into polar form with cis> (whatever that's called)?cis(theta) is merely an abreviation for cos(theta)+i*sin(theta), and is equivalent to exp(i*theta) and e^(i*theta)Thus given x = r*cos(theta) and y = r*sin(theta), one can write x + i*y = r*cis(theta) = r*exp(i*theta) = r*e^(i*theta) === Subject: In sci.math, Michael:> If I have 2 - sqrt(12)i how do I find the polar form?>> So far I've worked out that r = 4 and the argument is 5pi/6.(Note: the mathematical symbol for theta looks a bit like an Owith a horizontal hyphen through it.)If z = a + bi, then r = sqrt(a^2 + b^2) and theta = atan2(b,a),where atan2() is a fairly widespread function on computer systems.More conventionally, theta = atan(b/a) if a > 0, atan(b/a) + pi if a < 0,pi/2 if a = 0 and b > 0, -pi/2 if a = 0 and b < 0. (For a = b = 0,theta is conventionally taken to be 0. Since r is 0 it doesn'tmatter all that much in that case.)So r = sqrt(4 + 12) = 4 and theta = atan(-sqrt(12)/2)= atan(-sqrt(3)) = -pi/3.>> The next step I'm not sure about. Do I put it in the form r(cos(theta) +> isin(theta))? Making it 4(cos(5pi/6) + isin(5pi/6))? Then what do I do?Some use the notation (r,theta) but that's obviouslyslightly confusing if accidentally taken out of context.I think most simply state r = value, theta = value.Converting back to Cartesian isn't difficult:z = r*cos(theta) + i*r*sin(theta). On occasionone can also use the identity z = r*exp(i*theta)or your form z = r*(cos(theta) + i*sin(theta)).>> BTW - what is the correct notation on here for angle theta?By convention, just theta.>> TIA>-- #191, ewill3@earthlink.netIt's still legal to go .sigless. === Subject: > ... stuff deleted ...> ... given a map f : X --> Y between> sufficiently nice spaces (homotopy type of a CW complex should be nice> enough), the path-space construction: P_f = {(x,p) in X x map(I,X) | p(0) = x }yields a space homotopy-equivalent to X ... stuff deleted ...> ... and the map j> P_f -------> Y (x,p) |--> p(1)is a fibration. Further, the diagram f> X --------------->_Y> /|> /> /> i /j> /> /> /> _| /> P_fis commutative.In other words, every map is a fibration, up to> homotopy. Well, just as long as the spaces are> sufficiently well-behaved to permit the above> construction, and it's been long enough for me> since I worked with that construction that I> don't recall just what's needed.Dale> Just to tie up this loose end, I consulted Spanier (AlgebraicTopology, now published by Springer-Verlag). He claims it's truefor any spaces X,Y, and any (continuous) map f. I would be surprisedif some further technical condition (e.g., normality) weren't necessary,but Spanier doesn't mention it. The introduction to the text does saythat, absent any explicit restriction, the term space means anytopological space, so it could be that this construction holds forarbitrary topological spaces X,Y.I would, of course, welcome any correction on this matter.Dale. === Subject: I need help on the following problem. thatKerv={h in H| v(h)=0}={0} and v(H)is dense in H but does not coincidewith it. Is it true that v(H)=H or there can exist such an operator??I am looking forward to receiving your answers .Greetings Mladen === Subject: >I need help on the following problem. >that>Kerv={h in H| v(h)=0}={0} and v(H)is dense in H but does not coincide>with it. Is it true that v(H)=H or there can exist such an operator??>I am looking forward to receiving your answers .>Greetings Mladenbasis |n>, n = 1, 2, 3, ..., and define the linear operator v by v |n> = 1/n |n> for n = 1, 2, 3, .... Then v is continuous, Ker(v) = 0, and the range of v is dense, but the element sum_{n=1}^infty 1/n |n> Hope this helps.David McAnally-------------- === Subject: >>I need help on the following problem. >that>Kerv={h in H| v(h)=0}={0} and v(H)is dense in H but does not coincide>with it. Is it true that v(H)=H or there can exist such an operator??Certainly there can exist such an operator. For example say H isL^2(R) and v f(x) = f(x)/(1+x^2).>I am looking forward to receiving your answers .>>Greetings Mladen************************David C. Ullrich === Subject: > I need help on the following problem. > that> Kerv={h in H| v(h)=0}={0} and v(H)is dense in H but does not coincide> with it. Is it true that v(H)=H or there can exist such an operator??square summable sequences. === Subject: >[...]>>Well this morning I was pissed I didn't have a solution to B6 - so>you can imagine how I felt when you recorded my pissed-off>non-solution there following an actual solution. So I thought>about it. It's easy if int f = 0, which seems like it should be>the hard case, for example it's trivial if f >= 0. This morning>I was going to say just as a joke that you could get a solution>in general by interpolating between these two cases. But>it turns out that you can do exactly that. The part you want>to record for posterity starts here:Aargh. What's below is wrong. Wrong, wrong wrong.I still think it's curious that the case int f = 0 is easy,> and it still seems that the general case should follow,> since if f has a lot of cancellation that should make it> harder. But what's below is nonsense.>It's clear if f >= 0. Suppose that int f = 0. Choose a function>g so that |g| = 1 and gf >= 0. Then>> int int |f(x) + f(y)| >= int (f(x) + f(y)) g(x)>> = int f(x) g(x) = int |f(x)|.>>You can do the general case by interpolating between>these special cases: Suppose that int f > 0. Then>f = g + h, where int g = 0, h >= 0, and g and h have>disjoint support. Say g is supported on A and h is>supported on B. Then>> int int |f(x) + f(y)| >>= int_A int_A |f(x) + f(y)| + int_B int_B |f(x) + f(y)|> Let me try this again.int int |f(x) + f(y)| = int_A int_A |g(x)+g(y)| +int_B int_B (h(x)+h(y)) + 2 int_A int_B |g(x)+h(y)| >= int_A int_A |g(x)+g(y)| + int_B int_B (h(x)+h(y)) + 2 int_{x in A} int_{y in B} (g(x)+h(y))Now David's argument shows that the first integral on the extreme right is >= int_A |g(x)|. The second is equal to 2m(B) int_B h, and the third is equal to 2m(A) int_B h. This yieldsint int |f(x) + f(y)| >= int_A |g| + 2m(B) int_B h + 2m(A) int_B h = int_A |g| + 2int_B h >= int_A |g| + int_B h = int |f|.-- A. === Subject: >>[...]>>Well this morning I was pissed I didn't have a solution to B6 - so>>you can imagine how I felt when you recorded my pissed-off>>non-solution there following an actual solution. So I thought>>about it. It's easy if int f = 0, which seems like it should be>>the hard case, for example it's trivial if f >= 0. This morning>>I was going to say just as a joke that you could get a solution>>in general by interpolating between these two cases. But>>it turns out that you can do exactly that. The part you want>>to record for posterity starts here:> Aargh. What's below is wrong. Wrong, wrong wrong.> I still think it's curious that the case int f = 0 is easy,>> and it still seems that the general case should follow,>> since if f has a lot of cancellation that should make it>> harder. But what's below is nonsense.>>It's clear if f >= 0. Suppose that int f = 0. Choose a function>>g so that |g| = 1 and gf >= 0. Then>> int int |f(x) + f(y)| >= int (f(x) + f(y)) g(x)>> = int f(x) g(x) = int |f(x)|.>>You can do the general case by interpolating between>>these special cases: Suppose that int f > 0. Then>>f = g + h, where int g = 0, h >= 0, and g and h have>>disjoint support. Say g is supported on A and h is>>supported on B. Then>> int int |f(x) + f(y)| >>= int_A int_A |f(x) + f(y)| + int_B int_B |f(x) + f(y)|>>Let me try this again.>>int int |f(x) + f(y)| >> = int_A int_A |g(x)+g(y)| +int_B int_B (h(x)+h(y))> + 2 int_A int_B |g(x)+h(y)|>>= int_A int_A |g(x)+g(y)| + int_B int_B (h(x)+h(y))> + 2 int_{x in A} int_{y in B} (g(x)+h(y))>>Now David's argument shows that the first integral on the extreme right >is >= int_A |g(x)|. Does it? It looks more like >= m(A) int_A |g(x)| to me (althoughconsidering my record here what it looks like to me is of littleinterest...)>The second is equal to 2m(B) int_B h, and the third >is equal to 2m(A) int_B h. This yields>>int int |f(x) + f(y)| >>= int_A |g| + 2m(B) int_B h + 2m(A) int_B h>> = int_A |g| + 2int_B h>>= int_A |g| + int_B h>> = int |f|.************************David C. Ullrich === Subject: >[...]>>Well this morning I was pissed I didn't have a solution to B6 - so>>you can imagine how I felt when you recorded my pissed-off>>non-solution there following an actual solution. So I thought>>about it. It's easy if int f = 0, which seems like it should be>>the hard case, for example it's trivial if f >= 0. This morning>>I was going to say just as a joke that you could get a solution>>in general by interpolating between these two cases. But>>it turns out that you can do exactly that. The part you want>>to record for posterity starts here:> Aargh. What's below is wrong. Wrong, wrong wrong.> I still think it's curious that the case int f = 0 is easy,>> and it still seems that the general case should follow,>> since if f has a lot of cancellation that should make it>> harder. But what's below is nonsense.>>It's clear if f >= 0. Suppose that int f = 0. Choose a function>>g so that |g| = 1 and gf >= 0. Then>> int int |f(x) + f(y)| >= int (f(x) + f(y)) g(x)>> = int f(x) g(x) = int |f(x)|.>>You can do the general case by interpolating between>>these special cases: Suppose that int f > 0. Then>>f = g + h, where int g = 0, h >= 0, and g and h have>>disjoint support. Say g is supported on A and h is>>supported on B. Then>> int int |f(x) + f(y)| >>= int_A int_A |f(x) + f(y)| + int_B int_B |f(x) + f(y)|>>Let me try this again.>>int int |f(x) + f(y)| >> = int_A int_A |g(x)+g(y)| +int_B int_B (h(x)+h(y))> + 2 int_A int_B |g(x)+h(y)|>>= int_A int_A |g(x)+g(y)| + int_B int_B (h(x)+h(y))> + 2 int_{x in A} int_{y in B} (g(x)+h(y))>>Now David's argument shows that the first integral on the extreme right >is >= int_A |g(x)|. Does it? It looks more like >= m(A) int_A |g(x)| to me (although> considering my record here what it looks like to me is of little> interest...)You and me both.Uncle.-- A. === Subject: >[...]>>Now David's argument shows that the first integral on the extreme right >>is >= int_A |g(x)|. > Does it? It looks more like >= m(A) int_A |g(x)| to me (although>> considering my record here what it looks like to me is of little>> interest...)>>You and me both.>>Uncle.Yeah, but there _must_ be a one or two line proof along these lines.I mean, it's very simple if int f = 0. And int f = 0 says f has a lotof cancellation, which would make int int |f(x) + f(y)| small, sothe case int f > 0 must follow, by a similar argument.(Shoulda just said that the case int f > 0 followed and seemwhether anyone wanted to admit they didn't see how...)************************David C. Ullrich === Subject: >Rather, continue as:> = int_A int_A |g(x) + g(y)| + int_B int_B (h(x) + h(y))>= int_A int_A |g(x) + g(y)| + int_B h(x)Nuh-uh, this step is still wrong. You pick up a factor of 2 meas(B) onthe right-hand side. I suspect that no solution which ignores the termscoming from the cross-regions A x B and B x A can be made to work forfunctions f with int f <> 0: if f is large when it's positive and smallwhen it's negative, without the contributions |f(x) + f(y)| when f(x) ispositive and f(y) is negative, you won't get the inequality that you want.Dave === Subject: >Rather, continue as: = int_A int_A |g(x) + g(y)| + int_B int_B (h(x) + h(y))>= int_A int_A |g(x) + g(y)| + int_B h(x)Nuh-uh, this step is still wrong. You pick up a factor of 2 meas(B) on> the right-hand side. Ack!> I suspect that no solution which ignores the terms> coming from the cross-regions A x B and B x A can be made to work for> functions f with int f <> 0: if f is large when it's positive and small> when it's negative, without the contributions |f(x) + f(y)| when f(x) is> positive and f(y) is negative, you won't get the inequality that you want.-- A. === Subject: >> One of their favorite labels is crank, where the idea is that you> have some person who is unreasonable, who has ideas that don't work,> who refuses to acknowledge the truth.> Let's see now...> ...some person who is unreasonable, who has ideas that don't work,> who refuses to acknowledge the truth.> Sounds just like you, James!>>Your opinion is noted Alec McKenzie.>>I do admit that if enough people think that I'm just some nut, then I>>have to wonder.> _If_ enough people thought that? What reason do you have to>> think that _anyone_, with only one exception that I can think of>> right now, doesn't think of you as just some kind of nut?>Note that I made a *specific* challenge in my previous post, which has>so far been ignored. I'll talk about it more a little later.And note that you're not answering the specific question I asked,in regard to a specific thing you said.>Now then, I'm reasonable, as I recognize that hey maybe I am nutty,>but then again, I also know enough math to realize that mathematicians>haven't made a logical case for total dismissal of my prime counting>discovery, and I know enough about human nature to be very wary when>people rely on insults, like here David Ullrich is imputing that>everyone with one exception thinks I'm a nut!!!Again: What reason do you have to think that anyone thinks otherwise?************************David C. Ullrich === Subject: > One of their favorite labels is crank, where the idea is that you> have some person who is unreasonable, who has ideas that don't work,> who refuses to acknowledge the truth.> Let's see now...> ...some person who is unreasonable, who has ideas that don't work,> who refuses to acknowledge the truth.> Sounds just like you, James!>>Your opinion is noted Alec McKenzie.>>I do admit that if enough people think that I'm just some nut, then I>>have to wonder.> _If_ enough people thought that? What reason do you have to>> think that _anyone_, with only one exception that I can think of>> right now, doesn't think of you as just some kind of nut?>Note that I made a *specific* challenge in my previous post, which has>so far been ignored. I'll talk about it more a little later.And note that you're not answering the specific question I asked,> in regard to a specific thing you said.That's a rude question.My family doesn't think I'm insane you sick turd. So far you've shown just how despicable of a human being you can be,without any regard for common decency or caring, or ethics.If you have an issue with my prime counting discovery then why can'tyou keep to the mathematics?I have a *specific* challenge to you David Ullrich, I dare you to givean outlined dispute of the value of my prime counting discoveryproviding *all* the information necessary for readers to evaluate yourclaim, without trying to rely on links or insults.What kind of math professor are you if you can't handle a *math*challenge but need to insult instead? If you are a math expert, proveit.Give a point-by-point exposition to support your case without insults,innuendo, or any other attempts at sly or back-handed insults, butwith *mathematics* and logic.I don't think you have the capacity to engage in an honest and opendebate without trying to use tricks or insults David Ullrich. I thinkyou lack the capacity to have a *reasoned* discussion, but insteadrely on childish behavior.The challenge is to you now, show that you can reason and discussmathematics reasonably, if you can.James Harris === Subject: [snip]>Note that I made a *specific* challenge in my previous post, which hasso far been ignored. I'll talk about it more a little later.The specific challenge you mention above has been ignored because it represents a non-issue. In your previous post youinvite readers to attack a particular point when there is *already* a specific attack on a particular point on the table.You have so far *refused* to either acknowledge or defend the challenge to your claim that the so-called 'partialdifferential equation' solves the prime counting problem -- a claim you made repeatedly.C'mon, James Harris. It is *you* who claimed that the difference equation you posted does things which no other methoddoes do or can do. Name them! What things? Where is the proof that the so-called 'partial differential equation' solves theprime counting problem? Where is your evidence? Where is your data?Note that no one is fooled or tricked by your childish attempt to divert attention from the *real* issues to some side showby inviting certain challenges. You ARE ALREADY CHALLENGED ON YOUR OWN CLAIMS. Put up or SHUT UP.--There are two things you must never attempt to prove: the unprovable -- and the obvious.--Democracy: The triumph of popularity over principle.--http://www.crbond.com === Subject: >> One of their favorite labels is crank, where the idea is that you>> have some person who is unreasonable, who has ideas that don't work,>> who refuses to acknowledge the truth.> Let's see now...> ...some person who is unreasonable, who has ideas that don't work,>> who refuses to acknowledge the truth.> Sounds just like you, James!>>Your opinion is noted Alec McKenzie.>>I do admit that if enough people think that I'm just some nut, then I>have to wonder.> _If_ enough people thought that? What reason do you have to> think that _anyone_, with only one exception that I can think of> right now, doesn't think of you as just some kind of nut?>>Note that I made a *specific* challenge in my previous post, which has>>so far been ignored. I'll talk about it more a little later.> And note that you're not answering the specific question I asked,>> in regard to a specific thing you said.>>That's a rude question.I was rude to _you_? Golly.>My family doesn't think I'm insaneRight. Actually I was talking about your correspondents on usenetand elsewhere in the mathematical community. And I askedwhether you had any reason to think that any of those peopledid not think of you as some kind of nut - there's a significantdifference in strength between some kind of nut and insane.Look. _You_ said if enough people think that I'm just some nut, thenI have to wonder. This makes the question of how many peoplewould be enough, and why you think there are any exceptions,a perfectly natural question.> you sick turd. Uh, the expression you're looking for is ing dog .I like it when you complain about people being rude to you...>So far you've shown just how despicable of a human being you can be,>without any regard for common decency or caring, or ethics.>>If you have an issue with my prime counting discovery then why can't>you keep to the mathematics?>>I have a *specific* challenge to you David Ullrich, I dare you to give>an outlined dispute of the value of my prime counting discovery>providing *all* the information necessary for readers to evaluate your>claim,I and many other people have done this, many times.> without trying to rely on links or insults.>>What kind of math professor are you if you can't handle a *math*>challenge but need to insult instead? If you are a math expert, prove>it.>>Give a point-by-point exposition to support your case without insults,>innuendo, or any other attempts at sly or back-handed insults, but>with *mathematics* and logic.>>I don't think you have the capacity to engage in an honest and open>debate without trying to use tricks or insults David Ullrich. I think>you lack the capacity to have a *reasoned* discussion, but instead>rely on childish behavior.>>The challenge is to you now, show that you can reason and discuss>mathematics reasonably, if you can.>James Harris************************David C. Ullrich === Subject: First, I'll directly address the title Common sense: If crank labelwere believed. Some already believe the label of crank applies, sodialogue present, it appears that the majority believe you are a crankto some degree. If you wish to reverse that image, your best optionis to conduct yourself in a professional manner, not insult anyone forany reason, and fully respond to all questions and challenges aboutyour claims.> Some of you may have noticed these free-wheeling mathematical> discussions I've been having with all these people, and wondered.Maybe mostly you were wondering what they were doing on your> newsgroup.Well I've been someone who has dabbled in mathematical research in> full knowledge that I'm NOT a mathematician, but partly because it's> fun, and partly because I have confidence that people can miss things.> Well, I'm not a mathematician either.> Mathematicians don't believe they could miss anything simple enough> that a non-mathematician could find that's important. And I'm not> just saying that as I've read it more than once from mathematicians.> Thats just wrong. I have corrected mathematics professors on severaloccasions and they thanked me. I have yet to find any mistake in apublished paper by a mathematician, though when I find one, I do notexpect to be belittled.> Now as I've talked about my various ideas and research, math people> have talked a bit about the math, but mostly they've retaliated by> insulting me and saying nasty things about me on webpages.> The post archive on google tells a different story. I looked at theearly posts, and there were no insults.> Yes, it's odd but true.One of their favorite labels is crank, where the idea is that you> have some person who is unreasonable, who has ideas that don't work,> who refuses to acknowledge the truth.Only problem is that I enjoy tracing out the steps of my mathematical> arguments, and I can do things like give you a Java program that> works.> I have seen your mathematical arguments. Your tracing out the stepsis actually rather poor. In your Advanced Factorization/Core Errorthread, you only put in seven steps when I could see as many asthirty.You should try programming in C. Its much better for heavymathematical computation.> The truth is that I've dabbled in a lot of mathematical areas, poking> around looking for something dramatic, and pissed off some math> people.Does that make me a crank?> What you need to address is what pissed off the other sci.math users. > When you contact mathematicians about specifics, what are theresponses?> There's some guy who was going around quoting from me all the time in> his posts!Now then, use your common sense.Is it simpler that I'm really some crank, or that I've just upset a> lot of oversensitive people who think that negative labeling and> insults are the way to go?Now the problem is bad lessons learned on Usenet. I'm sure lots of> dabblers who had some ideas here or there were rapidly chased off of> the sci.math newsgroup when they were ganged up on and insulted. So> posters learned that they could control people by insults! They were> happy!!! They could insult people and get rid of them! But I came> along and decided that I didn't want to let people control my speech> by insults.So because I refused to be insulted into silence you have a weird> religion that's developed in the math community which is based on> obsessively insulting me!> You CAN stop the exchange of insults by not responding to them.> And I wanted others on other newsgroups to see that oddity.It's rather freaky, eh? But then again, who really thought math> people were normal? And don't worry, this post is very unlikely to> change anything.Yup, believe it or not, it will all just keep going. I'll talk about> math, there will be some who will argue with the math, while most will> just lob insults.> Stick to just the math and ignore the insults. When the insultersdont get a response, they will eventually stop.> Fascinating.> James Harris === Subject: > Granted, some might think I do the same, but he comes to me. That is,> David Ullrich makes sure to come to my threads and reply to my posts,> and then whines when I tell him to go away.>> He's a tag-along that just won't go away when he's told that he's not> wanted.This is usenet, a public service. You don't get to choose who participatesin your threads. === Subject: >> James Harris, barely-literate yard-ape.>> Yard ape, curtain climber, carpet shark, ankle biter, nose miner,> sprog, linoleum lizard, loin monkey, fartling, crotch fruit,> shriekling, flesh loaf, womb dropping, little sticky person, crotch> trophy, howling -machine.>> But give James Harris credit: he fought off the rusty coat hanger to> evenutally emerge as a twat lugie. Hey stooopid loud troll James> Harris, put up or shut up,>LOL! Git 'im! === Subject: I *dare* any posters who disagree to give just a point-by-point attack> on my prime counting function, numbering out each point, and providing> all the information in their post rather than just posting links.> That's just silly. Your prime counting function is correct, as hasbeen demonstrated several times.As I pointed out in an earlier post (quoting)# Thus we see that the proposed prime counting method# is indeed correct, though that wasn't in doubt.## Is this Legendre's method? That depends on one's point of view.# It's certainly not an exact copy, but it is not difficult to# see that Legendre's prime counting formula may be derived from# this method and conversely, so in that sense the two techniques# are equivalent. If one were inclined to be unchartiable, one# could call this obfuscated Legendre; otherwise, it could be# designated as streamlined Legendre.## Is it better than Legendre's method? Well, it does not require# knowing the primes, since they're computed on the fly.# Unfortunately, the resulting method is several orders of# magnitude slower than some existing methods, at least when# implemented as written.## Does it have any applicability other than to produce a slow# method of counting primes? I don't see any, though it is# tidy and compact. It might have some use as a pedagogical# device, perhaps as an exercise in a text, but I have to admit# that I don't see any use beyond that.## Is it publishable? Perhaps as a classroom note, but the journal# would have to be selected with care. It would face the same# difficulty as an improvement on an algorithm like bubble sort--# the response by a great number of reviewers would be, I suspect,# This is mildly interesting, but it hardly advances the state# of the art.Rick === Subject: A geometry can be expressed by a form w: T(M^n) -> C^n. We can defineinvariant vector fields by,w_i ( v_j) = d_ijA * operator by,*(w) e = sum(i1 .. in = 0 .. n - 1) sign_of_permutation(i1 ... in)e(v_i1, ..., v_ip) w_i(p+1) ^ ... ^ w_in / (p! (n-p)!)Some special types of geometries obey, ( l1 *(w) d *(w) d + l2 d *(w) d *(w) ) w = 0.For example, smooth groups have l1 = 0.A value of the parameters might approximate gravitation. l1 = l2 seemslikely.Other values of the parameters might be expressible as an algebraicrelation. The rules of physics might.A generalization of the equation is,( l0 + sum(i = 1, infinity) ( l_(2i - 1) ( *(w) d *(w) d )^i + l_(2i)( d *(w) d *(w) )^i ) ) w = 0.mihai === Subject: let us assume, we have an compact topological space X, where thetopology comes from an absolut value |.| on X. let us assume furtherwe have an surjective continous function f : X^n -> X^m and let usmeasure X^i by the ith product of the haar measure comming from X. myquestion is: if N has measure 0 in X^m, does f^(-1)(N) then also havemeasure 0? is there any literature dealing with these problems? thankyou for any answer...tanja === Subject: >let us assume, we have an compact topological space X, where the>topology comes from an absolut value |.| on X. let us assume further>we have an surjective continous function f : X^n -> X^m and let us>measure X^i by the ith product of the haar measure comming from X. my>question is: if N has measure 0 in X^m, does f^(-1)(N) then also have>measure 0? is there any literature dealing with these problems? thank>you for any answer...There are many things wrong with your set-up. First of all, a generaltopological space doesn't have an absolute value. Do you want X to beasubset of the complex numbers?Second, Haar measure is something on a topological *group*, in fact,a locally compact one.I am going to make a wild guess about what you mean. Please correctme if I am wrong. I am assuming that X is a subset of the complexesand that Haar measure is just Lebesgue measure restricted to X. Even then,the answer to your question is trivially no. Just consider anyfunction f:X->X which is constant on a set of positive measure and is stillsurjective. Then the inverse image of a point will be a set of positivemeasure.I doubt there is much literature on a problem so broad as this.--Dan Grubb === Subject: >>let us assume, we have an compact topological space X, where the>topology comes from an absolut value |.| on X. let us assume further>we have an surjective continous function f : X^n -> X^m and let us>measure X^i by the ith product of the haar measure comming from X. my>question is: if N has measure 0 in X^m, does f^(-1)(N) then also have>measure 0? Well, I have no idea what an absolute value on a compacttopological space is, nor what haar measure on a compacttopological space is. But whatever you mean, the answerto your question is almost surely _no_ - inverses of null setsunder continuous functions are not going to be null sets,except under very special conditions.>is there any literature dealing with these problems? thank>you for any answer...>>tanja************************David C. Ullrich === Subject: > I need a suggestion. I took linear algebra this semester up here in Montana> (MSU-Billings). I thought that I could handle it, but I'm really> struggling. In fact, I'm having to take an incomplete in the course because> it's just not making any sense to me. I've always been strong in math, but> matrices and vectors spaces have got me entirely stumped.Are there any good resources (either in print or online) out there that> anyone knows of that would help me out. Something like Linear Algebra for> Complete Morons would be nice . . .:) Okay, this is pretty simplistic, but you asked for it:http://ceee.rice.edu/Books/LA/contents.htmlIt's intended for highschool students as a precalculus course. Doesn'tassume any background. (I used it to teach myself.)-- - Laurel * * * http://amberdine.com === Subject: no, trust me, very basic is very good. i don't know why i'm so lost withthis, but i feel like a bumbling idiot.and to everyone: thank you very much for all the responses, both here in-- matt> I need a suggestion. I took linear algebra this semester up here inMontana> (MSU-Billings). I thought that I could handle it, but I'm really> struggling. In fact, I'm having to take an incomplete in the coursebecause> it's just not making any sense to me. I've always been strong in math,but> matrices and vectors spaces have got me entirely stumped.>> Are there any good resources (either in print or online) out there that> anyone knows of that would help me out. Something like Linear Algebrafor> Complete Morons would be nice . . .>> :) Okay, this is pretty simplistic, but you asked for it:>> http://ceee.rice.edu/Books/LA/contents.html>> It's intended for highschool students as a precalculus course. Doesn't> assume any background. (I used it to teach myself.)> -- > - Laurel * * * http://amberdine.com> === Subject: >no, trust me, very basic is very good. i don't know why i'm so lost with>this, but i feel like a bumbling idiot.>>and to everyone: thank you very much for all the responses, both here inI'm curious. Are you having problems with matrix arithmetic?I also hit a very large brick wall when my book went from talking about arithmetic to vectors and I still don't seemto be able to get past the section where the unit vectoris defined. I haven't spent much time on figuring outwhy yet but it has something to do with the notation |v|.It is possible that my brain is hardwired to map thetwo vertical glyphs to absolute value, which also causesme enormous problems. /BAH === Subject: My reply is interwoven within original post below.> Here is an unoriginal game (inspired by Dots and Boxes{name?}, Go,> and by Scrabble somewhat).> But this post is not just a game-idea, but a question about strategy. > The game can be played with any number(m) of players, m>=2,> where each player has a black pencil/pen and a colored pencil/pen of a > color different than the player's opponents' colors.> The game is played on an n-by-n grid, where n^2 is divisible by m.> I would suggest an n of at least 6 or 8 for 2 players. The players take turns each writing (in black) 1, 2, 3, ...(n^2/m), each > integer being written into any still-unoccupied grid-square.> (with his/her colored pencil) all grid-squares within any rectangle in > the grid, IF, and only if,each grid-square in the rectangle has an integer written in it,the SUM of every integer in the rectangle is any PRIME number,and all the squares in the rectangle are not yet colored in.> After each player has moved (ie written an integer and perhaps colored in > a rectangle)> (n^2/m) times, the winner is the player with the most grid-squares of > that player's pencil-color.> Variations:Players can only fill in rectangles which contain the square they just >I thought this would be the best at first. But now I believe thatbeing able to color in rectangles not necessarily including the lastinteger written might be better.For then the players can, for one thing, leave prime-rectangles forlater, hoping their opponent(s) do not fill them in.Anyway, either way would affect strategy differently. > Players can write their integers into the grid in any order they wish.> (I like this variation, but it requires remembering which integers have > already been played.)Players draw at-random their integers from a deck of cards. > (Either from 4 decks of 1 through (n^2/m), or from one master deck of 1 > through n^2.)> In this game, with or without any of the variations (or with any > variations of your own), what would be a good strategy???> One strategy might involve putting down consecutive integers inadjacent squares, so as to ensure that the line of integers iscomposite (when length of line is >= 3).Players can ensure that certain rectangles are composite until a givenpoint in the game, where the rectangle is finished with an integerwhich makes it prime.But the stategy depends upon what is known about an opponent'sunplayed integers (if integers are not necessarily playedsequencially).(If you do not know what I ma talking about above, then okay. I do notknow exactly myself...) > By the way, ideally, the game board will look aesthetically interesting > when the game is done, especially with the right m and n.> (Any suggestions for m and n from this standpoint?)> Actually what really matters, probably, regarding the beauty of thefinal board are the colors used, rather than the number of coloursused.And I bet most players would use x's and o's or something else as suchin-practice, instead of filling the squares with colored pencil, sincethen they only need one pencil.> Leroy Quet === Subject: > Here is Eucleides's proof that there are infinitely many Pythagorean> triplets.> If n is a natural, then n^2 - (n-1)^2 = (n+n-1)(n-n+1) = 2n-1. This> means that every odd natural (>1) is the difference between two> squares.> Some of these odd naturals are squares themselves. There are (at least)> as many Pythagorean triplets as there are odd squares. And because there> are infinitely many odd numbers, and an odd number's square is odd, then> there are infinitely many Pythagorean triplets.> Do I remember this proof correctly?Just for grins, here is a way to get every odd number as the smallestterm of a Pythagorean triplet. I noticed this when I hadn't yet hadany algebra in school, so I found the proof very difficult. Now ofcourse it is extremely easy.We were always given (3, 4, 5) and (5, 12, 13) as Pythagorean triplesin homework problems. What I noticed was that 4 + 5 = 9 = 3^2 andthat 12 + 13 = 25 = 5^2, and of course that 4 and 5 as well as 12 and13 differed by 1. After trying to extend this pattern to (7, 24, 25),(9, 40, 41) and perhaps a few more, I saw that it always worked. Iasked my big brother to prove it for me and the rat made me do it formyself. I had a hard time figuring out that the pattern was (2n+1,2n^2+2n, 2n^2+2n+1), but once that was done, it was easy enough tocalculate that (2n^2+2n+1)^2 = (2n^2+2n)^2 + 2(2n^2+2n) + 1 =(2n^2+2n)^2 + (4n^2+4n+1) = (2n^2+2n)^2 + (2n+1)^2 as desired.Now it is actually easy to see that this triple is primitive, forclearly the last two terms differ by 1 and thus cannot have a commonfactor, anything dividing the first two terms would also divide2n^2+n, hence n, hence 1, so they are relatively prime, and anythingdividing the first and third terms would have to divide 2n^2+1, hencen+1, hence n, hence 1, and so they are also relatively prime and thetriplet is thus primitive. I just figured that out now, not way backwhen.It would not surprise me if this result dates back to the ancientGreeks. Does anyone know?Achava === Subject: > Here's Euclid's proof that there are infinitely many Pythagorean triples.>> If n is a natural, then n^2 - (n-1)^2 = (n+n-1)(n-n+1) = 2n-1. This>> means that every odd natural (>1) is the difference between two squares.>> Some of these odd naturals are squares themselves. There are (at least)>> as many Pythagorean triplets as there are odd squares. And because there>> are infinitely many odd numbers, and an odd number's square is odd, then>> there are infinitely many Pythagorean triplets.>> Do I remember this proof correctly?Just for grins, here is a way to get every odd number as the smallest> term of a Pythagorean triplet. I noticed this when I hadn't yet had> any algebra in school, so I found the proof very difficult. Now of> course it is extremely easy.We were always given (3, 4, 5) and (5, 12, 13) as Pythagorean triples> in homework problems. What I noticed was that 4 + 5 = 9 = 3^2 and> that 12 + 13 = 25 = 5^2, and of course that 4 and 5 as well as 12 and> 13 differed by 1. After trying to extend this pattern to (7, 24, 25),> (9, 40, 41) and perhaps a few more, I saw that it always worked. I> asked my big brother to prove it for me and the rat made me do it for> myself. I had a hard time figuring out that the pattern was (2n+1,> 2n^2+2n, 2n^2+2n+1), but once that was done, it was easy enough to> calculate that (2n^2+2n+1)^2 = (2n^2+2n)^2 + 2(2n^2+2n) + 1 (2n^2+2n)^2 + (4n^2+4n+1) = (2n^2+2n)^2 + (2n+1)^2 as desired.It's very easy to derive directly, requiring only trivial algebraand some parity: n^2 odd n odd (< even^2 = even ); to wit:If (a,b,c) is a Pythagorean triple with c = b+1 (so primitive)then (b+1)^2 = b^2 + a^2 2b+1 = a^2 odd a odd, say a = 2n+1 2b+1 = (2n+1)^2 = 4n(n+1)+1 b = 2n(n+1), a = 2n+1, c = b+1Fibonacci did it by summing 2n+1 = (n+1)^2 - n^2, as is described in his entry at the MacTutor math history archive: Liber Quadratorum, written in 1225, is Fibonacci's most impressive piece of work, although not the work for which he is most famous. The book's name means the book of squares and it is a number theory book which, among other things, examines methods to find Pythagorean triples. Fibonacci first notes that square numbers can be constructed as sums of odd numbers, essentially describing an inductive I thought about the origin of all square numbers and discovered that they arose from the regular ascent of odd numbers. For unity is a square and from it is produced the first square, namely 1; adding 3 to this makes the second square, namely 4, whose root is 2; if to this sum is added a third odd number, namely 5, the third square will be produced, namely 9, whose root is 3; and so the sequence and series of square numbers always rise through the regular addition of odd numbers. Thus when I wish to find two square numbers whose addition produces a square number, I take any odd square number as one of the two square numbers and I find the other square number by the addition of all the odd numbers from unity up to but excluding the odd square number. For example, I take 9 as one of the two squares mentioned; the remaining square will be obtained by the addition of all the odd numbers below 9, namely 1, 3, 5, 7, whose sum is 16, a square number, which when added to 9 gives 25, a square number.-Bill Dubuque === Subject: Bruce Harvey scribbled the following:>> Here is Eucleides's proof that there are infinitely many Pythagorean>> triplets.>> If n is a natural, then n^2 - (n-1)^2 = (n+n-1)(n-n+1) = 2n-1.> Apart from the algbra you have it. Although the three expressions are indeed> equal the middle one should be> n^2 -(n^2-2n+1) 12 year old's algebra!!!!!!Why should it be that? I was using the rule a^2 - b^2 =(a+b)(a-b), with b being equal to (n-1).-- /-- Joona Palaste (palaste@cc.helsinki.fi) ------------- Finland ---------- http://www.helsinki.fi/~palaste --------------------- rules! --------/That's no raisin - it's an ALIEN! - Tourist in MTV's Oddities === Subject: > Bruce Harvey scribbled the following:>> Here is Eucleides's proof that there are infinitely many Pythagorean>> triplets.>> If n is a natural, then n^2 - (n-1)^2 = (n+n-1)(n-n+1) = 2n-1.>> Apart from the algbra you have it. Although the three expressions areindeed> equal the middle one should be>> n^2 -(n^2-2n+1) 12 year old's algebra!!!!!!>> Why should it be that? I was using the rule a^2 - b^2 (a+b)(a-b), with b being equal to (n-1).>but you did say proof and to my simple mind as a maths teacher, a proof isset out line by line stating any other theorems invoked.> -- > /-- Joona Palaste (palaste@cc.helsinki.fi) ------------- Finland --------> -- http://www.helsinki.fi/~palaste --------------------- rules! --------/> That's no raisin - it's an ALIEN!> - Tourist in MTV's Oddities === Subject: > Bruce Harvey scribbled the following:>> Here is Eucleides's proof that there are infinitely many Pythagorean>> triplets.>> If n is a natural, then n^2 - (n-1)^2 = (n+n-1)(n-n+1) = 2n-1.>> Apart from the algbra you have it. Although the three expressions areindeed> equal the middle one should be>> n^2 -(n^2-2n+1) 12 year old's algebra!!!!!!>> Why should it be that? I was using the rule a^2 - b^2 (a+b)(a-b), with b being equal to (n-1).example google?I asked the first original reference. Nobody replied. I'm interested in mathhistory.Here is a partial copy of my post (equations) dated above:For example:1) For ODD a , a general solution exists:p^2 - (p-1)^2 = q^2 p^2=(p-1)^2+q^2, becausep^2-(p^2-2p+1) 2p-1 =q^2Examples:5^2-4^2= 3^2 , where 3 is odd in Eq. in the title.13^2-12^2= 5^225^2-24^2= 7^241^2-40^2= 9^2....etc. infinitely for (odd)^2 on rhs.2) For EVEN b , a general parametric solution exists:s^2-(s-2)^2=t^2 s^2-(s^2-4s+4) =4(s-1) =t^2Examples:5^2 -3^2=4^2, where 4 is even in Eq.in the title.10^2-8^2=6^217^2-15^2=8^2.......etc. infinitely for (even)^2 on rhsMy point was: Because any square, even or odd, is the difference of twosquares, then there are infinite many Pythagorean triplets so that any evenor odd integer is a member in some Pythagorean triplet. As there areinfinite many primes, then there are infinite many different non-trivialPythagorean triplets.But who invented that first. Was it really Euclides? Somebody else?Tapio>> --> /-- Joona Palaste (palaste@cc.helsinki.fi) ------------- Finland --------> -- http://www.helsinki.fi/~palaste --------------------- rules! --------/> That's no raisin - it's an ALIEN!> - Tourist in MTV's Oddities === Subject: >> Bruce Harvey scribbled the following:>> Here is Eucleides's proof that there are infinitely many Pythagorean>> triplets.>> If n is a natural, then n^2 - (n-1)^2 = (n+n-1)(n-n+1) = 2n-1.>> Apart from the algbra you have it. Although the three expressions are> indeed> equal the middle one should be>> n^2 -(n^2-2n+1) 12 year old's algebra!!!!!!>> Why should it be that? I was using the rule a^2 - b^2 (a+b)(a-b), with b being equal to (n-1).>> example google?> I asked the first original reference. Nobody replied. I'm interested inmath> history.>> Here is a partial copy of my post (equations) dated above:>> For example:> 1) For ODD a , a general solution exists:> p^2 - (p-1)^2 = q^2 p^2=(p-1)^2+q^2, because>> p^2-(p^2-2p+1) 2p-1 =q^2>> Examples:>> 5^2-4^2= 3^2 , where 3 is odd in Eq. in the title.> 13^2-12^2= 5^2> 25^2-24^2= 7^2> 41^2-40^2= 9^2> ....> etc. infinitely for (odd)^2 on rhs.>> 2) For EVEN b , a general parametric solution exists:> s^2-(s-2)^2=t^2 s^2-(s^2-4s+4) =4(s-1) =t^2>> Examples:>> 5^2 -3^2=4^2, where 4 is even in Eq.in the title.> 10^2-8^2=6^2> 17^2-15^2=8^2> .......> etc. infinitely for (even)^2 on rhs>> My point was: Because any square, even or odd, is the difference of two> squares, then there are infinite many Pythagorean triplets so that anyeven> or odd integer is a member in some Pythagorean triplet. As there are> infinite many primes, then there are infinite many different non-trivial> Pythagorean triplets.> But who invented that first. Was it really Euclides? Somebody else?>> Tapio>I am not happy about the even numbers because infinity is a difficultconcept: withx^2 as x aproaches infinity being of a different order than x as xaproaches infinity.Or even (x^x)! as x aproaches infinity.They are different concepts of infinity.So in your series>13^2-12^2= 5^2> 25^2-24^2= 7^2> 41^2-40^2= 9^212, 24, 40 ...... is increasing faster than 5, 7, 9 .......so its a different order of infinityAs a concept, infinity needs pinning to a definite conceptual entity such asa number line or a grid of unit cubes formed by the grid lines of acartesian co-ordinate system sapnning infinite space.-- Bruce Harveybruce@bearsoft.co.ukThe Alternative Physics Sitehttp://users.powernet.co.uk/bearsoft>> --> /-- Joona Palaste (palaste@cc.helsinki.fi) ------------- Finland --------> -- http://www.helsinki.fi/~palaste --------------------- rules! --------/> That's no raisin - it's an ALIEN!> - Tourist in MTV's Oddities>> === Subject: Michigan State University grad student Michael Shafer has succeeded inidentifying the largest known prime number to date, using a distributedcomputer network of more than 200,000 computers located around the world.The new number is 6,320,430 digits long and is only the 40th Mersenne primeto have ever been discovered (Mersenne primes are an especially rare breedthat take the form of 2-to-the-power-of-P, where P is also a prime number). === Subject: > Michigan State University grad student Michael Shafer has succeeded in> identifying the largest known prime number to date, using a distributed> computer network of more than 200,000 computers located around the world.> The new number is 6,320,430 digits long and is only the 40th Mersenneprime> to have ever been discovered (Mersenne primes are an especially rare breed> that take the form of 2-to-the-power-of-P, where P is also a primenumber).Sounds like a waste of processor power (and electricity) to me. There is noreasonin discovering these large numbers (even if you want to use them forencryption.I believe the encryption process would need veeeery much time ;-}} ).Karl === Subject: > Michigan State University grad student Michael Shafer has succeeded in> identifying the largest known prime number to date, using a distributed> computer network of more than 200,000 computers located around the world.> The new number is 6,320,430 digits long and is only the 40th Mersenne> prime> to have ever been discovered (Mersenne primes are an especially rare breed> that take the form of 2-to-the-power-of-P, where P is also a prime> number).Sounds like a waste of processor power (and electricity) to me. There is no> reason> in discovering these large numbers (even if you want to use them for> encryption.> I believe the encryption process would need veeeery much time ;-}} ).I don't think Mersenne primes would be very useful for encryption. For example in the RSA method, what you need is the product of two large primes with the idea that nobody can factor that product. Give me any product of two primes of which one is a Mersenne prime, and I can factor it easily. === Subject: Mike Parker> Michigan State University grad student Michael Shafer has succeeded in> identifying the largest known prime number to date, using a distributed> computer network of more than 200,000 computers located around the world.> The new number is 6,320,430 digits long and is only the 40th Mersenneprime> to have ever been discovered (Mersenne primes are an especially rare breed> that take the form of 2-to-the-power-of-P, where P is also a primenumber).My mother phoned me today to tell me that she had seen something on CNNabout a breakthrough in mathematics. As soon as I got home I scoured CNN'swebsite, finding nothing. Turns out it's just a 6-million digit prime. Whata letdown.LH === Subject: Larry Hammick scribbled the following:> Mike Parker>> Michigan State University grad student Michael Shafer has succeeded in>> identifying the largest known prime number to date, using a distributed>> computer network of more than 200,000 computers located around the world.>> The new number is 6,320,430 digits long and is only the 40th Mersenne> prime>> to have ever been discovered (Mersenne primes are an especially rare breed>> that take the form of 2-to-the-power-of-P, where P is also a prime> number).> My mother phoned me today to tell me that she had seen something on CNN> about a breakthrough in mathematics. As soon as I got home I scoured CNN's> website, finding nothing. Turns out it's just a 6-million digit prime. What> a letdown.Finding new Mersenne primes is just a question on spending more and moretime and processor power on distributed computer networks.Now a real mathematical breakthrough would be for example solving afamous conjecture, like Goldbach's conjecture, either proving ordisproving it.-- /-- Joona Palaste (palaste@cc.helsinki.fi) ------------- Finland ---------- http://www.helsinki.fi/~palaste --------------------- rules! --------/'It can be easily shown that' means 'I saw a proof of this once (which I didn'tunderstand) which I can no longer remember'. - A maths teacher === Subject: Isn't there a power of 2 that is in fact prime?--OL === Subject: >Isn't there a power of 2 that is in fact prime?>>--OL>2^1 === Subject: Chergarj schrieb:>>Isn't there a power of 2 that is in fact prime?>>2^1 Fascinating! Two of the most fundamental mathematicalconstants in a simple formula... giving a prime... === Subject: <28085-3FD7D447-106@storefull-2315. public.lawson.webtv.net>,> Isn't there a power of 2 that is in fact prime?--OL> Yes, but it is not a large power, and was discovered to be prime long ago. === Subject: ><28085-3FD7D447-106@storefull-2315. public.lawson.webtv.net>,> Isn't there a power of 2 that is in fact prime?>>Yes, but it is not a large power, and was discovered to be prime >long ago.You mean we won't be seeing this in the papers then?Newsgroup participant discovers smallest prime. Ever. === Subject: <28085-3FD7D447-106@storefull-2315. public.lawson.webtv.net>,Isn't there a power of 2 that is in fact prime?Yes, but it is not a large power, and was discovered to be prime> long ago.I wonder if we could generalize the result. There may beothers of these, hmmm, not-large powers that turn out tobe prime.Jim Burns === Subject: <28085-3FD7D447-106@storefull-2315. public.lawson.webtv.net>,> Isn't there a power of 2 that is in fact prime?Yes, but it is not a large power, and was discovered to be prime> long ago.I wonder if we could generalize the result. There may be> others of these, hmmm, not-large powers that turn out to> be prime.I would be interested in a list of all known primes that are powers of Mersenne primes. I bet there are not many of them, probably not more than fourty at the moment. === Subject: > <28085-3FD7D447-106@storefull-2315.public.lawson.webtv.net>,> Isn't there a power of 2 that is in fact prime?>> Yes, but it is not a large power, and was discovered to be prime> long ago.>> I wonder if we could generalize the result. There may be> others of these, hmmm, not-large powers that turn out to> be prime.>> I would be interested in a list of all known primes that are powers of> Mersenne primes. I bet there are not many of them, probably not more> than fourty at the moment.How about zero? As in There are no prime numbers which arepowers of Mersenne primes. None at all. Ain't gonna happen.End of story. Next. === Subject: > <28085-3FD7D447-106@storefull-2315.public.lawson.webtv.net>,> Isn't there a power of 2 that is in fact prime?>> Yes, but it is not a large power, and was discovered to be prime> long ago.>> I wonder if we could generalize the result. There may be> others of these, hmmm, not-large powers that turn out to> be prime.>> I would be interested in a list of all known primes that are powers of> Mersenne primes. I bet there are not many of them, probably not more> than fourty at the moment.How about zero? As in There are no prime numbers which are> powers of Mersenne primes. None at all. Ain't gonna happen.> End of story. Next.p^n for p = 1. === Subject: Mike Parker scribbled the following:> <28085-3FD7D447-106@storefull-2315.public.lawson.webtv.net>,> Isn't there a power of 2 that is in fact prime?>> Yes, but it is not a large power, and was discovered to be prime>> long ago.>> I wonder if we could generalize the result. There may be>> others of these, hmmm, not-large powers that turn out to>> be prime.>> I would be interested in a list of all known primes that are powers of>> Mersenne primes. I bet there are not many of them, probably not more>> than fourty at the moment.> How about zero? As in There are no prime numbers which are> powers of Mersenne primes. None at all. Ain't gonna happen.> End of story. Next.Depends on your definition of power. If p is a Mersenne prime, thenp^1 sure as heck is a prime.-- /-- Joona Palaste (palaste@cc.helsinki.fi) ------------- Finland ---------- http://www.helsinki.fi/~palaste --------------------- rules! --------/It's time, it's time, it's time to dump the slime! - Dr. Dante === Subject: > Michigan State University grad student Michael Shafer has succeeded in > identifying the largest known prime number to date, using a distributed > computer network of more than 200,000 computers located around the world. > The new number is 6,320,430 digits long and is only the 40th Mersenne prime > to have ever been discovered (Mersenne primes are an especially rare breed > that take the form of 2-to-the-power-of-P, where P is also a prime number).When I read it the first time I found the most surprising not that hehad discovered a large power of 2 but that he had discovered one thatis prime. There must be something wrong with the core of mathematics.-- dik t. winter, cwi, kruislaan 413, 1098 sj amsterdam, nederland, +31205924131home: bovenover 215, 1025 jn amsterdam, nederland; http://www.cwi.nl/~dik/ === Subject: >Message-id: Michigan State University grad student Michael Shafer has succeeded in> identifying the largest known prime number to date, using a distributed> computer network of more than 200,000 computers located around the world.> The new number is 6,320,430 digits long and is only the 40th Mersenne>prime> to have ever been discovered (Mersenne primes are an especially rare breed> that take the form of 2-to-the-power-of-P, where P is also a prime>number).>>When I read it the first time I found the most surprising not that he>had discovered a large power of 2 but that he had discovered one that>is prime. There must be something wrong with the core of mathematics.Yup.>-- >dik t. winter, cwi, kruislaan 413, 1098 sj amsterdam, nederland,>+31205924131>home: bovenover 215, 1025 jn amsterdam, nederland; http://www.cwi.nl/~dik/--MensanatorAce of Clubs === Subject: > Dear all,It is easy to prove that if the first number in a row of Pascal's> triangle is a prime then all other numbers (except 1) in that row are> multiples of that prime.However, several sources say that this is also a sufficient condition> for this phenomenon, ie if the first number n is composite, then there> exists a binomial coefficient in that row not a multiple of n.I've tried looking for a proof online, but with no success. I would> greatly appreciate it if you could help me out.Apologies if this is rather trivial.RedIf we have n!/(k!(n-k)!) = binomial(n,k),then binomial(n,k) =(n/k) binomial(n-1,k-1), for k and n = positive integers.So, if GCD(n,k) = j, andn = n' j, k = k' j,then binomial(n,k) = (n' j)/(k' j) binomial(n-1,k-1) = multiple of n' / k'.And so, for n and k = positive integers, binomial(n,k) is divisible by n'/k'.But k' does not divide n', so k' divides binomial(n-1,k-1),since binomial(n,k) is an integer.So,n' = n/GCD(n,k)always divides binomial(n,k),for n and k = positive integers.Specifically, if n and k are relatively prime, then n always dividesbinomial(n,k).Yet n MAY still sometimes divide the binomial if it is not coprime with k.(What is the first example??? Is there an example ??)thanks,Leroy Quet === Subject: > Yet n MAY still sometimes divide the binomial if it is not coprime with k.> (What is the first example??? Is there an example ??)binomial(10,4) = 210-- Daniel W. Johnsonpanoptes@iquest.nethttp://members.iquest.net/~panoptes/ 039 53 36 N / 086 11 55 W === Subject: > Dear all,It is easy to prove that if the first number in a row of Pascal's> triangle is a prime then all other numbers (except 1) in that row are> multiples of that prime.However, several sources say that this is also a sufficient condition> for this phenomenon, ie if the first number n is composite, then there> exists a binomial coefficient in that row not a multiple of n.I've tried looking for a proof online, but with no success. I would> greatly appreciate it if you could help me out.Apologies if this is rather trivial.Red Here's something I posted several years ago: === Subject: === Subject:=== Subject:=== Subject:=== Subject:=== Subject:=== Subject:=== Subject:=== Subject:=== Subject:=== Subject:=== Subject:=== Subject:=== Subject:== === Subject: === Subject:=== Subject:=== Subject:=== Subject:=|> |> Is it true that GCD of {mC1,mC2,...,mC[m-1]} is p if m=p^n with p prime and|> 1 otherwise?|> Yes. |> Here mCn is m combination n, or the nth entry in the mth row of Pascal's|> triangle.|> |> If so, is there a really obvious proof? More important: can anybody name a|> reference (textbook, paper etc..)?|> Using a result due to Kummer which is nicely presented in [1], it's not _too_ hard to prove. Let me change your notation a bit: it'll be easier to follow the argument if m combination n is denoted by C(m,n). That said, Kummer's result is as follows: given n, k > 0, let c_p(n,k) = the number of carries generated when adding n & k using base p. Then Theorem(Kummer). If p is a prime, then p^{c_p(n,k)} is the highest power of p which divides C(n+k,k). If you grant me this, then I can argue as follows. Since C(m,1) = m, the gcd is always a divisor of m. So, if m=p^n, the gcd of the set is p^r for some r >= 0. But, given n and k (0 < n,k < p^n) such that n+k = p^n, there _has_ to be at least 1 carry generated when we add the base p versions of n and k -- that's the only way to generate the '1' that's the coefficient of p^n in the result. Hence, every element of our set is divisible by (at least) p. On the other hand, if 0 < k < p, then Kummer's result shows that C(p^n,kp^{n-1}) is _not_ divisible by p^2. Hence, the gcd is p in this case. For the other case, suppose that m is not a power of a prime, and let p be any prime which divides m. In the base p representation of m, there is either a term rp^u (with 1 < r < p) or a pair of terms rp^u + sp^v.(There are probaly a *bunch* of other terms, as well -- I don't care about those). In the first case, C(m,(r-1)p^u) is _not_ divisible by p; in the second case, C(m,rp^u) is not divisible by p. Since, for every prime p dividing m, there's some C(m,n) in the set that is not divisible by p, it follows that the gcd of the set is 1. 1. Peitgen,H.-O. _et_al._, Chaos and Fractals/New Frontiers of Science, Springer-Verlag, 1992. ISBN 0-387-97903-4 |> Flo.|> |> |> -- |> ----------------------------------------------------------|> Florian Breuer at University of Stellenbosch, South Africa|> reply to: s9520155@itu3.sun.ac.za|> ---------------------------------------------------------- === Subject: === Subject: === Subject:=== Subject:=== Subject:=== Subject:=== Subject:=== Subject:=== Subject:=== Subject:=== Subject:=== Subject:=== Subject:=== Subject:=== Subject:=== Subject:== === Subject: === Subject:=== Subject: The result that you're wanting to prove follows easily -- unless n is a prime, some C(n.k) with 1 < k < n is not a multiple of n. === Subject: Dear all,Trying to figure out the 1-dimensional representations of D_n, the dihedralgroup of order 2n.Should be easy...Let r be rotation, s be reflection.Then r^n = 1, s^2 = 1, rs = sr^-1...Now let F be the representation from D_n to k* , F : D_n --> k* wherek = complex numbers.Then F(r)F(s) = F(s)F(r^-1) <= F(r) = F(r^-1) since these numberscommute , so F(r^2) = 1 < === Subject: > F(r) = 1 or -1....likewise since s^2 = 1,F(s) = 1 or -1...So there are 4 1-dimensional representations of D_n for all n?Rob === Subject: > Dear all,Trying to figure out the 1-dimensional representations of D_n, the> dihedral group of order 2n.> Should be easy...Let r be rotation, s be reflection.Then r^n = 1, s^2 = 1, rs = sr^-1...Now let F be the representation from D_n to k* , F : D_n --> k* > where k = complex numbers.Then F(r)F(s) = F(s)F(r^-1) <= F(r) = F(r^-1) since these numbers> commute , so F(r^2) = 1 < === Subject: > F(r) = 1 or -1....likewise since s^2 = 1,> F(s) = 1 or -1...So there are 4 1-dimensional representations of D_n for all n?Are there four 1-dimensional reps of D_3?-- Robin Chapman, www.maths.ex.ac.uk/~rjc/rjc.htmlNeedless to say, I had the last laugh. Alan Partridge, _Bouncing Back_ (14 times) === Subject: >> Dear all,>> Trying to figure out the 1-dimensional representations of D_n, the> dihedral group of order 2n.> Should be easy...>> Let r be rotation, s be reflection.>> Then r^n = 1, s^2 = 1, rs = sr^-1...>> Now let F be the representation from D_n to k* , F : D_n --> k*> where k = complex numbers.>> Then F(r)F(s) = F(s)F(r^-1) <= F(r) = F(r^-1) since these numbers> commute , so F(r^2) = 1 < === Subject: > F(r) = 1 or -1....likewise since s^2 = 1,> F(s) = 1 or -1...>> So there are 4 1-dimensional representations of D_n for all n?>> Are there four 1-dimensional reps of D_3?Ouch, you are right. There are only 2 1-dimensional reps of D_3. Then howcan I generalize to D_n?>> -- > Robin Chapman, www.maths.ex.ac.uk/~rjc/rjc.html> Needless to say, I had the last laugh.> Alan Partridge, _Bouncing Back_ (14 times) === Subject: > Dear all,>> Trying to figure out the 1-dimensional representations of D_n, the>> dihedral group of order 2n.>> Should be easy...>> Let r be rotation, s be reflection.>> Then r^n = 1, s^2 = 1, rs = sr^-1...>> Now let F be the representation from D_n to k* , F : D_n --> k*>> where k = complex numbers.>> Then F(r)F(s) = F(s)F(r^-1) <= F(r) = F(r^-1) since these numbers>> commute , so F(r^2) = 1 < === Subject: > F(r) = 1 or -1....likewise since s^2 > 1, F(s) = 1 or -1...>> So there are 4 1-dimensional representations of D_n for all n?>> Are there four 1-dimensional reps of D_3?Ouch, you are right. There are only 2 1-dimensional reps of D_3. Then> how can I generalize to D_n?So far you have F(r) = +- 1 and F(s) = +-1. Are there any morerestrictions you can find on these? Have you used all the relationsin the group?-- Robin Chapman, www.maths.ex.ac.uk/~rjc/rjc.htmlNeedless to say, I had the last laugh. Alan Partridge, _Bouncing Back_ (14 times) === Subject: >> Dear all,>> Trying to figure out the 1-dimensional representations of D_n, the>> dihedral group of order 2n.>> Should be easy...>> Let r be rotation, s be reflection.>> Then r^n = 1, s^2 = 1, rs = sr^-1...>> Now let F be the representation from D_n to k* , F : D_n --> k*>> where k = complex numbers.>> Then F(r)F(s) = F(s)F(r^-1) <= F(r) = F(r^-1) since thesenumbers>> commute , so F(r^2) = 1 < === Subject: > F(r) = 1 or -1....likewise since s^2 > 1, F(s) = 1 or -1...>> So there are 4 1-dimensional representations of D_n for all n?>> Are there four 1-dimensional reps of D_3?>> Ouch, you are right. There are only 2 1-dimensional reps of D_3. Then> how can I generalize to D_n?>> So far you have F(r) = +- 1 and F(s) = +-1. Are there any more> restrictions you can find on these? Have you used all the relations> in the group?I guess the last thing I would have to do is analyze the conjugacy classesof D_n and that is all. (I can do this on my own)>> -- > Robin Chapman, www.maths.ex.ac.uk/~rjc/rjc.html> Needless to say, I had the last laugh.> Alan Partridge, _Bouncing Back_ (14 times) === Subject: >> Dear all,>> Trying to figure out the 1-dimensional representations of D_n, the>> dihedral group of order 2n.>> Should be easy...>> Let r be rotation, s be reflection.>> Then r^n = 1, s^2 = 1, rs = sr^-1...>> Now let F be the representation from D_n to k* , F : D_n --> k*>> where k = complex numbers.>> Then F(r)F(s) = F(s)F(r^-1) <= F(r) = F(r^-1) since these numbers>> commute , so F(r^2) = 1 < === Subject: > F(r) = 1 or -1....likewise since s^2 = 1,>> F(s) = 1 or -1...>> So there are 4 1-dimensional representations of D_n for all n?>> Are there four 1-dimensional reps of D_3?Ouch, you are right. There are only 2 1-dimensional reps of D_3. Then how> can I generalize to D_n?>> -- >> Robin Chapman, www.maths.ex.ac.uk/~rjc/rjc.html>> Needless to say, I had the last laugh.>> Alan Partridge, _Bouncing Back_ (14 times)1, time consuming: by learning some more representation theory or 2. lazy option: reading chapter 18 in james and liebeck:there is an obvious 2-d rep. show, that there are in fact many more such.you need to consider n odd and even separately. that odd and evenexplanantion will tell you why there are 2 1-d reps n odd, 4 n even.you're on the right track. if you want i could write out the proof, buti'd rather not have to. oh, the n odd and even thing means there aredifferent 'types' of conjugacy classes. if you can read the book cos it'smuch more clearly laid out than i'll manage to make it on here. === Subject: > I know guys like Abel and Galois did their best work early and then died,> but can people give me some examples of mathematicians who did their best> work in their early 20s (say), then continued to work for a long time but I would like to see an *objective* study on this.First, a group of unknown mathematicians' work would be evaluated forgreatness (whatever 'greatness' means...),without those doing the evaluating knowing any biographical info aboutthe mathematicians at first.And *then* the mathematicians' ages (and sexes and race and educationlevel and economic status and...) would be revealed.Perhaps even the evaluators' own biases can be studied as well, wherethey each fill out a survey (after evaluating the math work, butbefore learning anything personal about the mathematicians) as to whatthey GUESS what the mathematicians' biographical info might be.... So...by looking over MY past work posted here to sci.math over thelast few years, how old do you all *think* I might be???.....;)(And I know I have posted my age here on occasion. So no fair peekingat that info!)thanks,Leroy Quet === Subject: >> I know guys like Abel and Galois did their best work early and then died,>> but can people give me some examples of mathematicians who did their best>> work in their early 20s (say), then continued to work for a long time but> I would like to see an *objective* study on this.>[...]> So...by looking over MY past work posted here to sci.math over the> last few years, how old do you all *think* I might be???.....> ;)>> (And I know I have posted my age here on occasion. So no fair peeking> at that info!)We don't have to peek.You react negatively to the suggestion that mathematical genius peaksat an early age. Conclusion: you're old.Me too. At least I'm old enough to be past that peak. Of course, Ifirst realized I wasn't going to hit the greatness for which I wasdestined when, at twenty-four, I learned that Robert Johnson died atage twenty-four[1]. Meanwhile, I had never had a hit blues recordlike I expected. Of course, I didn't play an instrument or singeither, but evidently it was too late to learn.Or to quote Tom Lehrer, When Mozart was my age, he had been dead fortwo years.Footnotes: [1] Evidently, I was misinformed. He died at twenty-seven, but I'mpast that, too.-- So, at this time, I'd like to assure you that I am not interested inI'll have prosecutors knocking on your doors. I have no problem with === Subject: >message>> What with the war on terror, and Canada's puny military and corrupt>> police force, the only way to insure peace and safety for that>> country, is for it to be annexed by America.>> It is the only way foward for Canada aka Canuckistan.>> --------------------------------->> Well, another solution is the liberation of U.$.A by Canadians and the>> return of democracy to the Americans peoples.>> I am sure Canadians will be welcome with (french) kisses and flowers>when>> they will topple the Little Dictator and his gang of corporate crooks.>> Patriot act will be scraped; free press will be restaured, Health Care>> will be available to all citizens,>>Yeah, like it is in Canada. If you wait. And wait. And wait. And... oops,>died already.Or you can join an American HMO where they deny you care because theydon't want to pay out the money. ooopps one dead wife...mine!Capitalist medicine is an abomonation and a human rights violation.THOM>>But at least the bigtime politicians and bureaucrats get their healthcare!>(By paying cash in Yankee hospitals...)>>-- >zimriel sbc dot> at global net>.>http://pages.sbcglobal.net/zimriel/blog/zimblog.html> because everyone else is doing it>> === Subject: > What with the war on terror, and Canada's puny military and corrupt>> police force, the only way to insure peace and safety for that>> country, is for it to be annexed by America.>> It is the only way foward for Canada aka Canuckistan.>>You seem to forget that the Canadians kicked our ass in two conflicts....>Really? Which two? === Subject: >> What with the war on terror, and Canada's puny military and corrupt>> police force, the only way to insure peace and safety for that>> country, is for it to be annexed by America.>> It is the only way foward for Canada aka Canuckistan.>>You seem to forget that the Canadians kicked our ass in two conflicts....>> Really? Which two?>1775http://www.civilization.ca/cwm/chrono/1000invasion_ e.html1812http://www.civilization.ca/cwm/chrono/1774invasion_ repelled_e.html === Subject: >> What with the war on terror, and Canada's puny military and corrupt> police force, the only way to insure peace and safety for that> country, is for it to be annexed by America.>> It is the only way foward for Canada aka Canuckistan.>>You seem to forget that the Canadians kicked our ass in two conflicts....>Really? Which two?he'se probably talking about ice hockeyTHOM> === Subject: > What with the war on terror, and Canada's puny military and corrupt> police force, the only way to insure peace and safety for that> country, is for it to be annexed by America.>> It is the only way foward for Canada aka Canuckistan.>>You seem to forget that the Canadians kicked our ass in twoconflicts....>Really? Which two?>> he'se probably talking about ice hockeyThose ignorant of history are bound to repeat it. === Subject: Let c(1,k) = 1, for all positive integers k.For all m >= 2,Let c(m,k) = ---- ln(k) ------- > c(j,k) ln(m) / --- j|m j 1, f(x) = oo--- --- > ( > c(k,m/k) ) /m^x / /--- ---m=1 k|m(which in linear mode is...)f(x) = sum{m=1 to oo} (sum{k|m} c(k,m/k) ) /m^x.(Inner-sum is over all positive divisors, k, of m) Puzzle:What is a closed-form (in terms of known functions) for f(x)??thanks,Leroy Quet === Subject: > If you ing morons think that I will let you get away with not> giving me credit for my ing math discoveries then you have another> ing thing coming.As far as I know, you don't get paid for mathematical discoveries.Certainly you don't get paid by announcing them on a newsgroup. Consider -who's going to pay you, and for what? There exist a few prizes inmathematics that I've heard of, but you have to submit your work to thesejudges and so forth. To my knowledge, these prizes aren't altogetherspectacular. And you can forget about a Nobel Prize in Mathematics. Thereisn't one, as I'm sure you know.I have never heard of any corporation paying for a mathematical discovery,with the exception perhaps of those made in the R&D departments. Same withthe government, which probably wouldn't be able to even judge a discoveryanyway (they'd need a committee, and it probably would be composed ofpoliticians, not mathematicians).I can understand you being upset if you think you'd be denied money due toyou, or if you think someone else would be able to steal it from you byplagiarizing your work. But as I said - who's going to pay *anyone* for amathematical discovery?Be well.Baruch === Subject: synaptic energy redistribution (audio) filter http://apollonicon.com/music/gold.wavhttp://apollonicon.com/ music/black.wavhttp://apollonicon.com/music/gold.mp3http:// apollonicon.com/music/black.mp3google video filter?http://apollonicon.com/series/pierre_21.jpg === Subject: a good score. I know the word good is fairly arbitrary, but if weconsider the three cases:1) Want to get into a top 10 school2) Want to get into a top 20 school3) Want to get into an upper Tier 2 schoolThen for each of the above, what would be the subject testscore/percentile that one would recommend? === Subject: >Then for each of the above, what would be the subject test>score/percentile that one would recommend?I can tell you that a lot of mathematics graduate programs won't evenlook at your score; just that you took it. Doug === Subject: > a good score. I know the word good is fairly arbitrary, but if we> consider the three cases:>> 1) Want to get into a top 10 school> 2) Want to get into a top 20 school> 3) Want to get into an upper Tier 2 school> Then for each of the above, what would be the subject test> score/percentile that one would recommend?Get a 900, and I think that you can call that good. Otherwise, I would sayat least a 700. Most universities want the top 1/3 of test takers. That'swhat I have found anyway.Lurch === Subject: > a good score. I know the word good is fairly arbitrary, but if we> consider the three cases:1) Want to get into a top 10 school> 2) Want to get into a top 20 school> 3) Want to get into an upper Tier 2 school> Then for each of the above, what would be the subject test> score/percentile that one would recommend?Get good recommendations from your profs. If you did especially well in a course taught by a famous prof, that's the best. === Subject: a good score. I know the word good is fairly arbitrary, but if we> consider the three cases:1) Want to get into a top 10 school> 2) Want to get into a top 20 school> 3) Want to get into an upper Tier 2 school> Then for each of the above, what would be the subject test> score/percentile that one would recommend?Get good recommendations from your profs. If you did especially well in > a course taught by a famous prof, that's the best.I realize that, but for the purposes of this message I am concernedonly about GRE scores.Why are people so resistant to answering questions about GRE scores? Of all the times I've asked this question, I've never once gotten anumber back as an answer. Even my advisor was like Don't worry somuch about GRE scores. Just worry about doing your best. Well ifGRE scores weren't important, then why does practically everyuniversity in the country require them to get into their PhD program? Clearly at least one person at each graduate school must know what GREscores are good and which are not, otherwise nobody would ever takeGRE scores into consideration. That's all I'm asking for here. Iknow GRE scores aren't the final word on everything, but I hope thatfor once someone can finally give me a straight answer, and hopefullyrespond with 3 numbers/intervals corresponding to the above 3 rangesof schools. === Subject: The Prophet Nobody known to the wise as toolshed37@yahoo.com, opened the Book of Words, and read unto the people:>Why are people so resistant to answering questions about GRE scores? >Of all the times I've asked this question, I've never once gotten a>number back as an answer. Even my advisor was like Don't worry so>much about GRE scores. Just worry about doing your best. Well ifPeople don't answer it because, frankly, it's an ill-formedquestion. GRE scores _don't_ get you into good universities. Goodrecommendations/research history gets you into good universities. Youneed at least a good GRE to get into a mediocre university, but even agreat GRE won't get you into a great university. The subject GREcovers competence, not excellence; a GRE score above a certain levelguarantees you know a good survey of undergrad math -- knowing moreabove that simply means you have a good memory. The general GRE mayhonestly be of more value to math programs, since the main thing isnot so much what you know as how you think, and the general ishonestly a better predictor of that.But, y'know, don't let GRE scores bother you. If you think they'reimportant, study hard. Apply everywhere you'd apply anyways. I don'tsee how knowing the relationship between GREs and acceptance (onewhich is actually tenuous, as I say above) helps you in any way.>know GRE scores aren't the final word on everything, but I hope that>for once someone can finally give me a straight answer, and hopefully>respond with 3 numbers/intervals corresponding to the above 3 ranges>of schools.The numbers/intervals you're asking for don't exist. If it would makeyou happy, I could say '600-1000' for all three (I'm guessing at thelower bound at which 'competence' is assessed).+---------------------------------------------------- ---------+| D. Jacob Wildstrom -- Math monkey and freelance thinker || Graduate Student, University of California at San Diego || A mathematician is a device for turning coffee into || theorems. -Alfred Renyi |+------------------------------------------------------------ -+The opinions expressed herein are not necessarily endorsed by theUniversity of California or math department thereof. === Subject: > The Prophet Nobody known to the wise as toolshed37@yahoo.com, opened the Book of Words, and read unto the people:>Why are people so resistant to answering questions about GRE scores? >Of all the times I've asked this question, I've never once gotten a>number back as an answer. Even my advisor was like Don't worry so>much about GRE scores. Just worry about doing your best. Well ifPeople don't answer it because, frankly, it's an ill-formed> question. GRE scores _don't_ get you into good universities. Good> recommendations/research history gets you into good universities. You> need at least a good GRE to get into a mediocre university, but even a> great GRE won't get you into a great university. The subject GRE> covers competence, not excellence; a GRE score above a certain level> guarantees you know a good survey of undergrad math -- knowing more> above that simply means you have a good memory. The general GRE may> honestly be of more value to math programs, since the main thing is> not so much what you know as how you think, and the general is> honestly a better predictor of that.But, y'know, don't let GRE scores bother you. If you think they're> important, study hard. Apply everywhere you'd apply anyways. I don't> see how knowing the relationship between GREs and acceptance (one> which is actually tenuous, as I say above) helps you in any way.>know GRE scores aren't the final word on everything, but I hope that>for once someone can finally give me a straight answer, and hopefully>respond with 3 numbers/intervals corresponding to the above 3 ranges>of schools.The numbers/intervals you're asking for don't exist. If it would make> you happy, I could say '600-1000' for all three (I'm guessing at the> lower bound at which 'competence' is assessed).So with a GRE score of 600 you'd get into MIT? Wrong. What aboutwith a GRE score of 700? Wrong.People seem to confuse my question with what scores will get you intoa good university? However, nowhere did I ask that question. I saidwhat scores are good if you want to go to such and such university? Hence a score which would cause the reviewer to throw away yourapplication would not be considered good. So the correct responseshould be an interval which cause the reviewer to probably not throwaway your application. These intervals do exist, as a few people havepointed out that. For example, if you want to go to a top 10university your GRE score should be in the top 95 percentile or so. Yes, I understand that doesn't mean anything other than getting in thetop 95 percentile will cause them to not eliminate you. But afterall, that's what I was asking about. === Subject: Do negative numebrs exist in the real world or are they just a purelysymbolical and mathematical construct?--nethlek === Subject: > Do negative numebrs exist in the real world or are they just a purely> symbolical and mathematical construct?Do even positive numbers exist? To answer that, you need to defineexist I think. Something for philosophy rather than mathematics. Here is a start:Realism in Mathematicsby Penelope Maddy Paperback: 224 pagesOxford Univ PrISBN: 019824035X-- G. A. Edgar http://www.math.ohio-state.edu/~edgar/ === Subject: >Do negative numebrs exist in the real world Negative numebrs are the opposite of positive numebrs, so if you can provethe existence of positive numebrs, then you immediately see negative numebrs.Doug === Subject: >Do negative numebrs exist in the real world or are they just a purely>symbolical and mathematical construct?What are the respective charges of the electron and proton? === Subject: > Do negative numebrs exist in the real world or are they just a purely> symbolical and mathematical construct?Do positive numebrs exist in the real world or are they just a purelysymbolical and mathematical construct?-- Robin Chapman, www.maths.ex.ac.uk/~rjc/rjc.htmlNeedless to say, I had the last laugh. Alan Partridge, _Bouncing Back_ (14 times) === Subject: > Do negative numebrs exist in the real world or are they just a purely> symbolical and mathematical construct? --> nethleki think it just abstract. consider 3 apples. does it really three? is thesize of the apples is the same? === Subject: > Do negative numebrs exist in the real world or are they just a purely> symbolical and mathematical construct?> When you run a credit balance on a credit card or your phone bill, in other words when you pay more than you owe, they send you a bill for a negative amount. If the banks and credit card companies believe in negative numbers, who are the rest of us to disagree? === Subject: > Do negative numebrs exist in the real world or are they just a purely> symbolical and mathematical construct?Numbers (even couting numbers) don't exist in a physical sense. You can'tgo out to the shop and buy yourself a box of 7s for example...But if you pay for a box containing 8 apples and you notice that there isonly 7 in there you've applied this abstract notion of a counting numberto a real world phenomena.The same thing goes for negative numbers...They are useful for example in determining direction. e.g The stockmarket is going down today!Numbers provide a conceptual framework that has proven to be useful. Bruce. === Subject: >Numbers (even couting numbers) don't exist in a physical sense. You can't>go out to the shop and buy yourself a box of 7s for example...But I live at 7777 Seventy-Seventh street. How am I supposed to === Subject: >>Numbers (even couting numbers) don't exist in a physical sense. You can't>>go out to the shop and buy yourself a box of 7s for example...But I live at 7777 Seventy-Seventh street. How am I supposed to === Subject: >> Do negative numebrs exist in the real world or are they just a purely> symbolical and mathematical construct?>> Numbers (even couting numbers) don't exist in a physical sense. You can't> go out to the shop and buy yourself a box of 7s for example...As a teenager I used to buy boxes of Number 6s! === Subject: > Do negative numebrs exist in the real world or are >>they just a purely>> symbolical and mathematical construct?>> Numbers (even couting numbers) don't exist in a physical >>sense. You can't>> go out to the shop and buy yourself a box of 7s for >>example...>As a teenager I used to buy boxes of Number 6s!>At the beginning of every school year, I buy my kids a box of No. 2s. haha hehe. OK, I'll stop now. === Subject: Do negative numebrs exist in the real world or are they just a purely> symbolical and mathematical construct?Numbers (even couting numbers) don't exist in a physical sense. You can't> go out to the shop and buy yourself a box of 7s for example...But if you pay for a box containing 8 apples and you notice that there is> only 7 in there you've applied this abstract notion of a counting number> to a real world phenomena.The same thing goes for negative numbers...> They are useful for example in determining direction. e.g The stock> market is going down today!> Yes but you can have a box with five apples in it. You can't have a box with negative five apples in it. I think that's what the original poster was getting at. === Subject: > Do negative numebrs exist in the real world or are they just a purely> symbolical and mathematical construct?Numbers (even couting numbers) don't exist in a physical sense. You can't> go out to the shop and buy yourself a box of 7s for example...But if you pay for a box containing 8 apples and you notice that there is> only 7 in there you've applied this abstract notion of a counting number> to a real world phenomena.The same thing goes for negative numbers...> They are useful for example in determining direction. e.g The stock> market is going down today!> Yes but you can have a box with five apples in it. You can't have a box > with negative five apples in it. I think that's what the original > poster was getting at.Yes, but if I own a warehouse I can!This is very easy to apply to real life situations.Hypothetically ---- I own a warehouse that stocks among other things x, y and z widgets.Due to shortages experienced by my supplier my supply of z widgets isz = -230 units.In other words my orders to date for z widgets outstrips my z widgetstock by 230 units.I am sure stock status reports' for many manufacturers or distributorsdeal with negative numbers all the time. Also in many areas of financenegative numbers are the norm.Gee that reminds me, I have to get on my suppliers' ass because I amloosing $ on these z widget sales. ;-)Dan === Subject: > Yes but you can have a box with five apples in it. You can't have a box > with negative five apples in it. I think that's what the original > poster was getting at.I can't recall who it was first pointed it out, but there is nothinginherently natural about integer arithmetic. Yeah, integerarithmetic works for apples.But for clouds? If you add one cloud to one cloud, you don't get twoclouds. The individuation and the physics of clouds are differentthan for apples. It is a matter of experimentally determined factthat integer arithmetic works for apples, and not some automaticthing.This means that positive integers are not somehow the simple countingnumbers--they are the simple *apple* counting numbers. Or forcounting other discrete objects that work like apples do.Other things that don't work like apples are crumbs. If you cut anapple in half, you get two half-apples. But if you break a crumb intwo, you don't get two half-crumbs, you get two crumbs. So crumbs addlike apples do, but they don't divide like apples do.So nature uses all different kinds of numerical entities, and onlysome kinds of counting use positive numbers. If we are counting, forexample, generations, then it is perfectly natural to countdescendent generations with positive numbers and ancestor generationswith negative numbers (or vice versa).Or, if you are counting electrons, then you can have -5 electrons:when you have 5 positrons.Indeed, you can do that with apples too, which makes the quotedobservation above wrong. A little physics, and it turns out thatapples do *not* behave such that natural numbers are the rightcounting tools, but rather it turns out, integers! Because (howeverrare), there is such a beastie as an anti-apple.Thomas === Subject: