mm-471 === Subject: Re: Schauder basisskip...>This means that, for every>x in X and for every eps>0, if n is sufficiently large, then ||(Sum>(k=1,n) ex_k * x_k) - x||x_k) is in the open ball of radius eps and center x. The letter x in>ex is to emphasize that the scalars of the infinite linear combination>of the x_k's that leads to x depends on x.>If we define D = {ex_1 * x_1 ...+ ex_k * x_k | k in N (the naturals),>x in X}, then, for every x in X and every eps>0, the open ball>centered at x and of radius eps intersects D. Therefore, D is dense in>X. It remains to show (if it's true, of course) that D is countable. >Well, if X is countable, this is immediate (in fact, if X is countable>we have nothing to prove), but I'm still wondering how I can prove D>is countable or prove it contains a countable subset that's also dense>in X.> D is not countable. That's because the ex_j can be any real numbers,> and the reals are uncountable. But...>But we can take the set of all rational linear combinations of the x_n>(that is, the set of all linear combinations with rational>coefficients). Since the rationals are countable and are dense in R,>we get a countbale set dense in X and we are done. Right?> Yes!>If X is a vector space over the complexes, we can take the complexes>with rational real and rational imaginary parts.> Yes.>The thing gets more complicated if X is vector space over an arbitrary>field F...> If we're talking about a Banach space then we're talking about> real or complex scalars.>But, we didn't use the fact that X is Banach. The completeness of X>was not considered at all> Amazing. We've proved more than was required: If X is a normed> vector space and there exist e_1, ... such that every x in X can> be written x = a_1 e_1 + ... then X is separable.Yes. And now that the problem is solved, it doesn't look so hard. === Subject: Re: Schauder basis>[...]>Yes. And now that the problem is solved, it doesn't look so hard.>AmandaIt's not so hard - your biggest mistake in all this was when you saidyou thought it was probably beyond you. === Subject: Re: Antidiagonal, InfinityAgain, in binary there is one and exactly and only one antidiagonal,if that.If you demand the flexibility of selecting any of the b-1 numbers notthe element of the list expansion, or in other cases a value basedupon two or more consecutive values of the expansion, I said to modifythat to get a rational number. That's as simple as an infiniteprocess that guarantees some repeating terminus of the antidiagonal. That is not the case.Yet, where I am considering that, it is somewhat counter to myconsideration that the antidiagonal of a list of all elements of thereals would have dual representation because the reals comprise allinfinite bitstrings with a beginning, for convenience's sake the unitinterval. That is to say, where the list is of all possiblepermutations, there are no others, and at least one permutation is oneof those.Anyways in approaching that I consider what the diagonal is andvarious ways to construct an antidiagonal. For example if the decimaldiagonal is 5..., then the antidiagonal is 4..., a rational number,that simple everywhere-different sequence is always representing arational when the sequence represents a rational. When the diagonalsequence represents an irrational, then an algorithm is modified toproduce a rational sequence. Perhaps that is not possible. Forexample the diagonal might be a sequence normal to decimal, with eachof 0-9 equally probable to be the next element at any random point inthe sequence. There it would be necessary for me to show that somealgorithm outputs a sequence that is everywhere different from thenormal sequence and also represents a rational.31830988618379067153776752674502872406891929148091___ _______________5_____5____5____________________ 55555555555555555545555545555455555555555555555555____________ ________________4______4_________4____ 55555555555555555545555545555455554555545555455554You can see how that finite sequence has a repeating terminus of 55554but also perhaps how it could not continue infinitely. You canconstruct a non-normal irrational, but not necessarily a rational,from the naturally normal diagonal. Is it also not necessarily sothat a rational can be constructed from a non-normal sequence, or evenfrom artificially normal sequences?be constructed. That concurs with that for a given irrationalsequence another irrational sequence everywhere different can beconstructed, but a rational sequence may not, unless the irrationalsequence is not normal, and from a rational sequence a rationalsequence can be constructed that is everywhere different. So I dropmy argument that the everywhere non-diagonal of a list of rationalscan be made rational without reference to forcing. That's basicallybecause for a normal sequence no finite repeating terminus would beeverywhere different than the randomly distributed in occurrenceelements of the normal sequence.The antidiagonal of some (ir)rationals is not necessarily(ir)rational, in binary. Kovarik's continued fraction might be of arational. The antidiagonal of a list of irrationals might berational.I consider more the consideration of the set of all bitstrings. Theredoes not exist a sequence different from each of those bit strings, orit would be an element of that set.Consider not the list, but the set of all bitstrings. There does notexist a sequence different from each of those bitstrings, else itwould be an element of that set. By various fiats (axioms) or as Iclaim theorems of a null-axiom theory, the set of all reals is a set,and enumerable. Thus, where the set of bitstrings represents allreals, there does not exist a sequence different than each. A rose isa rose is a rose.That leads into a concern about the list of all infinite bit strings,formed by enumerating the abovementioned set, that the constructionitself of some other bitstring would fail to be everywhere different.Because of the representation of such a set, necessarily inclusive ofall possible bit strings, the antidiagonal process simply generates aset with the same value yet a differing representation. This is whatwe see in the case of the reals and the singular antidiagonal for anyenumeration, with dual representation of rationals.In a sense the conclusion of the antidiagonal process leads to dualrepresentation.For the Equivalency Function only the binary antidiagonal is allowed. The nested interval conditions do not hold. Present another reasonwhy you claim no mappings exist between the naturals and unit intervalof reals, indeed, any other. Good luck. === Subject: Re: Antidiagonal, Infinity> Again, in binary there is one and exactly and only one antidiagonal,> if that.Wrong! There are at least a countable number of anti-diagonal algorithms(1)Assume an anti-diagonal binary algorithm, such as that based on the two digit operations that guarantee a result with unique binary representation not already listed.(2) Apply it to your list and make a new list with this number first followed by the rest of the list is its originally given order.(3) go to (1)Each iteration will produce a number not in any previous lists, and countably many iterations are possible. === Subject: Re: Antidiagonal, InfinityYou say there are multiple antidiagonals because you generate anantidiagonal, and then add that to the list and diagonalize a newlist. If you keep generating antdiagonals that way, they aren't ofthe original list, which has one and exactly one binary antidiagonal.I think more about the antidiagonal of an infinite list ofparticularly all possible sequences of binary elements.This concept is that if a set contains every possible permutation,then no method exists to get a different permutation, because it wouldinstead be one of the possible permutations instead of different.With something like the binary sequences that represent reals, aset-wise antidiagonalization method is something like this:R[0,1] existsthere exists a, a is an element of R[0,1]there exists x_1, x_1 is an element of R[0,1]a is different than x_1 in the 1'st integral modulus after zerothere exists x_2, x_2 is an element of R[0,1] x_1a is different than x_2 in th 2'nd integral modulus after zeroThen, so on and so forth for each n'th element of R[0,1]there exists x_n, x_n is an element of R[0,1] x_1 U ... U x_n-1a is different than x_n in the n'th integral modulus after zeroThen for each element x of R[0,1], some n'th element of x is not equalto the n'th element of a. Where a is an element of R[0,1], that leadsto a problem that some n'th element of a is not equal to itself. Oneway to resolve that contradiction is to say that a doesn't exist as anelement of R[0,1].In extending from R[0,1] to R, the unit interval of reals to allreals, much the same procedure and conclusion results, except wherebefore a could be some real outside of the unit interval, in extensionto all reals a can not be a real.Another possible conclusion is to allow that a, while being differentthan each as described, is yet the same, for example via dualrepresentation of rationals whose denominator is a power of the base.Thus, either a does not exist or a is dually represented. Why wouldthat not be so? Alternatively, as the reals are uncountable, youmight say, or infinite, x_n, is never the last element of the reals toaffect the antidiagonal, yet x_n is always itself.One special feature of the reals is that each bit string represents areal on the unit interval, yes even that one.Many reals have multiple representations, the antidiagonal always hasone of the unused representations, else it would not be a real. Inthat sense a list of rationals might have a dually represented value aa rational or be irrational, or the antidiagonal of all irrationals isnecessarily rational, which is somewhat surprising, unless someirrational has dual representation.Select an integer between one and ten that is not 1, 2, 3, 4, 5, 6, 7,8, 9, or 10. Is your answer oo+4?In examining the process itself, it's necessary to explain howsomething can be different than everything, including itself, orperhaps more agreeably, that it's not. === Subject: Calculus BooksI'm looking for a good book on calculus. I'm interested in a bookthat's sort of the equivalent to Feynman Lectures of Physics in theCalculus world. I currently have books by Stein, Edwards, andStewart. This books are good in a practical sense; however, I wantsomething more insightful. It has to be rigourous, but at the sametime have good explanations. I don't mind if it's wordy. I've heardApostol and Spivak's books are a good choice. I've actually seenApostol and it looks promising; however, this opinion is based onreading the preface and a quick look through the chapters (no morethan a half-hour). Any suggestions? === Subject: Re: Calculus Books> I'm looking for a good book on calculus. I'm interested in a book> that's sort of the equivalent to Feynman Lectures of Physics in the> Calculus world. I currently have books by Stein, Edwards, and> Stewart. This books are good in a practical sense; however, I want> something more insightful. It has to be rigourous, but at the same> time have good explanations. I don't mind if it's wordy. I've heard> Apostol and Spivak's books are a good choice. I've actually seen> Apostol and it looks promising; however, this opinion is based on> reading the preface and a quick look through the chapters (no more> than a half-hour). Any suggestions?Calculus by Michael Spivakhttp://www.amazon.com/exec/obidos/ASIN/0914098896/qid= 1082162810/sr=2-3/ref=sr_2_3/102-1387591-6151359 === Subject: Re: y=tan(x)-x => x=?>y=tan(x)-x => x=? (in terms of y ...)>Not an elementary function.Of course there are series solutions>such as x = v - (2/15) v^3 + (3/175) v^5 - (2/1575) v^7 ->(16/202125) v^9 + ... where v = (3 y)^(1/3). You can also use>Newton's Method and the like.>For this case, due to x-shift and other branches, when not added that>way, is there a way to get all solutions?>Yes. All solutions are given by> x = k*pi + v - 2/15*v^3 + 3/175*v^5 - 2/1575*v^7 - 16/202125*v^9 + ...>where v = (3*(y + k*pi))^(1/3).> As RI has pointed out below, the series above has a small radius of> convergence. Nonetheless, the answer to GLN's question is still Yes.> I should have said:> Let F(x) = tan(x) - x, -pi/2 < x < pi/2, and let G be its inverse function.> Then all the solutions of y = tan(x) - x are given by> x = k*pi + G(y + k*pi), k integer.>The trouble with this method is that the series does not seem to>converge rapidly unless v is small.> I wouldn't expect it to converge at all unless |v| < (3 pi)^(1/3).> So my comment above was, at best, a gross understatement of the trouble.> Note that if f(x) = tan(x)-x, f'(x) = tan^2(x) = 0 when x = Pi,> and f(Pi) = -Pi.> Hmm. I had thought, in getting the series, that you had been thinking of a> function with domain (-pi/2, pi/2), in other words, my F(x) above. Then> x = pi would not be pertinent.> So an inverse for f should have a singularity at y = -Pi.> ??? G(y) has no singularity at y = -pi.It depends on which branch. Note that (the complex version of) f is a three-to-one function in a deleted neighbourhood of 0, so f^(-1) is a multivalued function. On one of the sheets there's a singularity (actually a branch point) at y=-Pi, and on one there's a branchpoint at y=Pi.Robert Israel israel@math.ubc.caDepartment of Mathematics http://www.math.ubc.ca/~israel University of British Columbia Vancouver, BC, Canada V6T 1Z2 === Subject: Re: Q: Orbital Intercept by support1.mathforum.org (8.11.6/8.11.6/The Math Forum, $Revision: 1.9 primary) id i3H21qc08209;Is there any chance you could help me out with this problem? === Subject: Re: Resistance to Change by support1.mathforum.org (8.11.6/8.11.6/The Math Forum, $Revision: 1.9 primary) id i3H21sB08270;They laughed at Einstein. They laughed at the Wright Brothers. But they> also laughed at Bozo the Clown. -- Carl Sagan>It seems that the correct quotation is:But the fact that some geniuses were laughed at does not imply that all >who are laughed at are geniuses. They laughed at Columbus, they laughed >at Fulton, they laughed at the Wright brothers. But they also laughed at >Bozo the Clown.>Jose Carlos SantosMight we take this one step futher?But the fact that some normal people get laughed at because theychoose to act as if they were stupid does notimply that all who are laughed at are not bonafied idiots. They laughed at Bozo the Clown, they laughed at the Three Stooges. But they also laughed at G.W. Bush. === Subject: Re: PDE literature by support1.mathforum.org (8.11.6/8.11.6/The Math Forum, $Revision: 1.9 primary) id i3H21ov08151;>I'm doing some work concerning numerical solution of PDE problems,>mainly problems for parabollic equations (heat, convection-diffusion).>Also interested in singularly perturbed problems.>Can anyone give a hint, where can I download some general literature>on these topics (actually i need free downloads): problems>formulation, correctness conditions, physical sense etc. ?>Any hint would be appreciated.when you first get on math forum, go to internet mathematics librarysome of the subcategories under differential equationshave links to on line journals === Subject: Re: another boring critisism of Cantor's Theorem> Could you explain why V can't be countable? Certainly you can't> prove that in any consistent first order formalism for which the> Loewenheim Skolem theorem applies.>It's a triviality to prove V can't be countable in ZFC. The>Loewenheim-Skolem theorem says that if ZFC is consistent, it has a>countable model. But that's not V.>Philosophically speaking, if we are discorsing in the first-order>language of set theory and uttering theorems of ZFC, we can always>suppose, without making any of our theorems false, that our discourse>is relative to a countable model. But as I say, that's different to>saying V can be countable.>Somehow, I don't think you explained anything. You merely restated>what you said the first time.>If you can prove V exists, you can prove that it is countable>relative to some meta-language. But you claim otherwise. Why?>I suppose I should admit that I don't know a great deal about>this topic, but you have hardly increased my knowledge of it.> If ZFC is consistent, and we are uttering theorems of ZFC in the> first-order language of set theory, we can always entertain the> possibility, without making any of our theorems false, that our> discourse, let's call it the object language, is relative to some> countable model. Then a metalanguage will be available in which what> we referred to as V in our object language, will now in fact be> countable. This possibility *may* hold of our language, I don't think> it *has* to hold, this may be a point of difference between us.> But in any case, you have to decide what language you're talking in.> Whether you're talking in the object language or the metalanguage, it> won't be true that V is countable. In both the object language and the> metalanguage, all theorems of ZFC are true, and it's a trivial theorem> of ZFC that V is not countable.> But then, just like the original thing only _seemed_ uncountable,> but in reality countable, your 'meta world' could also be only> seemingly uncountable, but be 'meta-meta' countable.> Or do i miss something?> Herman JurjusWe can always entertain the *possibility* of any language that itssemantics is relative to a model which is correctly called countablein some metalanguage. I don't think this possibility always has tohold. === Subject: lim inf (-1, 1/n)if A_n = (-1/n,1] if n is odd, and A_n = (-1, 1/n] if n is even thenlim sup A_n is (-1,1) and lim inf A_n is 0where lim sup is defined as intersection of unions and lim inf isdefined as union of intersections. === Subject: Re: lim inf (-1, 1/n)>if A_n = (-1/n,1] if n is odd, and A_n = (-1, 1/n] if n is even then>lim sup A_n is (-1,1) and lim inf A_n is 0>where lim sup is defined as intersection of unions and lim inf is>defined as union of intersections.Almost. The lim sup and lim inf are respectively (-1, 1] and {0}. I suspect your answer for the lim inf is just a matter of notation. Do you see why 1 is in the lim sup? (Or was there a typo in your proposed answer?)Cite sources of help on submitted homework. === Subject: A question on third order linear differential equationsLet x_1, x_2 be linearly independent sols. of a third order homogenouslinear differential equation. Is there a method for finding a third sol. x_3such that x_1, x_2 and x_3 are linearly independent? === Subject: Re: A question on third order linear differential equations>Let x_1, x_2 be linearly independent sols. of a third order homogenous>linear differential equation. Is there a method for finding a third sol. x_3>such that x_1, x_2 and x_3 are linearly independent?Yes. See reduction of order in just about any book on differentialequations. (Not a math book, an elementary text - might not bein a theoretical math book but it's in all the texts.) That's usuallypresented as a way to get a second solution to a second-orderequation given one solution, but you should have no troubleextending it to your problem. === Subject: Re: A question on third order linear differential equations>Let x_1, x_2 be linearly independent sols. of a third order homogenous>linear differential equation. Is there a method for finding a third sol.x_3>such that x_1, x_2 and x_3 are linearly independent?> Yes. See reduction of order in just about any book on differential> equations. (Not a math book, an elementary text - might not be> in a theoretical math book but it's in all the texts.) That's usually> presented as a way to get a second solution to a second-order> equation given one solution, but you should have no trouble> extending it to your problem.Well, I have trouble extending it. It ends up with a second order linearequation in an unknown function which I don't know how to solve. === Subject: Re: A question on third order linear differential equations>Let x_1, x_2 be linearly independent sols. of a third order homogenous>linear differential equation. Is there a method for finding a third sol. x_3>such that x_1, x_2 and x_3 are linearly independent?It suffices to find linear independent initial conditions:Let P1 = (x_1(0),x_1'(0),x_1''(0)) and P2 = (x_2(0),x_2'(0),x_2''(0))just find a point P3 = (x_3(0),x_3'(0),x_3''(0)) that does not lie inthe Span of P1 and P2. That should be easy using methods from linearalgebra. P3 uniquely determines a solution that satisfies yourcondition. === Subject: Re: A question on third order linear differential equationsBut I want a 'formula' in terms of x_1, x_2 and the coefficients of theequation, just like the formula in second order case.>Let x_1, x_2 be linearly independent sols. of a third order homogenous>linear differential equation. Is there a method for finding a third sol.x_3>such that x_1, x_2 and x_3 are linearly independent?> It suffices to find linear independent initial conditions:> Let P1 = (x_1(0),x_1'(0),x_1''(0)) and P2 = (x_2(0),x_2'(0),x_2''(0))> just find a point P3 = (x_3(0),x_3'(0),x_3''(0)) that does not lie in> the Span of P1 and P2. That should be easy using methods from linear> algebra. P3 uniquely determines a solution that satisfies your> condition.> Thomas === Subject: new st. mary's college moraga, ca observatory 21 pics. this is not a observatory it's a silo for 2 nuke missilesnew st. mary's college moraga, ca observatory 21 pics. http://community.webshotshttp://community.webshots.com/user/ nightstarsmoragahttp://tinyurl.com/2k5zslat 37.8404881 long -12210355 this is not a observatory it's a silo for 2 nuke missiles === Subject: Re: new st. mary's college moraga, ca observatory 21 pics. this is not a observatory it's a silo for 2 nuke mis === >Subject: new st. mary's college moraga, ca observatory 21 pics. this is not a>observatory it's a silo for 2 nuke mis>new st. mary's college moraga, ca observatory 21 pics. >http://community.webshots>http://community.webshots.com/user/ nightstarsmoraga>http://tinyurl.com/2k5zs>lat 37.8404881 long -12210355 >this is not a observatory it's a silo for 2 nuke missilesOne missle per silo, idiot.Although it could have multiple warheads. === Subject: Re: Angular measure3/10 === Subject: Re: functions that halt <9o04l1-jgu.ln1@lexi2.athghost7038suus.net> <407f780e$0$4548$afc38c87@news.optusnet.com.au <4080091c$0$567$b45e6eb0@senator-bedfellow.mit.edu>Tell me what the 'next' real is in any set of reals. You can't.> I don't understand your argument. Surely it is not:> 1. In the natural ordering of the reals, there is no next real after> any given real. Therefore the reals are uncountable.> That's certainly fallacious, as may be seen by replacing real byrational. So maybe you mean: He's not talking about a 'next' real in a total ordering of real values, but talking about the 'next' real that exists in the enumeration of the reals (in the case that they are listable/countable) For the rationals, there is definitely a next rational when one orders them in that standard way (in which I'm sure you are familiar... it is almost always used when showing the rationals are countable.) === Subject: Re: functions that haltOriginator: tchow@lagrange.mit.edu.mit.edu (Timothy Chow)> He's not talking about a 'next' real in a total ordering of real values, >but talking about the 'next' real that exists in the enumeration of the >reals (in the case that they are listable/countable)My point is that Cantor's diagonal argument does *not* show that thereals cannot be ordered in such a way that there is always a 'next'real after any given real. By saying that you can't name the 'next'real after pi in this context, the writer sounds like he's confusingthe well-orderability of the reals with their uncountability.Tim Chow tchow-at-alum-dot-mit-dot-eduThe range of our projectiles---even ... the artillery---however great, willnever exceed four of those miles of which as many thousand separate us fromthe center of the earth. ---Galileo, Dialogues Concerning Two New Sciences === Subject: Re: functions that halt <4080091c$0$567$b45e6eb0@senator-bedfellow.mit.edu My point is that Cantor's diagonal argument does *not* show that the> reals cannot be ordered in such a way that there is always a 'next'> real after any given real. By saying that you can't name the 'next'> real after pi in this context, the writer sounds like he's confusing> the well-orderability of the reals with their uncountability. That wasn't my interpretation at all... it sounded like the author was relating the countability/uncountability of a set with its property of being listable (with a first element), which is entirely acceptable. (But I do agree that asking what number comes next 'after pi' is kind of irrelevant... as there will exist a one-to-one correspondence of a set like the rationals with any rational at all after some given rational, a/b. The only possible answers to his question were any real you want or no real at all.) === Subject: Re: functions that halt>Tell me what the 'next' real is in any set of reals. You can't.> I don't understand your argument. Surely it is not:> 1. In the natural ordering of the reals, there is no next real after> any given real. Therefore the reals are uncountable.> That's certainly fallacious, as may be seen by replacing real byrational. So maybe you mean:> He's not talking about a 'next' real in a total ordering of real values,> but talking about the 'next' real that exists in the enumeration of the> reals (in the case that they are listable/countable)> For the rationals, there is definitely a next rational when one orders> them in that standard way (in which I'm sure you are familiar... it is> almost always used when showing the rationals are countable.)I think the problem is that you can't distinguish a computable real froman uncomputable one.You can write down some specifications (for reals) that areuncomputable, but I think you can't decide whether the real thatfulfills that spec just might happen to be a fraction of square roots orsome such (precisely because you can't compute it and so check). Atleast all the examples I have seen were of that kind.So if someone does not accept the proof that the cardinality of reals islarger than the cardinality of computable numbers (which can be listedby listing all programs), what can you use to convince him?The diagonalisation proof attempts to construct such a number which iscomputable outside of the formal system that is the Turing Machine it isapplied to.(Re)reading http://www.abelard.org/turpap2/tp2-ie.asp might be a goodidea; I did, and was surprised that computable numbers must be computedby Turing machines that keep on producing output infinitely...MichaelFeel the stare of my burning hamster and stop smoking! === Subject: Re: functions that halt E29yc_kQC&^> I think the problem is that you can't distinguish a> computable real from an uncomputable one.I'm not sure what you mean here. If you can describe anumber and prove that it's not computable, that counts asdistinguishing it in my book. If it's one of the uncountablenumber of reals that we can't even describe, you'd probablybest appeal to Wittgenstein.> You can write down some specifications (for reals) that> are uncomputable, but I think you can't decide whether the> real that fulfills that spec just might happen to be a> fraction of square roots or some such (precisely because> you can't compute it and so check). At least all the> examples I have seen were of that kind.No: all the proofs of uncomputability I can think of provethat a number really isn't computable. For example the realB defined as 0.bbbbb... where the n'th bit is 1 iff theprogramme with G.9adel number n halts is not computable. If itwere, then one could use another programme that tookprogrammes as argument, G.9adel encoded them and indexed B asa solution to the halting problem. Note that the proof saysnothing to specify the reason behind computing B; thecontradiction would arise if /any/ programme could compute Bin any fashion. So B isn't a fraction of the square root ofanything computable.> So if someone does not accept the proof that the> cardinality of reals is larger than the cardinality of> computable numbers (which can be listed by listing all> programs), what can you use to convince him?It depends on why they don't accept it. If they are arguingthat numbers such as B above have no meaning in nature, orthat the universe we inhabit is constructed entirely on acountable basis there is no way to refute that. I don'tthink we know a single physical constant to more than a fewbillion digits. Besides, every axiomatisation of the realshas a countable model; in a sense we cannot really escapefrom our discrete means of expressing mathematics.Also, from a practical point of view, if the someone is tooobtuse there may be nothing that will convince him.[1] FSVO the. We have to pick a particular notion ofcomputation and a particular G.9adel encoding -- so in factthere's a (countable) infinity of Bs...[2] I'm allowing for a certain amount of future scientificeffort here. J.97n Fairbairn Jon.Fairbairn@cl.cam.ac.uk === Subject: FW: Smart way to l0se the 1bs.. boundary=--5453756934327096 by support1.mathforum.org (8.11.6/8.11.6/The Math Forum, $Revision: 1.9 primary) with ESMTP id i3H7DgR08162; by support2.mathforum.org (8.11.6/8.11.6/The Math Forum, $Revision: 1.6 secondary) with SMTP id i3H7DJt26596;X-CS-IP: 220.116.200.78------------------------------------------------ ---------------------As seen on NBC, CBS, and CNN, and even Oprah! The health
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space as in general relativity. Whitehead showed you could do> relativity in flat space. It's all a device for thinking about things--Give Earth a Trickier Dick Cheeny -- out of office, after GIGA years.http://www.benfranklinbooks.com/http://www.rand.org/ publications/randreview/issues/rr.12.00/http:// members.tripod.com/~american_almanachttp://www.wlym.com/pdf/ iclc/howthenation.PDF === Subject: Re: Yao Ziyuan's Conjecture :-)> Yao Ziyuan's Conjecture> After a simple search within 100,000, Yao Ziyuan from Fudan University> found that only 4, 6, 8, 12 (even number) can be represented as the> sum of one and only one pair of primes. So he made another conjecture> one representation of different pairs of primes. LOL.> This practice demonstrated that we can easily make as seemingly> beautiful conjectures as the Goldbach one, as many as possible. This> lowers the uniqueness of the Goldbach conjecture and makes it much> less significant to prove merely one such conjecture, even if it is> eventually proven.nbr could be represented as the sum of two prime nbrs. I seem toremember that the largest nbr which could only be represented in twoways was 68.But more interestingly, apart from a long term rising trend inrepresentations, I found that the nbr of representations rose and fellwith a period of 3, so that 400 might have 5 representations, say,then 402 7, then 404 8, then 406 back to say 5, 408 8 , 410 9. Thesefigures are purely made up just by way of an illustration.Unfortunately I threw the details out a long time ago. === Subject: sheaf of functions using certain schemes....I need help on the following algebraic geometry exercise:Describe the points and the sheaf of functions on the followingschemes:(1) X = Spec C[x]/(x^2)(2) X = Spec C[x]/(x^2-x)(3) X = Spec R[x]/(x^2+1)I think I can probably handle any two of these given a discussion ofhow to solve the other one, but my class is so abstract that I'mhaving a hard time applying the definitions and actually computingthese sheaves and points..... === Subject: Re: (phi(m)+1) divides m> Let phi(m) > be the number of positive integers <= m and relatively prime with m.> I get, by hand, that the sequence of m's where> (phi(m)+1)|m> begins> 2, 3, 5, 6, 7, 10, 11, 13, 14, 17, 19,..> (Not in the EIS, apparently.)> What can be said about this sequence, such as its asymptotics, the> best way to determine if an integer is in it, etc ?Note that m = r (phi(m) + 1) can be rewritten m/r - 1 = (phi(m) / phi(m/r)) phi(m/r)If there are solutions other than m = p, m = 2p for p prime,phi(m) / phi(m/r) will be an integer greater than 1, and thenyou have a solution to the famous Lehmer's problem.---J K Hauglandhttp://www.neutreeko.com === Subject: Re: (phi(m)+1) divides m>According to Maple, these are all the members of the sequence up to 10000.According to Excel, there are no exceptions up to 20,000,000.John Robertson === Subject: Re: Yikes! I've Broken Incommensurability!> [snippity snip]> A> _______> | /> | /> | /> B | / C> | /> | /> |/> O> [Hope it displays correctly, I keep> changing my newsreader font to> fixed, but it doesn't stay, and I'm> 'tired' of changing it :-]> Imagine lower vertex at the center> of the circle, and the upper two ver-> tices on the circumference of the> Circle - all as the central angle is> varied 0 - 360 [0 to 2pi radians].> Errr...> Nope.> As you've described it, side B is a radius.side C is the radius. === Subject: Re: Yikes! I've Broken Incommensurability!> [snippity snip]> A> _______> | /> | /> | /> B | / C> | /> | /> |/> O>[Hope it displays correctly, I keep>changing my newsreader font to>fixed, but it doesn't stay, and I'm>'tired' of changing it :-]>Imagine lower vertex at the center>of the circle, and the upper two ver->tices on the circumference of the>Circle - all as the central angle is>varied 0 - 360 [0 to 2pi radians].> Errr...> Nope.> As you've described it, side B is a radius.> side C is the radius.Sorry, in my earlier post, I wasn't clear. WhatI meant was that side A and side C share avertex that is a point on the Circle.At the 'instant' of the diagram, above, side Ais the semi-chord. Side B extends from thecenter of the Circle to meet side A at 90.Forgive me, please. === Subject: Re: Simple differential equation query >Given the following equation eliminate the arbitrary constant: >1. x^3 - 3*(x^2)*y = c >Ok, differentiate both sides giving: 3x^2 - 6xy -3(x^2)y' = 0 >DIVIDE THROUGH BY 3X: x - 2y - xy' = 0 >Rearrange: (x-2y)dx - x dy = 0 (= answer given in the book) >[Q] But why can we be sure x != 0 ?! (and divide through by it?)If x can ever take the value 0, then c = 0. So handle c = 0 as aspecial case, which makes y = x/3 when x /= 0 and anthing when x = 0.In the event that y is continuous then y = x/3 and again x - 2y - xy' = 0which is the desired result for is it not stipulated for theproblem series that y is differentiable, hence continuous? >2. cy^2 = x^2 + y >DIVIDE THROUGH BY Y^2: c = (x^2 + y)/y^2 >Differentiate both sides and simplify: [ 2xy dx - (y+2x^2) dy ] / >y^4 = 0 >Now multiply both sides by y^4 and we're done. >[Q] But why can we be sure y != 0 ?!cy^2 = x^2 + y2cyy' = 2x + y'2cyyy' = 2xy + yy'2(x^2 + y)y' = 2xy + yy'2x^2 y' + yy' = 2xyLook, no division!---- === Subject: Limit PointsIn a metric space what are the limit points of {x}?Is the definition different for topological spaces?---- === Subject: Re: Limit PointsA point x is a limit point of a set if every open ball centered at xcontains a point in that set different from xit can be proved that a finite set doesn't have any limit points, so {x}doesn't have any limit points> In a metric space what are the limit points of {x}?> Is the definition different for topological spaces?> ---- === Subject: Re: Limit Points> A point x is a limit point of a set if every open ball centered at x> contains a point in that set different from x> it can be proved that a finite set doesn't have any limit points, so {x}> doesn't have any limit points> In a metric space what are the limit points of {x}?> Is the definition different for topological spaces?> ----Interestingly, a nonempty finite set is closed, meaning it containsall its limit points. Therefore, it contains all its limit pointssince it does not have any! === Subject: Re: Limit Points> In a metric space what are the limit points of {x}?The set {x} has no limit points. To say that y is a limit pointof {x} is to say that y belongs to the closure of {x} y, whichis the empty set if y = x and it is equal to {x} otherwise.> Is the definition different for topological spaces?Perhaps that some textbooks say that in a metric space a pointx is a limit point of a set S if, for every r > 0, the setB(x,r) x has some element of S, but this is equivalent tothe general definition. === Subject: Re: Limit Points> In a metric space what are the limit points of {x}?> The set {x} has no limit points. To say that y is a limit point> of {x} is to say that y belongs to the closure of {x} y, which> is the empty set if y = x and it is equal to {x} otherwise.> Is the definition different for topological spaces?> Perhaps that some textbooks say that in a metric space a point> x is a limit point of a set S if, for every r > 0, the set> B(x,r) x has some element of S, but this is equivalent to> the general definition.Exactly. However at Ask-a-Topologist web site, students there actas tho limit point is same as adherence point, ie closure point.Arggg, are they getting that errant notion from their text book? === Subject: Re: Limit Points>In a metric space what are the limit points of {x}?> The set {x} has no limit points. To say that y is a limit point> of {x} is to say that y belongs to the closure of {x} y, which> is the empty set if y = x and it is equal to {x} otherwise.>Is the definition different for topological spaces?> Perhaps that some textbooks say that in a metric space a point> x is a limit point of a set S if, for every r > 0, the set> B(x,r) x has some element of S, but this is equivalent to> the general definition.> Exactly. However at Ask-a-Topologist web site, students there act> as tho limit point is same as adherence point, ie closure point.> Arggg, are they getting that errant notion from their text book?Unfortunately, different texts have different definitions for limit point.Personally, I prefer to use accumulation point, boundary point,or cluster point (depending on what I mean) and avoid the ambiguous term.G. A. Edgar http://www.math.ohio-state.edu/~edgar/ === Subject: Re: Limit PointsI thought there were inconsistent definitions out there. For some, a limit point and an accumulation point are the same thing; for others not. For some, x is a limit point of {x}; for others, not. Am I wrong in this impression? === Subject: Re: Limit Points> I thought there were inconsistent definitions out there. For some, a > limit point and an accumulation point are the same thing; for others > not. For some, x is a limit point of {x}; for others, not. Am I > wrong in this impression?Perhaps not. BTW, did you see the definition of limit point atMathWorld? See:http://mathworld.wolfram.com/LimitPoint.htmlIt has only two sentences. The first one gives the same definition formetric spaces that I gave in my previous post. But the second one, forgeneral topological spaces, seems to be in contradiction with the firstone; I write seems because the expression open set around it looksambiguous to me (but then, I may be wrong; english is not even my secondlanguage). === Subject: Re: Limit PointsOK, I have surveyed thre analysis and topology books (list of the nine of them available on request) on my shelf. Some of these limit themselves to Euclidean space and others to metric spaces; the remainder refer to general topological spaces.All texts that mention the terms say that an accumulation point, also called a cluster point, is a point approached by a sequence of points that differ from the point in question. All but two also define a limit point as the same thing. Amongst the other two, one does not mention the term limit point at all. The other, Goldberg, Methods of Real Analysis, defines a limit point as one approached by *any* sequence of points in the set. Goldberg limits his discussion to metric spaces.Thus, for Goldberg, x is a limit point, but not a cluster point, of {x} For the others, in a T1 space, no point is a limit point of {x}. === Subject: Descending setsLet { A_xi } be a descending transfinite series of subsets ofA = A_0 with the property for all eta, xi < eta, A_eta subset A_xiLet |A| = omega_nu and mu = omega_(nu+1)Without loss of generality we can not have A_eta = /{ A_xi | xi < eta }for limit ordinals eta? / = cap = intersectionShow A_mu = A_(mu+1).Often there's some eta < mu with A_eta = A_(eta+1).Dare one conjecture that will always be possible?In particular if I and the transcendent transfinite spirit of Zenostubbornly persist to remove single elements from A, how soon will it beemptied? At A_mu or before?Then after lunch, one by one we'll put the elements back and for dinnerconservation, talk about how we reversed an ordinal. Tomorrow we'll usethis process to smuggle a set across the universe. ;-)---- === Subject: Re: Formal Languages Question Now I am having trouble expressing the language S->aSSb | e with an> expression such as a^n b^k so that i can use the lemma.> I doubt whether you need the whole language (as a set defined by some> predicate). Is some useful characteristic, single sentence such as> e.g.,> z = a^k b^k a^k b^k> (where k is the number provided by the pumping lemma) not enough?> Of course, you have to show that z can be generated by S->aSSb | e.> But that is not a serious problem.Not serious? Then you make jest?Nay, show how to produce a^k b^k a^k b^k. === Subject: Re: Formal Languages QuestionI just found out that the language i gave is actually the language of balanced parenthesis. So the question now is to prove that the language of balanced parenthesis is not a linear cfl one. === Subject: Show that a polynimial is reducible. How?i have two question: 1 - show that 2 x^9 -2 x^6 is reducible in Z5 2 - show that x^3 + 2 x^2+ x +2 is reducible in Z5[x]does anyone know how to solve these to question ?/Peter === Subject: Re: Show that a polynimial is reducible. How?1 - 2x^9-2 x^6 = (2 x^6) (x^3-1)2 - x^3+2 x^2+x+2=(x^2+1)(x+2)Bye. === Subject: Factorisation!I'm very interessted in factorisation algorithms, but as pupil inhighschool it's very difficult to get information to this topic Iunderstand. Can somebody explain following algorithms to me:[Eth] Brent algorithm[Eth] Pollard method[Eth] Williams method[Eth] Lenstra algorithm[Eth] Quadratic sieve method[Eth] ...If somebody has source code [C,...] I would like to get it. === Subject: Re: Factorisation> !> I'm very interessted in factorisation algorithms, but as pupil in> highschool it's very difficult to get information to this topic I> understand. Can somebody explain following algorithms to me:On top of Riesel and C&P, as mentioned by others, you'll wantDavid Bressoud, Factorization and Primality TestingDonald Knuth, The Art of Computer Programming, Vol 2. Seminumerical Algorithms> ? Brent algorithm'Rho'? Best covered in Riesel. C&P and Knuth OK too.> ? Pollard method'P-1'? Well covered in all of them.> ? Williams method'P+1'? Best covered in C&P> ? Lenstra algorithm'ECM'? Best covered in C&POne hint - become fluent with P-1 first, and P+1 and ECM will simply drop out as logical progressions. > ? Quadratic sieve methodBest covered in Bressoud and C&P> ? ...C&P and Riesel.> If somebody has source code [C,...] I would like to get it.There's pseudocode in all of them.However, get Mike Scott's Miracl bignum library as it has fairly competant C implementations of all of the above. www.indigo.ie? They aren't just good implementations, they are ones that you can learn from -- totally lucid code.Phil1st bug in MS win2k source code found after 20 minutes: scanline.cpp2nd and 3rd bug found after 10 more minutes: gethost.cBoth non-exploitable. (The 2nd/3rd ones might be, depending on the CRTL) === Subject: Re: Factorisation> !> I'm very interessted in factorisation algorithms, but as pupil in> highschool it's very difficult to get information to this topic I> understand. Can somebody explain following algorithms to me:> .89 Brent algorithm> .89 Pollard method> .89 Williams method> .89 Lenstra algorithm> .89 Quadratic sieve method> .89 ...> If somebody has source code [C,...] I would like to get it.A good book is Prime Numbers and Computer Methods for Factorization by Hans Riesel,which covers all these I believe. There is also a more recent bookPrime Numbers A Computational Perspective by Crandall and Pomerance, which is excellent.Chris === Subject: Re: FactorisationBTW, I am sure that your high school library could easily get these booksfor you through an inter-Library loan, and Librarians usually love helpingwith this sort of thing.> !> I'm very interessted in factorisation algorithms, but as pupil in> highschool it's very difficult to get information to this topic I> understand. Can somebody explain following algorithms to me:> . Brent algorithm> . Pollard method> . Williams method> . Lenstra algorithm> . Quadratic sieve method> . ...> If somebody has source code [C,...] I would like to get it.> A good book is Prime Numbers and Computer Methods for Factorization by> Hans Riesel,> which covers all these I believe. There is also a more recent bookPrime Numbers A Computational Perspective by Crandall and Pomerance,> which is excellent.> Chris === Subject: Re: who is captain in here?hot-girl (math2050@yahoo.co.kr)asked one of the hottest questions, not only for sci.math. :who is captain in here? where is sci.math server? who is a administrator? I wonder about how to operate sci.math.here is miraculousIt's question is still not properly answered, and important for all ofus !What made me angry - and frightened, was the letter frommensanator@aol.com.But first: hot-girl - is it a girl, or a boy, does this matter?(I like science fiction, so just a thought, may be it's acomputer-being,feeling lonely, asking :anybody there ...??, no reply - Sorry, iwasn't online that time.)It thinks, all other beings in sci-math. are male, writing:Sir...perfect genius...Female contributed much to math and science, often propagated by malesas their own ideas.(It's now under investigation, what the mother ofEinsteins first child gave to him - and what he made out of this, andwhat he did to her and his child).hot-girl, You are one of my teachers, You teach and Your questionsare even more educative for me. (My level: after more then 30 years ijust finished the basics of complex numbers, by finding that theimaginary axis is only another word for the second axis or y-axis,that there is no mathematical definition for it, it's not more and notless imaginary than the first or x-axis. So now i proceed toelementary functons in 2D. I'm like a snail reaching the first flooron a ramp of a parking garage). You are ahead of me, but may You canlearn from me too, as i learned some basic facts.What i know is, that math should never lead to numerology, like thismensanator did (he is either bad or a very poor-soul orboth).Mensanator is ignorant and uneducated. He wants to impress us orto frighten us with his words about a beast and the number 666.He doesn't know, that 6 is a lucky number for many sin-people.In the western sphere, You have the bible, the Christians have asecond part , the New Testament and in its last chapter, theApocalypsis Ioannis (http://apokalypse.de.ki) there is this beast= one manifestation of the devil or an evil person with supernaturalpowers. You can compare it to the white-bone-ghost in Sun-Wu-Kung(sometimes a beautiful young girl and sometimes a death-bringingsceleton). And 666 is the name of the beast encoded in a number.Inthis chapter is a lot of numerologie. Would You be impressed, ifsomeone tells You, that the number in Your address: 2050 has themeaning of the year, when You are going to die ?No, that's rubbish! Nobody can know these things. May be its just theyear, in which some of your question are answered.When people can not talk free, they use encoded language. Like with I Ging a military-general can give his son information, how toarrrange troops in the next battle.One can frighten people, who never learned to count, with numbers.Most probably women invented counting, by associating their menses tothe moon-cycles and to the cycle of the year - counting up to twelveor one further on, and predicting the birth of their babys by countingup to nine moon-cycles from conception. With math one can see into thefuture. It's not a bit miraculous for us any more.administrator, I was helping a guy with an e-mail problem and noticedhe used the salutation chow. Sometimes there just aren't anyexplanations. And Stephen replied: I think the explanation for thatnose high up :Mensanator ( now under: aol.compost)Yeah, i meant an explanation for how someone can be that dumbWhat kind of esteem this man (or woman) must have of itself ?May be in some languages chow has an explanation.Most people are very kind, just like George Cox.Now i challenge You, mensanator !An admin will know, if there is any captain on top of him, so tellus(may be it's a white Lady?). Considering the importance of theinternet, i would expect that leading figures in powerfulorganisations would like to have power over the net, or really haveit, an admin should know.And what is meant by you have to except the mark of the beast on yourhead or your hand ? - just writing nonsense ?! Why one has to disable a sandbox-protection of his computer (like finjan-safe-zone) inSometimes there just aren't any explanations. But at other times,there are.And now is the time to answer. I give mensanator 24+1 hour for it.(and may be rickO and A,N.Niel can tell us, what they mean by talkingabout a fire-theater , not every english-writing persons isfamiliar with Your personal education).I challenge mensanator - if he doesn't respond, i'll reveal somemathematical truth about the Ace of clubs, he is using like atitle.Just like his pseudonym mensanator:In Rom a senator was one of the older and supposed to be wiserpeople and with some powers to censorship and control, even about warand peace. (Transfer this thought to an admin of the net). And menssana in corpore sano is an latin expression, meaning a healthy soulin a healthy body.Up to now mensanator doesn't seem to live up to his choosen name, maybe he is not allowed to, may be he is a very poor soul. Even the adminof North koreahttp://www.dprkorea.com is more free, opening up to us a bit, allowing his people to read AnneFrank, even keeping his name as second son (and showing in this waythat a number in a hierarchie or family is not a burden for hispersonality)- and fulfilling his duty of preserving the preciousbiosof his peoples Internet from flashing with US-software. Doesmensanator have a name (sometimes there are reasons for anonymposting, i respect it) or is he lacking the powers to reveal it to us,this powerful admin?Does mensanator really wants to be someone, who helps, does hereally have this capacity? Mensanator, this hot-girl deserves betteranswers, be miraculous.....please.....Hero === Subject: Re: who is captain in here? === >Subject: Re: who is captain in here?>hot-girl (math2050@yahoo.co.kr)>asked one of the hottest questions, not only for sci.math. :who is captain in here? where is sci.math server? >who is a administrator? >I wonder about how to operate sci.math.>here is miraculous>It's question is still not properly answered, and important for all of>us !>What made me angry - and frightened, was the letter from>mensanator@aol.com.?>But first: hot-girl - is it a girl, or a boy, does this matter?>(I like science fiction, so just a thought, may be it's a>computer-being,>feeling lonely, asking :anybody there ...??, no reply - Sorry, i>wasn't online that time.)>It thinks, all other beings in sci-math. are male, writing:Sir...perfect genius...>Female contributed much to math and science, often propagated by males>as their own ideas.(It's now under investigation, what the mother of>Einsteins first child gave to him - and what he made out of this, and>what he did to her and his child).>hot-girl, You are one of my teachers, You teach and Your questions>are even more educative for me. (My level: after more then 30 years i>just finished the basics of complex numbers, by finding that theimaginary axis is only another word for the second axis or y-axis,>that there is no mathematical definition for it, it's not more and not>less imaginary than the first or x-axis. So now i proceed to>elementary functons in 2D. I'm like a snail reaching the first floor>on a ramp of a parking garage). You are ahead of me, but may You can>learn from me too, as i learned some basic facts.>What i know is, that math should never lead to numerology, like this>mensanator did (he is either bad or a very poor-soul or>both).Or neither.>Mensanator is ignorant and uneducated. Neither. Check out http://members.aol.com/mensanator>He wants to impress us or>to frighten us with his words about a beast and the number 666.Or maybe entertain. You didn't consider that possibility, did you?>He doesn't know, that 6 is a lucky number for many sin-people.And you call _me_ the numerologist? While you're on my Home Page,be sure to check out The Joy of Six.>In the western sphere, You have the bible, the Christians have a>second part , the New Testament and in its last chapter, theApocalypsis Ioannis (http://apokalypse.de.ki) there is this beast>= one manifestation of the devil or an evil person with supernatural>powers. You can compare it to the white-bone-ghost in Sun-Wu-Kung>(sometimes a beautiful young girl and sometimes a death-bringing>sceleton). And 666 is the name of the beast encoded in a number.In>this chapter is a lot of numerologie. Would You be impressed, if>someone tells You, that the number in Your address: 2050 has the>meaning of the year, when You are going to die ?I would be very depressed if I knew I was going to live that long.>No, that's rubbish! Whew!>Nobody can know these things. May be its just the>year, in which some of your question are answered.>When people can not talk free, they use encoded language. Like with I Ging a military-general can give his son information, how to>arrrange troops in the next battle.>One can frighten people, who never learned to count, with numbers.Good. That gives them motivation to learn, doesn't it?>Most probably women invented counting, by associating their menses to>the moon-cycles and to the cycle of the year - counting up to twelve>or one further on, and predicting the birth of their babys by counting>up to nine moon-cycles from conception. With math one can see into the>future. It's not a bit miraculous for us any more.>administrator, I was helping a guy with an e-mail problem and noticed>he used the salutation chow. Sometimes there just aren't any>explanations. And Stephen replied: I think the explanation for that>nose high up :>Mensanator ( now under: aol.compost)Yeah, i meant an explanation for how someone can be that dumb>What kind of esteem this man (or woman) must have of itself ?>May be in some languages chow has an explanation.Maybe since I actually knew the person, I knew what his intended use was.>Most people are very kind, just like George Cox.>Now i challenge You, mensanator !>An admin will know, if there is any captain on top of him, so tell>us (may be it's a white Lady?).Just because I was a network administrator at some unspecified periodin the past doesn't mean I am still a network administrator. I havegone on to more important and productive work.>Considering the importance of the>internet, i would expect that leading figures in powerful>organisations would like to have power over the net, I used to tell people that I had god-like powers over time and space,but that was just in reference to my local network. The Internet wasbeyond my domain.>or really have it, an admin should know.>And what is meant by you have to except the mark of the beast on your>head or your hand ? - just writing nonsense ?! Ok, I'll explain it so even you can understand it.The story goes that you must have the mark of the beast (666) toengage in transactions. It isn't soecifically stated what this mark actually is. Now assume that a transaction is a math question you wantanswered. Your question must be addressed to sci.math if you want itanswered. As I've shown, scimath=666, so you must stamp your postingswith the mark of the beast. Was that so hard to figure out?>Why one has to disable> a sandbox-protection of his computer (like finjan-safe-zone) inSometimes there just aren't any explanations. But at other times,>there are.>And now is the time to answer. I give mensanator 24+1 hour for it.Or what?>(and may be rickO and A,N.Niel can tell us, what they mean by talking>about a fire-theater , not every english-writing persons is>familiar with Your personal education).>I challenge mensanator - if he doesn't respond, i'll reveal some>mathematical truth about the Ace of clubs, he is using like a>title.Go ahead. I'm sure your lame attempt at humor won't compare tohttp://members.aol.com/mensanator666/2ofclubs/2ofclubs.htmI haven't had a chance to update that page since being promoted fromTwo to Ace (for the amazing feat of getting two usenet trolls ( Harris and T_o_m_P_o_t_t_e_r) to foam at the mouth in one day!>Just like his pseudonym mensanator:>In Rom a senator was one of the older and supposed to be wiser>people and with some powers to censorship and control, even about war>and peace. (Transfer this thought to an admin of the net). And mens>sana in corpore sano is an latin expression, meaning a healthy soul>in a healthy body.Instead of wildly wrong speculation, you could simply ask:mensanator - n. Old Norse 1. slayer of the MensaIn the autumn of 1996, the Mensa were holding theirannual All Hallows Eve Festival, when, unbeknownstto them, a traitor in their midst raised the portcullis of their fortress and allowed a Vikingraiding party to slip in, whereupon they slew theentire host with the jawbone of an ass and carriedoff the great prize.Upon the great warrior chieftan, Paul the Berserk, was bestowed the title Mensantor in honor of that great victory.>Up to now mensanator doesn't seem to live up to his choosen name, may>be he is not allowed to, may be he is a very poor soul. Stupid conclusion based on false premise.>Even the admin of North korea http://www.dprkorea.com >is more free, opening up to us a bit, allowing his people to read Anne>Frank, even keeping his name as second son (and showing in this way>that a number in a hierarchie or family is not a burden for his>personality)- and fulfilling his duty of preserving the preciousbios>of his peoples Internet from flashing with US-software. Does>mensanator have a name Paul the Berserk.>(sometimes there are reasons for anonym>posting, i respect it) or is he lacking the powers to reveal it to us,>this powerful admin?Didn't you just get done saying you respect why some people don't wantto have their real names posted? I have enough trouble with spam to myemail address (which is why you see some messages labeled .compost.Do I have to spell it out that .compost is a feeble attempt at spamblocking?)>Does mensanator really wants to be someone, who helps, does he>really have this capacity? Try doing a Google search on thank+mensanator.>Mensanator, this hot-girl deserves better answers, So if mensanator doesn't deserve respect for using a psuedonym,why should hot-girl _deserve_ better answers? And did I preventanyone else from answering?>be miraculousI was. You wouldn't have been able to figure out how to derive666 from scimath.>.....please.....>HeroIs that you real name? === Subject: Re: who is captain in here?> hot-girl (math2050@yahoo.co.kr)> asked one of the hottest questions, not only for sci.math. :who is captain in here? where is sci.math server? > who is a administrator? > I wonder about how to operate sci.math.> here is miraculous> It's question is still not properly answered, and important for all of> us !> What made me angry - and frightened, was the letter from> mensanator@aol.com.WHOOSH!Wayne Brown (HPCC #1104) | When your tail's in a crack, you improvisefwbrown@bellsouth.net | if you're good enough. Otherwise you give | your pelt to the trapper.e^(i*pi) = -1 -- Euler | -- John Myers Myers, Silverlock === Subject: Re: who is captain in here?===>Subject: Re: who is captain in here?>Message-id: hot-girl (math2050@yahoo.co.kr)> asked one of the hottest questions, not only for sci.math. :who is captain in here? where is sci.math server? > who is a administrator? > I wonder about how to operate sci.math.> here is miraculous> It's question is still not properly answered, and important for all of> us !> What made me angry - and frightened, was the letter from> mensanator@aol.com.>WHOOSH!I guess I was a fool for biting on the troll bait, but at least myreply allowed me to engage in a little shameless self promotion.>-- >Wayne Brown (HPCC #1104) | When your tail's in a crack, you improvise>fwbrown@bellsouth.net | if you're good enough. Otherwise you give> | your pelt to the trapper.e^(i*pi) = -1 -- Euler | -- John Myers Myers, Silverlock === Subject: Re: Resistance to Change>Please substantiate your assertion that the Boyer-Moore paper formally>expresses a proof of the unsolvability of the halting problem. Please>make your explanation self-contained and contain at least a little bit>of detail e.g. what are the formal axioms, rules of inference and>theorem, and the steps that lead from the axioms to the theorem?> I'm beginning to suspect that this is all a big troll - you're making> a fool of yourself just for fun. If not you'd read the friggin paper> before asking questions like this.>Charlie Volkstorf> ************************>Mr. Ullrich,>I am very interested in the subject of axiomaic systems and also the>halting problem. I have read here that several times Charley posted a>link to his paper that shows an axiomatic proof of this theorem and>several other theorems. He also seems to have copied parts of it into>messages and given additional explanation.>Your answer seems to be that other people have already done that, and>someone posted the above paper. I looked at that paper, and all I see>are a lot of LISP programs and I don't really see a proof of the>halting problem. Charlie seems to be saying the same thing, that this>paper doesn't do what its title says.>I would like to ask if you could please explain a little how these>other people you talk about were able to create an actual proof of>this theorem. Charlie asked you for the axioms and rules and the>proof itself, but your only answer seems to be that it is silly and he>is being foolish.>However, he has laid out his axioms and rules, and given at least one>proof, and talked about several others (as opposed to just the halting>problem proof.) I looked at his paper and system and it seems valid. >Everything is spelled out, although the syntax is not completely>familiar. But it is still explained in the paper and a little in his>postings, although he tends to be a little scattered in his>explanations in postings.>I am asking if you could explain (1) the axioms, rules, etc that you>say other people already did, and (2) what is wrong with Charley's>proofs. In the interest of an intelligent exchange of ideas on logic,>I think that is a reasonable request. Again, I don't see any actual>proof or axioms etc in the above paper, so maybe you can let us all>know what they are.>The only explanation that I can think of is that you really don't have>an answer and instead just call it foolish. But that is no answer.>You have said at least once or more that you think that Charley is>being foolish. But so far, he has laid out his work and you have>refused to explain your answers of how it was done elsewhere and what>is wrong with his work. It seems to me that he is not the one who is>being foolish at all.When I read this I immediately suspected that you must be Charley,just because the idea that there could be two people in the worldso confused about things that are so utterly simple seemed implausible. Someone else has noted that the two of you havethe same IP address...On the off chance that you're a real person:Charley is being incredibly foolish when he suggests thatthere's some problem with the standard proofs of theunsolvability of the halting problem. Astonishingly foolishwhen he suggests that nobody until him ever _thought of_formalizing the proof, and hilariously foolish when hesays that in fact nobody has done so, in the face ofdirect evidence to the contrary (you just see a bunchof Lisp code in that paper? Huh. That's very curious,that the paper would consist of a bunch of code, giventhat the aim of the paper is to present a program thatconstructs a certain proof...)No, I haven't stated any of the things you say I haven'tstated. That's because all those things are both verysimple and very well-known. I mean it _is_ utterly simple - I haven't given a referenceto the proof because I don't know that I've ever _read_the proof - I don't work in this field, many years ago whenI read about the problem I had no problem finding theproof myself, so I never tried to look it up. Maybe thatmeans I'm an amazing genius - I don't think that's whatit means, I think it means that the proof is more or lessobvious if you're familiar with the idea of how diagonalarguments work.But to show that the proof _is_ well-known, I triedit because it might not contain a proof, and thesecond hit looked like it contained a proof. And sure enough it did:http://www.cs.pitt.edu/~kirk/cs1510/notes/halt/ halt.htmlsayssincerely, === Subject: Re: Resistance to ChangeMr. Ullrich,appreciate it.> When I read this I immediately suspected that you must be Charley,> just because the idea that there could be two people in the world> so confused about things that are so utterly simple seemed > implausible.No, it's because there aren't two people as smart! Proof: Nobody elsehas axiomatized the theory of computation (or program synthesis ordatabase query processing.)> Someone else has noted that the two of you have the same IP address...Yikes! Oh No! Someone must have stolen my IP address without myknowledge or permission. Must've been when I used the computer arKinko's. > Charley is being incredibly foolish when he suggests that> there's some problem with the standard proofs of the> unsolvability of the halting problem.Never said that.> Astonishingly foolish> when he suggests that nobody until him ever _thought of_> formalizing the proof,Didn't say that either. You said that earlier (suggested that I saidit.)> and hilariously foolish when he says that in fact nobody has done so,suggesting that you weren't so sure.)> in the face of> direct evidence to the contrary (you just see a bunch> of Lisp code in that paper? Huh. That's very curious,> that the paper would consist of a bunch of code, given> that the aim of the paper is to present a program that> constructs a certain proof...)Does this paper formally prove the unsolvability of the HaltingProblem? Then where's the proof? What are the axioms, rules ofinference and steps in the proof? That is what you have notsubstantiated.> No, I haven't stated any of the things you say I haven't> stated. That's because all those things are both very> simple and very well-known. Yes, the proof is fairly simple. BTW: Still, it's not simple enoughfor Gregory Chaitin to understand it. Seehttp://www.cs.auckland.ac.nz/CDMTCS/chaitin/amsci.pdf top of lastcolumn on the 5th. page (# 168). He still hasn't gotten it right,after writing about it (over and over again) for 30 years! (Who seeshis mistake?)> Charley seems to think that the [standard] proof is somehow deficient> because it's not expressed in a formal language. This is simply> stupid. If he wants to say that writing the proof in a formal > language would be interesting he can say that.1. Is it better to axiomatize a theory than to carry it out by hand? (What did Hilbert say about it?)2. What are the advantages of formal methods?3. Who has done it before? http://citeseer.ist.psu.edu/boyer82mechanical.html ? No, there isno proof: no axioms, rules of inference or derivation of the theorem.4. How about the idea of reducing Peano's 5 axioms to a single simplewff that is demonstrably equivalent? Would that be an improvement? And what if that simple wff turned out to be one of only a handful ofaxioms that are used to generate theorems from the theory ofcomputation, such as Turing 1937? Would that be kind of cool, tounite the work of Peano and Turing into one formal system?5. What if this system also formalized (generated) theorems fromGodel's 1931 paper concerning recursive functions and relations (thatnobody has ever done before) - would that be of value?6. How about journals that have published attempts to formalize theseresults, but were only informal do you think they should publish apaper IF it did indeed formalize them?7. Does my paper formalize (axiomatize) these results?http://www.arxiv.org/html/cs.lo/0003071http:// www.mathpreprints.com/math/Preprint/CharlieVolkstorf/ 20021008.1/18. How about if the same rules of inference were used to synthesizecomputer programs that compute functions from Number Theory and alsoDatabase Query Processing? Would that be useful? Who has done thatbefore?> But suggesting,> as he has many times, that the informal proof is not a real> proof just because it's written in English is, well utterly stupid> is the only phrase that springs to mind.I never said that. (Where?)The $100.00 is for anyone who can show that someone else axiomatizedthe Theory of Computation (or show that my paper doesn't)! That iswhat is unsubstantiated.Charlie Volkstorf === Subject: Re: Resistance to Change> That's a complete, correct, utterly simple proof of the unsolvability> of the halting problem. [...]I would prefer the following (slight) variant though:------------------------------------------------------- ------The Halting Problem is: INPUT: A string P and a string I. We will think of P as a program withinput I. OUTPUT: 1 (or True), if P halts on input I, and 0 (or False) if P goesinto an infinite loop on input I. Theorem: There is no program to solve the Halting Problem. Proof: Assume to reach a contradiction that there exists a programHalt(P, I) that solves the halting problem, Halt(P, I) returns True ifand only if P halts on input I, False otherwise. Then given this programfor the Halting Problem, we could construct the following string/code Z: Program (String x) If Halt(x, x) then Loop Forever Else Halt. End.Consider what happens when the program Z is run with input Z.Case 1: Program Z halts on input Z. Hence, by the correctness of theHalt program, Halt returns True on input Z, Z. Hence, program Z loopsforever on input Z. Contradiction. Case 2: Program Z loops forever on input Z. Hence, by the correctnessof the Halt program, Halt returns False on input Z, Z. Hence, program Zhalts on input Z. Contradiction. End Proof. ------------------------------------------------------I think, it's important to note that the solution does not depend on aspecific program language used for program Z (and/or P). It should justbe the same language the program Halt(P,I) assumes for its input P, Iguess.> Hmm, looking at the proof I might quibble with the notation> used: Halt is the name of the hypothetical procedure that> we're showing does not exist and also the name of an> instruction in the programming language.Hmmm... Actually, not really a problem. 'Halt' and 'Halt(.,.)' *should*certainly denote different functions/procedures/commands (whatever),since 'Halt' doesn't take any arguments as input, but 'Halt(.,.)' takestwo arguments as input.On the other hand, we might certainly as well adopt some differentnotation. Another variant: Program (String x) If Halt(x, x) then Loop Forever Else Stop. End.- with the comment: The command/instruction 'Stop' just halts theprogram.F.P.S.Turing's original argumentation a good deal more complicated, and muchharder to understand. === Subject: Re: Resistance to Change>[...]>http://www.cs.pitt.edu/~kirk/cs1510/notes/halt/ halt.html>says>The Halting Problem is: >INPUT: A string P and a string I. We will think of P as a program. >OUTPUT: 1, if P halts on I, and 0 if P goes into an infinite loop on>I. >Theorem (Turing circa 1940): There is no program to solve the Halting>Problem. >Proof: Assume to reach a contradiction that there exists a program>Halt(P, I) that solves the halting problem, Halt(P, I)>returns True if and only P halts on I. The given this program for the>Halting Problem, we could construct the following>string/code Z: >Program (String x)>If Halt(x, x) then> Loop Forever>Else Halt.>End.>Consider what happens when the program Z is run with input Z >Case 1: Program Z halts on input Z. Hence, by the correctness of the>Halt program, Halt returns true on input Z, Z. Hence,>program Z loops forever on input Z. Contradiction. >Case 1: Program Z loops forever on input Z. Hence, by the correctness>of the Halt program, Halt returns false on input Z, Z.>Hence, program Z halts on input Z. Contradiction. >End Proof. >That's a complete, correct, utterly simple proof of the unsolvability>of the halting problem. And a very well-known proof to boot.>Charley seems to think that the proof above is somehow deficient>because it's not expressed in a formal language. This is simply>stupid. If he wants to say that writing the proof in a formal >language would be interesting he can say that. But suggesting,>as he has many times, that the informal proof is not a real>proof just because it's written in English is, well utterly stupid>is the only phrase that springs to mind.>(Hmm, looking at the proof I might quibble with the notation>used: Halt is the name of the hypothetical procedure that>we're showing does not exist and also the name of an>instruction in the programming language. I'd change the>name of the procedure to Halts:>Program (String x)>If Halts(x, x) then> Loop Forever>Else Halt.>End.>Wow, I've discovered a problem with the standard proof>of the unsolvability of the halting problem. I better write>a paper on this. Guffaw.>(Uh, note that the problem is not necessarily a problem;>in some languages different procedures can have the>same name if they have different signatures. But Halts()>seems like a better name for the procedure anyway.))Oops. I just noticed another problem with the proof above.Both cases are labelled Case 1. I have no idea how tofix this one, looks to me like the proof is simple Wrong.I guess I have to take back everything I've said. sincerely,> Carl ManningHey, you and Charlie have the same IP address! What an astonishingcoincidence! You must be posting from the same computer lab...perhaps you could discuss this brilliant discovery amongst yourselves?Nathan === Subject: Re: Resistance to Change> sincerely,> Carl Manning> Hey, you and Charlie have the same IP address! What an astonishing> coincidence! You must be posting from the same computer lab...> perhaps you could discuss this brilliant discovery amongst yourselves?> NathanOh really? More sarcasm without mathematical content! I guess weboth have each other pegged. :) LOL How about if I offer a $100.00reward* for anyone who can substantiate (elucidate) David Ullrich'sclaims? (or find a flaw in my 4 theorems) I realize that pales incomparison to the Clay Mathematical Institute rewards - and theproblem seems just as difficult!So don't worry. I won't hold it against you that you can't find thatelusive proof that David knows so much about. Nobody else can either.C & C(separated at birth)* US Postal money order or PayPal payment! === Subject: Re: Resistance to Change> sincerely,> Carl Manning> Hey, you and Charlie have the same IP address! What an astonishing> coincidence! You must be posting from the same computer lab...> perhaps you could discuss this brilliant discovery amongst yourselves?> Nathan>Oh really? More sarcasm without mathematical content! Giggle. You manufacture support from an imaginary playmate, andwhen someone points this out it has no mathematical content.>I guess we>both have each other pegged. :) LOL How about if I offer a $100.00>reward* for anyone who can substantiate (elucidate) David Ullrich's>claims? You really have no idea what a gibbering moron this makes yousound like, suggested that it's _my_ claim that there's no problemwith the well-known proof of the unsolvability of the halting problem?See http://www.cs.pitt.edu/~kirk/cs1510/notes/halt/halt.htmlEither point out an error in the proof or decide whether tosend the $100 to me or to the author of the page.>(or find a flaw in my 4 theorems) I realize that pales in>comparison to the Clay Mathematical Institute rewards - and the>problem seems just as difficult!>So don't worry. I won't hold it against you that you can't find that>elusive proof that David knows so much about. Nobody else can either.>C & C>(separated at birth)>* US Postal money order or PayPal payment! === Subject: Topic for Proof Treatise: Prove/Disprove Manure Really Stinks. by support1.mathforum.org (8.11.6/8.11.6/The Math Forum, $Revision: 1.9 primary) id i3HChMc08048;I have often pondered the signifcance of Mathematical proofs. I tend to think some math is true if it has a usefull and duplicable application(s). Otherwise proofs are just academic exercises....How Would a mathematician go about proving/disproving Manure really Stinks. How do you define Stinks. Or would your really want tobother with a definition. What kind of definition would be usefull and appropriate. All definitions I guess are not equal. Probably noneof them. Which is significant on its own. But then if there was someother criteria to frame the proof, such as a proposed problem to solve maybe a proof and defintion(s) would make more sense....I think Manure really does stink, myself. And I guess I can think of some proofs that I won't get into. Which should probably done for some Mathematical proofs I have heard of.Zim Olsonhttp://www.zimmathematics.com === Subject: Re: Topic for Proof Treatise: Prove/Disprove Manure Really Stinks.>How >Would a mathematician go about proving/disproving Manure really >Stinks. Where I come from, the smell of manure is often refered to as the smell ofmoney. QED, I suppose.Rich === Subject: Re: Topic for Proof Treatise: Prove/Disprove Manure Really Stinks. === >Subject: Topic for Proof Treatise: Prove/Disprove Manure Really Stinks.>I have often pondered the signifcance of Mathematical proofs. I tend >to think some math is true if it has a usefull and duplicable >application(s). Otherwise proofs are just academic exercises....How >Would a mathematician go about proving/disproving Manure really >Stinks. How do you define Stinks. Or would your really want to>bother with a definition. What kind of definition would be usefull >and appropriate. All definitions I guess are not equal. Probably none>of them. Which is significant on its own. But then if there was some>other criteria to frame the proof, such as a proposed problem to >solve maybe a proof and defintion(s) would make more sense....I >think Manure really does stink, myself. And I guess I can think of >some proofs that I won't get into. Which should probably done for >some Mathematical proofs I have heard of.>Zim Olson>http://www.zimmathematics.comOff Topic. You should address this to sci.chem. === Subject: Re: Non-Noether Conserved Quantity?P.S. ...I was on the point of apologizing to you, out of some old time fellowfeeling. But I note in this thread, Daryl McCullough, a now rare andserious poster, injects a rare gem of a question in sci.physics, andyou immediately responded with some nonsense which hijacked theenergies of Bjoern Feuerbacher -- through his own inexperience.Even without recognizing your persona I was disappointed that apromising thread was diverted into nonsense so quickly. === Subject: Re: Non-Noether Conserved Quantity?> In message , Bjoern Feuerbacher > [...]>Why don't you actually answer my questions for a change, instead of >ignoring most of them, and evading the rest?> DYOC. Johns Hopkins seem to have let him go.> Hopkins doesn't let many people go. Since to > begin with, don't they hire many people who actually> believe in quantum mechanics. To end with > they work a lot more with > Admiral Rickover and Company than they do with Einstone.Ohmygod ... the tone, Johns Hopkins ...Oh. I see Richard Herring was there first. I had to Google on 'tard,with a confirmatory search on goober. === Subject: Re: Non-Noether Conserved Quantity?>In message , Bjoern Feuerbacher >[...]>Why don't you actually answer my questions for a change, instead of >ignoring most of them, and evading the rest?>DYOC. Johns Hopkins seem to have let him go.> Hopkins doesn't let many people go. Since to > begin with, don't they hire many people who actually> believe in quantum mechanics. To end with > they work a lot more with > Admiral Rickover and Company than they do with Einstone.> Ohmygod ... the tone, Johns Hopkins ...> Oh. I see Richard Herring was there first. I had to Google on 'tard,> with a confirmatory search on goober. It matters less to me what Richard Herring does, that what a retard like Feynmann does, if you haven't noticed. === Subject: Re: Is calculus wrong?[[ This message was both posted and mailed: see the To, Cc, and Newsgroups headers for details. ]]> I feel> that there is an inconsistency here. What do you think?No, it is quite consistent.Doesn't model the real world? You could argue that, but doit in sci.physics, not sci.math ...G. A. Edgar http://www.math.ohio-state.edu/~edgar/ === Subject: Re: Is calculus wrong?> Is our Calculus wrong?> The concept of limits was visualized using a figure drawn on paper. In> describing this figure we have used two contradictory notions. On one> hand we said we are approaching a limit and on other we still used the> same gross level view of the figure.The 19-th century was the time when purely visual understanding of functions, derivatives and integrals were replaced by rigourous formal definitions of limits. Calculus is helped and aided by pictures, but the reasoning does not depend on pictures in any way. One of the jokes we had when I was a kid, was the German textbook on differential and integral calculus mit acht figuren.The analysis of real and complex functions is quite alive and well. It serves physics, engineering, economics and other disciplines effectively.Bob Kolker === Subject: Re: Is calculus wrong?An isomorphism is when we use one system as an example of anothersystem. For example, (no pun intended) if I talk about apples witharithmetic, telling students that since 2 apples and 3 apples make 5apples, to help explain 2+3=5, this is a useful tool. This is muchlike using geometry, with its lines and tangents and slopes, toexplain calculus. It works quite well for the most part. However,remember that apples are not exactly like numbers: for example,numbers never rot, or decompose.So isomorphisms, like apples to arithmetic, work well to explainthings, but we have to remember that they don't always work in theexact same fashion.> Is our Calculus wrong?> The concept of limits was visualized using a figure drawn on paper. In> describing this figure we have used two contradictory notions. On one> hand we said we are approaching a limit and on other we still used the> same gross level view of the figure. When we approach a limit we must> also magnify the figure to see exactly what is happening. If we> approach 100 times closer to a point we should magnify the figure by> 100 times or a thousand times to see the result. To observe> microscopic things we need a microscope. It is the same thing as> saying that we are moving closer and closer to a distant star and> still thinking that the star will maintain the same small size. I feel> that there is an inconsistency here. What do you think? Please let me> know at subhendu.das@excite.com> Now consider how we proved that the derivative is a tangent. Imagine> the figure, a circle, and a line OP, starting at O on the circle,> intersecting at Q and extending beyond to P. If we keep the point O> fixed and move the point Q closer and closer to O along the> circumference, then the line OP will move and become a tangent at O.> We see the same fallacy here; we are not using a microscope. As the> point Q moves towards O we must magnify the figure. If you do that> then you will see that the figure is basically not changing, only> becoming bigger and bigger, and the line will never become tangent. Do> you agree with me? Is our calculus wrong? Please let me know your> opinion at subhendu.das@excite.com === Subject: Re: Is calculus wrong?* Subhendu Das> If you do that> then you will see that the figure is basically not changing, only> becoming bigger and bigger, and the line will never become tangent.This is actual true. The line never becomes tangent. That is why weuse words like 'approaching' and not 'reaching'.However, as others have pointet out. Use epsilon-delta if you try tocritisize limits, not gemoetry.Jon Haugsand Dept. of Informatics, Univ. of Oslo, Norway, mailto:jonhaug@ifi.uio.no http://www.ifi.uio.no/~jonhaug/, Phone: +47 22 85 24 92 === Subject: Re: Is calculus wrong?No.===Subject: Re: Is calculus wrong?| Is our Calculus wrong?|| The concept of limits was visualized using a figure drawn on paper. In| describing this figure we have used two contradictory notions. On one| hand we said we are approaching a limit and on other we still used the| same gross level view of the figure. When we approach a limit we must| also magnify the figure to see exactly what is happening. If we| approach 100 times closer to a point we should magnify the figure by| 100 times or a thousand times to see the result. To observe| microscopic things we need a microscope. It is the same thing as| saying that we are moving closer and closer to a distant star and| still thinking that the star will maintain the same small size. I feel| that there is an inconsistency here. What do you think? Please let me| know at subhendu.das@excite.com||| Now consider how we proved that the derivative is a tangent. Imagine| the figure, a circle, and a line OP, starting at O on the circle,| intersecting at Q and extending beyond to P. If we keep the point O| fixed and move the point Q closer and closer to O along the| circumference, then the line OP will move and become a tangent at O.| We see the same fallacy here; we are not using a microscope. As the| point Q moves towards O we must magnify the figure. If you do that| then you will see that the figure is basically not changing,Exsqeeze me?!? Try actually drawing something like this and then see if you wantto make this claim. only| becoming bigger and bigger, and the line will never become tangent. Do| you agree with me? Is our calculus wrong? Please let me know your| opinion at subhendu.das@excite.com === Subject: Re: 3^n + 130532We can prove that there are infinitely many 3-Sierpinski numbersin the same way that we can prove the infinitude of Sierpinskinumbers. If I am not mistaken, k can be chosen such that 3^n + k(or k 3^n + 1) is always divisible by one of the odd prime factorsof 3^48 - 1, namely 5, 7, 13, 17, 41, 73, 97, 193, 577, 769 and6481 (we can even leave out one of 97, 577 and 769). But I did notfind any small numbers with this property.---J K Hauglandhttp://www.neutreeko.com === Subject: Re: 3^n + 130532> We can prove that there are infinitely many 3-Sierpinski numbers> in the same way that we can prove the infinitude of Sierpinski> numbers. If I am not mistaken, k can be chosen such that 3^n + k> (or k 3^n + 1) is always divisible by one of the odd prime factors> of 3^48 - 1, namely 5, 7, 13, 17, 41, 73, 97, 193, 577, 769 and> 6481 (we can even leave out one of 97, 577 and 769). But I did not> find any small numbers with this property.I'll check your working:(set fonts to sane...) 17 1/16 _ 1/8 193 1/16 / >- 1/4 41 1/8 / >- 1/2 5 1/4 / 2 from 97 1/48 _ 1/24 _ 1577 1/48 / _ 1/12 /769 1/48 / / _ 1/6 / 6481 1/24 / / / 73 1/12 / >- 1/2 / 7 1/6 / 13 1/3 /If you check mine:a) k==4 (mod 5) places 5 in the n==0 (mod 4) slotsb) k==9 (mod 41) places 41 in the n==2 (mod 8) slotsc) k==9 (mod 193) places 193 in the n==6 (mod 16) slotd) k==8 (mod 17) places 17 in the n==14 (mod 16) slotsSo that's all even powers covered.a.b.a.c.a.b.a.d.a.b.a.c.a.b.a.d.a.b.a.c.a.b.a.d.e) k==2 (mod 7) places 7 in the n==1 (mod 6) slotsf) k==12 (mod 13) places 13 in the n==3 (mod 6) slotsg) k==3 (mod 73) places 73 in the n==5 (mod 12) slotsh) k==3 (mod 6481) places 6481 in the n==11 (mod 24) slotsi) k==3 (mod 97) places 97 in the n==23 (mod 48) slotj) k==574 (mod 577) places 577 in the n==47 (mod 48) slotaebfagceafbhaedfagbeafciaebfagdeafbhaecfagbeafdjRun the CRT to getMod(1581339422187635434, 1620742097628261335)So 1581339422187635434 should work.Double-check:(00:11) gp > for(i=0,47,print1( ,factor(1581339422187635434+3^i)~[1,1])) 5 577 17 13 5 7 13 73 5 13 193 7 5 23 41 13 5 7 13 73 5 13 41 7 5 79 193 13 5 7 13 73 5 13 17 7 5 6481 19 13 5 7 13 73 5 13 23 7There are a large number of choices -- a was from 4; b,c were from 2; d was forced; e was from 3; f,g,h from 2; i,j combined from 6 => total# = 4*2*2*3*2*2*2*6 = 2304 -- therefore I expect a value <10^15 works.Phil1st bug in MS win2k source code found after 20 minutes: scanline.cpp2nd and 3rd bug found after 10 more minutes: gethost.cBoth non-exploitable. (The 2nd/3rd ones might be, depending on the CRTL) === Subject: Re: 3^n + 130532> Is this always composite, does anybody know, please?> PS I'd like to christen this a 3-Sierpinskiesque number, if it doesn't > already have a name?> PPS I think I can show that there are an infinite number of Sierpinski > numbers - does this make sense/is this new?One thing we can rule out is primes of the form 6x+13^n + 130532 = 6x+13^n + 130531 = 6x(3^n + 130531) mod 6 = 4Hence x will never be an integerTherefore them are no primes of the form 6x+1 in the 3^n + 130531 listUnfortunately, 6x-1 is still open. === Subject: Re: 3^n + 130532>very simple) probably is right...> But why break the habit of a lifetime? :-)Indeed - all my other proofs are _certainly_ right! :-) === Subject: Re: 3^n + 130532>Is this always composite, does anybody know, please?>PS I'd like to christen this a 3-Sierpinskiesque number, if it doesn't >already have a name?>PPS I think I can show that there are an infinite number of Sierpinski >numbers - does this make sense/is this new?> again!> I ran a check on it last night using a program called PrimeForm, and> it found a probable prime with n=17411. This isn't proving that> 3^17411+130532 is prime, just that it is probably prime. The only> thing about this number is that it has 8308 digits(!), so it will be> very difficult to prove it prime, without resorting to a distributed> computing attack on it.> AnthonyExcellent, excellent, excellent!You're calculating way quicker than me - I wouldn't have found this for yonks!range for Francois Morain's ECPP, so I'll give that a try and see if I can set it going...J === Subject: Re: 3^n + 130532> Is this always composite, does anybody know, please? PS I'd like to christen this a 3-Sierpinskiesque number, if it > doesn't already have a name?> PPS I think I can show that there are an infinite number of > Sierpinski numbers - does this make sense/is this new?> again!> I ran a check on it last night using a program called PrimeForm, and> it found a probable prime with n=17411. This isn't proving that> 3^17411+130532 is prime, just that it is probably prime. The only> thing about this number is that it has 8308 digits(!), so it will be> very difficult to prove it prime, without resorting to a distributed> computing attack on it.> Anthony> Excellent, excellent, excellent!> You're calculating way quicker than me - I wouldn't have found this for > yonks!> range for Francois Morain's ECPP, so I'll give that a try and see if I > can set it going...> JNo :-(, ...Try Primo...!J === Subject: Re: 3^n + 130532> Is this always composite, does anybody know, please?> PS I'd like to christen this a 3-Sierpinskiesque number, if it > doesn't already have a name?> PPS I think I can show that there are an infinite number of > Sierpinski numbers - does this make sense/is this new?> again!> I ran a check on it last night using a program called PrimeForm, and> it found a probable prime with n=17411. This isn't proving that> 3^17411+130532 is prime, just that it is probably prime. The only> thing about this number is that it has 8308 digits(!), so it will be> very difficult to prove it prime, without resorting to a distributed> computing attack on it.> Anthony> Excellent, excellent, excellent!> You're calculating way quicker than me - I wouldn't have found this for > yonks!> range for Francois Morain's ECPP, so I'll give that a try and see if I > can set it going...> J> No :-(, ...> Try Primo...!> JI might recommend taking a look at the record-length primes that havebeen computed with Primo. You can find it at this link:http://www.ellipsa.net/primo/record.htmlGood luck with your calculations!Anthony === Subject: Re: 3^n + 130532>Is this always composite, does anybody know, please?>PS I'd like to christen this a 3-Sierpinskiesque number, if it doesn't >already have a name?>PPS I think I can show that there are an infinite number of Sierpinski >numbers - does this make sense/is this new?> !> I have checked for all numbers n below 11000, and all have turned up composite. > Anthony If this turns out to always be composite, it will be hard to prove such simply using congruences on the exponent. For example, when n = 59 we get the factorization 3^59 + 130532 = p1*p2*p3where p1 = 1587251 p2 = 2413771 p3 = 3688182084440719We can check that p1 divides 3^n + 130532 when n == 59 (mod 793625 = 5^3 * 7 * 907) p2 divides 3^n + 130532 when n == 59 (mod 804590 = 2 * 5 * 61 * 1319 p3 divides 3^n + 130532 when n == 50 (mod 1229394028146906 = 2 * 3 * 277 * 54907 * 24572009)One of the exponent congruences must be modulo a multiple of 793625, 805490, or 1229394028136906 .John Adams served two terms as Vice President and one as President, but lostreelection. Later his son became President despite losing the popular vote.That son lost his reelection attempt badly. Now history is repeating itself.pmontgom@cwi.nl Microsoft Research and CWI Home: San Rafael, California === Subject: Re: 3^n + 130532> Is this always composite, does anybody know, please?> PS I'd like to christen this a 3-Sierpinskiesque number, if it> doesn't already have a name?> PPS I think I can show that there are an infinite number of> Sierpinski numbers - does this make sense/is this new?> !> I have checked for all numbers n below 11000, and all have turned> up composite.> Anthony> If this turns out to always be composite, it will be hard> to prove such simply using congruences on the exponent.And in fact, classical conjectures then say that it is not always composite.A counter-exemple should appear somewhere for 10000 For example, when n = 59 we get the factorization> 3^59 + 130532 = p1*p2*p3> where> p1 = 1587251> p2 = 2413771> p3 = 3688182084440719> We can check that> p1 divides 3^n + 130532 when n == 59 (mod 793625 = 5^3 * 7 *> 907) p2 divides 3^n + 130532 when n == 59 (mod 804590 = 2 * 5> * 61 * 1319 p3 divides 3^n + 130532 when n == 50 (mod> 1229394028146906 = 2 *> 3 * 277 * 54907 * 24572009)> One of the exponent congruences must be modulo a multiple of> 793625, 805490, or 1229394028136906 . === Subject: Re: What type series is this?> Using this formula, I can easily prove what I was trying to prove:> No positional numbering system has one and only one> representation for each real number.A good result. It can also be proved using topology...The association from a representation to the numberis continuous, but the set of representations istotally disconnected, while the set of numbers isconnected, so they are not homeomorphic.Doesn't require positive digits, just that there isa finite choice of digits for each place.Another interesting one: A positional numbering systemfor *complex numbers* ... If every number has at least onerepresentation, then some number has at least 3 differentrepresentations.G. A. Edgar http://www.math.ohio-state.edu/~edgar/ === Subject: Weak and strong derivativeIf f is a function : A -> R , where A is an open set of R^n, f isC^{infinity}(A), except one point, f is L^1(A) and the same for itsderivatives, can I say that its strong partial derivative is also the weakpartial derivative? === Subject: Re: Weak and strong derivative> If f is a function : A -> R , where A is an open set of R^n, f is> C^{infinity}(A), except one point, f is L^1(A) and the same for its> derivatives, can I say that its strong partial derivative is also the weak> partial derivative?What have you tried? At first glance the n = 1 looks simple, and the n > 1 case should follow easily. === Subject: Re: Curious quote by A.N.Whitehead on Shakespeare> I was quite young when I first realized that I understood some books > better than the teacher, or, worse, that the teacher was merely > parroting blather currently fashionable in the academic world.> wonder if you'd care to perform a public act of recall of an example of > said parroting of blather... none of my highschool teachers even > approached such a parroting act... unless man vs man; man vs society; > man vs himself etc... was ever remotely fashionable?Not until my first year of college for that one.I'm afraid I've succeeded in repressing the exact memories altogether.John W. KennedyCompact is becoming contract,Man only earns and pays. -- Charles Williams. Bors to Elayne: On the King's Coins === Subject: Re: Curious quote by A.N.Whitehead on ShakespeareOh great! Yet another for our collection, a LaRouchie!You know, the possibilities for psychotic synergy between Oxfordians and LaRouchies are simply astounding, both being obsessed with British aristocracy and all.John W. KennedyBut now is a new thing which is very old--that the rich make themselves richer and not poorer,which is the true Gospel, for the poor's sake. -- Charles Williams. Judgement at Chelmsford === Subject: Re: Curious quote by A.N.Whitehead on Shakespeareyou mean, PS#1, unless Cambridge was founded, firstly. Harry Potter goes to a PS; y'know?... and, ifyou want to know about the Rhodesian brainwashing programme-- that Bill Clinton did not totally submit to,in my vague opinion --you can read about the history of that, as well.> Oh great! Yet another for our collection, a LaRouchie! --Give Earth a Trickier Dick Cheeny -- out of office, after GIGA years.http://www.benfranklinbooks.com/http://www.rand.org/ publications/randreview/issues/rr.12.00/http:// members.tripod.com/~american_almanachttp://www.wlym.com/pdf/ iclc/howthenation.PDF === Subject: Re: Curious quote by A.N.Whitehead on Shakespeare> Hi. HH here.> I've been quite curious about this curious quote:... To this day I can't read King Lear, having had> the advantage of studying it accurately in school.> -ALFRED NORTH WHITEHEADI found the attribution on the web to Atlantic, v. 138, pg. 197,and lo and behold, The College of Dupage Library holds this inbound volume. This would be late 1926, although I forgot tocheck the exact issue.It's from _THE EDUCATION OF AN ENGLISHMAN_, an essay ofseven small pages in two columns. He dwells mostly onlocal lore and mood, and explains the general tenor ofthe classical education he was afforded by a school inDorsetshire, at Sherborne, in the 1870's .The context does not amplify on the gist of this quotation.The only help is in a closely preceding mention of theirstudy of the Bible in Greek, where he says, In this Greekpresentation of religion the passion for accurate philologysometimes overcame the religious interest. Also immediately preceding, btw : The Platonizing Jewsof Alexandria are mixed in my mind with monastery buildingsin Dorsetshire on warm Sunday afterenoons in May.Lew Mammel, Jr. === Subject: Re: Curious quote by A.N.Whitehead on ShakespeareOops, I see Chris Green beat me to it. Well, no matter. === Subject: Re: Curious quote by A.N.Whitehead on Shakespeare> | > I'm using the handle bookburn partly because of Bradbury's novel> | > Fahrenheit 451, the temperature at which books burn. Society> burned> | > books that interferred with its agenda, and refugees collected> outside> | > cities, reading to each other from memory. bb> |> | You are missing either a comma or a major plot point.> Can you be clearer? I read the novel, saw the movie, but could be> missing something interesting that relates to the point about people> learning. Could be commas set off bookburn and Fahrenheit 451,> but I don't see how to add a single comma to gain a major plot point.|_All_ books are burned in the Fahrenheit 451 world. No discrimination.John W. KennedyGive up vows and dogmas, and fixed things, and you may grow like That. ...you may come to think a blow bad, because it hurts, and not because it humiliates. You may come to think murder wrong, because it is violent, and not because it is unjust. -- G. K. Chesterton. The Ball and the Cross === Subject: Re: Curious quote by A.N.Whitehead on Shakespeare> hey hey, hi hi;> Schroedinger's cat will never die.> But the kitty litter> isn't very dry;> hey hey, hi hiThat which trickles down is yellow. === Subject: Re: Curious quote by A.N.Whitehead on Shakespeare> |> | > Education with inert ideas is not only useless: it is, above all> things,> | > harmful - Corruptio optimi, pessima.> | > | > Do not teach too many subjects, and again, What you teach,> teach> | > thoroughly.> | > | Teach with fervent interest only the subjects that enthrall you.> Don't> | teach subjects for which you lack paramount interest; your students> will> | learn your boredom, lack of interest and ineptness.> The argument goes that teaching is different from learning, especially> with respect to the controversy surrounding mastery, or> competency-based education.> Those who can toss stuff like that around have replaced common sense with> excessive erudition.> (The NEA justifies its position against the Voucher System on the basis> of the importance of cross-cultural learning and schools going to> greater lengths in helping slow learners, disadvantaged, etc..)> To hell with those pampered dumb brats sucking up scarce school dollars.> Put your money on the winners, providing them with resources and> opportunity to learn as they will instead or boring them to tears with> standard curriculum and wasting their potential.> Some favor teaching programmable specifics in a sequential,> non-repetitive, cumulative curricula and tend to blame mere learning> about warm and fuzzy stuff as responsible for low national test scores.> Complusuary education is oxymoron for boot camp training.> Throw the unruly out of school. But no, now school has become> a population wide experiment in prescription drugging young kids> into sombies. More ill health being piled upon ill health.Are we to believe that you would have been a winner if you hadn'tbeen bored to tears by the standard curriculum ? There are excellentfree dictionaries on-line for when you get the urge to use difficultwords so you don't have to put yourself out on a limb:http://dictionary.cambridge.org/define.asp?key=56863&dict =CALD> This dichotomy is represented in The Dead Poets Society where the> teacher is artful, but the head master is only interested in measurable> results. The irony is that those colleges, like St. Johns, emphasizing> reading the Great Books and discussing in Socratic dialogue, have the> best GRE test scores, I hear. bb> Indeed, verifying what I proclaim. === Subject: Re: Curious quote by A.N.Whitehead on Shakespeare>Are we to believe that you would have been a winner if you hadn't>been bored to tears by the standard curriculum ?Well, the quality of teaching makes a great deal of difference. I didvery poorly in mathematics until I had a new teacher. No miracles, butfrom 'poor' to 'reasonable'. But if I'd had Teach 2 from Day 1, maybeI'd have got to 'good'. Who knows?The good news is that nothing is compulsory.The bad news is that everything is prohibited.http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk === Subject: Re: Curious quote by A.N.Whitehead on Shakespeare>Are we to believe that you would have been a winner if you hadn't>been bored to tears by the standard curriculum ?> Well, the quality of teaching makes a great deal of difference. I did> very poorly in mathematics until I had a new teacher. No miracles, but> from 'poor' to 'reasonable'. But if I'd had Teach 2 from Day 1, maybe> I'd have got to 'good'. Who knows?What level was this? College? How much do you remember now? Is itstill meaningful to you? Have you heard of Father Guido Sarducci'sFive Minute University? ( You can learn in five minutes everythingyou will remember, so why bother with the rest ? )Lew Mammel, Jr. === Subject: Re: Curious quote by A.N.Whitehead on Shakespeare <4081730A.92062CD4@worldnet.att.netI read in sci.lang.translation that Lewis Mammelt>) about 'Curious quote by A.N.Whitehead on Shakespeare', on Sat, 17>Are we to believe that you would have been a winner if you hadn't>been bored to tears by the standard curriculum ?> Well, the quality of teaching makes a great deal of difference. I did> very poorly in mathematics until I had a new teacher. No miracles, but> from 'poor' to 'reasonable'. But if I'd had Teach 2 from Day 1, maybe> I'd have got to 'good'. Who knows?>What level was this? College? Sixth form at grammar school in England. Equivalent to 11 and 12 gradein US?>How much do you remember now? Is it>still meaningful to you? Since I'm an electronics engineer, I still use a lot of it and it hadbeet be meaningful!>Have you heard of Father Guido Sarducci's>Five Minute University? No. Sounds a bit Jesuitical.(;-)>( You can learn in five minutes everything>you will remember, so why bother with the rest ? )I can't agree with that. After 66 years I'm still learning. But perhapsI'm just that much slower than the good cleric. (;-)The good news is that nothing is compulsory.The bad news is that everything is prohibited.http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk === Subject: Re: Curious quote by A.N.Whitehead on Shakespeare... To this day I can't read King Lear, having had> the advantage of studying it accurately in school.> -ALFRED NORTH WHITEHEAD> Um, well, is literature supposed to be read and understood> *accurately*? Is there only one way to perceive Shakespeare's King> Lear?In the days of yore, Shakespeare plays were the soap opera of the day.People went to them not to learn nor study nor analyse but for enjoymentand gossip about what sordid life the nobles live.So the approach to literature in school misses altogether the essence.I would suppose Shakespeare (an obscene pen name pun?) would be besttaught with a pleasant dose of history of those times. Not dry politicalhistory, but juicy how people lived in those days and how they liked theirkings.Truth is stranger than fiction.That's why history is so much fun. === Subject: Re: Question about set closure in metric space>self-learning? Is it worth spending $50 - $75 on it (Amazon)? Your>advice appreciated.> I find Halmos a little old-fashioned and perhaps not the best book for > beginners. An excellent introduction is Bartle, The Elements of > Integration. This thin volume is quite well-written and easy to > follow. After that, you might be better prepared to look at Halmos (or > Rudin's Real Analysis).> Also, do you need to learn some topology as well? Munkres is a good choice.days is you've got to be a millionaire to buy texts, nothing appearsto be for less than $50!Incidentally, on your recommendation I bought Halmos' Set Theory book. I have read only the beginning chapters, and upon first reading itappears somewhat superficial, maybe even trivial. However, every timeI re-read a passage some new subtlety emerges, and after repeatedreadings it is anything but superficial and certainly not trivial. Iguess this is a sign either of my slowness, the excellence of thebook, or perhaps both.very valuable assistance. === Subject: Re: Product of these fractions never a power of 2 ?> [...]> 1 1 1> (3 + ---)( 3 + ---)( 3 + ---) =/= 2^m> a b c> You can bound solutions a, b, c as follows:> [...]I received the following email which wasn't posted in this thread.I'm not sure what the netiquette is regarding this; but hopefullythe sender won't mind if I reproduce it here without mentioningtheir name:Curiously, it's possible to rule out solutions to(3 + 1/a)(3 + 1/b)(3 + 1/c) = 32 a, b, c *all odd* positive integersjust by getting some simple bounds and looking at the factors of 2.Note that (because we're assuming a,b, and c are all odd)(3a + 1)(3b+1)(3c+1) == 32 (mod 64),and each factor is divisible by 2 at least once. To cover thepossibilities we have3x + 1 == 2 (mod 4) when x == 3 (mod 4)3x + 1 == 4 (mod 8) when x == 1 (mod 8)3x + 1 == 8 (mod 16) when x == 13 (mod 16)The values of a, b, and c must each satisfy one of thesecongruences. Now, assuming thata <= b <= cwe easily obtain the bounds9/5 < a <= 1/(32^(1/3) - 3), i.e.1.8 < a < 5.72...The only value of a in this interval satisfying any of thecongruences isa = 3.But a = 3 would force at least one of (3 + 1/b) or (3 + 1/c)to be a fraction with a factor of 3 in the numerator when inlowest terms, a condition which disallows b and c both beingintegers (which is probably the reason for the OP's restrictionthat none of a, b, and c be divisible by 3). So there are nosolutions with a, b, and c all odd.Of course, one has(3 + 1/1)^3 = 64, a power of 2 (a = b = c = 1)but this solution violates the restriction that a, b, c all begreater than 1.------------------------------------------------------------ ---------------John R Ramsden (jr@adslate.com)---------------------------------------------- -----------------------------Eternity is a long time, especially towards the end. Woody Allen === Subject: Re: How to Solve this nonlinear ODE system> everybody! I have a system of nonliear ODE as what follows:> dx/dt=A1*y^2+B1*y+C1> dy/dt=A2*X^2+B2*x+c2> x(t=0)=M0, X(t=infinity)=Mf;> y(t=0)=N0, y(t=infinity)=Nf;> A1,A2,B1,B2,C1,C2, M0,Mf,N0,Nf are constants;> Could anybody give some suggestions about how to get a closed> form of x(t), y(t)? You reply will be highly appreciated!> [...]Seeing again my solution to the above, it struck me how long-windedit is towards the end (a bit like Woody Allen's eternity - see .sig),and I was wondering if anyone can think of a simple[ish] direct wayof obtaining a parametric solution of: a.(x^3 + 3x) + b.(y^3 + 3y) + c = 0in terms of Weierstrass functions (or Jacobian elliptic functionsif more convenient, although that seems unlikely given the cubicnature of the equation).---------------------------------------------------- -----------------------John R Ramsden (jr@adslate.com)---------------------------------------------- -----------------------------Eternity is a long time, especially towards the end. Woody Allen === Subject: Re: How to Solve this nonlinear ODE system>Seeing again my solution to the above, it struck me how long-winded>it is towards the end (a bit like Woody Allen's eternity - see .sig),>and I was wondering if anyone can think of a simple[ish] direct way>of obtaining a parametric solution of:> a.(x^3 + 3x) + b.(y^3 + 3y) + c = 0>in terms of Weierstrass functions (or Jacobian elliptic functions>if more convenient, although that seems unlikely given the cubic>nature of the equation). You can let x = 2*sinh(u/3) y = 2*cosh(v/3)where 2*a*sinh(u) + 2*b*sinh(v) + c = 0. Perhaps start with two values A, B such that A + B + c = 0.Solve x^3 + 3*x = A/aby substituting x = w - 1/w, which yields w^3 - 1/w^3 = A/a.Solve the quadratic for w^3.John Adams served two terms as Vice President and one as President, but lostreelection. Later his son became President despite losing the popular vote.That son lost his reelection attempt badly. Now history is repeating itself.pmontgom@cwi.nl Microsoft Research and CWI Home: San Rafael, California === Subject: geophysics/math Ph.D. proposal, comments desired.I'm currently editing my geophysics/applied math Ph.D. proposal and would like comments back, preferably to my campus e-mailaddress n06drd@mun.ca (where that is zero and not Oh) on itspotential originality and on any literature review referencesI may have missed.Now the possible disadvantage of my posting it here is thatsomeone might steal my ideas but I judge that unlikely,along the lines of my presenting a poster paper in July andthen someone immediately writing a journal paper basedon it without referencing me. But if someone does buildthis post and the web page PDF copy of my proposal.The advantage of posting is that I might learn of newreferences or possible duplication by me of an approachof someone else such that I should shift my focusslightly to ensure origiality. Also comments Iget, while they may not be in time for me to editthe proposal before probable April 20 1800 UTCsubmission to the examining committee, mighthelp me prepare for questions during the April 27 defense.If you do comment, in exchange I could proofread apaper of yours at a later date (after the end of April)and I am a very good proofreader of other people'smaterial but not quite as good at proofreadingmy own material.OK, yesterday's draft of the proposal in PDF formis at http://www.nfld.com/~dalton/proposal/proposal.pdf .And the title for now isSeismic wave and ray theory in elastic media:Solution of equations of motion by method of characteristics,principal symbols, and Fourier integral operators,withcomparison to numerical results and real data.and the abstract for now isMy proposed research will focus on the mathematics of seismic wavetheory in elastic media. In particular I will solve the three coupledCauchy's equations of motion in anisotropic inhomogeneous media usingthe standard method of characteristics, a variant based on principalsymbol analysis, Fourier-integral operator (FIO) theory, and numericalanalysis. I have begun and will continue to apply the method ofcharacteristics to the equations of motion. I have also begun toapply Principal Symbol theory, related to Fourier Integral Operators,to the equations of motion and from that should also get the samecharacteristics. This would also put the equations in a frameworkamenable to application of Fourier-integral operators. In parallelwith that I will try to apply Fourier-integral operator theory tosimple cases so that solutions can be tested against known solutions.Then I will extend that theory to the inhomogeneous anisotropic caseand ideally show that it extends the results of ray theory. Howeverto handle the general case I expect the FIO theory will reduce theequations somewhat but some numerical solution will still be requiredto complete the solution but less than for full numerical solution ofthe equations. All that will involve some computer implementation,and comparison to real data over well known geology. The FIOmodelling results for the inhomogeneous anisotropic case could bechecked by e.g. inserting the isotropic elasticity matrix into thealgorithm and checking that the solution reduces to that for theisotropic case. I will also check it against a full numericalsolution for at least one test case.Followups set to sci.physics .http://www.nfld.com/~dalton === Subject: What is a Huang-Hilbert transformation?Can anyone explain to me in plain words what a Huang Hilbert transformationis and what it is used for? === Subject: homologyHiI have this exercise in homology / algebraic topology, which I can't quitefigure out. I hope somebody here can help me:Show that H_1(X,A) is not isonorphic to ~H_1(X/A) if X = [0,1] and A is thesequence 1, 1/2, 1/3, ... together with its limit 0.Here is what I have done so far:Let Y be the the space obtained by collapsing all the points in A /in X to asingle point, Y =X/A this space must be the shrinking wedge of circles.Let C_n be the circle of Y with radius 1/nConsidering the retractions r_n: Y --> C_n collapsing alle C_i's except C_n.Each of these retractions r_n induces a surjection R_n: H_1(Y) --> H_1(C_n).Since the reduced holomogy H_1 of a circle is Z,I get that R_n: H_1(Y) --> ZNow the product of all these R_n's is a homomorphism R: H_1(Y) --> theinfinite direct product Z x Z x ...This product is as far as I can see uncountable.Now I have some questions:Is it possible to determine H_(Y) this way?Is it possible to show that R is surjective? And if so...how?Now I look at the reduced holomogy H_1(X,A)I know that H_1(X) = 0 and H_0(X) = 0 so I have the short exact sequence:0 --> H_1(X,A) --> H_0(A) --> 0This mean that H_1(X,A) is isomorphic to H_0(A)I know that A is a countable set of points, so my guess is that H_0(A) isthe countably infinite direct sum of Z.But I dont know if this is correct or how to show it.Can anybody help me with this or tell me about the relation between theuncountable direct product and the countable infinite direct sum....Or give me another hint how to solve this exercise.Anne === Subject: Re: Question about a sequence equation>Or even cleaner> s_i = 2*s_{i-2} + s_{i-1} + 1> Or super clean:> s_i = 2*s_{i-1} + (i mod 2), with s_1 = 1.> Well, but the even cleaner one is a linear nonhomogeneous recurrence> with a polynomial in the nonhomogeneous part (covered by one of the> cases in the web page I pointed to) whereas (i mod 2) is not polynomial> (not that it's harder to solve, but there's less guidance from standard> techniques).Yes, now I see better what the clean means (not necessary fastercomputation).Michael Taktikos, Hamburg, Germany> --> David Eppstein http://www.ics.uci.edu/~eppstein/ === Subject: Difficult Algebra ProblemI have a problem that I'm having a tough time with. Let R be a ring (perhaps without 1). Prove that (S,+,.) is a ring with unitywhen S=R X Z, (r,m)+(s,n)=(r+s,m+n), and (r,m)(s,n)=(rs+ms+nr,mn).Z is the integers. The additive identity is just (0,0) right? My main problem is that I'm not sure how to deal with the Unity. If R mightnot have 1, then how can S definitely have 1 since it's R X Z? If R has aunity 1, how does that unity relate to the unity of S? Are they the same? Would it contradict the uniqueness of unity?Please Help! === Subject: Re: Difficult Algebra Problem> I have a problem that I'm having a tough time with. Let R be a ring (perhaps without 1). Prove that (S,+,.) is a ring with unity> when S=R X Z, (r,m)+(s,n)=(r+s,m+n), and (r,m)(s,n)=(rs+ms+nr,mn).> Z is the integers. The additive identity is just (0,0) right? > My main problem is that I'm not sure how to deal with the Unity. If R might> not have 1, then how can S definitely have 1 since it's R X Z? If R has a> unity 1, how does that unity relate to the unity of S? Are they the same? > Would it contradict the uniqueness of unity?> Please Help!Do you know what the ring R looks like? I don't how R could have theform (x,y) for a unity like S does. If the unity is just 1 then itisn't the same as the unity in S and the uniqueness of unity wouldhave nothing to do with this.I might be misunderstanding this problem. It's strange. === Subject: Re: Difficult Algebra Problem> I have a problem that I'm having a tough time with.Let R be a ring (perhaps without 1). Prove that (S,+,.) is a ring withunity> when S=R X Z, (r,m)+(s,n)=(r+s,m+n), and (r,m)(s,n)=(rs+ms+nr,mn).SNIPWe want a (s,n) such that (r,m)(s,n)=(r,m) therefore r=rs+ms+nr and m=mnclearly the second part implies n=1 which is feasible since n e Zso now we know r = rs+ms + r = s(r+m) + rif we let s=0 (since R is a ring, 0 has to be in it), the above equationbecomes r = rSo unity in S is (0,1). Notice this does NOT require unity in R.-Tralfaz === Subject: Re: Difficult Algebra Problem> I have a problem that I'm having a tough time with. Let R be a ring (perhaps without 1).> Prove that (S,+,.) is a ring with unity> when S=R X Z, (r,m)+(s,n)=(r+s,m+n), and (r,m)(s,n)=(rs+ms+nr,mn).>[...]> If R has a unity 1, how does that unity relate to the unity of S?> Are they the same? Would it contradict the uniqueness of unity?Since R is not even a subset of S, the two unities are certainly not equal. Even if you regard R as a subset of S via the identificationr --> (r,0) (for r in R)you can check, that (r,0)(0,n) = (nr,0).Hence no element of the form (r,0) can be the unity of S.So if you start with a ring unity, the new ring S willhave another unity.Marc === Subject: Re: Difficult Algebra Problem> I have a problem that I'm having a tough time with. Let R be a ring (perhaps without 1). Prove that (S,+,.) is a ring with unity> when S=R X Z, (r,m)+(s,n)=(r+s,m+n), and (r,m)(s,n)=(rs+ms+nr,mn).> Z is the integers. The additive identity is just (0,0) right? According to your rule, do you get (r,m)+(0,0)=(r,m) ?> My main problem is that I'm not sure how to deal with the Unity. If R might> not have 1, then how can S definitely have 1 since it's R X Z? If R has a> unity 1, how does that unity relate to the unity of S? Are they the same? Did you try (r,m)(s,n) = (s,n) and see what equations you get?Can you choose r,m to make them always true?> Would it contradict the uniqueness of unity?> Please Help!Is uniqueness part of the definition? No, it is a theorem.How do you prove it? === Subject: Re: Bush's dealx-mimeole: Produced By Microsoft MimeOLE V6.00.2600.0000> taht really sucks!> also, if you really want to know,> most of us would consider Lewinsky to have> been a (perhaps not whitting) Israeli mole, although> Goldberg could pull all of that truck, herself.> just look-up Get Clinton on larouchepub.com --> and don't move your lips, when reading American Almanac!Oh please. Dont be so ing lameMimicZGF0YWZsZXhAY2FubmFiaXNtYWlsLmNvbQ== ( www.hidemyemail.net )Without knowledge you have fear. With fear you create your own nightmares.Alzheimer's, cheaper than rohypnolThere are 10 types of people in the world. Those that understand Binary,and those that dont.He who controls Google, controls the world. === Subject: Re: Bush's deal> George W. Bush has a heart attack and dies. He goes to Hell where the> devil is waiting for him.I don't know what to do with you here, says the devil You're on my> list but I have no room for you. You definitely have to stay here, so> I'll tell you what I'm going to do. I've got three folks here who> weren't quite as bad as you. I'll let one of them go, but you have to> take their place.> I'll even let YOU decide who leaves.> George thought that sounded pretty good, so he agreed.> The devil opened the first room: in it was Richard Nixon and a large> pool of water. He kept diving in and surfacing empty-handed over and> over and over. Such was his fate in hell.No ! George said. I don't think so. I'm not a good swimmer and I> don't think I could do that all day long.> The devil led him to the next room: in it was Tony Blair with a> sledgehammer and a room full of rocks. All he did was swing that> hammer, time after time after time.No, I've got this problem with my shoulder. I would be in constant> agony if all I had to do was break rocks all day! commented George.> The devil opened a third door. In it, George saw Bill Clinton, lying> on the floor with his arms folded behind his head, and his legs staked> in a spread eagle pose. Bent over him was Monica Lewinsky, doing what> she does best.> George Bush looked at this in disbelief for a while and finally said:Yeah, I can handle this.> The devil smiled and said........ OK, Monica, you're free to> go!Oh heavens.... ROTFLMFAO!!!!!!!!!!!! :*) I wasnt expecting that punchline.Im literally laughing my ass off!!! Good one, and I like Bush, LOL. === Subject: Re: Bush's dealmaybe I should dysinclude the Mensa list, but*why* do you like Dubya, other than his wonderful gladhandings? > Im literally laughing my ass off!!! Good one, and I like Bush, LOL.--Give Earth a Trickier Dick Cheeny -- out of office, after GIGA years.http://www.benfranklinbooks.com/http://www.rand.org/ publications/randreview/issues/rr.12.00/http:// members.tripod.com/~american_almanachttp://www.wlym.com/pdf/ iclc/howthenation.PDF === Subject: Re: Bush's deal> George W. Bush has a heart attack and dies. He goes to Hell where the> devil is waiting for him.I don't know what to do with you here, says the devil You're on my> list but I have no room for you. You definitely have to stay here, so> I'll tell you what I'm going to do. I've got three folks here who> weren't quite as bad as you. I'll let one of them go, but you have to> take their place.> I'll even let YOU decide who leaves.> George thought that sounded pretty good, so he agreed.> The devil opened the first room: in it was Richard Nixon and a large> pool of water. He kept diving in and surfacing empty-handed over and> over and over. Such was his fate in hell.No ! George said. I don't think so. I'm not a good swimmer and I> don't think I could do that all day long.> The devil led him to the next room: in it was Tony Blair with a> sledgehammer and a room full of rocks. All he did was swing that> hammer, time after time after time.No, I've got this problem with my shoulder. I would be in constant> agony if all I had to do was break rocks all day! commented George.> The devil opened a third door. In it, George saw Bill Clinton, lying> on the floor with his arms folded behind his head, and his legs staked> in a spread eagle pose. Bent over him was Monica Lewinsky, doing what> she does best.> George Bush looked at this in disbelief for a while and finally said:Yeah, I can handle this.> The devil smiled and said........ OK, Monica, you're free to> go!> Oh heavens.... ROTFLMFAO!!!!!!!!!!!! :*) I wasnt expecting thatpunchline.> Im literally laughing my ass off!!! Good one, and I like Bush, LOL.> RobIt is an old punchline, Rob, I've heard the same story in many differentways about many different people.jt === Subject: Re: Bush's deal === >Subject: Re: Bush's deal>Message-id: <5Lagc.14642$k05.3148@newsread2.news.pas.earthlink.net> oo> ____|mn> / /_/ / _ - Herc, The Unrecognised Truman> / K-9/ /_/ - Join www.chatty.net -> /____/_____ - Nanotechnology is gonna be HUGE... (RMF)> --------------> George W. Bush has a heart attack and dies. He goes to Hell where the> devil is waiting for him.I don't know what to do with you here, says the devil You're on my> list but I have no room for you. You definitely have to stay here, so> I'll tell you what I'm going to do. I've got three folks here who> weren't quite as bad as you. I'll let one of them go, but you have to> take their place.> I'll even let YOU decide who leaves.> George thought that sounded pretty good, so he agreed.> The devil opened the first room: in it was Richard Nixon and a large> pool of water. He kept diving in and surfacing empty-handed over and> over and over. Such was his fate in hell.No ! George said. I don't think so. I'm not a good swimmer and I> don't think I could do that all day long.> The devil led him to the next room: in it was Tony Blair with a> sledgehammer and a room full of rocks. All he did was swing that> hammer, time after time after time.No, I've got this problem with my shoulder. I would be in constant> agony if all I had to do was break rocks all day! commented George.> The devil opened a third door. In it, George saw Bill Clinton, lying> on the floor with his arms folded behind his head, and his legs staked> in a spread eagle pose. Bent over him was Monica Lewinsky, doing what> she does best.> George Bush looked at this in disbelief for a while and finally said:Yeah, I can handle this.> The devil smiled and said........ OK, Monica, you're free to> go!> Oh heavens.... ROTFLMFAO!!!!!!!!!!!! :*) I wasnt expecting that>punchline.> Im literally laughing my ass off!!! Good one, and I like Bush, LOL.> Rob>It is an old punchline, Rob, I've heard the same story in many different>ways about many different people.So Bush didn't really die and go to Hell?>jt === Subject: Re: number of indep. soloutions to diffyqs?I believe your question is about completeness.The references cited by the other respondents are very good, butyou might have to consult some more advanced texts as well.______________________________________________________> I've taken some classes in solving differential equations, and Iunderstand> all the different techniques, and everything, but am confused as to how we> can be assured that our techniques yield *all* possible solutions.> Especially when we do things like, if x1 is a solution, put x2(x) => x1(x)*f(x) into the differential equation and obtain another solution. Is> there a general way to tell how many linearly independent solutions a> differential equation has, (especially regardless of homogeneity and> linearity)? I understand why these methods work, of course, but can't see> exactly how we can be sure we are obtaining all the solutions. I can see> intuitively a little why it should be the case (especially when using> eigenvalues of a matrix in the matrix form of a diffyq x'=Ax, but wouldlike> something more rigorous).> Jeremy === Subject: Re: Question about first-order logic > There seems to be poor readers in this newsgroup. :-) Yep. === Subject: Need some clarification.This might be a really stupid question to ask but could someoneexplain to me what I need to do for these problems. I've read themthrough several times and looked through my notes and my book and Idon't know what exactly needs to be done. If someone is willing topush me in the right direction it would greatly be appreciated.Question: If G is a group that acts on a set X, then for any x E X we define theorbit of x to be O(x) = {g x : g E G} and we also define thestabilizerof x to be Gx = {g E G : g x = x}.Each of the following four parts describes a group action of G on X.Ineach case compute Ox and Gx for every x E X.(a) Let G = Z and let X = R^2. We define an action of G on X asfollows: For n E Z and (x, y) E R^2 we define n (x, y) to be thepoint in R^2 obtained by rotating (x, y) by an angle of pi(n)/2radiansin a counterclockwise direction about the origin. (Hint: In orderto compute G(x,y) for (x, y) E R^2, consider two cases first when(x, y) = (0, 0), and then when (x, y) /= (0, 0). )(b) Let G = R and let X = S1. (Recall that S1 is the circle, which maybe viewed as S1 = {z E C : |z| = 1} = {e^(i*theda) : 0 <= theda <2(pi)}.) We define an action of G on X by defining r z = e^(ir)z;that is, rotate z by anangle of r radians in a counterclockwise direction about the origin.(c) Let G = R and let X = R^2. We define an action of G on X asfollows:For r E R and (x, y) E R^2 we define r (x, y) = (x + 2r, y + r).(d) Let G = Z2 and let X = R. We define an action of G on X asfollows:For n E Z2 and x E R we definen x = ( x if n = 0) (-x if n = 1) === Subject: Closest Rank Algorithm?I need an algorithm similar to amazon.com which would give me n items that were rated highest by the users that rated item x high. i.e. people who liked this book also liked those 5..So,N = number of items.X = number of users.For a given items i and user u, R(i,u) | {Rmin <= R(i,u) <= Rmax, R(i,u) belongs to N+} is the rating of the item i by the user u.What i need is:Given an item i, what are the m (m=5 for example) items that were ranked highest by users that ranked i high?There are some ambiguities in this quite informal problem description:1. What does it mean item ranked high by a user? imho it means R(i,u) > avg ( R(i,u) for all u, i), i.e. higher than the average of all ratings by all users.2. What does it mean items that were ranked highest by users that ranked item i high? No idea. Help me interpret that please.P.S.If you reply, please reply to me as well, not just the newsgroup. === Subject: Re: Force and accelerationIn sci.math, Donald G. Shead Cut<> That's no way to talk about your twin. At least he *knows* that> pounds are units of mass, even though he is dishonest and pretends> otherwise.> If you guys would quit fighting each other, and take some time out to> think about physics:Translation: swallow whole Donald G. Shead's collective wisdom.You do realize that you're not exactly the most respected physicisthere, I hope? :-)> That pounds and newtons are measures of force,That bit, at least, is correct.> and slugs and kilograms are measures of inertia;No, they're measures of mass; inertia is merely a concept,not a measurable quantity. Of course one can equate thetwo, which more or less makes sense -- but most people don'tbother and simply write '1 kg'. (Or, if one insists on usingImperial units, '1 slug' or '1 pound-mass'.)> you'll find that inertia is the ratio of the force> exerted on and/or by an object; body or mass of matter,> to the rate of change in velocity that it causes.So what?At best it gives a method by which one can measure mass.#191, ewill3@earthlink.netIt's still legal to go .sigless. === Subject: Re: Force and acceleration>Cut<> Weight never has the meaning given there when anybody talks about net> weight. That is a term of commerce, not of physics.>Do you mean commerce buys and sells mass?No, but people do measure many of the goods they buy and sell in unitsof mass, such as pounds or kilograms. But you've known that for manyyears, Dumb Donny.> Weight never has the meaning given there when anybody talks aboutatomic weight or molecular weight--terms which are used in> physics.>Those are chemist's terms, not physicisist's.Nonsense. When I first learned this, physicists' atomic weights weredifferent from chemists' atomic weights. Now both are based oncarbon-12.> Weight never has the meaning given there when anybody talks abouttroy weight. There is no troy ounce force, and there never has been> a troy ounce force.>What gives troy weight, weight?> Weight never has the meaning given there when anybody talks about the> units called the pennyweight or the hundredweight (whether long or> short).>What's the difference between long and short weight?17 millimeters?Short weight is what you can go to jail for giving. A shorthundredweight is something entirely different, a unit of mass equal to45.359237 kg.> Weight never has the meaning given there when anybody talks aboutcarat weight of a diamond--one gram equals 5 carats.>Do you mean a 5 carat diamond is some rock?> Weight never has the meaning given there when anybody talks aboutdrained weight of a jar of olives.>That means the weight of the water was drained off, doesn't it?> Weight never has the meaning given there when anybody talks about thedeadweight of a ship.>Does that mean when the engines die a ship is dead in the water?> Weight never has the meaning given there when anybody talks aboutflyweight, bantamweight, cruiserweight, or the 63 kg weight> class in boxing or wrestling or judo.>Does that mean heavyweights mass only about 90 kg?In some sports, that's the class without an upper limit.> Weight never has the meaning given there when anybody talks about the> weight of a hammer in the hammer throw, the weight of a shot in the> shot put, the weight of a bowling ball, etc.>Since when I was a kid too?Since Moby Dick was a minnow.Even though you are older than dirt, people had been measuring thisweight which is the same thing as mass in physics jargon for over7000 years before you were born.> Weight never has the meaning given there when anybody talks abouttest weights used in calibrating or certifying a scale.>How about the weights used in calibrating spring scales?Same is true of them--it's just that in that case, in addition to thetest weights, you'd also need some other independent measurement ofthe strength of the local gravitational field, if you want to testtheir accuracy in measuring force. You don't need that if you aretesting their accuracy in measuring mass at a particular location.For all the spring scales I have seen, there is no calibration thatcan be done--the most you are able to do on any of them is to zerothem.> Weight never has the meaning given there when anybody talks aboutbrass weights or stainless steel weights or the> often-unadorned-with-an-adjective set of weights used with a> balance.>Are you saying that weight means mass?You've known that for many years that it often does, Dishonest Don.You repeatedly keep playing on that ambiguity, every time you whineabout kilograms being used as units of weight. You know that therewill always be some fool reading your messages who isn't as smart asyou are, someone you can hoodwink by being deceptive about that.> Weight never has the meaning given there when anybody talks about the> weight of a variable in mathematics. (Had to get in something> relevant to the sci.math newsgroup, one of them in which Dense Donny> started this thread.)>What ever happened to the 16 ounce pound - the weight of 2 - 8 oz cups of water?That is, and always was, a figment of Dumb Donny's imagination. http://ourworld.compuserve.com/homepages/Gene_Nygaard/ === Subject: Re: Force and accelerationSo far no known language is perfect in the sense of lacking ambiguities.Because language and the uses to which it is put are constantly changing, nolanguage is ever likely to be completely unambiguous. New languages evolveprimarily to adapt to the ever-changing needs of the users and the fact thatthe language they were taught as children is insufficient to meet the needsthey encounter as adults.The English language has some very fundamental ambiguities (such as the lackof distinction between singular and plural in the second person pronoun, orbetween dative and accusative phrases). That is a small hindrance indeed tothe hundreds of millions of people around the world who use the languageevery day.Having pointed that much out, I now need to point out that when anindividual finds it impossible to adapt to broadly accepted socialconventions (such as using a single word to represent multiple conceptsdistinguishable by context), such lack of socialization becomes a pathologyof its own.sHead's intractability on the matters which he consistently brings up, whichappear to be a problem only to *him*, is indicative of a deep-rootedpsychological problem which should receive professional attention.As long as he remains non-violent, the sociopath is relatively benign. LikeTed Kazinski, however, there is always a possibility that, unmonitored, hecan go off the deep end and declare war on them - those people who arenot like him.sHead is sick and probably needs 24/7 care.Tom DavidsonRichmond, VA === Subject: Re: Force and acceleration> So far no known language is perfect in the sense of lacking ambiguities.> Because language and the uses to which it is put are constantly changing, no> language is ever likely to be completely unambiguous. New languages evolve> primarily to adapt to the ever-changing needs of the users and the fact that> the language they were taught as children is insufficient to meet the needs> they encounter as adults.> The English language has some very fundamental ambiguities (such as the lack> of distinction between singular and plural in the second person pronoun, or> between dative and accusative phrases). That is a small hindrance indeed to> the hundreds of millions of people around the world who use the language> every day.> Having pointed that much out, I now need to point out that when an> individual finds it impossible to adapt to broadly accepted social> conventions (such as using a single word to represent multiple concepts> distinguishable by context), such lack of socialization becomes a pathology> of its own. But since it only a socialization issue between Novelists and people who make robots, who don't socialize to begin with, it's not really like a heady problem that people as stupid as chemistry dictionary dorks get involved in.> sHead's intractability on the matters which he consistently brings up, which> appear to be a problem only to *him*, is indicative of a deep-rooted> psychological problem which should receive professional attention.> As long as he remains non-violent, the sociopath is relatively benign. Like> Ted Kazinski, however, there is always a possibility that, unmonitored, he> can go off the deep end and declare war on them - those people who are> not like him.> sHead is sick and probably needs 24/7 care.> Tom Davidson> Richmond, VA === Subject: Re: martingale inequality, indep. random variablesDOOB'S INEQUALITY for p=2 gets you the constant 4 that you want>Alright, I'm obviously missing something easy here, but suppose X_nis>a martingale with sup E[(X_n)^2]. Write X_n = X_0 + Y_1 + ... + Y_n,>with X_0 and the Y_i being independent random variables.>Define K_n = sup(m>n) |X_m - X_n|. Show that>E[(K_m)^2] < = 4 SUM(n+1,oo) E[(Y_i)^2]. (*)>Now, I know that>SUM(n+1,oo) E[(Y_i)^2] = E [( SUM(n+1,oo) Y_i )^2].>If I could somehow take the sup outside of the expectation in (*),>then I would have the inequality but in fact I wouldn't need the 4,>and I guess that's what's puzzling me...any hints?>For general martingales one could obtain an inequality like this from>Doob's inequality, although it seems to me that I would get 16 instead>of 4. For sums of independent random variables there is Levy's>inequality, which I think really would give you the constant 4.Neither>of these inequalities are obvious (in the sense that one is likely to>figure them out by oneself). Look in the book Some random series of>functions by Kahane - Levy's inequality is in Chapter 2 or 3, Ithink.> Also, I recall seeing a rather simpler argument for this, which is partof a> proof of the law of large numbers. I think it is due to Kolmogorov. Inany> case, the result is not so obvious, and you need to find it in a booksomewhere.> OK, I found Levy's inequality:> Suppose X_i are i.r.v.s such that> P {|X_i + ... + X_n| >= L/2} <= d> for 1 <= i <=n.> Then> P {sup |X_1 + ... + X_n| > = L} <= d/(1-d).> But I still don't see how this applies...it gives results about sups> of the sum, but I want something on the expectation of the square of> that sup.... === Subject: Re: martingale inequality, indep. random variablesDOOB'S INEQUALITY gives what you want, with the constant 4 in theL^2-integrable case === Subject: Re: stopping time for a uniformly integrable martingaleThese = the facts stated after his question? Aren't they true?> Let X be an integral random variable. Let T be a stopping time for for> a filtration {F_n}. Define X_n = E(X | F_n). For all these> definitions, n belongs to 0,1,...,oo (the extended natural numbers).> How does one show that> E(X | F_T) = SUM(all n) {T=n}X_n = X_T> almost surely???> I know this definition makes the sequence {X_n} a uniformly integrable> martingale. Also, I think we can write> E(X_T) = SUM(all n) E(X_T | {T=n}) = SUM(all n) E(X_n | {T=n}).> I think it has to do with Doob's optional stopping theorem, but I> haven't been able to apply it in just the right way I guess. Also,> it's not given that T is bounded, so there might be convergence> issues....suggestions are very welcome, thank you> Why do you think these are true? === Subject: analysis problemdefine f(x)= x + x^2(sin (1/x^2)) if x =/= 0 and is 0 when x = 0. I need toshow that there exist no interval containing 0 throughout which f isincreasing. So I found f ' (x) = 1 + 2xsin (1/x) - (2/x)cos (1/ x^2) if x=/=0 and 0 elsewhere.assume x is near 0 but positive. Then the term 2x sin (1/x^2) is negligible.Want to show 1 - (2/x)cos (1/ x^2) oscillate between +/- .????? === Subject: re:analysis problemI'm not sure what you need to show, but cos(1/x^2) and sin(1/x^2)oscillate infinitely often as x->0.http://www.newsfeed.com The #1 Newsgroup Service in the World! >100,000 Newsgroups---= 19 East/West-Coast Specialized Servers - Total Privacy via Encryption =--- === Subject: Re: analysis problem> define f(x)= x + x^2(sin (1/x^2)) if x =/= 0 and is 0 when x = 0. I needto> show that there exist no interval containing 0 throughout which f is> increasing.What are the zero's of the function?Clearly x=0 is one. Check for othersthen check f' at those points. If it is negative, good. If it is 0, checkf'' to see if it a point of inflection or a local max/min, althoughtechnically by your question it doesnt make a difference since if f'(x)=0,there is not increasing at x. However, your professor may interpret itdifferently. For example, they may say f(x) = x^3 is an increasing functionover all intervals.-Tralfaz === Subject: Re: analysis problem> define f(x)= x + x^2(sin (1/x^2)) if x =/= 0 and is 0 when x = 0. I need> to> show that there exist no interval containing 0 throughout which f is> increasing.> What are the zero's of the function?> Clearly x=0 is one. But x = 0 is the only zero of f in small enough intervals containing 0 (for example, (-1,1)).> Check for others> then check f' at those points. If it is negative, good. If it is 0, check> f'' to see if it a point of inflection or a local max/min,None of this is necessary.> although> technically by your question it doesnt make a difference since if f'(x)=0,> there is not increasing at x.Sorry, that's wrong.> However, your professor may interpret it> differently. For example, they may say f(x) = x^3 is an increasing function> over all intervals.It's not a matter of interpretation. x^3 is strictly increasing on the whole real line by definition. The definition of increasing does not mention derivatives - nor should it. === Subject: Re: analysis problem> define f(x)= x + x^2(sin (1/x^2)) if x =/= 0 and is 0 when x = 0. I need to> show that there exist no interval containing 0 throughout which f is> increasing. So I found f ' (x) = 1 + 2xsin (1/x) - (2/x)cos (1/ x^2) if x> =/=0 and 0 elsewhere.> assume x is near 0 but positive. Then the term 2x sin (1/x^2) is negligible.> Want to show 1 - (2/x)cos (1/ x^2) oscillate between +/- .?????Consider the points x = 1/sqrt(nPi), n = 1,2,... === Subject: Re: When should I stop iterative method? by support1.mathforum.org (8.11.6/8.11.6/The Math Forum, $Revision: 1.9 primary) id i3HKZ3s28029;>I use iterative methods (Jacobi, Gauss-Seidel, ...) for solving linear>equation systems and i want to know when should I stop the iteration?>I know that the condition for stopping has something to do with Banach's>theorem or something like this:>d(x*,x^(k+1))<=q/(1-q)[d(x^(k),x^(k+1)], x* is real solution;>but i dont understand it!>So, what the condition to stop iterative procedure for solving linear>equation systems?Stop when you are no longer having fun === Subject: Re: Hungarian method for non-square assignment matrix (non-bipartite)> To OUP,> I thought the Munkres algorithm==Hungarian method,> both of which were designed for two sets of equal size.The Munkres algorithm that I'm familiar with is not limited to sets of equal size. The book Multiple-Target Tracking With Radar Applications by Samuel S. Blackman has a detailed description of this algorithm.There is also an iterative version of this algorithm called the Jonker-Volgenant-Castanon (a.k.a. JVC) algorithm.OUP === Subject: Re: Computer based proofs> I'm not quite sure what is meant by a published version.Appel, K.; Haken.W. and Koch, J. Every Planar Map is FourColorable. I: Discharging. Illinois J.. Math. 21 429-490, 1977. === Subject: Re: Computer based proofs I'm not quite sure what is meant by a published version.> Appel, K.; Haken.W. and Koch, J. Every Planar Map is Four> Colorable. I: Discharging. Illinois J.. Math. 21 429-490, 1977.Surely this did not contain 400 microfiche pages?In any case, the document I was referring to was evidentlya precursor of this - in effect, a preprint,which appeared to be a complete proof, in some 150 duplicated pages.Timothy Murphy e-mail (<80k only): tim /at/ birdsnest.maths.tcd.ietel: +353-86-2336090, +353-1-2842366s-mail: School of Mathematics, Trinity College, Dublin 2, Ireland === Subject: Representations of the circleWhy are the irreducible unitary representations of the circle the same asthe dual of the circle? I can't see any connection here:Dual of circle = group of continuous homomorphisms from circle to circle,which are the functions x ---> exp(2Pi*ikx) where k is in Z.Irreducible unitary representations : We have the regular representation ofS^1 on L^2(S^1) by R(y)f(x) = f(x+y), where f is in L^2(S^1). R : S^1 ---U (L^2(S^1)) where U (L^2(S^1)) is the unitary representations ofL^2(S^1). R is irreducible. Are there other irreducible unitaryrepresentations?Is there something going on here? Are the characters of a locally compactabelian group the same as the irreducible unitary representations of thelocally compact abelian group? Is this true? What if the group is justlocally compact?I appreciate any insight into this! === Subject: Re: A problem proving a Ring Isomorphism>I am using Gallian's book and am trying to complete the proof of>THeorem 15.6 Field of Quotients. I'm trying to prove that the>mapping phi: D -> F given by x -> x/1 is a ring isomorphism from D to>phi (D).>I've proven that it's one-to-one and also that it's a ring>homomorphism. My problem is that I'm not sure how to prove that it's>onto. It would seem awkward to use a/b since I'm given x/1 rather than>any arbitrary a and b.>I appreciate any help completing the theorem.> Reread the problem: you are not asked to show that phi is an> isomorphism from D to F: you are merely asked to show that it is an> isomorphism from D to> phi(D) = { phi(x) : x in D} = {f in F: there exists x in D with f=phi(x)}.> Every function is surjective onto its image.I knew that I was having to prove that phi is an isomorphism from D tophi(D). I just did not understand how to prove it. It just seemedlike it 'obviously' had to!Jacob> === =========================================================== === =====It's not denial. I'm just very selective about> what I accept as reality.> --- Calvin (Calvin and Hobbes)> === =========================================================== === ========Subject: differential equations teachingOk, so I'm finally able to settle down enough to take someconventional classes, and one of them is basic differential equations.Halfway through the class, I see that it has rapidly degenerated into:1. Spend 2 minutes doing differential equations2. Spend 3 hours doing basic algebra to clean up the mess3. Repeat over and over and overAnd looking at the trend so far, one can only conclude it will becomemore so before the end.Please god tell me all math isn't this way.Or if it is, put a bullet in my head.Also, when people write math problems, do they just randomly throwwhatever numbers pop in their heads into a differential operator? Until now, it's usually seemed like they've taken efforts to minimizethe above nonsense, ie by having strategic things cancel out,radicands conveniently being powers, etc.Use the very nice differential equations method to change thisdifferential equation into a system of 20 equations in 20 unknowns,all quadratic. Then solve. NOOOO!!!