mm-57 === An efficient way to compute the variance uses the raw-score formula of statistics. If you take the defn. of variance formula and expand it out and replace mu with its estimate (sample mean) you get the raw-score formula in terms of computation, you will only require the sum of the sample and thesum of the squares of the sample along with the number of samples.Clay> Dear all, In one of my program, I need to compute the variance of a 8x8 data matrixas> fast as possible... Any fast algorithm with lowest complexity? By the way, since what I actually need is an indication of signal local> activity, is there any other measure which can also be a indicator o? activity and is less complex than computing variance?> -Walala === In one of my program, I need to compute> the variance of a 8x8 data matrix as> fast as possible...What does it means ?You just have 16 samples of a signal and you want the variance ?For me it is not clear why deviation fromthe mean is a good indicator of activity.Obviously, there is no fast algorithm for computing a sumof 16 terms !BUT if you compute the variance on a moving windows, thereis a very fast algorithm, that you can ?ure out pretty easily.Your just have to perform :1. compute mean m and replace your image I by M=(I-m)^22. compute moving average along X direction. This can be doneby a recursive algorithm, because if S(k) is the moving averageand F(k) is the initial function (e.g. a row of M), you haveS(k) = S(k-1)+F(k)-F(k-9) (here I assume window of size 8)3. compute moving average along Y direction.All this stuff needs about O(n) operations where n is the number of pixelsin the original image and it's independant of the size of the window.Gabriel === > You just have 16 samples of a signal and you want the variance ?Sorry, I meant 64 samples.> Obviously, there is no fast algorithm for computing a sum> of 16 terms !Sorrrry once again 8x8=64 not 16 ...G. === We look at the usual long multiplication of, for example, 123*48. 123 x 48 ------- 984 +492------- 5904. However, I wish to concentrate just on the tens and units ?ures of the resulting product. This is called ?multiplying modulo 100.' That is, any whole number of 100s can be thrown away in the process. Then, (100+23)*48 == 48*100+23*48 (is congruent to)== (20+3)*(40+8) == 2*4*100+3*40+8*20+3*8 == 120+160+24 == 104 == 04 modulo 100. In calculating the remainder of product (integers w*z) after dividing by positive integer, t, it can often be made easier by taking away convenient multiples of the modulus, t, from w or z respectively before executing the multiplication. Let w = at+b, say, and z = ct+d, say. Then, wz = (at+b)(ct+d) = at(ct+d) +b(ct+d) = t(act +ad +bc) +bd == bd modulo t. Bd should usually be less than w*z, but it may require to be reduced further. I photographed car number plate ?MP163' at Hanson St, Newtown, Wellington on today, 26-5-2002. This number plate could be shorthand for Mersenne numbers, 2^prime-1. (Figure 2 raised to a prime index, subtract 1.) The world's largest known prime number in 2001 often is2^13.4million-1. (Greater than 13 million 2s (Dominion Post, NZ Herald, GIMPS greatinternet mersenne prime search.)By the way, the 40th known Mersenne prime exponent isa twin prime, 10x(23x63)^2 +/-1. And a previous recordholder was virtually a palindrome, Table Mountain, increasingdecreasing.Exponent (1*2*34*44432+1)= 3021377. [sic.] _____ / A theorem of mathematics number theory says if(a is a positive integer )..a^prime-1 has factor/s they must be of the form 2*k*p+1. However, the Penguin Dictionary of Curious and Interesting Numbers (1997), entry 28, table of perfect numbers, does not give M_163 as a Mersenne prime. Therefore, I have written myprogram ?powabc1' in BBC interpreted Basic64, which tests for just such factors.(On Acorn A5000 computer, UK 1990, RISC OS-reduced instructionset computer, 4 Megabytes RAM randomaccess memory.)In this case, several programs found 150287 and 704161, etc. divide M_163. Or 2^163 == 1 modulo 150287. Have I found a factor of M_163? The following, I believe, shows that I have.Check. 2^163= 2^3*(2^20)^8 (is congruent to)== 8*1048576^82^20==1048576-6*150287 == 146854 mod 150287 == -3433. Squaring 2^40= 11785489== 63103 Squaring 2^80==3,981,988,609 ==134544== -15743 Squaring 2^160==247,842,049 ==18786 2^163==8*18786 ==150288==1 mod 150287. Q.e.d.By the way, my methods found (the least prime) factor1580,187,223 of (10^9)^(10^9)+3. (sci.math sensation 2001.)This is, digit 1 followed by 9 billion zeroes. Surpassedonly by Graham's number. I suspect gigaplex =10^billion. (There is a typo error in Penguin Dictionaryof Curious and Interesting Numbers, 1997.) yours sincerely, / Donald S. McDonald (Wellington, New Zealand) === There was a time when people spoke their minds, and were not afraid to offend -and that since then, too many truths have been buried.Mark Kurlansky, 1968: The Year That Rocked The World(Ballantine, 2004) thanks to Frank LauriaIn 1968 I was in La Jolla CA at UCSD during time Greg Benford describes inTimescape living on Bonair Street Wind an Sea Beach near UnicornTheater with Ken Kesey's Merry Prankster Bus parked nearby frequently.I was also teaching at San Diego State with Fred Alan Wolf....PZ: I can't imagine anything more wrong-headed. And you say Rovelli is a bigshot?That is why I say Rovelli's position is incoherent.JS: Is coherence in the mind of the beholder?PZ: If you want to treat g_uv as a physical ?ld, based on its dynamical character(i.e. matter-dependence), then the natural thing to do is separate the backgroundgeneralized Minkowski kinematical metric (which is NOT matter dependent) aschronogeometric, and treat the gravitational g_uv alone as physical -- byRovelli's own argument.JS: That will not work. It will not tip the light cones. It will not give the correct bending of light.Also you are too vague on what you mean by matter on the RHS ofGuv(Einstein) = -(alpha)(alpha')Tuv(Matter)alpha = e^2/hc ~ 1/137alpha' = 8pi(Witten's reciprocal string tension)alpha' ~ (10^-32 cm)^2 in a common convention.I also include on RHStuv(Vacuum) ~ [(alpha)(alpha')]^-1/zpfguv/zpf = Lp^-1[Lp^3|Vacuum Coherence|^2 - 1]Repulsive dark energy is /zpf > 0Attractive dark matter is /zpf < 0FRW Omega(Dark Energy + Dark Matter) ~ 0.96With Omega(Total) = 1 i.e. FLAT SPACEPreferred foliation is where CMB is maximally isotropic to ~ 10^-5.This allows accurate navigation with weightless warp drive and traversable wormholes both supported by con?urations of dark energy and dark matter exotic w = -1 vacua.PZ: Yet he doesn't even mention this.JS: There was a time when people spoke their minds, and were not afraid to offend -and that since then, too many truths have been buried.Mark Kurlansky, 1968: The Year That Rocked The World...JS: Also at quantum level Rovellimention's Dirac's insight that the Heisenberg Picture is better thanSchrodinger Picture and that time as in the ? time's arrowis not dynamical time but is a statistical thermodynamic construct.PZ: Sure, if you want to quantize everything and abandon time.Unruh's for example, and some of the others.Unruh has some important ideas however.PZ: But then I fail to see any material distinction between relabelingthe bare unindividuatedspacetime points (passive diffeomorphism), on the one hand, andshifting all physical?lds (including the GR metric ?ld) with respect to such a rawmanifold (activediffeomorphism), on the other. Kretschman's point appears to be fullyvalid in both cases:how can physics in general -- any sensible physics -- possibly dependon a mere re-labelingof raw unindividuated spacetime points; or, for that matter, on acommon shift of all physicalsystems, including the *physical* metric ?ld g_uv, with respect tosuch a set of unindividuatedpoints?JS: Admittedly a sticky wicket that I also need to understand moredeeply.PZ: It's an arti?ial model that has nothing to do with physical relativity IMO.JS: I found this remark by Goldstein helpful:In the ADM formulation 4-diffeomorphism invariance amounts to the requirement that one ends up with the same space-time, up to coordinate transformations, regardless of which path in multi-?gered space-time is followed, i.e. which lapse function N is uses. p.278OK so this idea goes back to the archetypal notions of classical thermodynamics with a state function, to holonomic integrability of equality of mixed partial derivatives with not multiply-connected manifolds, to a closed Cartan exterior differential form on a cycle (no boundary), no topological defects and all that.The passive coordinate transformations are like EM gauge transformation (e/c)Au -> (e/c)Au + hChi,u in a ?ed gauge constraint.PZ: Rotating a system in isotropic space is connected with a true physical symmetryof the system including the vacuum in which it is embedded. Yes, the symmetryof the system Hamiltonian under such a transformation is an active transformationalsymmetry that is characteristic of the particular system -- unlike the invariance of theproper formal expression of any physical law under a *mere* coordinate transformation.JS: Note also 12.2.2 p.279 alluding to your digging up Kretchmann from Dr. Frankenstein's favorite graveyard. ;-)The fundamental symmetry at the heart of general relativity is its invariance under general coordinate transformations of spacetime. It is important to stress that almost any theory can be formulated in such a 4-diffeomorphism invariant manner by adding further structure to the theory (e.g. a preferred foliation of spacetime as a dynamical object). General relativity has what is sometimes called serious diffeomorphism invariance, meaning that it involves no spacetime structure beyond the 4-metric and, in particular, singles out no special foliation of spacetime.Goldstein and Teufel then knock standard QGrav including even Ashtekar -> Loop Spin Foams that are perhaps near to being falsi?d by NASA's EINSTEIN inJack better check this story out:Gary S. Bekkum...How to getlocalization in space and the ? time as we experience it in ourimmediate inner consciousnesshas nothing to do with the particular local coordinate representationlike r and t in, for example,K = e^2GM/c^2rdr/dt = c/Kfor null geodesicand in his Tables generally in the context of potentially practicalmetric engineering of the guv ?ld using the EM Au ?ld in spite ofthe enormous gravity string tension ~ c^4/G ~ 10^19 Gev per 10^-33 cm.PZ: You are blocking his actual de?ition of r. Classic operationalism does notapply to a theory of this type. That is a critical point. Miss that and of coursenothing makes sense.JS: I am not ready to renounce PW Bridgman's Operationalism. Indeed, nothing Hal Puthoff says about the foundations of his PV makes any sense to my mind. If it ain't broke, don't ? it. Of course I am not a doctrinaire positivist like Stephen Hawking proudly proclaims he is....JS: Correct, with the proviso that matter includes both real, i.e.on mass shell, sources as well as virtual, i.e. off mass shellsources. The virtual sources divide into two classes:I. Non-exotic near EM ?ld Fuv giant coherent quantum states ofvirtual photons that contribute to Omega(Matter) of the FRW metric andto Tuv in Einstein's local ?ld equation.II. Exotic vacuum w = -1 zero point stress-energy density local tensor~ (String Tension)/zpfguv for both repulsive dark energy /zpf > 0 ofnegative pressure and attractive dark matter /zpf < 0 of positivepressure.These exotic vacuum virtual sources contribute Omega(Exotic Vacua) ~0.96 to Omega(Total) = 1 in our large-scale spatially ?t-in?ary local Level I Hubble sphere brane world as inLenny Susskind's megalopolis Landscape subject to the naturalselection of the Weak Anthropic Principle (WAP)OK, I think I made an error above including brane worlds in sense of parallel worlds?Here is why I think I made an error (If I did so did Hawking and Scienti? American in their popular science reports):D-Branes are extended surfaces without edges. In order that the black hole be a localized object, it is assumed that our ordinary four dimensions (three space and one time) are all orthogonal to these D-Brane surfaces ... Thus to us these D-Branes would look as though they were located at a point (or at least a very small region) of our observable three dimensions of space. W. G. Unruh p. 168 Black holes, dumb holes, and entropy, i.e. the D-Branes are in the compacti?d Calabi-Yau space. I have to look again at Hawking's The Universe in a Nutshell that seems to give the wrong idea here? Perhaps I mis-remember?Note also Ed Witten's formula generalizing Heisenberg's quantum uncertainty principle, i.e. eq. (5.9) p. 136Delta X > h/DeltaP + alpha'(DeltaP)/hThe second gravity-string source of uncertainty should give the irreversible statistical arrow of time not found when alpha' = 0 i.e. in?ite string tension, or in?ite space-time stiffness of action without reaction as is also found in the signal locality of orthodox quantum theory in sense of Antony Valentini's papers.Mass without mass, but with a strong micro-gravityG* ~ 10^40G on 1 fermi scale. The wormhole has an attractive dark matter exotic vacuum core whereVacuum Coherence --> 0just like inside a quantized vortex of circulation in super?eII.Therefore, in the core/zpf ~ - (1 fermi)^-2w = -1Therefore the quantum pressure is positive and the exotic vacuum core gravitates asGrad^2V(Exotic Vacuum) ~ -c^2(1 fermi)^-2this prevents the spread out electric charge from exploding and also compensates any quantized rotation centrifugal forces. For now keep charge and rotation zero for simplicity. That is I here only model a spin 0 neutral micro-geon. That means I would need a high-power graviton laser as the Heisenberg uncertainty scattering probe microscope. That's OK since this is only a gedankenexperiment.The SSS metric then has the factor1 - 2GM/c2rWhere G(mass density) is replaced by c^2/zpfGM is replaced by ~ c^2/zpfR^3for a micro-geon of size Rr is DeltaX as in Witten's formula above with DeltaP as the scattering momentum transfer between gravitons and the micro-geon.Therefore, the Schwarzschild factor is (neglecting factors of 2, pi etc all lumped into dimensionless parameter b1 - bc^2/zpfR^3/DeltaXThe critical value of Delta X is then the event horizon where the Schwarzschild factor vanishes - can it be reached?This micro-geon is a solution of the exotic vacuum local ?ld equationGuv(Einstein) + /zpfguv = 0At critical Delta X, the geon looks like a POINT PARTICLE from the huge space-warp induced by the probe's momentum transfer Delta P.C is the circumferencedC/dR = 2pi (1 - bc^2/zpfR^3/DeltaX)^1/2Where one considers the radial size ?ed at R the scale of the throat of the wormhole.So when can we haveDeltaX = bc^2/zpfR^3 ?Note that alpha' may be large of order (10^-11 cm)^2 not (10^-32 cm)^2 as in Witten's idea. === Interesting!Jack,Superstring theory does not view the Planck scale of spacetime as a quantumfoam but rather as the Planck scale is approached the dimensionality ofspacetime goes to 10-d. In string theory the spacetime does ?te butthis ?tion is harmonic rather than chaotic. In fact the assumptionthat the harmonics of the strings absorbs all the quantum ?tion can beused to derive the dimensionality of spacetime. Also Lorentz invariance isassumed in this calculation. This was ?st done by L. Brink and H.B.Nielsen in 1973 (A Simple Physical Interpretation of the Critical Dimensionof Space-time in Dual Models, *Physics Letters* 45B:4 (1973) 332-336. Thispaper is also included in the anthology edited by John Schwartz,*Superstrings: the First 15 Years of Superstring Theory, Vol. 1* (WorldScienti?, 1985). [Note that Dual Models is the old name for stringtheory, when it was still evolving away from the terminology of s-matrixtheory. However, the Mandelstam labels of S, T, and U duality haveresurfaced in membrane theory!] I mentioned the Brink-Nielsen view of string theory in my paper Notes onpdf.] Also on page 6 of F.W. Stecker's pdf paper [referred to in the NASAreport], he says We note that there are variants of quantum gravity andlarge extra dimension models which do not violate Lorentz invariance and forwhich the constraints considered here do not apply. BTW: In the Acknowledgments on page 8, Serge Rudaz is one of fourpeople thanked for helpful discussions. I remember meeting Serge Rudaz inseminars. He was then a young physics student (at Cornell?) who was an oldacquaintance of yours. He told us about instantons -- which was a new ideathen. I have not heard of him since 1976 -- until seeing thisacknowledgement! Nuff said! Saul-PaulJS: Yes, Serge was with me at UCSC in Summer 1973 when I went to see Jean Cocteau's Orphee on campus with Helen Quinn (who was close to having he baby at that time) and I think Serge and a few others. This was days before I went to SRI to meet with Puthoff and Targ on the tape you have. The story is in the book Destiny Matrix.----------Therefore quantum foam is suspect. Also Bohm's quantum potentialview of vacuum ?tions is relevant in context of the recentpaper from Teheran.I need to follow the experiment below more carefully.Jack better check this story out:Gary S. Bekkum === i have realised a few mathematical functions?, properties?, lately andwas wondering about them, such as whether they are already known, orare even important.if anyone is interested, hit me up,AIM:heartxenocide === I really hope no one takes this as spam, I'm a student member of theMAA, and I've posted here a few, brief times, however since I'm stilla lower division undergraduate most of the subject matter is far abovemy head, so I'm not a regular (yet!)With that said, I have created some math t-shirt designs that justmake me smile and I'd like to share them with the math community, withthe hopes that they delight someone else as much as they delight me.the url is http://www.cafeshops.com/subjective and the designs areunder Math and Science (click on the Einstein picture)All comments, critiques, commendations, cat-calls and creative input === I am stuck in high school maths mode, and can't seem to get into university level maths. This might be because I am entirely self taught, but I don't know. Does anyone else have this problem?I am at a level where I understand most high school maths, and I've studied Calculus Made Easy. It would be helpful to have some kind of way to check my knowledge.Does anyone know of any good textbooks that cover high school maths with worked exercises, and any texts that help the transition from high school maths to the more exciting stuff at university level? A book that takes time to explain things, point out applications and say why rather than just how. I am trying to understand maths, not just learn some techniques or shortcuts.By the way, I would prefer internet resources and small paperback books. There's no way I can afford college textbooks unfortunately.Johnathan === I am stuck in high school maths mode, and can't seem to get into> university level maths. This might be because I am entirely self> taught, but I don't know. Does anyone else have this problem? I am at a level where I understand most high school maths, and I've> studied Calculus Made Easy. It would be helpful to have some kind of> way to check my knowledge. Does anyone know of any good textbooks that cover high school maths> with worked exercises, and any texts that help the transition from> high school maths to the more exciting stuff at university level? A> book that takes time to explain things, point out applications and say> why rather than just how. I am trying to understand maths, not just> learn some techniques or shortcuts. By the way, I would prefer internet resources and small paperback> books. There's no way I can afford college textbooks unfortunately. JohnathanYou could check out:http://store.doverpublications.com/ by-subject-science-and-mathematics-mathematics-calculus.htmlth ey are cheap and useful. You could also try Schaum's outlines; they arealso very good.For web content, try:http://www.math.temple.edu/~cow/If you run a google search, you will ?d a plethora of math relatedwebsites. Many, many, many more than I care to list. Make google your bestfriend. You can ?d anything you could possibly want to know using googlein about 30 seconds.Lurch === > I am stuck in high school maths mode, and can't seem to get into> university level maths. This might be because I am entirely self> taught, but I don't know. Does anyone else have this problem?> I am at a level where I understand most high school maths, and I've> studied Calculus Made Easy. It would be helpful to have some kind of> way to check my knowledge.> > Does anyone know of any good textbooks that cover high school maths> with worked exercises, and any texts that help the transition from> high school maths to the more exciting stuff at university level? A> book that takes time to explain things, point out applications and say> why rather than just how. I am trying to understand maths, not just> learn some techniques or shortcuts.> By the way, I would prefer internet resources and small paperback> books. There's no way I can afford college textbooks unfortunately.> JohnathanYou could check out:> http://store.doverpublications.com/ by-subject-science-and-mathematics-mathematics-calculus.htmlth ey are cheap and useful. You could also try Schaum's outlines; they are> also very good.For web content, try:http://www.math.temple.edu/~cow/If you run a google search, you will ?d a plethora of math related> websites. Many, many, many more than I care to list. Make google your best> friend. You can ?d anything you could possibly want to know using google> in about 30 seconds.LurchIn particular, include ext:pdf site:.edu in your searches. You'lljust get postscript notes, usually written up by professors.'cid === There was a time when people spoke their minds, and were not afraid to offend -and that since then, too many truths have been buried.Mark Kurlansky, 1968: The Year That Rocked The World(Ballantine, 2004) thanks to Frank LauriaIn 1968 was in La Jolla CA at UCSD during time Greg Benford describes inTimescape living on Bonair Street Wind an Sea Beach near UnicornTheater with Ken Kesey's Merry Prankster Bus parked nearby frequently.I was also teaching at San Diego State with Fred Alan Wolf.OK, now I have looked at the rest of Rovelli's argument, I'll work throughthis one more time.PZ: Rovelli's position is very odd. First he says:...Of course, nothing [in GR] prevents us... from singling out thegravitational?ld as ?the more equal among equals', and declaring that location isabsolute inGR, because it can be de?ed with respect to it. (p 108)JS: But he rejects that Paul. He says doing that misses the greatEinsteinian insight.The great Einsteinian insight being the conditional and physical nature ofthe gravitational metric ?ld -- which con?with the great Einsteinian insightstrict equivalence.The opposite of a profound truth is another profound truth. -- Niels BohrWhat Rovelli doesn't seem to understand is that this all makes perfect sense onceyou give up strict equivalence and distinguish the background and physical metrics.JS: I do not understand this distinction. Please give more details what you mean.Have you read pp. 112 - 114 that completely demolishes Hal Puthoff' suse ofdr/dt = c' = c/K radial null geodesicin his Tables.PZ: It does no such thing. I would not even characterize pp 112-114 as an argument.It is simply a sketch of a model in which *everything* is quantized except the rawmanifold.JS: It shows no intrinsic meaning to Puthoff's r and t as he means it in his Tables.PZ: He wants to throw away time in order to keep a uni?d g_uv.Why do you think this is an argument against c' = c/K? As far as I can see it is simplya different theory.Rovelli brie?siders an alternative approach in which we retain the Minkowskibackground of standard QFT. But there he hasg_uv = n_uv + ?tionswhich makes no sense to me. He does not seem to understand the distinction betweenkinematical g_uv and dynamic gravitational g_uv. He cannot get his head over the uni?dmetric.What does he mean by ?tions?JS: What do you mean by kinematical g_uv and dynamic gravitational g_uv apart from Ruvwl = 0 in the former and not in the latter.JZ: Sounds like sheer nonsense to me. Nonsense because it is divorced from the physicalfundamentals.JS: No argument from me on that one.PZ: This of course is exactly what the classic Einsteinchronogeometric model does,going all the way back to special relativity.JS: I think you are misreading Rovelli.PZ: The Einsteinian model is a chronogeometric model, in which the metric g_uv re?thefundamental structure of spacetime.JS: If you mean, for example,dT = goo^1/2dtdR = grr^1/2drThen I agree that dT and dR are physical and dt and dr are not.However, to get a gravity shift of light frequency dodT'/goo'^1/2 = dT/goo^1'2treating dt as a kind of nonlocal invariant.If you mean more than this, then explain with detailed examples.PZ: That is the great Einsteinian insight -- which is.unfortunately, based on strict Einstein equivalence, which is ?titious.JS: Again I really do not understand what you mean by this sentence.PZ: Now Rovelli wants to pretend that the great Einsteinian insight is something else entirely-- that the gravitational ?ld is a physical ?ld.Loony tunes. He is tying himself up in knots.JS: Yes, in global specialrelativity, NO in local general relativity.PZ: In Einstein general relativity, the uni?d metric g_uv represents the fundamental structureof spacetime, and in inseparable from it. That's Einstein.It doesn't even make sense to me to say that this chronogeometric model holds only locally.PZ: That is precisely what distinguishes theEinsteinian from the Lorentzian model. The transformational andmetric structureis not, in the classic Einsteinian model, separable from spacetimeitself.But then he says:There is no absolute referent of motion in GR; the dynamical ?ldsmove withrespect to each other. (p 108)JS: Again you are misreading. There is no contradiction here inRovelli's argument.PZ: This is like arguing that everything is relative because everything is relative to theabsolute, including the absolute.Sounds like Lewis Carroll.JS: ;-)PZ: None of this has anything to do with Einstein general relativity, which treats theinertial ?ld as real. The uni?d metric derives its physical meaning from thisequivalence.Rovelli ignores all this and simply takes the uni?d Einstein g_uv as given.PZ: This second assertion seems to approach the metric ?ld of GR asjust another ?ld, whichis very close to and even indistinguishable from the physical rubberrod and clock modelof PV and Yilmaz -- just another physical ?ld which happens to havemetric properties.And of course such a ?ld is fully relational with respect tounindividuated spacetime pointson a raw manifold stripped of all coordinate systems, transformationproperties, and metrics.JS: Yes on just another ?ld. But NO that it's like PV and Yilmaz. Nottrue at all because,at least in PV, Hal uses an absolute non-dynamical background globalMinkowski spacePZ: That is what Rovelli *should* be doing, but he doesn't even consider thispossibility. He seems to think you can treat uni?d g_uv as a physical ?ld.JS: Why do you think you cannot?PZ: I can't imagine anything more wrong-headed. And you say Rovelli is a bigshot?That is why I say Rovelli's position is incoherent.JS: Is coherence in the mind of the beholder?PZ: If you want to treat g_uv as a physical ?ld, based on its dynamical character(i.e. matter-dependence), then the natural thing to do is separate the backgroundgeneralized Minkowski kinematical metric (which is NOT matter dependent) aschronogeometric, and treat the gravitational g_uv alone as physical -- byRovelli's own argument.JS: That will not work. It will not tip the light cones. It will not give the correct bending of light.Also you are too vague on what you mean by matter on the RHS ofGuv(Einstein) = -(alpha)(alpha')Tuv(Matter)alpha = e^2/hc ~ 1/137alpha' = 8piWitten's reciprocal string tension)alpha' ~ (10^-32 cm)^2 in a common convention.I also include on RHStuv(Vacuum) ~ [(alpha)(alpha')]^-1/zpfguv/zpf = Lp^-1[Lp^3|Vacuum Coherence|^2 - 1]Repulsive dark energy is /zpf > 0Attractive dark matter is /zpf < 0FRW Omega(Dark Energy + Dark Matter) ~ 0.96With Omega(Total) = 1 i.e. FLAT SPACEPreferred foliation is where CMB is maximally isotropic to ~ 10^-5.This allows accurate navigation with weightless warp drive and traversable wormholes both supported by con?urations of dark energy and dark matter exotic w = -1 vacua.PZ: Yet he doesn't even mention this.JS: There was a time when people spoke their minds, and were not afraid to offend -and that since then, too many truths have been buried.Mark Kurlansky, 1968: The Year That Rocked The WorldPZ: So he has not made any argument at all against a bimetric approach. He has simplyignored it, even though his own argument points to it.JS: with a literal meaning for coordinates r & t, otherwise his formuladr/dt = c/Kis physically meaningless, which it is in GR as explained by Rovelli onpp. 112 - 114.PZ: Only if you insist exclusively on operational meaning -- which would also knock outF = ma, which by a similar argument is empirically meaningless.JS: Yes, until you also add things likeF = - GMmr/r^3F = eE + e(v/c)xBetc.That is, Hal's use of engineering is precisely missing the thirdstep on Rovelli's p. 108.PZ: Rovelli's third step is merely a sketch of a proposal to quantize everything, whileretaining a uni?d g_uv treated in its entirety as a physical ?ld.This is not an argument.Rovelli's argument for his proposal, such as it is, is to be found on p 109:In my *opinion*, this is the right way to go.Well, in my *opinion*, it's fundamentally wrong-headed. In addition, Rovelli hasgrossly mischaracterized the Feynman-type alternative -- which shows that he hasnot understood it; although he is right that under this alternative, the GR conceptualrevolution is indeed dis-valued, but to a much greater extent than he seems to realize.JS: Also p. 112Recall that Einstein described his great intellectual struggle to ?dGR as ?understanding the meaning of coordinates'.This is my key objection to Puthoff's and Ibison's use of r ant tin their PV modeling.They do not IMHO understand the meaning of coordinates: in GR. Neitherdoes Yilmaz apparently.PZ: I have no idea of what you are getting at here. Einstein's point about coordinatesdepends entirely on his strict equivalence thesis, which is untenable.JS: I guess I have never understood your idea here. Can you try to explain it again withcomplete clarity?PZ: Once you abandon strict equivalence, the uni?ation of gravitational and inertialg_uv is formal and arbitrary. It has no deep physical meaning. Then we recoverchronogeometric background coordinates together with a physical rubber-rod-and-clock non-inertial g_uv.Rovelli doesn't seem to understand that.JS: Neither do I.pp 112 - 114 make this clear IMHO.PZ: This is not an argument -- it's merely a proposal: In my opinion....JS: Also at quantum level Rovellimention's Dirac's insight that the Heisenberg Picture is better thanSchrodinger Picture and that time as in the ?ti me's arrowis not dynamical time but is a statistical thermodynamic construct.PZ: Sure, if you want to quantize everything and abandon time.Unruh's for example, and some of the others.Unruh has some important ideas however.PZ: But then I fail to see any material distinction between relabelingthe bare unindividuatedspacetime points (passive diffeomorphism), on the one hand, andshifting all physical?lds (including the GR metric ?ld) with respect to such a rawmanifold (activediffeomorphism), on the other. Kretschman's point appears to be fullyvalid in both cases:how can physics in general -- any sensible physics -- possibly dependon a mere re-labelingof raw unindividuated spacetime points; or, for that matter, on acommon shift of all physicalsystems, including the *physical* metric ?ld g_uv, with respect tosuch a set of unindividuatedpoints?JS: Admittedly a sticky wicket that I also need to understand moredeeply.PZ: It's an arti?ial model that has nothing to do with physical relativity IMO.JS: I found this remark by Goldstein helpful:In the ADM formulation 4-diffeomorphism invariance amounts to the requirement that one ends up with the same space-time, up to coordinate transformations, regardless of which path in multi-?gered space-time is followed, i.e. which lapse function N is uses. p.278OK so this idea goes back to the archetypal notions of classical thermodynamics with a state function, to holonomic integrability of equality of mixed partial derivatives with not multiply-connected manifolds, to a closed Cartan exterior differential form on a cycle (no boundary), no topological defects and all that.The passive coordinate transformations are like EM gauge transformation (e/c)Au -> (e/c)Au + hChi,u in a ?ed gauge constraint.PZ: Rotating a system in isotropic space is connected with a true physical symmetryof the system including the vacuum in which it is embedded. Yes, the symmetryof the system Hamiltonian under such a transformation is an active transformationalsymmetry that is characteristic of the particular system -- unlike the invariance of theproper formal expression of any physical law under a *mere* coordinate transformation.JS: Note also 12.2.2 p.279 alluding to your digging up Kretchmann from Dr. Frankenstein's favorite graveyard. ;-)The fundamental symmetry at the heart of general relativity is its invariance under general coordinate transformations of spacetime. It is important to stress that almost any theory can be formulated in such a 4-diffeomorphism invariant manner by adding further structure to the theory (e.g. a preferred foliation of spacetime as a dynamical object). General relativity has what is sometimes called serious diffeomorphism invariance, meaning that it involves no spacetime structure beyond the 4-metric and, in particular, singles out no special foliation of spacetime.Goldstein and Teufel then knock standard QGrav including even Ashtekar -> Loop Spin Foams that are perhaps near to being falsi?d by NASA's EINSTEIN inJack better check this story out:Gary S. BekkumPZ: However, moving *everything physical* -- including the uni?d g_uv -- along the rawspacetime manifold is quite another kettle of ?h. It is devoid of physical content IMHO.But again, a space-time frame of reference is not *merely* a coordinate transformation,since it represents the *motion* of a possible observer. Thus there is no *a priori* reasonwhy physical laws should take the same form in different frames of reference, contraryto Einsteinian doctrine. Of course they *may* as a matter of fact, but that is very differentfrom insisting a priori that they always *should*.That's yet another Einsteinian red herring.PZ: What is physically signi?ant here is not this abstract andarti?ial de?ition of diffeomorphismwith respect to a raw manifold conceived as an unindividuated pointset, but a shift of physical?lds with respect to the metric-transformational structure ofspacetime, which of course in GRdepends on the distribution of matter.JS: Precisely, yes that is the idea I think. It's a return to I thinkLeibniz's relationism?PZ: Descartes. He is almost literally putting Descartes before the horse ofphysical relativity.JS: ;-)How to getlocalization in space and the ? time as we experience it in ourimmediate inner consciousnesshas nothing to do with the particular local coordinate representationlike r and t in, for example,K = e^2GM/c^2rdr/dt = c/Kfor null geodesicand in his Tables generally in the context of potentially practicalmetric engineering of the guv ?ld using the EM Au ?ld in spite ofthe enormous gravity string tension ~ c^4/G ~ 10^19 Gev per 10^-33 cm.PZ: You are blocking his actual de?ition of r. Classic operationalism does notapply to a theory of this type. That is a critical point. Miss that and of coursenothing makes sense.JS: I am not ready to renounce PW Bridgman's Operationalism. Indeed, nothing Hal Puthoff says about the foundations of his PV makes any sense to my mind. If it ain't broke, don't ? it. Of course I am not a doctrinaire positivist like Stephen Hawking proudly proclaims he is.PZ: So it appears that Rovelli ends up in a position where he isessentially arguing that the matter-dependence of the metric ?ld implies that the GR metric is really aphysical metric, and the GRmetric ?ld is to be regarded as a physical ?ld like any otherphysical ?ld.That is, the *uni?d* metric ?ld. That is Rovelli's tacit, yet arbitrary, assumptionIMO.Then, the physicsdepends only on the relative disposition of the various physical?lds with respect to each other.JS: Correct, with the proviso that matter includes both real, i.e.on mass shell, sources as well as virtual, i.e. off mass shellsources. The virtual sources divide into two classes:I. Non-exotic near EM ?ld Fuv giant coherent quantum states ofvirtual photons that contribute to Omega(Matter) of the FRW metric andto Tuv in Einstein's local ?ld equation.II. Exotic vacuum w = -1 zero point stress-energy density local tensor~ (String Tension)/zpfguv for both repulsive dark energy /zpf > 0 ofnegative pressure and attractive dark matter /zpf < 0 of positivepressure.These exotic vacuum virtual sources contribute Omega(Exotic Vacua) ~0.96 to Omega(Total) = 1 in our large-scale spatially ?t-in?ary local Level I Hubble sphere brane world as inLenny Susskind's megalopolis Landscape subject to the naturalselection of the Weak Anthropic Principle (WAP)OK, I think I made an error above including brane worlds in sense of parallel worlds?Here is why I think I made an error (If I did so did Hawking and Scienti? American in their popular science reports):D-Branes are extended surfaces without edges. In order that the black hole be a localized object, it is assumed that our ordinary four dimensions (three space and one time) are all orthogonal to these D-Brane surfaces ... Thus to us these D-Branes would look as though they were located at a point (or at least a very small region) of our observable three dimensions of space. W. G. Unruh p. 168 Black holes, dumb holes, and entropy, i.e. the D-Branes are in the compacti?d Calabi-Yau space. I have to look again at Hawking's The Universe in a Nutshell that seems to give the wrong idea here? Perhaps I mis-remember?Note also Ed Witten's formula generalizing Heisenberg's quantum uncertainty principle, i.e. eq. (5.9) p. 136Delta X > h/DeltaP + alpha'(DeltaP)/hThe second gravity-string source of uncertainty should give the irreversible statistical arrow of time not found when alpha' = 0 i.e. in?ite string tension, or in?ite space-time stiffness of action without reaction as is also found in the signal locality of orthodox quantum theory in sense of Antony Valentini's papers.PZ: But while this may allow or even imply a relational view of theraw spacetime manifold, in theCartesian sense, it is clearly not physical general relativity, inthe classic Einsteinian sense,which requires fundamental identi?ation of the inertial andgravitational metrics.JS: I do not understand what you just said. EEP in every signi?antsense still holds IMHO.PZ: You are in a loop.JS: Ground Hog Day. Help let me out of my bottle Oh Thief of Baghdad. The Magic Flying Carpet is obviously the weightless Alcubierre timelike geodesic faster than light warp drive powered by dark energy and dark matter exotic vacua con?urations. See my animated picture of this in http://qedcorp.com/APS/StarGate1.movPZ: EEP is NOT Einstein equivalence. EEP is merely a correspondence principle.Einstein strict equivalence is NOT valid. And even EEP is not strictly valid asadvertised (see e.g. Ohanian and Ruf?i Ch. 1).given guv ?ld still works for example.PZ: This simply re?weak equivalence -- equality of gravitational and inertial mass.That does not imply Einstein equivalence. It works whether we use a uni?d g_uvor go to a bimetric formalism, and regardless of whether we consider inertial forcesas real or ?titious.JS: The so-called ?titious or inertial forces, e.g. G-Force when a jet takes off (0 to 120 mph in 2 sec) from an aircraft carrier are physically real. I can tell you that from ?st-hand experience. The use of ?titious like the use of hidden variable are unfortunate choices of words. Extra variable is better for the latter.PZ: So this is not a valid argument IMO. It is an example of the classical logical fallacyaf?ming the antecedent.JS: The tidal stretch-squeezeworks etc.PZ: Of course. So?The point is that you can always tell the difference between a real gravity ?ld andan inertial ?ld. They are NOT completely physically equivalent.JS: If you mean Ruvwl =/= 0 locally for a real gravity ?ld, and is zero for an inertial ?ld, I agree.However, I do not see how you can writeguv = guv(inertial) + guv(real)That is, apart fromguv = Globally Flat Metric + du,v + dv,uI do not claim we can physically distinguish the two terms on RHS nor is thesecond term small compared to ?st.The Bohm pilot constraint for the extra variable, i.e. actual distortion of Hagen Kleinert's elastic-plastic 4D world crystal latticei.e. density of vortex line topological defects of curvature disclination and possibly torsion dislocations isdu = Lp^2(Goldstone Phase of Vacuum Coherence),u,u is ordinary partial derivative.Compare my equation here to Goldstein's eq. 12.4 on p. 282.PZ: Consequently,uni?d g_uv has no deep physical meaning or necessity -- as Feynman argued.PZ: Which all seems to contradict his statement,...Of course, nothing [in GR] to prevents us... from singling out thegravitational ?ld as ?themore equal among equals', and declaring that location is absolute inGR, because it can bede?ed with respect to it.JS: No, you have simply misread the context of Rovelli's remark. Readit again more carefully. This is not a valid objection at all toRovelli's argument IMHO. The way I read him, his argument issplendidly globally self-consistent.PZ: The way I read him, he doesn't actually *have* an argument. He simply *prefers*to quantize space and time intervals rather than unpack Einstein's uni?d g_uv.PZ: So IMO Rovelli's position is incoherent. If anything, he isarguing for an *alternative*non-Einsteinian interpretation of GR in which matter-dependent g_uvis to be treated as a*physical ?ld*, which means it can in principle be distinguishedfrom the kinematical inertial?ld with its trivially valid transformable metric tensor.JS: We are back to Square One. The Rock has rolled back down onSisyphus. I cannot pinpoint the precise misconception that is drivingyour position here.PZ: It is no wonder you are having this dif?ulty, since it is *Rovelli's* misconceptionthat is causing the problem.Rovelli doesn't seem to understand that recognition of the dynamical character ofnon-inertial g_uv fundamentally distinguishes it from the kinematical g_uv, whichlatter doesn't depend on the distribution of matter. So the natural thing to do isto split uni?d g_uv and thus clearly separate the dynamical and kinematical metric?lds.JS: Show me an algorithm to do that in any problem.PZ: Yet he doesn't even consider this.In other words, Rovelli is really a *Yilmazian*.JS: Not in my book.PZ: Actually, you are right -- because he does not follow the natural developmentof his own argument to its logical conclusions. If he did, his ?st alternative (p 109)would fall squarely in the Feynman-Yilmaz category, with rubber rods and clocksand a ?ckground inertial metric.JS: It seems to me the objective is to eliminate any ?ckground non-dynamical metric.Nondynamical means ACTION WITHOUT REACTION.Note, I have it formally in my equations but it is not physically measurable separately.Indeed, the pre-in?ary vacuum is the perfectly ?rld crystal with no vortex string topologicaldefects of effective multiple-connectivity in the space of the vacuum coherence order parameter whichis zero everywhere prior to the in?ary vacuum phase transition like a normal metal going super-conducting.PZ: Obviously it is a ?ld that depends on the distribution ofmatter, if that's what hemeans. But it is the only ?ld that is de?ed in terms of aspacetime metric, so itis obviously unique in that sense.JS: Read Rovelli's paper in the book. Then tell me what you think.PZ: I read it. Several times. I've been scratching my head for severaldays now.See above. === > I can't ?d a proof of the (multivariable) chain rule that makes sense.Assume g is differentiable at x and f is differentiable at g(x), where differentiable means in the total derivative sense. Let dg(x) and df(g(x)) denote the associated linear differential approximants. Then f(g(x+h)) - f(g(x)) = df(g(x))[g(x+h)) - g(x)] + o(g(x+h)) - g(x)) = df(g(x))[dg(x)(h) + o(h)] + o(g(x+h)) - g(x)) = df(g(x))[dg(x)(h)] + df(g(x))[o(h)] + o(g(x+h)) - g(x)).The ?st term in the last sum is what we want to see, namely the composition of df(g(x)) and dg(x) evaluated at h. So we're done if we can show both df(g(x))[o(h)] and o(g(x+h)) - g(x)) are o(h), which is not too hard. === > I can't ?d a proof of the (multivariable) chain rule that makes sense.Assume g is differentiable at x and f is differentiable at g(x), where >differentiable means in the total derivative sense. Let dg(x) and >df(g(x)) denote the associated linear differential approximants. Then f(g(x+h)) - f(g(x)) = df(g(x))[g(x+h)) - g(x)] + o(g(x+h)) - g(x)) = df(g(x))[dg(x)(h) + o(h)] + o(g(x+h)) - g(x)) = df(g(x))[dg(x)(h)] + df(g(x))[o(h)] + o(g(x+h)) - g(x)).The ?st term in the last sum is what we want to see, namely the >composition of df(g(x)) and dg(x) evaluated at h. So we're done if we can >show both df(g(x))[o(h)] and o(g(x+h)) - g(x)) are o(h), which is not too >hard.Fine, but she said I want to see a real proof that uses de?itions and little greek letters...I suppose we can leave it to the reader to change a few lettersto greek to make things easier to follow. But if she's never seenthis proof then possibly she's never seen the de?ition:(Def: o(h) means some function e(h) with the propertythat e(h)/||h|| -> 0 as h -> 0.)Def: f: R^n -> R^m is _differentiable_ at x if there exists alinear map T: R^n -> R^m such that f(x + h) = f(x) + Th + o(h);if so then T = df(x).(Then we should also point out how the notation she maybe looking at follows from this: If df(x) exists then the matrixcorresponding to that linear map has the partial derivativesof the components of f for its entries, and the formula yousee for the chain rule in some calculus books is justgiving the product of two matrices.)************************David C. Ullrich === > I can't ?d a proof of the (multivariable) chain rule that makes sense.>Assume g is differentiable at x and f is differentiable at g(x), where >differentiable means in the total derivative sense. Let dg(x) and >df(g(x)) denote the associated linear differential approximants. Then> f(g(x+h)) - f(g(x)) = df(g(x))[g(x+h)) - g(x)] + o(g(x+h)) - g(x))> = df(g(x))[dg(x)(h) + o(h)] + o(g(x+h)) - g(x))> = df(g(x))[dg(x)(h)] + df(g(x))[o(h)]> + o(g(x+h)) - g(x)).>The ?st term in the last sum is what we want to see, namely the >composition of df(g(x)) and dg(x) evaluated at h. So we're done if we can >show both df(g(x))[o(h)] and o(g(x+h)) - g(x)) are o(h), which is not too >hard.Fine, but she said I want to see a real proof that uses > de?itions and little greek letters...> How many students have you found who've said that? Not many?It reads to me as though this person is taking a second year course at anAmerican University. The text books taught from can be pretty dire when itcomes to formal proof. Indeed one teaches three ?different' (at least) chainrules for special cases, rather than just _the_ chain rule.I'm sure that the course instructor would be happyto provide some way for the OP to satisfy her curiosity, even if it'spointing her towards the library and a relevant book. But just in case, asyou're the Analyst round here, which ones would be useful in demonstratingthat actually you don't want too many greek letters ?g around? IsRudin any good? Lot's of grad programs seem to prefer it.> I suppose we can leave it to the reader to change a few letters> to greek to make things easier to follow. But if she's never seen> this proof then possibly she's never seen the de?ition:(Def: o(h) means some function e(h) with the property> that e(h)/||h|| -> 0 as h -> 0.)Def: f: R^n -> R^m is _differentiable_ at x if there exists a> linear map T: R^n -> R^m such that f(x + h) = f(x) + Th + o(h);if so then T = df(x).(Then we should also point out how the notation she may> be looking at follows from this: If df(x) exists then the matrix> corresponding to that linear map has the partial derivatives> of the components of f for its entries, and the formula you> see for the chain rule in some calculus books is just> giving the product of two matrices.)> ************************David C. Ullrich === > > I can't ?d a proof of the (multivariable) chain rule that makes sense.>Assume g is differentiable at x and f is differentiable at g(x), where >differentiable means in the total derivative sense. Let dg(x) and >df(g(x)) denote the associated linear differential approximants. Then> f(g(x+h)) - f(g(x)) = df(g(x))[g(x+h)) - g(x)] + o(g(x+h)) - g(x))> = df(g(x))[dg(x)(h) + o(h)] + o(g(x+h)) - g(x))> = df(g(x))[dg(x)(h)] + df(g(x))[o(h)]> + o(g(x+h)) - g(x)).>The ?st term in the last sum is what we want to see, namely the >composition of df(g(x)) and dg(x) evaluated at h. So we're done if we can >show both df(g(x))[o(h)] and o(g(x+h)) - g(x)) are o(h), which is not too >hard.> Fine, but she said I want to see a real proof that uses > de?itions and little greek letters...> >How many students have you found who've said that? Not many?It reads to me as though this person is taking a second year course at an>American University. The text books taught from can be pretty dire when it>comes to formal proof. Indeed one teaches three ?different' (at least) chain>rules for special cases, rather than just _the_ chain rule.I'm sure that the course instructor would be happy>to provide some way for the OP to satisfy her curiosity, even if it's>pointing her towards the library and a relevant book. But just in case, as>you're the Analyst round here, which ones would be useful in demonstrating>that actually you don't want too many greek letters ?g around? Um, all the comments about greek letters have been tongue in cheek.I don't know what text would be useful for demonstrating that youdon't want too many greek letters ?g around, because theidea that you don't want too many greek letters ?g aroundis news to me.I suspect that you were being facetious, actually asking aboutdemonstrating something else. But I can't ?ure out what thesomething else might be.>Is>Rudin any good? Lot's of grad programs seem to prefer it.> I suppose we can leave it to the reader to change a few letters> to greek to make things easier to follow. But if she's never seen> this proof then possibly she's never seen the de?ition:> (Def: o(h) means some function e(h) with the property> that e(h)/||h|| -> 0 as h -> 0.)> Def: f: R^n -> R^m is _differentiable_ at x if there exists a> linear map T: R^n -> R^m such that> > f(x + h) = f(x) + Th + o(h);> if so then T = df(x).> > (Then we should also point out how the notation she may> be looking at follows from this: If df(x) exists then the matrix> corresponding to that linear map has the partial derivatives> of the components of f for its entries, and the formula you> see for the chain rule in some calculus books is just> giving the product of two matrices.)> ************************> David C. Ullrich************************David C. Ullrich === Need help on math, visit www.helptosolve.com Just try.Want to help others with math, visit www.helptosolve.com and join the team. === >Dean said that Northeasterners don't talk about religion. >That's not true, because I know of Northeasterners who spend almost>all day talking about The Virgin Mary, Hearing Confession, who's Rabbi>is where, what Temple this person goes to, I have another Bar Mitzvah,>Episcopal Parishoners this, American Baptists convention that.>What Northeast is Dean from ??> What planet are you from?We have people from every planet on Earth in California. --- Formergovernor Gray Davis-- http://hertzlinger.blogspot.com === > Many of the problems with Bush's agenda is the dishonest> reinterpretation of reality that is done so often by the> Democrats.Citations, please. === > Dean said that Northeasterners don't talk about religion. That's not true, because I know of Northeasterners who spend almost> all day talking about The Virgin Mary, Hearing Confession, who's Rabbi> is where, what Temple this person goes to, I have another Bar Mitzvah,> Episcopal Parishoners this, American Baptists convention that.What Northeast is Dean from ??What does this have to do with mathematics?-- http://hertzlinger.blogspot.comX-Cise: tanbanso@iinet.net.auX-CompuServe-Customer: YesX-Coriate: admin@interspeed.co.nzX-Ecrate: tanandtanlawyers.comX-Pose: george_cox@btinternet.comX-Punge: Micro$oft === >Dean said that Northeasterners don't talk about religion. K3wl? How is that on topic for sci.math, sci.skeptic, alt.atheism oralt.christnet? Of the 5 groups that you posted to, onlyalt.politics.democrats is relevant; clearly your intent was to trollfor a crss-posted ?ar.-- Shmuel (Seymour J.) Metz, SysProg and JOATnot reply to spamtrap@library.lspace.org === > Dean said that Northeasterners don't talk about religion. Maybe you should furnish an actual quote before you build a castle in the > air upon what you think he might have said. ?'My father used to tell us how much strength he got from religion, but > we didn't have Bible readings. There are traditions where people do > that. We didn't,'' he said. ?'People in the Northeast don't talk about > their religion. It's a very personal private matter, and that's the > tradition I was brought up in.'' Howard Dean, to Boston Globe last > week. Quoted in countless other papers.You gotta interpret that in context. It means northeastern politiciansdon't talk to the papers about their religion (they leave that to preachers). It was de?itely more polite than what I would have said, which would be, I didn't come here today to talk about religion, so what's your next question? === > Dean said that Northeasterners don't talk about religion. > Maybe you should furnish an actual quote before you build a castle in the > air upon what you think he might have said. > ?'My father used to tell us how much strength he got from religion, but > we didn't have Bible readings. There are traditions where people do > that. We didn't,'' he said. ?'People in the Northeast don't talk about > their religion. It's a very personal private matter, and that's the > tradition I was brought up in.'' Howard Dean, to Boston Globe last > week. Quoted in countless other papers.You gotta interpret that in context. It means northeastern politicians>don't talk to the papers about their religion (they leave that to >preachers). It was de?itely more polite than what I would have said, >which would be, I didn't come here today to talk about religion, so >what's your next question?By the same logic the previous poster used, Bush has also told lies.President Bush's compassionate agenda resonates with the people ofboth New York and California, -Tracey Schmitt,spokeswoman for the Bush-Cheney ?04campaignThat's not true, because I know of Californians who are not impressedwith Bush's compassionate agenda. -----Yang a.a. #28a.a. pastor #-273.15, the most frigid church of Celcius nee Kelvin EAC Econometric Forecast and Socerey DivisionProudly plonked by Lani Girl and CrazyalecThe Bush ?balanced' budget: -525 billion and worseningThe Bush ?economic' policy: -3 million jobs and countingThe Bush Iraq lie: -472 GIs, one friend's co-worker's son and mountingHaving Bush up my country: Worthless === > Dean said that Northeasterners don't talk about religion.We don't, certainly not when compared to other parts ofthe country.Most people I know consider it an impolite subject, atleast in public & amongst strangers. === > Dean said that Northeasterners don't talk about religion.> Maybe you should furnish an actual quote before you build a castle inthe> air upon what you think he might have said.> ?'My father used to tell us how much strength he got from religion, but> we didn't have Bible readings. There are traditions where people do> that. We didn't,'' he said. ?'People in the Northeast don't talk about> their religion. It's a very personal private matter, and that's the> tradition I was brought up in.'' Howard Dean, to Boston Globe last> week. Quoted in countless other papers.I heard my father once say that people in the South arevery conservative religiously. Well I live in Atlanta nowand am friends with some folk at the Unitarian Church.My father. What a dirty, rotten liar. === |Did you see my reply to the OP?Yes, although the contents were not still clear in mind when I lastAmanda's acquaintance objected to her proof based on its being aproof by contradiction. I guess I think the distinction between aproof by proving the contrapositive and a proof by contradiction isfuzzy enough not to make this strictly incorrect. For the questionof whether the proof is valid, I think you'd agree it's also not adistinction that could be relevant. People consider the proof okaynot because it's crossed this fuzzy line; people consider the proofokay because we're considering a context where proof by contradictionand the whole complex of related forms of reasoning are all accepted.You had two main reasons why proof by contradiction was consideredworse:|(i) it's easy to give a wrong proof by contradiction, where |the contradiction arises from some error ||(ii) if you give a direct proof that A implies B, by assuming|A and then deducing B, the steps in the proof can give|some insight into what A really entails - you show A implies|B by showing A implies C and C implies B, and along the|way you've shown two facts that might be interesting and|useful elsewhere, that A implies C and that C implies B.|You don't get this sort of bonus from a proof by contradiction,|since in the course of the proof you're assuming things|which it turns out never actually hold.I think the practice of constructive proof may shed some light onthis. The conclusion of a constructive proof tells you more aboutthe nature of the proof than the conclusion of a classical proof,generally. In particular, when the conclusion is negative, the proofwas a proof by contradiction (essentially) and when the conclusionis positive it wasn't.I can't tell whether the circumstances reducing the risk of (i) andenhancing the prospects of (ii) are different from the circumstanceswhere the theorem (as it would be stated in constructive terms) ismore solidly stated.In constructive mathematics one has the general advice of Bishopto cut down on negations. If we seek to tighten up our theorems bygetting rid of ?negations, then we also as a side-effectrefrain from proofs by contradiction.Lots of negations and implications can be upgraded by supplying themwith more solid content. Bishop has a paper which uses Goedel'sDialectica paper for this. Goedel has a method of rewritingstatements which puts them into a form (there exists w) (for all t) P(w,t)where w ranges over a set of possible witnesses to the truth ofthe statement, and t ranges over a set of possible cases. If thisstatement is false, one would like to do more than just negate it;one would like to say something about the function f:w->t for whichP(w, f(w)) fails for all w. A proof of the negative statementimplicitly provides such an f, as witness. Even when a statementis negative, then, there can be implicit solid content in theconstruction demonstrating the fact, in terms of information onand around this f.I get the impression that in cases where a theorem is negative,but has relatively tangible constructive content, one is not soespecially prone to err in the way described in (i), because oneis regarding the construction in the proof (of f, say), whichactually *does* exist, and trying to see whether *it* is asadvertised. In the proof that there are in?itely many primes,to pick a simple example, the engine is the method for gettinga new prime out of a ?ite set of old primes. An argument whichfocusses on this kind of concrete construction doesn't seem tosuffer from the kind of problem that some attempts at proof bycontradiction do.I'm going on impressions, though, and it seems like it wouldtake somewhat tricky casework to get a more solid sense for whatkinds of proof do and do not tend to suffer from these problems.Keith Ramsay === |Did you see my reply to the OP?Yes, although the contents were not still clear in mind when I lastAmanda's acquaintance objected to her proof based on its being a>proof by contradiction. Although I don't think that even he was saying the proof wastherefore _wrong_, just that it was not the best possible proof.(Cf for example the title of the thread; it's about ?ding abeautiful proof, not a _valid_ proof...)>I guess I think the distinction between a>proof by proving the contrapositive and a proof by contradiction is>fuzzy enough not to make this strictly incorrect. I'm honestly not sure what you mean by that sentence, butregarding the minor premise, I don't see what's fuzzy aboutthe distinction. To prove A implies B:(a) Assume ~B. Prove ~Aor(b) Assume A and ~B. Prove P and ~P for some P.Some proofs of A implies B have the form (a); somehave the form (b). What's fuzzy here?Oh. You're claiming that the distinction is fuzzy enoughthat those of us who are saying he was wrong instating the proof was a proof by contradiction are noton solid ground? I disagree. Um, lemme put that alittle more strongly: that's not so. The proof Amandagave is of the form (a), not of the form (b).I mean that's just a mathematical _fact_. You can sayyou don't see why it matters, ?e. But you say aboveyou think the distinction between (a) and (b) isfuzzy - I don't see any fuzziness, and it's simply afact that (a) is an outline of the proof she gave, forappropriate A and B, while (b) simply isn't.>For the question>of whether the proof is valid, I think you'd agree it's also not a>distinction that could be relevant. People consider the proof okay>not because it's crossed this fuzzy line; people consider the proof>okay because we're considering a context where proof by contradiction>and the whole complex of related forms of reasoning are all accepted.Yes of _course_. Of the people in this thread who do see the difference between (a) and (b) above, some of whom have beensaying that (a) is preferable, _none_ of them have stated oreven hinted that (b) is invalid.>You had two main reasons why proof by contradiction was considered>worse:|(i) it's easy to give a wrong proof by contradiction, where >|the contradiction arises from some error >|>|(ii) if you give a direct proof that A implies B, by assuming>|A and then deducing B, the steps in the proof can give>|some insight into what A really entails - you show A implies>|B by showing A implies C and C implies B, and along the>|way you've shown two facts that might be interesting and>|useful elsewhere, that A implies C and that C implies B.>|You don't get this sort of bonus from a proof by contradiction,>|since in the course of the proof you're assuming things>|which it turns out never actually hold.I think the practice of constructive proof may shed some light on>this. The conclusion of a constructive proof tells you more about>the nature of the proof than the conclusion of a classical proof,>generally. In particular, when the conclusion is negative, the proof>was a proof by contradiction (essentially) and when the conclusion>is positive it wasn't.I can't tell whether the circumstances reducing the risk of (i) and>enhancing the prospects of (ii) are different from the circumstances>where the theorem (as it would be stated in constructive terms) is>more solidly stated.In constructive mathematics one has the general advice of Bishop>to cut down on negations. If we seek to tighten up our theorems by>getting rid of ?egat ions, then we also as a side-effect>refrain from proofs by contradiction.Lots of negations and implications can be upgraded by supplying them>with more solid content. Bishop has a paper which uses Goedel's>Dialectica paper for this. Goedel has a method of rewriting>statements which puts them into a form (there exists w) (for all t) P(w,t)where w ranges over a set of possible witnesses to the truth of>the statement, and t ranges over a set of possible cases. If this>statement is false, one would like to do more than just negate it;>one would like to say something about the function f:w->t for which>P(w, f(w)) fails for all w. A proof of the negative statement>implicitly provides such an f, as witness. Even when a statement>is negative, then, there can be implicit solid content in the>construction demonstrating the fact, in terms of information on>and around this f.I get the impression that in cases where a theorem is negative,>but has relatively tangible constructive content, one is not so>especially prone to err in the way described in (i), because one>is regarding the construction in the proof (of f, say), which>actually *does* exist, and trying to see whether *it* is as>advertised. In the proof that there are in?itely many primes,>to pick a simple example, the engine is the method for getting>a new prime out of a ?ite set of old primes. An argument which>focusses on this kind of concrete construction doesn't seem to>suffer from the kind of problem that some attempts at proof by>contradiction do.I'm going on impressions, though, and it seems like it would>take somewhat tricky casework to get a more solid sense for what>kinds of proof do and do not tend to suffer from these problems.The context here, or at least the context I had in mind, wasproofs by students in classes where half the point to the classis learning to read and write proofs (beginning algebra,analysis, topology classes are often in this category).In that context I can tell you from experience that (i)is a real danger. Of course it's much less of a problemwhen we're talking about proofs in the real world writtenby grownups - one has an idea what _sort_ of contradictionto expect, so when one gets a totally irrelevant contradictionone looks for the error instead of saying qed.>Keith Ramsay************************David C. Ullrich === > For the greater cogency and obviousness in your paper THERE> SHOULD BE a TABLE with componentries of system, which one are> sorted out on their in? to precision of system GPS as a whole.Such a table was posted by Sam Wormley on the 22nd, seeThen any layman can see that we can neglect neglible small> relativistic corrections as contrasted to by other factors> de?ing and restricting limiting accuracies GPS as a whole.> VI. Summary> Excluding the deliberate degradation of SA, the dominant error source> for satellite ranging with single frequency receivers is usually the> ionosphere. It is on the order of four meters, depending on the> quality of the single-frequency model. For dual-frequency (P/Y-code)> receivers (which eliminate SA) the Standard Error Model of Table I> has one principal change (in addition to the elimination of the SA> error). The ionospheric error is reduced from four meters to about> one meter.> The GR correction is about 44 microseconds or 13km per day> and would be cumulative. You can hardly call that negligible.1. What periodicity of corrections of parameters in GPS? 2. What parameters are adjusted in GPS? 3. What medial - statistical values have parameters adjusted in GPS in each session of corrections?--Aleksandr === > For the greater cogency and obviousness in your paper THERE> SHOULD BE a TABLE with componentries of system, which one are> sorted out on their in? to precision of system GPS as a whole.> Such a table was posted by Sam Wormley on the 22nd, see> Then any layman can see that we can neglect neglible small> relativistic corrections as contrasted to by other factors> de?ing and restricting limiting accuracies GPS as a whole.> VI. Summary> Excluding the deliberate degradation of SA, the dominant errorsource> for satellite ranging with single frequency receivers is usually the> ionosphere. It is on the order of four meters, depending on the> quality of the single-frequency model. For dual-frequency (P/Y-code)> receivers (which eliminate SA) the Standard Error Model of Table I> has one principal change (in addition to the elimination of the SA> error). The ionospheric error is reduced from four meters to about> one meter.> The GR correction is about 44 microseconds or 13km per day> and would be cumulative. You can hardly call that negligible. 1. What periodicity of corrections of parameters in GPS?The corrections are of the order of nanoseconds per day socon?m GR to roughly one part in 10,000 by that simplisticcomparison. There is much more information available in webpages if you want to look for more details.> 2. What parameters are adjusted in GPS?> 3. What medial - statistical values have parameters adjusted> in GPS in each session of corrections?Happy New YearGeorge === To base 10:STEP 1: For the characteristic: carry out repeated division of the number by10 until the result falls below 10 and count the number of times.STEP 2: For the mantissa: raise the result to the power of 10 usingmultiplication only, then divide by 10 again as in Step 1. Continue to Step2 for further digits.This process generates the logarithm digit by digit, to the same accuracy asthe other arithmetical functions. Also works ef?iently in binary.This has almost certainly been tried before. I would be interested in any === equation.The equation isAx=0A is a very large sparse matrix which have 1473-by-1473.Sum(x_i) is 1.0All x are not zero.Please, would you like to let me know how to solve the simultaneousequation by fortran.Additionally, My major is not mathmatics. Thus, it is dif?ult tosolve the equation in a method of pseudoinverse, SVD, etc.. Please,let me know that, easily and in detail. === > equation. The equation is Ax=0 A is a very large sparse matrix which have 1473-by-1473.> Sum(x_i) is 1.0> All x are not zero. Please, would you like to let me know how to solve the simultaneous> equation by fortran. Additionally, My major is not mathmatics. Thus, it is dif?ult to> solve the equation in a method of pseudoinverse, SVD, etc.. Please,> let me know that, easily and in detail.>Well, I haven't dealt with matrices that large, but maybe you could tryCramer's rule. As for the code, you are on your own, I don't know Fortran.You could try:http://www.library.cornell.edu/nr/bookfpdf.htmlLurch === > The equation is> Ax=0> A is a very large sparse matrix which have 1473-by-1473.>Well, I haven't dealt with matrices that large, but maybe you could try>Cramer's rule. You know, I think all of us have a tendency to think we can answermore questions well than we really can. I don't know a whole heckuva lotabout numerical analysis, but this strikes me as a really, really badanswer. For one thing, Cramer's rule gives an explicit solution toAx=b when A is invertible; the OP's matrix A is surely notinvertible, lest the only solution be x = 0. For another thing,Cramer's rule expresses the answer in terms of (here) 1474 determinantsof 1473x1473 matrices. How do you propose that the determinants beevaluated? A naive algorithm sums 1473! products and introduces thepossibility of tremendous quantities of round-off error and massivecancellations. Even using row operations, while much faster, is stilltime consuming and prone to error if the entries are not, say, small integers. As useful as Cramer's rule can be for theoretical work,I imagine it's essentially _never_ used for computing numerical solutionsto linear equations with more than a handful of variables.So what response might be better for the OP?It's probably true that any good matrix package can handle yourmatrix (a couple thousand rows is not considered huge these days)but since you say your matrix is sparse, you would probably bene?from using routines speci?ally written for this common special case.Here is a link which was posted the other day in sci.math.num-analysis(which is a much more appropriate group for technical questionsof this type): http://vlsicad.cs.ucla.edu/sparse.htmlOf course the equation Ax=0 has no solution with sum(x_i)=1 if A isnonsingular, so it would be good to think about how you know thatyour problem has a solution. More generally, it is likely to helpthose who are helping you if you can indicate where your matrix comesfrom, since that may signal the use of special routines e.g. forsolving differential equations numerically.dave === > > The equation is> Ax=0> A is a very large sparse matrix which have 1473-by-1473. >Well, I haven't dealt with matrices that large, but maybe you could try>Cramer's rule. You know, I think all of us have a tendency to think we can answer> more questions well than we really can. I don't know a whole heckuva lot> about numerical analysis, but this strikes me as a really, really bad> answer. For one thing, Cramer's rule gives an explicit solution to> Ax=b when A is invertible; the OP's matrix A is surely not> invertible, lest the only solution be x = 0. For another thing,> Cramer's rule expresses the answer in terms of (here) 1474 determinants> of 1473x1473 matrices. How do you propose that the determinants be> evaluated? A naive algorithm sums 1473! products and introduces the> possibility of tremendous quantities of round-off error and massive> cancellations. Even using row operations, while much faster, is still> time consuming and prone to error if the entries are not, say,> small integers. As useful as Cramer's rule can be for theoretical work,> I imagine it's essentially _never_ used for computing numerical solutions> to linear equations with more than a handful of variables. So what response might be better for the OP? It's probably true that any good matrix package can handle your> matrix (a couple thousand rows is not considered huge these days)> but since you say your matrix is sparse, you would probably bene?> from using routines speci?ally written for this common special case.> Here is a link which was posted the other day in sci.math.num-analysis> (which is a much more appropriate group for technical questions> of this type):> http://vlsicad.cs.ucla.edu/sparse.html Of course the equation Ax=0 has no solution with sum(x_i)=1 if A is> nonsingular, so it would be good to think about how you know that> your problem has a solution. More generally, it is likely to help> those who are helping you if you can indicate where your matrix comes> from, since that may signal the use of special routines e.g. for> solving differential equations numerically. daveHey, it's an open forum! I consider this NG like an online math club. Ioffer suggestions, and they aren't always useful, or correct. None of thisstuff is being published, so relax. He isn't paying me for my help; so, heis free to take my advice, or not. It is up to him. I also provided a linkto an online book of Numerical analysis in Fortran, which should answer hisquestion.Lurch === > The equation is> Ax=0> A is a very large sparse matrix which have 1473-by-1473.>Well, I haven't dealt with matrices that large, but maybe you could try>Cramer's rule. You know, I think all of us have a tendency to think we can answer>more questions well than we really can. [...]I have an explanation for that... hmm, no I don't.************************David C. Ullrich === I am looking for a formula for the calculation of the midpoint for thesmallest, an area A circumscribing circle. Is there like for trianglesa connection between the center of gravity and the center of thatcircle? Are any formulas for such a circle known?Carolin HauÛner === hiwikipedia needs our help to carry on:http://www.wikimedia.org/letter.htmlthanks to allbyemax === What's happened to you ?I get up early every morning to read your diatribes and I haven't seen anything for a few days now.Does this mean I have to learn maths if I want to be a part of this newsgroup ?Does this mean I have to rely on comics for my cackles each morning ?I hope the FBI didn't turn on you and that the Evil Mathematical Establishment (tm) haven't imprisioned you in an in?ite series !Please hurry back, my humour is suffering and my education lacking - at least I was being *forced* to learn maths while you posted for no other reason than trying to understand the people who replied to you!Ivan.So this poster who's opinion, by his own admissions in terms ofmathematics is worthless, still feels that his opinion is of value,clearly because he's at least learned the true nature of the mathcommunity. JSH writing about me in the Focus on point of dispute, more math thread ... I've been villi?d by James, does this make me famous? === the application of nonlinear systems (particularly catastrophetheory) to human behavior. Through the years I have struggled withbalancing the criticisms of catastrophe methodology and the heuristicmerits of the theory. I've read most of the catastrophe literature andtheory and singularities.Although the proponents of catastrophe theory are also somewhatconvincing, I question its applicability and implementation inpsychological research. I'm at a point where I need to make adecision:Do I drop this line of research or do I continue working toward thedevelopment of catastrophe applications (e.g., write grants to developsoftware for analyzing catastrophes/bifurcations in psychologicaldata)?Kate === the application of nonlinear systems (particularly catastrophe> theory) to human behavior. Through the years I have struggled with> balancing the criticisms of catastrophe methodology and the heuristic> merits of the theory. I've read most of the catastrophe literature and> theory and singularities.Although the proponents of catastrophe theory are also somewhat> convincing, I question its applicability and implementation in> psychological research. I'm at a point where I need to make a> decision:Do I drop this line of research or do I continue working toward the> development of catastrophe applications (e.g., write grants to develop> software for analyzing catastrophes/bifurcations in psychological> data)?KateIt would seem that this is more a question for your advisor/committee/faculty to help you answer. IMO, as a grad student it is generallyadvisable to do something that gives you a high probability ofproducing a respectable dissertation ASAP. A speculative ?hingexpedition (i.e. one where you're not sure there are any ?h in thelake as opposed to the standard risk of just not catching any of ?hthere are) is not what you should undertake early in your career.However, if you still want to pursue it, ask around about fundingprospects, that is is anyone supporing this type of work? Maybethere is all kinds of homeland securtiy money being thrown atthis area in an attempt to ?ure out terrorists or something (don'tlaugh, they're spending billions on a missle defense system thathasn't worked yet). This is where faculty should be able, throughtheir connections, to help you with information on research andfunding trends. But unless your advisor knows about this area andis supportive of the idea, you're asking for problems, IMO.Good luck,Russell === > the application of nonlinear systems (particularly catastrophe> theory) to human behavior. Through the years I have struggled with> balancing the criticisms of catastrophe methodology and the heuristic> merits of the theory. I've read most of the catastrophe literature and> theory and singularities. Although the proponents of catastrophe theory are also somewhat> convincing, I question its applicability and implementation in> psychological research. I'm at a point where I need to make a> decision: Do I drop this line of research or do I continue working toward the> development of catastrophe applications (e.g., write grants to develop> software for analyzing catastrophes/bifurcations in psychological> data)? KateWhy study pseudo-science anyway? === } Why study pseudo-science anyway?All the better to refute asinine one-liners, my dear. === > } Why study pseudo-science anyway? All the better to refute asinine one-liners, my dear.>Are you claiming it isn't a pseudo-science?Lurch === the application of nonlinear systems (particularly catastrophe> theory) to human behavior. Through the years I have struggled with> balancing the criticisms of catastrophe methodology and the heuristic> merits of the theory. I've read most of the catastrophe literature and> theory and singularities.> Although the proponents of catastrophe theory are also somewhat> convincing, I question its applicability and implementation in> psychological research. I'm at a point where I need to make a> decision:> Do I drop this line of research or do I continue working toward the> development of catastrophe applications (e.g., write grants to develop> software for analyzing catastrophes/bifurcations in psychological> data)?> > KateWhy study pseudo-science anyway?Which one? ;-)Russell === > Does the natural density of all positive integers that arethe sum of two odd> primes = 1/2? How about the sum of two squares? The sum oftwo squarefree> integers?**************************************************If the Goldbach conjecture is true, then the answer to your?st question is yes.If a number is the sum of two squares then it can't have aprime factor that is 3 modulo 4 and whose highest power isodd. Since the series 1 + 1/3 + 1/7 + 1/11 + 1/19 + . . .diverges, this would imply that the natural density of thenumbers that are the sum of two squares is 0. ( [ (1+1/3)(1+1/7)(1+1/11) . . . ] ^ (-1) = 0.)_________________________________________________________ Eric J. Wingler (wingler@math.ysu.edu)Dept. of Mathematics and StatisticsYoungstown State UniversityOne University PlazaYoungstown, OH 44555-0001330-941-1817 === > Does the natural density of all positive integers that are>the sum of two odd> primes = 1/2? How about the sum of two squares? The sum of>two squarefree> integers?**************************************************> If the Goldbach conjecture is true, then the answer to your>?st question is yes.If a number is the sum of two squares then it can't have a>prime factor that is 3 modulo 4 and whose highest power is>odd. Since the series 1 + 1/3 + 1/7 + 1/11 + 1/19 + . . .>diverges, this would imply that the natural density of the>numbers that are the sum of two squares is 0.> ( [ (1+1/3)(1+1/7)(1+1/11) . . . ] ^ (-1) = 0.)I give up. Supposing that everything you say is true, whichI imagine it is, how does it follow that the sums of two squareshave density 0?(My guess is that you deduce somehow that the sum of thereciprocals of the sums of two squares is ?ite. If so that'sinteresting because the sum of 1/(j^2 + k^2) is in?ite...)__________________________________________________ _______Eric J. Wingler (wingler@math.ysu.edu)>Dept. of Mathematics and Statistics>Youngstown State University>One University Plaza>Youngstown, OH 44555-0001>330-941-1817>************************David C. Ullrich === >If a number is the sum of two squares then it can't have a>prime factor that is 3 modulo 4 and whose highest power is>odd. Since the series 1 + 1/3 + 1/7 + 1/11 + 1/19 + . . .>diverges, this would imply that the natural density of the>numbers that are the sum of two squares is 0.> ( [ (1+1/3)(1+1/7)(1+1/11) . . . ] ^ (-1) = 0.)>I give up. Supposing that everything you say is true, which>I imagine it is, how does it follow that the sums of two squares>have density 0?Let S(p) be the set of positive integers that are either not divisible by por are divisible by p^2. The natural density of S is 1 - 1/p + 1/p^2.Any positive integer that is the sum of two squares must be in S(p) forall primes p = 3 mod 4. If these primes are p_1, p_2, p_3, ..., thenatural density of intersection_{j=1}^n S(p_j) is product_{j=1}^n (1 - 1/p_j + 1/p_j^2) = product_{j=1}^n exp(-1/p_j) (1+O(1/p_j^2)) <= C exp(-sum_{j=1}^n 1/p_j))which goes to 0 as n -> in?ity because the series sum_{j=1}^infty 1/p_j diverges.Robert Israel israel@math.ubc.caDepartment of Mathematics http://www.math.ubc.ca/~israel University of British Columbia Vancouver, BC, Canada V6T 1Z2 === >If a number is the sum of two squares then it can't have a>prime factor that is 3 modulo 4 and whose highest power is>odd. Since the series 1 + 1/3 + 1/7 + 1/11 + 1/19 + . . .>diverges, this would imply that the natural density of the>numbers that are the sum of two squares is 0.> ( [ (1+1/3)(1+1/7)(1+1/11) . . . ] ^ (-1) = 0.)>I give up. Supposing that everything you say is true, which>I imagine it is, how does it follow that the sums of two squares>have density 0?Let S(p) be the set of positive integers that are either not divisible by p>or are divisible by p^2. The natural density of S is 1 - 1/p + 1/p^2.Ah. That's the bit that hadn't clicked - couldn't see where the minussigns in the expansion of 1/(1+1/p) were going to come in, but thereit is. Duh.>Any positive integer that is the sum of two squares must be in S(p) for>all primes p = 3 mod 4. If these primes are p_1, p_2, p_3, ..., the>natural density of intersection_{j=1}^n S(p_j) is >product_{j=1}^n (1 - 1/p_j + 1/p_j^2) > = product_{j=1}^n exp(-1/p_j) (1+O(1/p_j^2))> <= C exp(-sum_{j=1}^n 1/p_j))>which goes to 0 as n -> in?ity because the series sum_{j=1}^infty 1/p_j >diverges.Robert Israel israel@math.ubc.ca>Department of Mathematics http://www.math.ubc.ca/~israel >University of British Columbia >Vancouver, BC, Canada V6T 1Z2************************David C. Ullrich === THe cost of a long-distance telphone call is determined by a?e for teh ?st 5 minutes and a ?ed amount for each additional minute. If a 15-minute telephone call costs $3.25 and a 23-minute call costs $5.17, ?d the cost of a 30-minute call. I was thinking of setting it up as a system of equations but im not really sure, can someone explain how i would set this problem up, cause alwyas get stumped on these type of questions. TIA---= 19 East/West-Coast Specialized Servers - Total Privacy via Encryption =--- === > THe cost of a long-distance telphone call is determined by a?e for> teh ?st 5 minutes and a ?ed amount for each additional minute. If a15-> minute telephone call costs $3.25 and a 23-minute call costs $5.17, ?d> the cost of a 30-minute call.> I was thinking of setting it up as a system of equations but im not> really sure, can someone explain how i would set this problem up, cause> alwyas get stumped on these type of questions. TIANews==----> http://www.newsfeed.com The #1 Newsgroup Service in the World! >100,000> ---= 19 East/West-Coast Specialized Servers - Total Privacy via Encryption=---Let x = the ?eand y = the ?ed amount after the ?st ?e,then5x + 18y = 5.175x + 10y = 3.25You get x = .17 and y = .24.Lurch === > THe cost of a long-distance telphone call is determined by a?e for> teh ?st 5 minutes and a ?ed amount for each additional minute. If a>15-> minute telephone call costs $3.25 and a 23-minute call costs $5.17, ?d> the cost of a 30-minute call.>Let x = the ?e>and y = the ?ed amount after the ?st ?e>,then5x + 18y = 5.17>5x + 10y = 3.25You get x = .17 and y = .24.Lurch>No, a ?e is ?ed and pays for anything up to including 5minutes, not a per minute fee. You should have x in the equationsinstead of 5x. The ?st ?e minutes cost .85 (the ?e) and theadditional minutes are .24 each. A 2 minute call would also cost .85because you don't apply the ?e on a per minute basis.--Lynn--Lynn === > THe cost of a long-distance telphone call is determined by a?efor> teh ?st 5 minutes and a ?ed amount for each additional minute. If a>15-> minute telephone call costs $3.25 and a 23-minute call costs $5.17,?d> the cost of a 30-minute call.>Let x = the ?e>and y = the ?ed amount after the ?st ?e>,then>5x + 18y = 5.17>5x + 10y = 3.25>You get x = .17 and y = .24.>LurchNo, a ?e is ?ed and pays for anything up to including 5> minutes, not a per minute fee. You should have x in the equations> instead of 5x. The ?st ?e minutes cost .85 (the ?e) and the> additional minutes are .24 each. A 2 minute call would also cost .85> because you don't apply the ?e on a per minute basis. --Lynn --Lynn>Let c=cost m=cost per minute over 5 and x=call lengthc=.85+m(x-5)c=.85+m(x-5)c=.85+mx-5m, x>5As Lynn said, anything below 5 remains .85A 15 minute call costs $3.25 so x=15 and c=3.253.25=.85+15m-5m2.4=10mm=$.24So Now we know m and our formula becomes c=.24x-.35So when x=30, c=6.85. Therefore a 30 minute call costs $6.85David Moran === Can the equation for c be transformed into an elliptic curve?> The Barcelona conjecture:> Let c=(x+y+z)^p/(pxyz2^p)> for integer c,x,y,z and p prime greater than or equal to 5, the> > Barcelona conjecture is that no solutions exist with gcd(c,xyz)=1 (no> c exist that shares no factor with x or y or z).> I haven't seen this conjecture before, but compare the Beal conjecture:> www.math.unt.edu/~mauldin/beal.htmlYes, I was aware of the Beal conjecture and brie?empted to prove> it also :)The reason you hadn't seen the Barcelona conjecture is that it is> virtually unknown outside of this newsgroup since I've only posted it> here and in the research math group. I came up with it while> attempting to prove FLT using elementary techniques ( ok, once we are> done laughing the question remains - who hasn't? I mean even JSH keeps> on trying.)In some respects it should be easier to prove FLT using the Barcelona> conjecture as the latter places less restrictions on the value of c -> maybe even Fermat was working on this approach as it only requires> elementary methods, though I really doubt it as it isn't documented in> Ribenboim's book on FLT.If anyone can lend me a hand I'm trying to get a grip on how FLT was> tied to elliptic curves, my goal being to see how feasible it is to> apply the same methods to the Barcelona conjecture - for the moment it> is way too dif?ult for me.> === BTW; did anyone here bother to check out David Sereda, and of hishttp://www.ufonasa.com/ EVIDENCE the case for NASA UFOsIn some recent additions to my MAZDA like Internal Rocket RotaryCombustion Engine (IRRCE sfc = 15+KW/kg), there seems we also haveourselves a wee bit of lunar He3 to burn off.http://guthvenus.tripod.com/gv-h2o2-irrce.htmThe taking of lunar He3 is ?st come ?st served, that could bethe likes of China or Russia because, we're obviously not smartenough.Venus still offers life; via moon He3 could help turn the trickI've got a few more words of wisdom to offer on behalf of the ARTEMISPROJECT (lunar He3) http://guthvenus.tripod.com/gv-lse-he3.htmThe rest of this report isn't entirely related to energy so much as itrelates to truth or consequences. Such as for this next topic of therebeing other life NOT as we know it on Venus, that's obviously opposingthe sorts of anti-humanity folks that couldn't care less if our entireworld was destroyed by their resident warlord. Perhaps these folks canget their next level of future funding from the same source as Bush,Salem Laden.As for making policy look like happenstance, and/or vice versa, is keyto snookering folks. http://guthvenus.tripod.com/moon-04.htmThough as for we humans need not, and perhaps we should not ventureourselves much beyond Venus L2 (VL2). Wouldn't want to contaminate aperfectly good planet with our inferior DNA nor lack of morals,especially of this group that's bashing honest research just out ofspite. Besides, their stealth donkey-carts could be far more lethalthan what our WMD donkey-carts can manage.As far as our human physiology being adaptable to pressure. Under suchpressure things are not nearly as hot as we've been told, and you wontneed but a fraction of a percent of O2. Of course, that degree ofadaptation might have to be accommodated at a modus rate of a few barsper day.http://guthvenus.tripod.com/venus-air.htmI have a few other recent/ongoing comments on H2O2/C12H26 and of He3:http://guthvenus.tripod.com/gv-irrce.htmhttp:// guthvenus.tripod.com/gv-hybrid-irc.htmhttp:// guthvenus.tripod.com/gv-cm-ccm-01.htmhttp:// guthvenus.tripod.com/gv-lm-1.htmhttp://guthvenus.tripod.com/ radio-maybe.htm === Portfolio of PAF as of 28DEC03BCE 400 21.90 $8,760.00BLS 50 27.92 $1,396.00BMY 100 27.80 $2,780.00 Q 50,000 3.92 $196,000.00SBC 11,600 25.68 $297,888.00realestate land 3APR03 of 3 lots $19,000science-art of pictures,porcelain etc starting JAN03 for $12,160.realestate land 30JUL03 another lot $11,500.and Wyeth at a small pro? and with the proceeds bought 200 moreshares of BCE.Sold DT because it is hard to play DT as a Crossover switchingcampaign. Sold Verizon because it is overpriced compared to SBC. Andsold Wyeth because I was never really aware of the history of phenfen (excuse the spelling) until I saw a PBS program on that drug andthe history of the company of Wyeth in relation to that drug. Afterseeing the history of phen fen, I could not help but think that Wyethis a company that fosters a culture of money grubbing ever more thanit fosters a culture that they would seek health medicines to makethe world better. For a company to know that phenfen was dangerous inEurope and yet bring that drug over into the USA to sell as a dietdrug, even knowing that it had a past history of dangerousness, tellsme that Wyeth entire corporate upper management needs to be ?ed. AndI do not want to own a drug company of that sort of history of placingmoney-grubbing over that of good science.Wyeth should emulate Johnson & Johnson or Merck as companies that getthe science before they ever think about money.I am wanting and trying to get the PAF portfolio positioned for theyear 2004 such that it follows the VonNeumann Game Theory of theOptimal Strategy for Playing the StockMarket. The key and centraltheme of the OS of Stockmarket is switching campaigns of theCrossover.Through these many years of playing the stockmarket since 1978, Ibeleive I have found the OS of StockMarket and am trying to arrangethe portfolio so that I can faithfully abide by this OS for 2004 andmany years beyond.Archimedes Plutoniumwhole entire Universe is just one big atom where dotsof the electron-dot-cloud are galaxies === Here I thought in this GOOGLE site, of whatever God was restrictedand/or moderated to NASA/NSA/DoD, now DHS.Seems there's some folks that certainly talk and act the part likeGod, as they certainly are those willing and able to terminatewhatever life as we know it, especially mine. Though I guess I'm justhappy that I'm not one of those nice Cathars having to dodge anotherround of exterminations by the Pope, though our resident warlord hascertainly been doing his fair share of mastering carnage based uponlies similar to but not even nearly as good as what the Catholicchurch used to justify their actions. Although, we've got the sowhat's the difference as our ultimate quali?r that trumps anythingPope.BTW; did anyone here bother to check out David Sereda, and of hishttp://www.ufonasa.com/ EVIDENCE the case for NASA UFOsIn some of my recent additions to the MAZDA like Internal RocketRotary Combustion Engine (IRRCE sfc = 15+KW/kg), there seems we alsohave ourselves a wee bit of lunar He3 to burn off.http://guthvenus.tripod.com/gv-h2o2-irrce.htmThe taking of lunar He3 is ?st come ?st served, that could bethe likes of China or Russia because, we're obviously not smartenough.Venus, not Mars, still offers life; via moon He3 could help turn thetrickI've got a few more words of wisdom to offer on behalf of the ARTEMISPROJECT (lunar He3) http://guthvenus.tripod.com/gv-lse-he3.htmThe rest of this report isn't entirely related to energy so much as itrelates to truth or consequences. Such as for this next topic of therebeing other life NOT as we know it on Venus, that's obviously opposingthe sorts of anti-humanity folks that couldn't care less if our entireworld was destroyed by their resident warlord. Perhaps these folks canget their next level of future funding from the same source as Bush,Salem Laden.As for making policy look like happenstance, and/or vice versa, is keyto snookering folks. http://guthvenus.tripod.com/moon-04.htmThough as for we humans need not, and perhaps we should not ventureourselves much beyond Venus L2 (VL2). Wouldn't want to contaminate aperfectly good planet with our inferior DNA nor lack of morals,especially of this group that's bashing honest research just out ofspite. Besides, their stealth donkey-carts could be far more lethalthan what our WMD donkey-carts can manage.As far as our human physiology being adaptable to pressure. Under suchpressure things are not nearly as hot as we've been told, and you wontneed but a fraction of a percent of O2. Of course, that degree ofadaptation might have to be accommodated at a modus rate of a few barsper day.http://guthvenus.tripod.com/venus-air.htmI have a few other recent/ongoing comments on H2O2/C12H26 and of He3:http://guthvenus.tripod.com/gv-irrce.htmhttp:// guthvenus.tripod.com/gv-hybrid-irc.htmhttp:// guthvenus.tripod.com/gv-cm-ccm-01.htmhttp:// guthvenus.tripod.com/gv-lm-1.htmhttp://guthvenus.tripod.com/ radio-maybe.htm === Dear all,I want to ask what is the inverse operation of Kroneck product?More speci?ally, we know that matrix operationA*X*B=kron(A, B')*vec(X)where kron is the Kronecker product of matrices as de?ed in matlab; vec(X)is the stacked vector version of matrix X. All matrices are square...Now I want to reverse the operation, suppose I have a big matrix C,how to ?d A and B to get C=kron(A, B')?Under what condition these A and B cannot be found? Then how to ?d themapproximately, i.e., optimal in the mean-square sense or under othercriteria? That's to say, ?d A and B, such that kron(A, B')=C1 where C1 isa reasonably good approximation to C?-Walala === walala:Maybe if you gave the homework questions verbatim from the Prof, we could beof more help. It seems your interpretation of your tasks is confusing somepeople. Then again, if you really knew the questions, you wouldn't beposting for answers.Jim> Dear all, I want to ask what is the inverse operation of Kroneck product? More speci?ally, we know that matrix operation A*X*B=kron(A, B')*vec(X) where kron is the Kronecker product of matrices as de?ed in matlab;vec(X)> is the stacked vector version of matrix X. All matrices are square... Now I want to reverse the operation, suppose I have a big matrix C, how to ?d A and B to get C=kron(A, B')? Under what condition these A and B cannot be found? Then how to ?d them> approximately, i.e., optimal in the mean-square sense or under other> criteria? That's to say, ?d A and B, such that kron(A, B')=C1 where C1is> a reasonably good approximation to C?> -Walala === > walala: Maybe if you gave the homework questions verbatim from the Prof, we couldbe> of more help. It seems your interpretation of your tasks is confusing some> people. Then again, if you really knew the questions, you wouldn't be> posting for answers. Jim > Dear all,> I want to ask what is the inverse operation of Kroneck product?> More speci?ally, we know that matrix operation> A*X*B=kron(A, B')*vec(X)> where kron is the Kronecker product of matrices as de?ed in matlab;> vec(X)> is the stacked vector version of matrix X. All matrices are square...> Now I want to reverse the operation, suppose I have a big matrix C,> how to ?d A and B to get C=kron(A, B')?> Under what condition these A and B cannot be found? Then how to ?dthem> approximately, i.e., optimal in the mean-square sense or under other> criteria? That's to say, ?d A and B, such that kron(A, B')=C1 where C1> is> a reasonably good approximation to C?> -Walala>Dear Jim,This really isn't my professor's homework problem... our school is now inbreak so there are no damn homeworks right now...This is a problem I am currently interested in... please tell me which partof my description confuses you? Then I can make myself clearer...Rgs,-Walala === How would I compute the probability of a draw in tac tac toe (noughts and crosses) assuming each player was playing randomly (ie no thought involved). What about the probability that player 1 wins?--Interbangchange nospam to optimusprime to reply === >How would I compute the probability of a draw in tac tac toe (noughts >and crosses) assuming each player was playing randomly (ie no thought >involved). What about the probability that player 1 wins?Assuming X goes ?st and that the players alternate until the grid isfull, the number of ?al complete grids can be found by computing 9C4- this is the number of ways of choosing the 4 cells that get OsOf course the 9C4 includes many games that are merely rotations orre?ns of each other. It also ignores the fact that many of thegames would really be over before the grid is full. But you may ?dthat ignoring such issues provides the most straightforward approach.In particular, all the positions among the 9C4 can be regarded asequally likely, which will not be the case if you consider positionsat the real end of the game.What you have to do next is ?d the number of drawn positions, i.e.the number of ?led-in grids which do not contain a winning lineeither for X or for O. You could approach this by enumerating theplaces in the grid where a winning line can arise and then consideringthe possible arrangements of the other symbols. You will need to bevery careful to avoid counting twice the positions with more than onewinning line.Hope this helps === > > So you know that tan' pi/4 = whatever.> Now what does that *mean*?> (Can you recall the *de?ition* of derivative?)> It means that you can apply l'Hopital's rule without knowing in> advance what lim_{x -> pi/4} (tan(x) - 1)/(x - pi/4) is.> Try again! That's no de?ition of derivative.> How do you use L'H's rule to calculate this limit without> already knowing what it is?> > The de?ition of derivative of tan(x) may be deduced from the> derivatives of sin(x) and cos(x) and the quotient rule for> derivatives, the derivative of the numerator and denominator of> (tan(x) - 1)/(x - pi/4) can be found without being aware that> it is a difference quotient.> If f(x) = tan(x) - pi/4 = sin(x)/cos(x), then> f'(x) = (cos(x)*cos(x) - sin(x)(-sin(x))/cos(x)^2 + 0> = 1/cos(x)^2> Excellent: you can compute derivatives. Alas you seem> to have forgotten what they are. :-(> You have (d/dx)(tan x - pi/4) = 1/cos^2 x [dunno what the pi/4 is doing,> but it's irrelevant anyway]. Now what does that mean?> (Heavy hint: apply the de?ition of derivative.)> and if g(x) = x -pi/4 then g'(x) = 1> Any point to this?> Since f(pi/4) = g(pi/4) = 0 but g'(pi/4) and f'(pi/4) are> continuous and nonzero at x = pi/4, L'Hopital applies.> But why waste time using L'H?It is not a matter of whether it is optimal to do it the way I> showed, but merely a question of whether it is possible, and I have> shown it to be possible.No you didn't --- you used the limit itself in the processof applying L'H :-(-- Robin Chapman, www.maths.ex.ac.uk/~rjc/rjc.htmlNeedless to say, I had the last laugh. Alan Partridge, _Bouncing Back_ (14 times) === > [snip]>In his Commutative Algebra, D. Eisenbud has another de?ition:>De?ition 2. Let R be a commutative ring. An element p of R is prime if> p is not a unit and the following is true: If a and b are elements of>R such that p divides ab, then p divides a or b.>Is De?ition 2 common in the commutative algebra community?> It is common in algebraic number theory as well.Then I must wonder what the common de?ition of divides is. According> to the de?ition which I typically use, 0 divides 0. And then according> to De?ition 2, we would have 0 being a prime, which surely we don't> want.Not necessarily --- the zero ideal isn't prime in every ring.Def 2 just says that p is prime iff p generates a prime ideal.Of course, in algebra, it's prime ideals, not prime elements, thatare of major interest.-- Robin Chapman, www.maths.ex.ac.uk/~rjc/rjc.htmlNeedless to say, I had the last laugh. Alan Partridge, _Bouncing Back_ (14 times) === bccDear Gary, Jack and Tony :worked for some time on the notion of Self ReferentialNoise as models of reality. Wheelers's spacetime FOAMis just another interpretation of Noise. You couldtake that Noise as your absolute frame ofreference.JS: The new EINSTEIN results seem to argue against this model?I am not sure of that of course. Sirag says the foam is not reallyrandomly chaotic but coherently harmonic and that sets thenumber of extra dimensions in Calabi-Yau space? On the other handChristian Beck seems to agree with you and says he can determinethe 25 epicycles of the standard model (some say only 17) fromchaotic strings. This would seem choose a de?ite location on Susskind's Landscape in opposition to the WAP ideas of chaotic papers and books by Lee Smolin.CC: One day you may want to look at :Carlos Castro `` The String Uncertainty RelationsFollow from the New Relativity Principle .Foundations of Physics. {bf 8} ( 2000 ) page 1301.for a way to derive the stringy uncertainty relationsfrom ?st principles.JS: Is the claim being made that the new term beyond Heisenberg uncertainty is the source of irreversibility as in the arrow of time? Remember Hawking talks about a new source of uncertainty although Susskind seems to think that is wrong?Note also Ed Witten's formula generalizing Heisenberg's quantum uncertainty principle, i.e. eq. (5.9) p. 136Delta X > h/DeltaP + alpha'(DeltaP)/hThe second gravity-string source of uncertainty should give the irreversible statistical arrow of time not found when alpha' = 0, i.e. in?ite string tension, or in?ite space-time stiffness of action without reaction as is also found in the signal locality of orthodox quantum theory in sense of Antony Valentini's papers.Note the conformal lookw = 1/z + alpha'z === > proofs> why do authors usually consider the proofs so important in mathematical> texts ?Because that is what mathematics is without.> Isn't it usually better when only a few people read and check the proofs,No. If you refuse study proofs then you are cravenly deferring to authority.-- Robin Chapman, www.maths.ex.ac.uk/~rjc/rjc.htmlNeedless to say, I had the last laugh. Alan Partridge, _Bouncing Back_ (14 times) === > proofs> why do authors usually consider the proofs so important in mathematical> texts ?Because that is what mathematics is without.Is this sentence a word without or something?> Isn't it usually better when only a few people read and check the proofs,No. If you refuse study proofs then you are cravenly deferring to authority.************************David C. Ullrich === : > ----------------------------- <^> <(?e? : <^> ----------------------------- : > : > : > Any number having this form can be produced by an RM. : > Some examples of computable numbers: : > : > (0) : > (1) : > 11(0) : > 01(110) : > : > The length of the initial string plus the length of the repeating string : > must be less than or equal to the number of states of the RM that : > produced the number. : > : > : > I don't see this. Here is a simpli?d conceptual diagram of a Russell : Machine. : > : > s1 s2 s6 : > 0 s5 : > --------------------- : > 1 s3 : > s4 s7 : > s8 : > : > There is one piece of information missing, which state s8 goes to. : > Add to this s8 -> s7 : > : > This RM will output 0 0 1 1 0 0 1 1 1 1 1 1 1 1 : > notation is 0 0 1 1 0 0 (1 1) : > : > If it can't halt then the states get reused. : : I assume that s1->s2->s3->s4->s5->s6->s7->s8->s8. : The ouput is 001100(1).Then it DOES halt, DUMBASS. s8 *IS* a halt state.Are you now going to retract your claim that RMs don't halt becausethey don't have halt states? === : > What kinds of numbers are we talking about here? : > Rational? Real? Complex? Supernatural? In?itesimal? : > : I have made the proof a little more rigorous.But you haven't answered the question.WHAT IS a number??? : First, I de?e how to compute a computable number.That is ENTIRELY premature. FIRST, you have to de?e NUMBER! : I do this with a very non-standard type of Turing machine. : Let's call these Russell machines (RM). : A number is computable if it can be represented by : the in?ite binary string produced by a RM.This is just stupid. A TM can do anything you need to do. : A RM has a single, in?itely long tape. : Every position of the tape is initially set to 0. : A RM starts at the leftmost end of the tape. : RMs can perform two operations, labeled 0 and 1. : : 0 = move write head one position to the right : 1 = write a 1 to current location and move one position right : : RMs never read from the tape because they would always read 0. : RMs never halt because they have no halt states.The non-halting is stupid. It basically makes it impossible tohave a well-de?ed result. If you ever DO have a well-de?edresult, observers can always back-allege that the machine actuallyDID halt, as soon as the result BECAME well-de?ed. You can allegethat it is still running but WE can allege that what it is now doingno longer deserves to be CALLED running. : The state of an n-state RM can be speci?d with : (1 + Ceil( log2( n ) ) ) bits where the ?st bit represents the : operation to perform and the next Ceil(log(2(n)) bits : represent which state to switch to.This is ungrammatical. If the bits represent which state to switchto then they DO NOT represent the state you are CURRENTLY in!But you SAID the state of an n-state RM can be speci?d with....I guess speci?d is just ambiguous. : An n-state RM can be fully speci?d by listing all states : which requires n * (1 + Ceil(log2(n))) bits.OK. : Some examples of RMs and their output: : : States RM Output : 1 0 (0)... : 1 1 (1)... : 2 01 11 01(1)... : 2 11 00 (10).... : 3 001 010 100 (001)... : : The output of a RM has the following form: : There is a ?ite, possibly empty initial string that is written once, : and a ?ite, never empty repeating string that is written over and over. : A computable number can be written as the initial string followed by : the repeating string in parenthesis.In other words, this thing only produces rational numbers.That is a stupid limitation. : Any number having this form can be produced by an RM. : Some examples of computable numbers: : : (0) : (1) : 11(0) : 01(110) : : The length of the initial string plus the length of the repeating string : must be less than or equal to the number of states of the RM that : produced the number. : : Now, prove that no set can contain every RM computable number.But it can; this is just the rational numbers. They are a set. : The standard diagonal argument has a problem - it is usually : impossible to determine if the diagonal number produced is : computable.No, it isn't; that is NOT the problem.I just threw the rest of it away.Bothering to create an alternative paradigm IS STUPID.You should have STUCK to TMs. You relieve yourself of theburden of explanation to everybody (of what non-standardthing you mean) -- everybody ALREADY knows what a TM is.And whenEVER you are asked a direct question,JUST ANSWER IT, if you are going to respond.WHAT KIND OF *NUMBERS* are you talking about (forjudging computability)? Natural? Real? Complex?Rational? Supernatural? In?itesimal? *ANSWER* THE ING *QUESTION*, DUMBASS! === > : Let S be the set of all computable numbers> : and assume S is countable.I have made the proof a little more rigorous.First, I de?e how to compute a computable number.> I do this with a very non-standard type of Turing machine.> Let's call these Russell machines (RM). > A number is computable if it can be represented by> the in?ite binary string produced by a RM. [...]Let C be the set of all RM-computable binary strings, according to your de?ition. To show that C is countable, it suf?es to demonstrate a one-to-one function f : C -> N, where N is the set of natural numbers { 0, 1, 2, ... }. This is not dif?ult.First, let's agree that any RM M with n states can be uniquely encoded as a natural number. How we choose to do so isn't important, as long as we agree upon the rule -- so let's say for argument's sake that we use your idea as a basis. To encode M, write 1, followed by n zeroes, followed by another 1, and then a sequence of n strings with ceil(lg(n)) + 1 bits each, encoding the transition rules in ascending numerical order as you described. Treat the resulting string as a natural number written in binary, and let that be the encoding for M. Whatever this number is, I'll denote it E(M). It should be obvious that if M1 and M2 are distinct RM's, then E(M1) <> E(M2).Now for any RM-computable string c., let RM(c) be the set of all RM's that compute c. There must be AT LEAST one member of this set, since c is RM-computable*. Let M(c) be the unique element of RM(c) that ful?s these two properties: 1. M(c) in RM(c) 2. For all M in RM(c), E(M(c)) <= E(M).In other words, M(c) is the RM for c that maps to the smallest natural number among all the RM's that compute c, under the RM-encoding rule. It's not important that we pick this one in particular, but doing so eliminates all ambiguity.So: We can now de?e a one-to-one function f : C -> N as follows: f(c) := E(M(c))Quickly, let's argue that this is one-to-one: Let c1 and c2 be RM-computable strings with c1 <> c2. Then M(c1) <> M(c2)**, and by the de?ition of E, E(M(c1)) <> E(M(c2)), so we're all set.This suf?es to show that the false diagonalization proof you sketched out is inapplicable here.-M* And, actually, there are in?itely many RM's for any RM-computable string. The proof is left as an exercise for the reader. ;)** I hold this truth to be self-evident. But if you disagree, it's not so terrible to prove it from your RM de?itions.P.S.- I mean for <> to denote the does not equal relation.P.P.S.- This level of detail is overkill for just getting the intuition, but imprecision can be even MORE confusing, I ?d.-- http://www.dartmouth.edu/~sting/ | Dartmouth College, Hanover, NH, USA === in message > : Let S be the set of all computable numbers> : and assume S is countable.> I have made the proof a little more rigorous.> First, I de?e how to compute a computable number.> I do this with a very non-standard type of Turing machine.> Let's call these Russell machines (RM).> A number is computable if it can be represented by> the in?ite binary string produced by a RM. [...] Let C be the set of all RM-computable binary strings, according to your> de?ition. To show that C is countable, it suf?es to demonstrate a> one-to-one function f : C -> N, where N is the set of natural numbers {> 0, 1, 2, ... }. This is not dif?ult.I didn't think so until a few days ago.It's harder than it looks.> So: We can now de?e a one-to-one function f : C -> N as follows: f(c) := E(M(c)) Quickly, let's argue that this is one-to-one: Let c1 and c2 be> RM-computable strings with c1 <> c2. Then M(c1) <> M(c2)**, and by the> de?ition of E, E(M(c1)) <> E(M(c2)), so we're all set.Let x be the string produced by the comparator.By construction, x was not produced by f().E() depends on f(). E(M(x)) is unde?ed.x represents a RM computable natural number.Russell- 2 many 2 count === > Let C be the set of all RM-computable binary strings, according to your> de?ition. To show that C is countable, it suf?es to demonstrate a> one-to-one function f : C -> N, where N is the set of natural numbers {> 0, 1, 2, ... }. This is not dif?ult.I didn't think so until a few days ago.> It's harder than it looks.So: We can now de?e a one-to-one function f : C -> N as follows:> f(c) := E(M(c))> Quickly, let's argue that this is one-to-one: Let c1 and c2 be> RM-computable strings with c1 <> c2. Then M(c1) <> M(c2)**, and by the> de?ition of E, E(M(c1)) <> E(M(c2)), so we're all set.Let x be the string produced by the comparator.I'm sorry, perhaps I missed something. What comparator?> By construction, x was not produced by f().> E() depends on f(). E(M(x)) is unde?ed.> x represents a RM computable natural number.Setting aside for the moment that I do not know what string you mean by x, I can safely assert that E does not depend upon f. I chose E to be a simple encoding rule, so that we could be easily convinced that it is a one-to-one mapping from RM's to natural numbers. Its de?ition does not depend upon f's de?ition.What do you mean by an RM-computable natural number? Your de?ition of RM-computability talks about binary strings of in?ite length. Due ot their regular structure, you can ENCODE such a string uniquely as a natural number. That's essentially what I proved above. But you did not show a one-to-one mapping from RM-computable strings to natural numbers in your original de?ition! The obvious mapping -- just dropping the parentheses and gluing the bits together) doesn't quite work, because (for example) all these distinct RM-computable strings map to the same number: 010(10), 0010(10), 00010(10), ...If you don't like referring to a speci? RM, an alternate proof formulation would be to ?st prove that RM-computable strings have the structure you described: wx+ where w in (0+1)* and x in (0+1)(0+1)*. Once you prove that, you can encode any RM-computable string in binary by mapping 0 => 0, 1 => 11, and . to 10 and writing .w.x (the dots guarantee a unique natural number interpretation even when w begins with one or more zeroes). Again, the choice of code is unimportant except insofar as we have to agree what it is.-M-- http://www.dartmouth.edu/~sting/ | Dartmouth College, Hanover, NH, USA === Let x initally be (0).> If s has the form 111...111(0) and the length of the initial> segment of s is longer or equal to the length of the initial> segment of x then take the initial segment of s, append a 1, and> make this new string the initial segment of x. Examples: s x> (0) 1(0)> 1(0) 11(0)> 11(0) 111(0) Prove that x differs from every member of S. x differs from every s that does not end with (0).> x differs from every s with an inital segment not of the form> 111.111. x differs from every s with form 111...111(0).> Therefore, x differs from every member of S.> Well ... let S be the set of al RM computable numbers of the form> 1*(0) (any number of sequential ones followed by a repeating of> zeros). In this way, you will not be able to compute a x which> differs from every possible member of S (at least not using your> technique).> Why not?> x will differ from every member of S and x will be a RM computable> number.> Another way to look at his :> if all the numbers in a set S or of the form 111...11(0), you can de?ea> set S' (containing natural numbers) such that an element of S which has a> sequence of m 1's corresponds to an element m of S'. Your x' would thenbe> m+1. Now if you consider the set S I used in my previous post, it would> correspond tot the entire set of natural numbers. As for each m,contained> in this set, m+1 is also contained, there cannot exist an x' which doesnot> belong to this set.Earlier in this post, someone said the natural numbers are computable.Let's use your set as an example. We can interpret the strings right toleft.Now, each binary string represents a natural number in base 1.Let's call the set S.S(0) = (0)S(1) = (0)1S(2) = (0)11...I give a constructive method of creating a RM computable number, x,that is not in S. How can my method fail to produce x?You assume that every string that corresponds to a ?ite number is in S.This is not true if my proof is correct.I can only think of two reasons why I would not be able to compute x.1) S contains a member with in?itely many 1's2) S contains a member with so many 1's that addingone more 1 results in an in?itely long string of 1's.If you can think of another reason why x can not be computed,please post it.Can you show that x is impossible to compute?Russell- 2 many 2 count === > Let x initally be (0).> If s has the form 111...111(0) and the length of the initial> segment of s is longer or equal to the length of the initial> segment of x then take the initial segment of s, append a 1, and> make this new string the initial segment of x.> Examples:> s x> (0) 1(0)> 1(0) 11(0)> 11(0) 111(0)> Prove that x differs from every member of S.> x differs from every s that does not end with (0).> x differs from every s with an inital segment not of the form> 111.111. x differs from every s with form 111...111(0).> Therefore, x differs from every member of S.> Well ... let S be the set of al RM computable numbers of the form> 1*(0) (any number of sequential ones followed by a repeating of> zeros). In this way, you will not be able to compute a x which> differs from every possible member of S (at least not using your> technique).> Why not?> x will differ from every member of S and x will be a RM computable> number.> Another way to look at his :> if all the numbers in a set S or of the form 111...11(0), you can> de?e > a> set S' (containing natural numbers) such that an element of S which> has a sequence of m 1's corresponds to an element m of S'. Your x'> would then > be> m+1. Now if you consider the set S I used in my previous post, it> would correspond tot the entire set of natural numbers. As for each> m, > contained> in this set, m+1 is also contained, there cannot exist an x' which> does > not> belong to this set.Earlier in this post, someone said the natural numbers are computable.> Let's use your set as an example. We can interpret the strings right> to left.> Now, each binary string represents a natural number in base 1.> Let's call the set S.S(0) = (0)> S(1) = (0)1> S(2) = (0)11> ...I give a constructive method of creating a RM computable number, x,> that is not in S. How can my method fail to produce x?Because every x would be of the form (0)11..1, and because of the de?ition of S, any such RM number is contained in S.> You assume that every string that corresponds to a ?ite number is in> S. This is not true if my proof is correct.That was how S was de?ed : it contains all the strings of the form (0)11..1 (this can be considered as all unary representations of natural numbers).> I can only think of two reasons why I would not be able to compute x.1) S contains a member with in?itely many 1's> 2) S contains a member with so many 1's that adding> one more 1 results in an in?itely long string of 1's.If you can think of another reason why x can not be computed,> please post it.3) for any s in S, s-with-a-1-added-to-the-back is also contained in SCan you show that x is impossible to compute?As there can not exist an element which is both member of a set and not contained in the set, yes.Russell> - 2 many 2 count> -- PentoDe wereld was soep, en het denken meestal een vork,tot smakelijk eten leidde dat zelden. - H. Mulisch === > I give a constructive method of creating a RM computable number, x,> that is not in S. How can my method fail to produce x? Because every x would be of the form (0)11..1, and because of the> de?ition of S, any such RM number is contained in S.The de?ition of S leads to contradiction.S can not contain every natural number.> You assume that every string that corresponds to a ?ite number is in> S. This is not true if my proof is correct. That was how S was de?ed : it contains all the strings of the form> (0)11..1 (this can be considered as all unary representations of natural> numbers).I show that there exists an RM computable number of the form (0)11...1that is not in set S. I can even show how this number can be constructedby a Turing machine.RM's are a subset of TMs.Any RM can be emulated by a universal Turing machine (UTM).We are only concerned with the subset of RM's that output an initial,?ite and contiguous string of 1's followed by an in?ite string of 0's.The UTM can generate the output tape for each of these RM's.These tapes are then read by a second TM I will call a Comparator (CTM).The CTM compares each input tape with the CTM's output tape.If the input tape has a longer initial string of 1's, the CTM rewinds and1.After all of the RM tapes have beed read by the CTM we examine theoutput of the CTM. This tape must contain the representation of anatural number.Every tape read by the CTM represents a natural number.The CTM output tape contains the representation of the successorof some member of S. The successor of a natural number is anatural number.S can not contain a representation of every natural number.> I can only think of two reasons why I would not be able to compute x.> 1) S contains a member with in?itely many 1's> 2) S contains a member with so many 1's that adding> one more 1 results in an in?itely long string of 1's.> If you can think of another reason why x can not be computed,> please post it. 3) for any s in S, s-with-a-1-added-to-the-back is also contained in SNot true. I show how to construct such a number that is not in S.> Can you show that x is impossible to compute? As there can not exist an element which is both member of a set and not> contained in the set, yes.The de?ition of S leads to contradiction.S can not exist.Russell- 2 many 2 count === > > I give a constructive method of creating a RM computable number, x,> that is not in S. How can my method fail to produce x?You have yet to say What KIND of numbers RM numbers CAN OR CAN'T be.Are they natural? Rational? Real? Complex? Supernatural? In?itesimal?IT MATTERS. ANSWER the question!> > Because every x would be of the form (0)11..1, and because of the> de?ition of S, any such RM number is contained in S.The de?ition of S leads to contradiction.No, it doesn't.> S can not contain every natural number.It can and it does.YOU de?ed it. Do you have any idea howSTUPID this makes you look, de?ing a set and thensaying that it can't contain things it obviously contains?> You assume that every string that corresponds to a ?ite number is in> S. No, we don't assume it, we just NOTICE it.You de?ed S as the class of all outputs of RMs that printedsome natural number of 1s and then stopped.> This is not true if my proof is correct.Ergo, your proof is not one.> That was how S was de?ed : it contains all the strings of the form> (0)11..1 (this can be considered as all unary representations of natural> numbers).YOU de?ed S that way. So S contains all natural numbers.> I show that there exists an RM computable number of the form (0)11...1> that is not in set S. No, you don't.> I can even show how this number can be constructed> by a Turing machine.No, you can't. > RM's are a subset of TMs.No, they're not. For one thing, you alleged that they never halted.Are you going to retract that?> Any RM can be emulated by a universal Turing machine (UTM).> We are only concerned with the subset of RM's that output an initial,> ?ite and contiguous string of 1's followed by an in?ite string of 0's.Since RM output tapes were supposed to START OUT as all 0's, can't thethe RM just HALT after it gets through printing all its 1's?> The UTM can generate the output tape for each of these RM's.And put it where, exactly? TM's, by default, only have ONE output tape.> These tapes are then read by a second TM I will call a Comparator (CTM).No, they aren't. There are an in?ite number of these tapes and the CTMnever ?ishes reading them all. > The CTM compares each input tape with the CTM's output tape.The CTM does NOT HAVE an output tape, other than its input tape.That's just how TMs ARE DEFINED. === ----------------------------- <^> <(?)> <^> -----------------------------> RM's are a subset of TMs.> Any RM can be emulated by a universal Turing machine (UTM).> We are only concerned with the subset of RM's that output an initial,> ?ite and contiguous string of 1's followed by an in?ite string of 0's.>So you're not proving there is no complete RM list, 1st you areproving there is no complete restricted RM list?Is this based on modelling the diagonal number from your previous post? and then prove that it is not in my list.> 0.000...> 0.1000...> 0.11000...> 0.111000...> 0.1111000...> 0.11111000...> 0.111111000...> ...> Good luck trying to prove the diagonal number is> not in the list using a countable number of operations. Seems too easy, surely? If I understand you correctly the diagonal> number is: 0.11111.... Every number in your list consists of a ?ite string of 1s followed> by zeros (000...). The diagonal number doesn't. Ergo it isn't in the> list.I can ?d an entry in my list that matches the diagonal number to any?ite number, n, of positions. This is true for all n.My list is in?ite.There is at least one entry in my list that has a 1 in every ?iteposition.How can you prove the diagonal number is not in my list?Russellconvenience, I've changed the layout very slightly... > 0.111000... > 0.1111000... > 0.11111000...> 0.111111000... ^--------Herc === ----------------------------- <^> <(?)><^> -----------------------------> RM's are a subset of TMs.> Any RM can be emulated by a universal Turing machine (UTM).> We are only concerned with the subset of RM's that output an initial,> ?ite and contiguous string of 1's followed by an in?ite string of0's.So you're not proving there is no complete RM list, 1st you are> proving there is no complete restricted RM list?This is the only subset of RM's anyone has concerns about.I think everyone agrees my method works for all the other RMs.> Is this based on modelling the diagonal number from your previous post?Partly.> and then prove that it is not in my list.> 0.000...> 0.1000...> 0.11000...> 0.111000...> > 0.1111000...> 0.11111000...> 0.111111000...> ...> Good luck trying to prove the diagonal number is> not in the list using a countable number of operations.> Seems too easy, surely? If I understand you correctly the diagonal> number is:> 0.11111....The diagonal method can be converted into the computable number proof.Of course, when I responded to your thread I was arguing against Cantor'sdiagonal proof. I am arguing for it in this thread.Forcing the diagonal number to be computable shows that invokingin?ity is like killing a ?h a machine gun.All we really need to prove it that the diagonal has more 1's thanany of the real numbers in the list above. The diagonal can havea ?ite number of 1's and still not be in the list.I suspect that the diagonal proof can be modi?d to show thatthe rational numbers are uncountable.Let R be the set of all rational numbers, r, such that 0 <= r < 1.If R can be ordered such that the diagonal is a rational number,the diagonal proof shows the rationals to be uncountable.Most people will argue that the diagonal of this set must bean irrational number. I have never seen a proof of this.It is easy to come up with a list of rationals that have a rationaldiagonal. The set I give above is one such set.Russell- 2 many 2 count === > Let R be the set of all rational numbers, r, such that 0 <= r < 1.> If R can be ordered such that the diagonal is a rational number,> the diagonal proof shows the rationals to be uncountable.And if my grandmother had wheels, she'd be a wagon.There are several ways to put that subset of the rational numbers intoone-to-one correspondence with the positive integers.> Most people will argue that the diagonal of this set must be> an irrational number. I have never seen a proof of this.> It is easy to come up with a list of rationals that have a rational> diagonal. The set I give above is one such set.Of course, that set was not all of the rationals in that range.Here is an example of the beginning of a complete list:01/21/32/31/43/41/52/53/54/51/65/61/7...Identifying a rational given its position (or vice-versa) is probablygoing to require generating the list up to that position, but this listis obviously complete. Therefore, the set of rational numbers in [0,1)is countable.You want a proof that any such complete list has an irrational diagonal?Okay:Assume that a complete list with a rational diagonal can be found. Thediagonalization process would generated a rational number not in thelist. This would contradict the assumption. Therefore, either the listis incomplete or the diagonal is not rational. (My list is complete, sothe diagonal must not be rational. Your list had a rational diagonal,but was obviously incomplete.)When applied to an allegedly complete list of the reals in [0,1), thediagonally-generated number does not have the option of being other thanreal, so the only possible conclusion is that the list was incomplete. -- Daniel W. Johnsonpanoptes@iquest.nethttp://members.iquest.net/~panoptes /039 53 36 N / 086 11 55 W === > Let R be the set of all rational numbers, r, such that 0 <= r < 1.> If R can be ordered such that the diagonal is a rational number,> the diagonal proof shows the rationals to be uncountable. And if my grandmother had wheels, she'd be a wagon. There are several ways to put that subset of the rational numbers into> one-to-one correspondence with the positive integers. > Most people will argue that the diagonal of this set must be> an irrational number. I have never seen a proof of this.> It is easy to come up with a list of rationals that have a rational> diagonal. The set I give above is one such set. Of course, that set was not all of the rationals in that range.Of course.> Here is an example of the beginning of a complete list: 0> 1/2> 1/3> 2/3> 1/4> 3/4> 1/5> 2/5> 3/5> 4/5> 1/6> 5/6> 1/7> ... Identifying a rational given its position (or vice-versa) is probably> going to require generating the list up to that position, but this list> is obviously complete. Therefore, the set of rational numbers in [0,1)> is countable.Maybe. That is the point of the proof.> You want a proof that any such complete list has an irrational diagonal?> Okay: Assume that a complete list with a rational diagonal can be found. The> diagonalization process would generated a rational number not in the> list. This would contradict the assumption. Therefore, either the list> is incomplete or the diagonal is not rational. (My list is complete, so> the diagonal must not be rational. Your list had a rational diagonal,> but was obviously incomplete.)How are you proving your list is complete?To prove that the set contains all rational numbersyou will have to show there is no way to orderthe set such that the diagonal is rational.There are a lot of ways to order a set of rationals.Russell- 2 many 2 count === > How are you proving your list is complete?Any rational in [0,1) can be uniquely written as a ratio between twocoprime nonnegative integers m/n. That is an entry among the ?stn(n-1)/2 + 1 entries on the list, although specifying the exact locationinvolves a summation on the Euler phi-function. Anyway, that entry onthe list corresponds to no other rational. (This last proviso ismoderately important, because some people like to present completelists of reals in which a given list entry can have more than one realnumber associated with it.)> To prove that the set contains all rational numbers> you will have to show there is no way to order> the set such that the diagonal is rational.I just proved that the set contains all rational numbers in [0,1).To prove that a given integer is even, is it necessary to show both thatits units digit in base two is 0 and that its units digit in base ten isin {0,2,4,6,8}?> There are a lot of ways to order a set of rationals.If you are talking about the complete set of rationals, the number ofways is the same as the number of real numbers. If you think a relevantordering exists, either point out a ? my proof or describe theordering.Otherwise, you might as well quibble with a proof that the sum of any?ite set if even numbers is not odd by pointing out that there are alot of ways to choose a set of even numbers.-- Daniel W. Johnsonpanoptes@iquest.nethttp://members.iquest.net/~panoptes /039 53 36 N / 086 11 55 W <-sOdnVAq4PkNeXGiRVn-sA@comcast.com> <8aGdnb0k8ZEW73CiRVn-jA@comcast.com> <1g6p2lp.1nq0zj71e3df92N%panoptes@iquest.net> <9tCdnYk507_tD3KiRVn-hQ@comcast.com> === > Let R be the set of all rational numbers, r, such that 0 <= r < 1.> If R can be ordered such that the diagonal is a rational number,> the diagonal proof shows the rationals to be uncountable.> And if my grandmother had wheels, she'd be a wagon.> There are several ways to put that subset of the rational numbers into> one-to-one correspondence with the positive integers.> Here is an example of the beginning of a complete list:> 0> 1/2> 1/3> 2/3> 1/4> 3/4> 1/5> ...> Identifying a rational given its position (or vice-versa) is probably> going to require generating the list up to that position, but this list> is obviously complete. Therefore, the set of rational numbers in [0,1)> is countable. Maybe. That is the point of the proof.et cetera, et cetera. It's equivalent to the abbreviation Q.E.D.There's no reason to say Maybe. [I repeat my opinion that you should search Google before continuingto post in this thread. Pedagogy is fun, and I'll be the ?st to admitI have bene?ted greatly from it, but it tends to clutter up the groupsif it's let run amok, IMHO.]> How are you proving your list is complete? Actually, he didn't -- he just said, It's obvious, and moved on.A rigorous proof would use the traditional diagonal method -- NOTCantor's diagonalization, but a different kind of diagonal analogyI think attributed to Godel. It involves laying out the plane of(positive) rational numbers as follows: 1/1--1/2 1/3--1/4 ... .' .' .' 2/1 2/2 2/3 2/4 ... | .' .' 3/1 3/2 3/3 3/4 ... .' 4/1 4/2 4/3 4/4 ... | ... ...You'll need a ?ed-width font to see the ASCII-art line thatI've drawn zigzagging across the diagonals of the grid. This lineobviously passes through every number in the grid. And everypositive rational number is *somewhere* on that grid, as you cansee from the way it's laid out. So the line passes through everypositive rational number, in sequence. Straighten out theline, and remove duplicates, and add zero and the negative rationals,and you're done -- you have a complete list of all the rationals.It begins 0, 1, -1, 1/2, -1/2, 2, -2, 3, -3, 1/3, -1/3, 1/4, -1/4, 2/3, ...and continues to in?ity. Now match up the elements of thatlist, one-to-one, with the positive integers 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, ...Ta-da! [The next bit has been re-ordered for clarity.]> To prove that the set contains all rational numbers> you will have to show there is no way to order> the set such that the diagonal is rational.> There are a lot of ways to order a set of rationals. > You want a proof that any such complete list has an irrational diagonal?> Okay:> Assume that a complete list with a rational diagonal can be found. The> diagonalization process would generated a rational number not in the> list. This would contradict the assumption. Therefore, either the list> is incomplete or the diagonal is not rational.[Q.E.D.]-Arthur === ----------------------------- <^> <(?)> <^> -----------------------------> RM's are a subset of TMs.> Any RM can be emulated by a universal Turing machine (UTM).> We are only concerned with the subset of RM's that output an initial,> ?ite and contiguous string of 1's followed by an in?ite string of> 0's.> So you're not proving there is no complete RM list, 1st you are> proving there is no complete restricted RM list? This is the only subset of RM's anyone has concerns about.> I think everyone agrees my method works for all the other RMs. > Is this based on modelling the diagonal number from your previous post? Partly. > and then prove that it is not in my list.> 0.000...> 0.1000...> 0.11000...> 0.111000...> 0.1111000...> 0.11111000...> 0.111111000...> ...> Good luck trying to prove the diagonal number is> not in the list using a countable number of operations.> Seems too easy, surely? If I understand you correctly the diagonal> number is:> 0.11111.... The diagonal method can be converted into the computable number proof. Of course, when I responded to your thread I was arguing against Cantor's> diagonal proof. I am arguing for it in this thread. Forcing the diagonal number to be computable shows that invoking> in?ity is like killing a ?h a machine gun. All we really need to prove it that the diagonal has more 1's than> any of the real numbers in the list above. The diagonal can have> a ?ite number of 1's and still not be in the list. I suspect that the diagonal proof can be modi?d to show that> the rational numbers are uncountable. Let R be the set of all rational numbers, r, such that 0 <= r < 1.> If R can be ordered such that the diagonal is a rational number,> the diagonal proof shows the rationals to be uncountable. Most people will argue that the diagonal of this set must be> an irrational number. I have never seen a proof of this.This is my argument against the diagonal. I can ?d a rationalon the list of computables that equals any speci? representation (?ite)of the ?irrational' diagonal construct number.If the rational number equals the irrational number then its the same number.I'm pretty sure Cantor falls on its head, I can give an algorithm for all numbersUTM(Z), and increasing portions of the list it makes. That is all anyone canask, and from that noone can make an ?in?ite' diagonal construct at all in practicality.Every number is on the list because the most they can differ by is (0..9)/oo.Herc> It is easy to come up with a list of rationals that have a rational> diagonal. The set I give above is one such set.> Russell> - 2 many 2 count> === > I give a constructive method of creating a RM computable number, x,> that is not in S. How can my method fail to produce x?> Because every x would be of the form (0)11..1, and because of the> de?ition of S, any such RM number is contained in S.The de?ition of S leads to contradiction.> S can not contain every natural number.> You assume that every string that corresponds to a ?ite number is> in S. This is not true if my proof is correct.> That was how S was de?ed : it contains all the strings of the form> (0)11..1 (this can be considered as all unary representations of> natural numbers).I show that there exists an RM computable number of the form (0)11...1> that is not in set S. I can even show how this number can be> constructed by a Turing machine.RM's are a subset of TMs.> Any RM can be emulated by a universal Turing machine (UTM).> We are only concerned with the subset of RM's that output an initial,> ?ite and contiguous string of 1's followed by an in?ite string of> 0's. The UTM can generate the output tape for each of these RM's.> These tapes are then read by a second TM I will call a Comparator> (CTM). The CTM compares each input tape with the CTM's output tape.> If the input tape has a longer initial string of 1's, the CTM rewinds> additional 1.After all of the RM tapes have beed read by the CTM we examine the> output of the CTM. This tape must contain the representation of a> natural number.Every tape read by the CTM represents a natural number.> The CTM output tape contains the representation of the successor> of some member of S. The successor of a natural number is a> natural number.S can not contain a representation of every natural number.> I can only think of two reasons why I would not be able to compute> x. > 1) S contains a member with in?itely many 1's> 2) S contains a member with so many 1's that adding> one more 1 results in an in?itely long string of 1's.> If you can think of another reason why x can not be computed,> please post it.> 3) for any s in S, s-with-a-1-added-to-the-back is also contained in> S Not true. I show how to construct such a number that is not in S.> Can you show that x is impossible to compute?> As there can not exist an element which is both member of a set and> not contained in the set, yes.The de?ition of S leads to contradiction.> S can not exist.OK, consider the set of natural numbers, N.Also consider the operation + 1.Is it not true that for each n in N, n + 1 is also in N ?Now, consider the function f : N -> RM-numbers :f(0) = (0)f(1) = (0)1f(2) = (0)11...and so on, with f(n) corresponding to its own RM-number for each natural number n.Clearly, not all the different RM-numbers are reached by this function f. Consider the set F = f(N) of numbers which are. For each element s of F, we can ?d a unique natural number n such that s = f(n). This means we can give the inverse function of f, call this g.Now, for each s in F, there can not be an x which is s followed by an extra 1, which is not already in F : this would mean that g(x)=g(s)+1, with g(s) a natural number, would not be a natural number.If you still consider this line of thinking to be wrong, please give me the exact x for which value it goes wrong.-- PentoDe wereld was soep, en het denken meestal een vork,tot smakelijk eten leidde dat zelden. - H. Mulisch === OK, consider the set of natural numbers, N.> Also consider the operation + 1. Is it not true that for each n in N, n + 1 is also in N ?Maybe.I might not be the person you want to ask this question to.My proof shows that no set can contain every computablenatural number. If N does not contain every computablenatural number, how can we say N contains all natural numbers?> Now, consider the function f : N -> RM-numbers : f(0) = (0)> f(1) = (0)1> f(2) = (0)11> ...> and so on, with f(n) corresponding to its own RM-number for each natural> number n. Clearly, not all the different RM-numbers are reached by this function f.> Consider the set F = f(N) of numbers which are. For each element s of F,we> can ?d a unique natural number n such that s = f(n). This means we can> give the inverse function of f, call this g.> Now, for each s in F, there can not be an x which is s followed by anextra> 1, which is not already in F : this would mean that g(x)=g(s)+1, with g(s)> a natural number, would not be a natural number.Since g() is the inverse of f(), and x was not generated by f(),g(x) may not be de?ed.x is RM computable so there exists a RM that will output it.This means f() can not emulate every possible RM.Russell- 2 many 2 count === > OK, consider the set of natural numbers, N.> Also consider the operation + 1.> Is it not true that for each n in N, n + 1 is also in N ?Maybe.>I might not be the person you want to ask this question to.>My proof shows that no set can contain every computable>natural number. If N does not contain every computable>natural number, how can we say N contains all natural numbers?(I haven't been following this thread, so please make allowances if what I say here is either redundant or irrelevant.)The standard de?itions of computable are equivalent to computable by some Turing machine. Now clearly, each particular natural number K can be generated by some TM; indeed, it's even computable by a ?ite-state machine (with K states).Furthermore, the in?ite sequence of all natural numbers together (e.g., in base 1, 010110111011110111110...) can be generated by a (non-halting) TM -- the algorithm repeatedly copies the last string of 1's (which can be done ?itely by temporarily replacing the most recent 1 copied with some other symbol, to keep track of how much has already So in what sense isn't every natural number computable?[snip]-- ---------------------------| B B aa rrr b || BBB a a r bbb | | B B a a r b b | | BBB aa a r bbb | ----------------------------- === ----------------------------- <^> <(?)> <^> ----------------------------- > OK, consider the set of natural numbers, N.> Also consider the operation + 1.> Is it not true that for each n in N, n + 1 is also in N ?> >Maybe.>I might not be the person you want to ask this question to.>My proof shows that no set can contain every computable>natural number. If N does not contain every computable>natural number, how can we say N contains all natural numbers? (I haven't been following this thread, so please make allowances if what> I say here is either redundant or irrelevant.) The standard de?itions of computable are equivalent to computable> by some Turing machine. Now clearly, each particular natural number K> can be generated by some TM; indeed, it's even computable by a> ?ite-state machine (with K states). Furthermore, the in?ite sequence of all natural numbers together> (e.g., in base 1, 010110111011110111110...) can be generated by a> (non-halting) TM -- the algorithm repeatedly copies the last string of> 1's (which can be done ?itely by temporarily replacing the most recent> 1 copied with some other symbol, to keep track of how much has already So in what sense isn't every natural number computable?>Check out this 3 state TM that counts from 0 upwards in binary. Everysecond position on the tape represents the number.Hercknock knock knock on the door, feet still bleeding === >message> OK, consider the set of natural numbers, N.> Also consider the operation + 1.> Is it not true that for each n in N, n + 1 is also in N ?>Maybe.>I might not be the person you want to ask this question to.>My proof shows that no set can contain every computable>natural number. If N does not contain every computable>natural number, how can we say N contains all natural numbers? (I haven't been following this thread, so please make allowances if what> I say here is either redundant or irrelevant.) The standard de?itions of computable are equivalent to computable> by some Turing machine. Now clearly, each particular natural number K> can be generated by some TM; indeed, it's even computable by a> ?ite-state machine (with K states). Furthermore, the in?ite sequence of all natural numbers together> (e.g., in base 1, 010110111011110111110...) can be generated by a> (non-halting) TM -- the algorithm repeatedly copies the last string of> 1's (which can be done ?itely by temporarily replacing the most recent> 1 copied with some other symbol, to keep track of how much has already So in what sense isn't every natural number computable?Consider all TM's that write an initial, ?ite and contiguous strings of1'sand then halt. Let S be the set of all output tapes from these TM's.De?e another TM I call a comparator (CTM).CTM compares the input tape to its output tape.If the input tape has more 1's, the CTM rewindsto the beginning of its output tape, copies the input tape,We let CTM read all the tapes in S.What is on the output tape of CTS?The output of CTM must have a ?ite number of 1's.Every tape read by CTM was ?ite in length.The output of CTM has exactly one more 1 thansome input tape in S.S can not contain every possible string thatrepresents a natural number.Russell- 2 many 2 count === comp.theory and sci.math need to come off the list of newsgroupsfor this thread. Those groups surely have more important thingsto discuss. : : Consider all TM's that write an initial, ?ite and contiguous strings of : 1's : and then halt.OK. There is one of these TMs for every natnum. : Let S be the set of all output tapes from these TM's.That's basically the set of all natural numbers. : De?e another TM I call a comparator (CTM). : CTM compares the input tape to its output tape.CTM *DOES* *NOT* *HAVE* an output tape.CTM is a TM. In general, TMs DO NOT HAVE output tapes.TMs have ONE tape. They use it for input.They also write on it, but that does not make it an output tape.It is at best an input/output tape. : If the input tape has more 1's,This is ridiculous. The input tape IS the output tape, if CTMis a TM. It can NEVER have a DIFFERENT number of 1's from itself. : the CTM rewinds to the beginning of its output tape, copies the input tape,That is not how TMs work. What actually happens is that the TM readsat the end, and then halts. : We let CTM read all the tapes in S.No, we don't, because S has an in?ite number of tapes, so CTM(if it really is a TM, which, as you have de?ed it, IT ISN'T,because it has an output tape) will never ?ish reading allthese tapes. : What is on the output tape of CTS?That's a typo; CTS does not exist; do you mean CTM? : The output of CTM must have a ?ite number of 1's.Right. : Every tape read by CTM was ?ite in length.Right. : The output of CTM has exactly one more 1 than : some input tape in S.Wrong.S has in?itely many input tapes and there is no upper bound onhow long they are. : S can not contain every possible string that : represents a natural number.As you de?ed it, it does indeed contain exactly that;it represents the natnums in unary.-- --- It's dif?ult ... you need to be united to have any strength, but internal issues have to be addressed. --- E. Ray Lewis, on liberalism in America <-sOdnVAq4PkNeXGiRVn-sA@comcast.com> <8aGdnb0k8ZEW73CiRVn-jA@comcast.com> <19idnd3Ywuot6HKiRVn-sA@comcast.com> === > [ Obviously, every natural number N is computable by an N-state FSM. ]> So in what sense isn't every natural number computable? Consider all TM's that write an initial, ?ite and contiguous strings of> 1's and then halt. Let S be the set of all output tapes from these TM's. S is an in?ite set which is also countable.> De?e another TM I call a comparator (CTM).> CTM compares the input tape to its output tape.> If the input tape has more 1's, the CTM rewinds> to the beginning of its output tape, copies the input tape, We let CTM read all the tapes in S. What do you mean read all the tapes in S? S has in?itelymany members. If CTM tries to read all the members of S, itwill never ?ish.> What is on the output tape of CTS? Nothing -- CTM never halts, as it never ?ishes reading itsinput tapes.> The output of CTM must have a ?ite number of 1's.> Every tape read by CTM was ?ite in length.> The output of CTM has exactly one more 1 than> some input tape in S. Non sequitur.> S can not contain every possible string that> represents a natural number. Non sequitur. Surely you've had this explained to you in the past,about how some in?ities are bigger than others, and whichones, and how? Check Google Groups if you haven't, or don'tremember -- I'm sure there's plenty of tutorial informationon there. Check sci.math's archives, too.-Arthur === What are the parameteric coordinates of closed loops generated by intersection point F between b and c and intersection point I between a and c extensions in a quadrilateral of sides a,b,c,d ( side a smallest,side d largest,angle th variable/parameter between a and d )? These occur in a fourbar linkage mechanism . The book 4 Bar Atlas(by Hrones and Nelson)does not include parameteric equations. TIA. === I need to know how to calculate x^y where y is not an integer. Anyhelp in this matter would be appreciated. === > I need to know how to calculate x^y where y is not an integer. Any> help in this matter would be appreciated.If y is rational, i.e. y = a/b, then b th root (x^a). For example,x^2/3 = cube root of (x^2). Otherwise, check out:http://mathworld.wolfram.com/Power.htmlLurch === > I need to know how to calculate x^y where y is not an integer. Any> help in this matter would be appreciated.If y is rational, i.e. y = a/b, then b th root (x^a). For example,x^2/3 = cube root of (x^2). Otherwise, check out:http://mathworld.wolfram.com/Power.html??? I don't see a mathematical de?ition of x^y on thatpage, nor anything else that might be what he's lookingfor when he asks how to calculate it...>Lurch>************************David C. Ullrich === >I have another more general question, if you don't mind : is there an>intuitive meaning for a nilpotent group ? Nilpotent groups are closely connected to nilpotent lie algebras,>which is where the name actually comes from, as I understand it, and>where nilpotent actually makes some sense.>As to intuitive meaning, that will depend a lot on you, I guess.[...]>Others think of them as groups constructed through central extensions,>which is not a bad way to think about them either.Some of us just instinctively think, Product of p-groups. RealisticallyI just think about p-groups, period, and then mutter something aboutdirect products at the end of the story. (And if you want an intuitivemeaning of p-groups, think about layers of small vector spaces overthe ?ld of characteristic p, forming the quotients of chains ofnormal subgroups. I don't necessarily think only of central extensions,by the way; in fact one of the prototypes I keep in mind is a semidirectproduct of a Z/p acting on a p-dimensional vector space over GF(p).I'll bet most people don't think about the dihedral group of order 8this way...)Of course, some of us carry along a related intuitive notion thatgroup means ?ite group. You'll have to modify the previous paragraph if you think otherwise.daveX-Received: (from approve@localhost) by support1.mathforum.org (8.11.6/8.11.6/The Math Forum, $Revision: 1.9 primary) id hBSDc1T02534; === [.snip.]J. Willekens === > Notice that the in Noble Verse 57:25 above, Allah Almighty says clearly We> sent down iron.... and He didn't say We created iron from earth....> Allah Almighty's claim was very accurate and precise. We sent down> iron..... clearly states that iron was created outside the earth and was> brought down by the Will of Allah Almighty for a purpose, and that is> (material for) Mighty war, as well as many bene?s for mankind, that Allah> Noble Quran, 57:25)>Hypothetically, if this is proven incorrect, and the iron did not come down,would you be willing to give up on the Quran?Bill X-Cise: tanbanso@iinet.net.auX-CompuServe-Customer: YesX-Coriate: admin@interspeed.co.nzX-Ecrate: tanandtanlawyers.comX-Pose: george_cox@btinternet.comX-Punge: Micro$oft === at 02:12 PM, Mark K. Bilbo said:>There is no down in space. There is if you send a goose up. I don't know if that's enough downfor a jacket.-- Shmuel (Seymour J.) Metz, SysProg and JOATnot reply to spamtrap@library.lspace.org === speak thusly:> at 02:12 PM, Mark K. Bilbo said:> >There is no down in space. There is if you send a goose up. I don't know if that's enough down> for a jacket.The poor goose...-- Mark K. Bilbo X-Cise: tanbanso@iinet.net.auX-CompuServe-Customer: YesX-Coriate: admin@interspeed.co.nzX-Ecrate: tanandtanlawyers.comX-Pose: george_cox@btinternet.comX-Punge: Micro$oft === at 07:30 PM, Goran Jakupovic said:>Like somebody else already said not just iron, but all atoms starting>with helium and heavier now in solar system were products of>supernova.No. Helium is predominantly primordial, Beryllium and Lithium arealmost entirely primordial. The conditions for light elementnucleosynthesis are very different from the conditions for heavierelements. Stars produce Helium, but they destroy Lithium andBeryllium. There's more Helium in the Universe now than right afterthe big bang, but not a lot more.-- Shmuel (Seymour J.) Metz, SysProg and JOATnot reply to spamtrap@library.lspace.org === > > down is relative like meaning closer to core like when you get down> from> bed. but the quran has things being created on earth but for some odd> reason> it diverges with iron. it says we sent down iron. iron was not created> on> earth according to quran. how did the quran know that iron came down?> down> meaning from elsewhere. it was not made on this earth. god caused iron> to> descend. coincidence?> > It's untrue. Iron was here when the earth was formed. It did not come> later.> And if anything, it came up from the core from volcanoes and the like.you are mistaken in a small way. iron not even from this solar system. it> came from other stars and had to land on earth. maybe it was primitive> molten earth but earth was here. if earth was not here what iron land on?> simple logics no offense. the miracle is that quran say many things created> on earth and if this book from man who forging gods word man just say iron> like people and animals and plants and mountains was created on earth. but> for some reason quran treats iron different and say that it is sent down to> earth. why not just say it was created on earth? because that would be> wrong. --> saab siddiqui al mujahed> but you have to change the (a) to @ for it to workIron is an element, copper is an element, carbon is an element, and so on.What scienti? basis do you have for your belief that iron came latter thanthe others? What made up the earth that the iron landed on?Bill === thusly:> thusly:> right. i did not say it came to earth after it ?ished with animals> plants> and all that. i only noted that the quran has many things created on> earth> but for some reason does not have iron created on earth.> What about all the *other elements that weren't formed here?what about them? are you trying to raise an argument ex silentio? if it> turns out on usenet you never once say your mothers maiden name does that> necessarily mean you did not know your mothers maiden name? as for the> elements other than iron i will be agnostic on what the author of the quran> knew about them for now.So this is like one of those christian arguments. God failed to mentionanything *useful like penicillin but seems to have mumbled something vagueabout iron.-- Mark K. Bilbo <245fb07.0312261913.713872dc@posting.google.com>X-Cise: tanbanso@iinet.net.auX-CompuServe-Customer: YesX-Coriate: admin@interspeed.co.nzX-Ecrate: tanandtanlawyers.comX-Pose: george_cox@btinternet.comX-Punge: Micro$oft === at 07:13 PM, raynand@netzero.net (Jefferson Rourke) said:>Atheism is simply a lack of belief in gods.No, that's Agnosticism. Atheism is the belief in the lack of a god.-- Shmuel (Seymour J.) Metz, SysProg and JOATnot reply to spamtrap@library.lspace.org === > at 07:13 PM, raynand@netzero.net (Jefferson Rourke) said:>Atheism is simply a lack of belief in gods.No, that's Agnosticism. Atheism is the belief in the lack of a god.How about un-theist. Does that work for you? I think the god-conceptis a nonexistant mind created reality that it is used as a tool todupe the gullible.I think religious mysticism is a form of mental illness and madnessthat is unique to the human mind on this planet. This still work foryou?I think the god-concept and religion have held back the development ofthe human race by 2000 to 3000 years. Instead of looking for thenonexistent afterlife the human race should be working to build abetter life here and now. If not for religion and the god-concept itis a possible that we could be on other planets by now and havelifespans of over 500 years. The loss and waste of potential in thehuman race because of the god-concept is immense.Still working for you?If all of this does not ? within your de?ition parameters pleaselet me know about my ill-de?ed thought processess.Jefferson RourkeLaissez-Faire! <245fb07.0312261913.713872dc@posting.google.com> <3fee0f44$21$fuzhry+tra$mr2ice@news.patriot.net> <245fb07.0312272002.3afa03c1@posting.google.com>X-Cise: tanbanso@iinet.net.auX-CompuServe-Customer: YesX-Coriate: admin@interspeed.co.nzX-Ecrate: tanandtanlawyers.comX-Pose: george_cox@btinternet.comX-Punge: Micro$oft === at 08:02 PM, raynand@netzero.net (Jefferson Rourke) said:>How about un-theist. Does that work for you?It's not a question of whether it works for me; it's a question ofwhether it works for the English language. The English terms areagnostic and atheist. What would work for me is honesty, which you arenot exhibiting.>I think religious mysticism is a form of mental illness and madness>that is unique to the human mind on this planet. Then you were lying when you stated that Atheism is simply a lack ofbelief in gods. You have gone beyond not believing in a god tobelieving that there is no god. >I think the god-concept and religion have held back the development>of the human race by 2000 to 3000 years.Perhaps it did. And perhaps it had the oposite effect. Do you haveevidence, or is it just a matter of faith for you?>Still working for you?Nope. But if your faith works for you, . . .>If all of this does not ? within your de?ition parameters please>let me know about my ill-de?ed thought processess.You might start with post hoc ergo propter hoc.-- Shmuel (Seymour J.) Metz, SysProg and JOATnot reply to spamtrap@library.lspace.org === speak thusly:> at 08:02 PM, raynand@netzero.net (Jefferson Rourke) said:> >How about un-theist. Does that work for you?It's not a question of whether it works for me; it's a question of> whether it works for the English language. The English terms are> agnostic and atheist. What would work for me is honesty, which you are> not exhibiting.Nope. Wrong.Some of the colloquial connotations that have accreted to the words aresimilar to what you're claiming but colloquial meaning shifts around allthe time.Atheism is lacking belief in any gods. The word was coined to mean that.That is what atheists use the word to mean. That is the meaning.-- Mark K. Bilbo === thusly:> at 07:13 PM, raynand@netzero.net (Jefferson Rourke) said:>Atheism is simply a lack of belief in gods.> No, that's Agnosticism. Atheism is the belief in the lack of a god.How about un-theist. Does that work for you? I think the god-concept> is a nonexistant mind created reality that it is used as a tool to> dupe the gullible.Actually, there's no point to trying to change terms. Theists would trashany term used.And atheism actually *is un- or maybe more accurately non- theism.Since a- means without. As in amoral means *without morals ascontrasted to immoral which is *not moral. The in- pre? meaningopposite of or not.What they try to claim is atheism is, is more something you might callintheism (to coin a word). That would be opposite of theism. Atheism works ?e. Fits the way we do things in the language (hence theword was brought into the language to mean without theism). Theistmisunderstanding or even deliberate obfuscation notwithstanding...-- Mark K. Bilbo === > thusly:> at 07:13 PM, raynand@netzero.net (Jefferson Rourke) said:>Atheism is simply a lack of belief in gods.> No, that's Agnosticism. Atheism is the belief in the lack of a god.How about un-theist. Does that work for you? I think the god-concept> is a nonexistant mind created reality that it is used as a tool to> dupe the gullible.Actually, there's no point to trying to change terms. Theists would trash> any term used.And atheism actually *is un- or maybe more accurately non- theism.> Since a- means without. As in amoral means *without morals as> contrasted to immoral which is *not moral. The in- pre? meaning> opposite of or not.What they try to claim is atheism is, is more something you might call> intheism (to coin a word). That would be opposite of theism. Atheism works ?e. Fits the way we do things in the language (hence the> word was brought into the language to mean without theism). Theist> misunderstanding or even deliberate obfuscation notwithstanding...Hey Mark:I was just trying to have a bit of fun with the guy and see what hisresponse would be. I thought I had the de?ition right the ?st timeand I was writing off of the top of my head without double checking.Hope you had a happy Winter Solstice,Jefferson Rourke === thusly:> thusly:> > at 07:13 PM, raynand@netzero.net (Jefferson Rourke) said:>Atheism is simply a lack of belief in gods.> > No, that's Agnosticism. Atheism is the belief in the lack of a god.> How about un-theist. Does that work for you? I think the god-concept> is a nonexistant mind created reality that it is used as a tool to> dupe the gullible.> Actually, there's no point to trying to change terms. Theists would trash> any term used.> And atheism actually *is un- or maybe more accurately non- theism.> Since a- means without. As in amoral means *without morals as> contrasted to immoral which is *not moral. The in- pre? meaning> opposite of or not.> What they try to claim is atheism is, is more something you might call> intheism (to coin a word). That would be opposite of theism. > Atheism works ?e. Fits the way we do things in the language (hence the> word was brought into the language to mean without theism). Theist> misunderstanding or even deliberate obfuscation notwithstanding...Hey Mark:I was just trying to have a bit of fun with the guy and see what his> response would be. I thought I had the de?ition right the ?st time> and I was writing off of the top of my head without double checking.No big thing. I was just rattling along on an interesting (to me at least)subject.I can't help it. I'm moving more and more into linguistics as (if thingshold together) will be my next ?ld.Words fascinate me to no end...-- Mark K. Bilbo === speak thusly:> at 07:13 PM, raynand@netzero.net (Jefferson Rourke) said:>Atheism is simply a lack of belief in gods.No, that's Agnosticism. Atheism is the belief in the lack of a god.No, atheism is lacking belief in gods.We know, we're atheists.-- Mark K. Bilbo X-Cise: tanbanso@iinet.net.auX-CompuServe-Customer: YesX-Coriate: admin@interspeed.co.nzX-Ecrate: tanandtanlawyers.comX-Pose: george_cox@btinternet.comX-Punge: Micro$oft === at 11:42 AM, Saab Siddiqui said:>im snipping mr metz points that i have no response to at this>time.Good; that is proper quoting style for Usenet. You'll see peopleis generally something to avoid and not to imitate.>not that star collide with earth but that matter from star like iron>collide with earth.The Earth was formed by the accretion of matter. Much of that matterwas Iron. There was already a substantial amount of Iron when theEarth was very small. The material that fell later included a lot ofelements besides Iron, and had no higher percentage of Iron than theinitial material. Given the outgassing of lighter elements, theprimordial proto-Earth probably had a higher concentration of Ironthan the new material falling on it did.-- Shmuel (Seymour J.) Metz, SysProg and JOATnot reply to spamtrap@library.lspace.org X-Cise: tanbanso@iinet.net.auX-CompuServe-Customer: YesX-Coriate: admin@interspeed.co.nzX-Ecrate: tanandtanlawyers.comX-Pose: george_cox@btinternet.comX-Punge: Micro$oft === at 04:56 PM, Mark K. Bilbo said:>The process is that iron forms in stars. The stars go nova and eject>material which includes iron. No. Iron forms in signi?ant quantities only in stars that gosupernova. A simple nova is not hot enough or dense enough.-- Shmuel (Seymour J.) Metz, SysProg and JOATnot reply to spamtrap@library.lspace.org X-Cise: tanbanso@iinet.net.auX-CompuServe-Customer: YesX-Coriate: admin@interspeed.co.nzX-Ecrate: tanandtanlawyers.comX-Pose: george_cox@btinternet.comX-Punge: Micro$oft === >Not just large, but dense. A white dwarf star is about the size of>the Earth,Well, I prefer a yellow dwarf, but would rather that it remain a safe93,000,000 miles away ;-)>I do wonder what would happen if the impacting object was a neutron star,Lethal. The details would depend on the size, but I imagine that theradiation would kill us before we had a chance to observe the rest.-- Shmuel (Seymour J.) Metz, SysProg and JOATnot reply to spamtrap@library.lspace.orgX-Cise: tanbanso@iinet.net.auX-CompuServe-Customer: YesX-Coriate: admin@interspeed.co.nzX-Ecrate: tanandtanlawyers.comX-Pose: george_cox@btinternet.comX-Punge: Micro$oft === at 01:51 AM, Steve Knight said:> Great. Some camel ing, rag head, sand muncher, At least he is not a racist xenophobe like you. *PLONK*-- Shmuel (Seymour J.) Metz, SysProg and JOATnot reply to spamtrap@library.lspace.org === >How do you prove what the (imaginary) zeroes of the Fibonacci