mm-3499 === Subject: Re: Minkowski Metric The metric associated with one particular choice of coordinate system > is unique to that particular choice of coordinate system. > Mathematically, you have ds^2 = g_ij dq^i dq^j Rewriting in matrix form, we have ds^2 = [g] * [dq^2] = g_ij dq^i dq^j Where [g_00, g_01, g_02, g_03] > ** [g] = [g_10, g_11, g_12, g_13] > [g_20, g_21, g_22, g-23] > [g_30, g_31, g_32, g_33] [dq^0 dq^0, dq^0 dq^1, dq^0 dq^2, dq^0 dq^3] > ** [dq^2] = [dq^1 dq^0, dq^1 dq^1, dq^1 dq^2, dq^1 dq^3] > [dq^2 dq^0, dq^2 dq^1, dq^2 dq^2, dq^2 dq^3] > [dq^3 dq^0, dq^3 dq^1, dq^3 dq^2, dq^3 dq^3] ** * = Dot product of 2 4-by-4 matrices I know what you are trying to do but the above is not the way to do it. No, you still have no clue. > One big problem is that if you define [g] and [dq^2] as you did - that > is, as 4x4 matrices - then their product [g] * [dq^2] is also a 4x4 > matrix. I did not define ([g] * [dq^2]) as a multiplication of two 4-by-4 matrices. I defined them as DOT PRODUCT where the definition is also explained as [g] * [dq^2] = g_ij dq^i dq^j > [...] Then you'll have this formula: ds^2 = [dq-transpose] * [g] * [dq] [dq-transpose] x [g] x [dq] = [g] * [dq^2] This is the same as my ones above. Clearly, if the following is true, ds^2 = [g] * [dq^2] = g_ij dq^i dq^j Then [g] must be only valid to the coordinate [dq^2] and no other coordinates. Therefore, [g] cannot be a tensor. > Once again: on the RHS you have now the product of three matrices: 1x4 > times 4x4 times 4x1, which result in a 1x1 matrix ds^2. This is still quite misleading but it's much closer to be correct. I am already several steps ahead of you. When are you going to catch up? > If [dq^2] is different from choice of coordinate system to another, how > can you justify [g] is the same from coordinate system to another?It's not. I don't know how many times I must repeat the same: 1. [g] is a shorthand notation for the matrix of g_ij's, where each > g_ij is a function on the manifold, The above is correct. However, the following is wrong still. *function* on vectors (namely: the dot product function - a > coordinate-independent thing). If both ds^2 and [g] are tensors, then you are implying (ds^2 = [g]) which has been an utterly absurd conclusion on your part. === Subject: Re: Minkowski Metric > The metric associated with one particular choice of coordinate system >> is unique to that particular choice of coordinate system. >> Mathematically, you have >> ds^2 = g_ij dq^i dq^j >> Rewriting in matrix form, we have >> ds^2 = [g] * [dq^2] = g_ij dq^i dq^j >> Where >> [g_00, g_01, g_02, g_03] >> ** [g] = [g_10, g_11, g_12, g_13] >> [g_20, g_21, g_22, g-23] >> [g_30, g_31, g_32, g_33] >> [dq^0 dq^0, dq^0 dq^1, dq^0 dq^2, dq^0 dq^3] >> ** [dq^2] = [dq^1 dq^0, dq^1 dq^1, dq^1 dq^2, dq^1 dq^3] >> [dq^2 dq^0, dq^2 dq^1, dq^2 dq^2, dq^2 dq^3] >> [dq^3 dq^0, dq^3 dq^1, dq^3 dq^2, dq^3 dq^3] >> ** * = Dot product of 2 4-by-4 matrices >> I know what you are trying to do but the above is not the way to do it. No, you still have no clue. > One big problem is that if you define [g] and [dq^2] as you did - that >> is, as 4x4 matrices - then their product [g] * [dq^2] is also a 4x4 >> matrix. I did not define ([g] * [dq^2]) as a multiplication of two 4-by-4 > matrices. I defined them as DOT PRODUCT where the definition is also > explained as [g] * [dq^2] = g_ij dq^i dq^j > [...] >> Then you'll have this formula: >> ds^2 = [dq-transpose] * [g] * [dq] [dq-transpose] x [g] x [dq] = [g] * [dq^2] This is the same as my ones above. Clearly, if the following is true, ds^2 = [g] * [dq^2] = g_ij dq^i dq^j Then [g] must be only valid to the coordinate [dq^2] and no other > coordinates. Therefore, [g] cannot be a tensor. > Once again: on the RHS you have now the product of three matrices: 1x4 >> times 4x4 times 4x1, which result in a 1x1 matrix ds^2. >> This is still quite misleading but it's much closer to be correct. I am already several steps ahead of you. When are you going to catch > up? > If [dq^2] is different from choice of coordinate system to another, how >> can you justify [g] is the same from coordinate system to another?It's >> not. I don't know how many times I must repeat the same: >> 1. [g] is a shorthand notation for the matrix of g_ij's, where each >> g_ij is a function on the manifold, The above is correct. However, the following is wrong still. > 2. matrix [g] defines a tensor (denoted by g or ds^2) which is a >> *function* on vectors (namely: the dot product function - a >> coordinate-independent thing). If both ds^2 and [g] are tensors, then you are implying (ds^2 = [g]) > which has been an utterly absurd conclusion on your part. In this case the metric tensor g maps the spacetime displacement dX to a real number R given by R = ds^2 = g(dX.dX) That's how the metric tensor is defined. Pete === Subject: Re: JSH: Re-cap, when is unique also important? > What is not in doubt is that back in 2002 after a problem solving >> effort I found my own way to count prime numbers where last week I kept >> talking about the sieve form of my prime counting function. >> But that's not what I found years ago. >> To understand the issues now you need to understand just a bit about >> counting prime numbers, as in all of human history there have been only >> two basic ways to count them: >> 1. Brute force, like from 1 to 10, you check that no natural numbers >> below 2 divide it, except 1, so it is prime, as is 3, then you find >> that 2 divides 4 so it's not, and then no naturals except 1 divide 5 so >> it is, and so on... >> 2. Get smarter and notice that you can count the primes by first >> finding primes. That is, you find the primes below the positive square >> root of the number you're counting up to, and get counts using those >> primes. >> Natural numbers are just the counting numbers, starting at 1, next 2, >> then 3 and so forth. >> The brute force method doesn't work that well, so people have figured >> out smart ways with the second approach. And with it you have sieve >> methods, where again, you use primes to count more primes. >> In thousands of years of human history there have been just these two >> ways known to exactly count prime numbers, until I found my prime >> counting function, where crucial here is in understanding what hasn't >> been mentioned. >> I did not find a sieve function. Years ago when I posted I did not >> post a sieve function. >> What I found is a function that unlike any other previously known, >> finds the primes it needs to do counting the smarter way, where you >> just tell it that 2 is prime and it figures out the rest. >> That is a P(x,y) function. Where y is like x, just another natural >> number. >> In contrast with sieve functions like my prime counting function in its >> sieve form P(x,n), there n is a count of prime numbers--the helper >> primes you need to count primes. >> Guess what? I didn't first give the sieve form of my prime counting >> function as it was a sci.math poster named Wim Benthem who did so, >> years ago, after I put up something unlike anything mathematicians had >> ever seen before--a function that did what people did, count primes by >> first finding primes, on its own. >> For days last week I argued with posters about whether or not there is >> another known multi-variable prime counting function, as several >> posters lied until cornered and then switched to saying my prime >> counting function could be trivially related to a previously known phi >> function. >> But they lied again, as that's not the function I actually discovered. >> And the one I actually discovered cannot be so related to anything else >> known. It cannot be directly related to any sieve function. >> If I am wrong a poster should relate my P(x,y) function to something >> previously known. >> Those who followed the discussion may remember I asked posters if there >> was anything else unique about my prime counting function besides being >> multi-variable, and you may notice they did not give you the answer I >> give to you now. >> So you have the lies about there being another multi-variable prime >> counting function, collapsing into lies that my prime counting function >> was just trivially related to another multi-variable function, when in >> fact what I actually discovered and posted about those years ago, can't >> be related to anything else known, and it can do what no other known >> mathematical function can do. >> So what gives? >> Why would mathematicians lie if it's so grand, and is there anything >> else to this prime counting function of mine? >> Well some of you know that modern mathematics can get a little >> complicated. You may also know that mathematicians can get a lot of >> schooling to study difficult topics for years to gain expertise in >> their subject areas. >> It can be a difficult business with extreme complexity, difficult >> arguments and years of effort just to understand the basics. >> And I might have cut the Gordian knot in one of the most high profile >> areas--prime numbers. >> Imagine you are a Ph.D in mathematics specializing in prime numbers, >> and you sent a grant proposal for federal funds totalling $500,000 US >> to fund your research where most of that is your SALARY for five years >> of research. And then some nobody, from nowhere comes up with a simple >> damn function that opens the door to a simple explanation and your >> research is not needed. >> Do you just give up on half a million dollars over the next five years? >> Didn't think of it that way? Don't understand how mathematical >> research gets funded? >> I give a simple answer, and mathematicians lose income--if they >> acknowledge it. >> If they don't, and notice, they didn't, those research grants keep >> coming, the money keeps flowing, and that mathematics Ph.D is still >> worth something. >> Alternative explanations? >> Give them please. >> You have a unique function that does what no other in human history has >> ever done in counting prime numbers. Yet mathematicians have done >> their best to completely ignore it for over four years. >> Oh yeah, is there anything else to its uniqueness? >> In its simplicity may be found the answers to the 'why' of prime >> numbers. Answers so simple, they might even make sense to >> non-mathematicians. >> A slashing breakdown of complexity, replaced with beautiful simplicity. >> Yet most mathematicians completely ignore it, while you get Usenet >> posters who lie about its details, continually getting caught in lies >> and omissions. >> Come on, deep down, you knew it had to be about money. >> So simple answer is, they lie about it because of the money. >> James, you still do not understand why your work is not acknowledged, > do you? M > of course he does, he hasn't got any work, he is pure troll. === Subject: TI 84 Plus Silver calculator: Cheapest place to buy? I'm a 48 yr old man. Laid off from job and now a full time college student taking college level trigonometry this year. Where is best and cheapest place to buy a new Texas Instruments 84 Plus Silver graphing calculator? Local Walmart has it for $130. Can I do better via mail order or online? === Subject: Re: Is continuum completely filled up? <4vvevuF1dt4kfU1@mid.individual.net> <45a18eed@news2.lightlink.com> <45a25f3d@news2.lightlink.com> <45a3ab25@news2.lightlink.com > What TO thinks and what mathematics shows rarely make contact. >> You would argue if I said 2+2=4. Why? It is one of the few of TO's comments that conforms to anything > mathematical. > The successor operation, which is enough to imply an infinite set, is >> not actually an order relation, though it it commonly used to generate >> one. >> So, this comes after that is not a statement of the order of this and >> that? Hmm...sounds like one to me. > TO does not seem to know what being an 'order relation' involves. A strong order relation, <, on a set S is a subset of SxS which is > assymetric (if x transitive (if x < y and y < z then z < z) and > connected ( if x =|= y then either x < y or y < x). Which of those do you think does not apply to the naturals as a result > of successor()? Is your thinking really that fuzzy or are you just pretending? None of those apply to the naturals. This is about a relation we write <. The naturals are not a relation. Successor() is not a relation. All of those properties apply to <, which is a relation. - Randy === Subject: Re: Is continuum completely filled up? > TO does not seem to know what being an 'order relation' involves. > > A strong order relation, <, on a set S is a subset of SxS which is > assymetric (if x transitive (if x < y and y < z then z < z) and > connected ( if x =|= y then either x < y or y < x). Which of those do you think does not apply to the naturals as a result > of successor()? Is your thinking really that fuzzy or are you just pretending? That's a good question. But, I doubt Tony will answer it. -- === Subject: Integer or Irrational Consider the following equation under the given conditions: y = (ab)^1/2[(AB)^1/k(UV)^1/2k] (1) Conditions: 1. (a, b) = 1, but none is a perfect square 2. A, B are rational but none is a k-th power. 3. U, V are rational but none is a perfect square 4. prime k > 5 5. Both a, b > k 6. Each of A, B, U, V < 1. To determine a set of conditions(if exist) under which y will always remain an integer > k. Otherwise, y will remain irrational. Any help to determine the conditions will be highly appreciated. === Subject: Re: JSH: Idea for TV comedy series <45a2e0f3$0$313$426a74cc@news.free.fr> <50hebsF1fqt9rU1@mid.individual.net > The Last Danish Pastry a .8ecrit : >> In the TV series Numb3rs an FBI agent has a brother who is a math >> professor. This professor applies his mathematical knowledge to >> solve various crimes. >> Consider a series (provisionally titled The Hamm3r) in which an >> FBI agent has a brother who is . James applies his >> mathematical knowledge to try to solve various crimes with >> hilarious results. > > Yes, and the FBI agent could be the (adoptive) son of Maxwell Smart, > also known as Agent 86. Ah yes. Nice tie-in. I always liked the opening sequence to that show: the doors closing. And Agent 99 was very lovely... > Here's my idea for the series pilot. The brother's are introduced as the FBI agent is buying a life insurance policy on someone and getting his oh-so-smart sibling to help pick out which one has the best expected return on investment. Next scene, the FBI agent is telling his bosses that he thinks the whole terrorist war can be won in like a month, if they can just get a knowledgeable guy on the inside to figure out how they train to be able to transmit those powerful terrorist secret messages through media interviews with lawyers, etc. A guy in short who can talk that al Gebra talk like he's just finished a class in it. Hilariously the FBI's plans go awry when the CIA wiretaps the brothers' cellphone and hotmail accounts, mistaking him for real-al Gebra, gives the boy genius an extraordinary rendition to an undisclosed location where he enjoys loud music and waterboarding. I think the second hour of the pilot can be like a reality TV show, where we goofily bring in a bunch of people off the street with no idea where they are being detained and kind of compete to see who can get themselves voted out of the house first. At the end fake-al Gebra brings it all home as terrorists succumb to his endless ranting about the Hammer, lying newsgroup correspondants, and the journal editors who let the math results of the millennium slip through their fingers. They gladly confess to anything the CIA wants just to be free of his paranoid megalomania. The denouement has the brothers tearfully reunited. Our hero has a medal, a laptop, and everything for saving the country. In the parting shot we see the FBI agent weeping as he pulls the life insurance policy out of his desk and tears it to shreds just as we notice it was made out on... his brother. --c === Subject: Re: JSH: Idea for TV comedy series > In the TV series Numb3rs an FBI agent has a brother who is a math > professor. This professor applies his mathematical knowledge to solve > various crimes. Consider a series (provisionally titled The Hamm3r) in which an FBI > agent has a brother who is . James applies his > mathematical knowledge to try to solve various crimes with hilarious > results. -- > Clive Tooth > http://www.shutterstock.com/cat.mhtml?gallery_id=61771 Hi Clive, I recommend writing a pilot immediately. All the best, Jason === Subject: Re: Reference Nntp-Posting-Host: apps.cwi.nl ... > sin(pi/7) and cos(pi/7) can be given explicitly, but, as they are > solutions of a cubic equation, their expression is pretty complicate > and involves intermediate complex numbers even if the result is real. Fairly complicated, but it can be done. Let me give it a try: Set z = exp(2.pi/7), now we have: z^7 - 1 = 0 and so z^6 + z^5 + z^4 + z^3 + z^2 + z + 1 = 0. Now set y = z + 1/z (= 2c = 2.cos(2.pi/7)): y^3 + y^2 - 2.y - 1 = 0 or 8.c^3 + 4.c^2 - 4.c - 1 = 0 To solve the cubic use the following method for the cubic x^3 + a.x^2 + b.x + c = 0 set the following: Q = (12.b - 4.a^2) R = (36.a.b - 108.c - 8.a^3) K1 = cbrt(R + sqrt(Q^3 + R^2))/2 K2 = cbrt(R - sqrt(Q^3 + R^2))/2 W = (-1 + sqrt(-3))/2 now the roots are: X_i = (-2.a + W^i.K1 + W^(2i).K2)/6. (maple is not able to verify this, at least I do not find a way.) which I expanded to the above generic solution for cubics.) Filling in (and if I do the calculations correctly), I get K1 = cbrt((7 + 21.sqrt(-3))/2) and with that and a = 1/2, follow the three solutions for the cosine. There are three because all of cos(2.pi/7), cos(4.pi/7) and cos(6.pi/7) share the initial equations. Now we know: -1 < cos(6.pi/7) < cos(4.pi/7) < cos(2.pi/7) < 1 and so (with numerical verification) we get: c_1 = cos(6.pi/7) c_2 = cos(4.pi/7) c_3 = cos(2.pi/7). As cos(pi/7) = - cos(6.pi/7) we need some backtracking. Using K1 above and K2 = cbrt((7 - 21.sqrt(-3))/2) we get: cos(pi/7) = (1 - W1.K1 - W2.K2)/6 (which conforms remarkably with other sources) and you can fill in the numbers for W1, W2, K1 and K2. And so: cos(pi/7) = (1 - - (-1 + sqrt(-3))/2 * cbrt((7 + 21.sqrt(-3))/2) - (-1 - sqrt(-3))/2 * cbrt((7 - 21.sqrt(-3))/2))/6. which may be simplified to: cos(pi/7) = (4 + + (1 - sqrt(-3)) * cbrt(28 + 84.sqrt(-3)) + (1 + sqrt(-3)) * cbrt(28 - 84.sqrt(-3)))/24. Which is not even a very complicated expression. Getting sin(pi/7) is trivial from this. -- dik t. winter, cwi, kruislaan 413, 1098 sj amsterdam, nederland, +31205924131 home: bovenover 215, 1025 jn amsterdam, nederland; http://www.cwi.nl/~dik/ === Subject: Re: Uncomputable numbers are all in your head > > > > > > > > > > Define a real number as the output of a program, we can use a Universal Turing Machine > > > > > > > > > > and a natural index for every possible program. > > > > > > > > > > > > > > > > > > real_n <=> UTM(n:N) > > > > > > > > > > > > > > > > > > e.g. UTM(5) is the 5th number > > > > > > > > > > UTM(100) is the 100th number. > > > > > > > > > > > > > > > > > > To calculate the digits of the numbers give an input parameter DIGIT > > > > > > > > > > to the number-program, and convert the output into MOD 10. > > > > > > > > > > > > > > > > > > UTM(n)(digit) mod 10 > > > > > > > > > > > > > > > > > > e.g. say the 1000th number happens to be pi/10, then > > > > > > > > > > UTM(1000) (1) mod 10 = 3 > > > > > > > > > > UTM(1000) (2) mod 10 = 1 > > > > > > > > > > UTM(1000) (3) mod 10 = 4 > > > > > > > > > > > > > > > > > > The mod 10 is not required but it ensures digits output are from 0 - 9, and makes the > > > > > > > > > > set of programs much richer in real numbers. > > > > > > > > > > > > > > > > > > How does Cantors proof hold up against such a definition of numbers? > > > > > > > > > > > > > > > > > > > > > > > > > > > Perfectly well. If you require that reals be computable you should > > > > > > > > > > require that bijections be computable as well. Then Cantor's proof > > > > > > > > > > shows that there is no effective enumeration of the set of computable > > > > > > > > > > numbers. > > > > > > > > > > > > > > > > > > How so? > > > > > > > > > > > > > > > > > > Herc > > > > > > > > > > > > > > > > > > Let f(m,n) be a total recursive function in two variables whose range > > > > > > > > > is contained in the set of decimal digits. If we think of the function > > > > > > > > > n->f(m,n) as a computable sequence of digits, then f may be viewed as > > > > > > > > > an effective enumeration of a set of such sequences. (We may get a > > > > > > > > > repetition of the same sequence, but we don't need to worry about > > > > > > > > > that). There is an effective procedure for constructing a computable > > > > > > > > > sequence which differs from the sequence n->f(m,n) for all m. Just > > > > > > > > > construct the anti-diagonal number. This is guaranteed to be computable > > > > > > > > > since f is total recursive. > > > > > > > > > > > > > > > > It may be computable, but its not indexable, so it doesn't qualify as an indexed real. > > > > > > > > > Cantors proof is invalid if you require that all reals are indexed by a UTM, the > > > > > > > > > antidiag isn't. > > > > > > > > > > > > > > > > > > > > > > > > It is if it's the antidiag for an effective enumeration. In that case, > > > > > > > > > there will be some Turing machine that computes it. > > > > > > > > > > > > > > > > If you take the enumeration whereby n corresponds to the computable > > > > > > > > > real computed by Turing machine number n, that's not an effective > > > > > > > > > enumeration, because it's not decidable whether a given number actually > > > > > > > > > corresponds to a real. In that case the argument doesn't apply. > > > > > > > > > > > > > > > > > > > > > > > If a TM computes the antidiagonal, call it TM_a, then there must exist some number a, > > > > > > > > UTM(a) = TM_a. Are you saying TM_a exists because there is no a where UTM(a) > > > > > > > > computes the antidiagonal. > > > > > > > > > > > > > > > > Herc > > > > > > > > > > > > > > > > The antidiagonal for what? > > > > > > > > > > > > > > > > The antidiagonal for an effective enumeration is computable. That shows > > > > > > > > that an effective enumeration cannot include every computable real. > > > > > > > > > > > > > > > > As I said, if you let the n-th real in the list be the one computed by > > > > > > > > the Turing machine with number n, that's not an effective enumeration, > > > > > > > > because not every Turing machine computes a real, > > > > > > > > > > > > > > Why not? > > > > > > > > > > > > > > > > > > > > > There are various issues that can be got around by changing the > > > > > > > > definition of Turing machine. But the one issue that can't be got > > > > > > > > around is that not every Turing machine halts. > > > > > > > > > > > > > > It does not need to. 3.14 is a real number just as > > > > > > > 3.140000000000........ > > > > > > > > > > > > > > > > > > > > The problem is that there's no effective way of deciding whether the > > > > > > > Turing machine is going to go on forever without producing another > > > > > > > digit or whether it will eventually produce another digit. So the point > > > > > > > stands, it is not an effective enumeration. > > > > > > > > > > > > OK, let's say it is not an effective enumeration. But the Turing > > > > > > > machine will either halt or not. If it does not halt we get 3.14, if > > > > > > > it does halt we get 3.140000.... (Some of them will produce the > > > > > > > actual pi.) In any case all the Turing machines will produce nothing > > > > > > > but real numbers. Whether it halts or not, whatever it will produce > > > > > > > will be a real number. > > > > > > > > > > > > The antidiagonal will not be computable because at some point it will > > > > > > > get stuck and stop producing digits. That is, there is no Turing > > > > > > > machine that will produce the anti-diagonal. I think this is what Herc > > > > > > > was trying to demonstrate. > > > > > > > > > > > > > > > > > > That's right, there is an enumeration, not an effective one, and the > > > > > > > anti-diagonal for it is not computable. If that is Herc's claim then I > > > > > > > agree with him. My point that there is no effective enumeration of the > > > > > > > computable reals still stands. If you believe in non-effective > > > > > > > enumerations of the computable reals then you should also believe in > > > > > > > non-computable reals. > > > > > > > > > > > > Non-effective enumeration means that some reals will be represented by > > > > > > finite strings. A non-computable real means that no algorithm for its > > > > > > computation exists. > > > > > > > > > > > > Case in point is the scenario above. There is no algorithm that will > > > > > > compute the anti-diagonal. (An attempt to compute it will result in an > > > > > > infinite loop and thus in a finite string that will not be different > > > > > > from all the strings in the list.) By definition no algorithm exists to > > > > > > compute infinite, incompressible strings that carry infinite amount of > > > > > > information. > > > > > > > > > > > > In any case it does not matter. You can require that the function be > > > > > > total. Then you will find out that the reals are not r.e. OK. But the > > > > > > computable reals are still countable. You make a list indexed by > > > > > > integers and the anti-diagonal is not copmutable. Again, I believe this > > > > > > ,or something to that effect, was Herc's point. > > > > > > > > > > > > > > > > > Well, my point is that if you only believe in computable reals you > > > > > > should also only believe in computable bijections, in which case you > > > > > > should still accept Cantor's theorem. > > > > > > > > > > Yes, I do believe only in computable reals. That includes all the > > > > > > rational numbers, plus pi, e, the solutions of all algebraic equations > > > > > > and much more. That is enough for me. > > > > > > > > > > How does the belief in computable bijection imply the belief in > > > > > > Cantor's theorem? Which part of the theorem? That the anti-diagonal is > > > > > > not on the list or that the anti-diagonal exists? > > > > > > > > > > > > > > > Cantor's argument proves that there is no effective enumeration of the > > > > > > computable reals. > > > > > > > > > > I accept it. But I accept that the anti-diagonal exists only if it is > > > > > computable. If you list all the computable reals then the anti-diagonal > > > > > is not computable, and effective enumeration is not required to > > > > > establish this. > > > > > > > > > > > > > > Please pay attention. There is no effective enumeration of the > > > > > computable reals. Given an effective enumeration of some of the > > > > > computable reals, the anti-diagonal exists, is computable, and is not > > > > > in the set enumerated. If you list all the computable reals, that is > > > > > not an effective enumeration. (And, as you correctly point out, the > > > > > anti-diagonal is not computable). You are welcome to believe only in > > > > > computable reals if you want. But if so then you should also believe > > > > > only in effective enumerations, > > > > > > > > Why so? > > > > > > > > > > > > Well, I can't think of a justification for refusing to accept > > > > > non-computable reals that wouldn't also entail not accepting > > > > > non-effective enumerations. They're pretty much the same kind of thing. > > > > > Maybe you've thought of such a justification. Please tell me all about > > > > > it. > > > > > > > > I simply don't see why the machines absolutely have to terminate. > > > > > > > > > > > > so you shouldn't talk about the > > > > > possibility of listing all the computable reals. That's not a > > > > > possibility in your world. > > > > > > > > Maybe not. But I do not need it as I am not attempting the diagonal > > > > > argument. > > > > > > > > There is a list of modified Turing machines, which output every symbol > > > > > they write on the tape. You can order tem lexicographically and by the > > > > > input. (I think Herc was attempting a similar construct a little > > > > > differently.) They will compute all the reals. Many of them will get > > > > > stuck in infinite loops but so what? There are no more reals than those > > > > > computed by the machines in the list. The anti-diagonal is not > > > > > computable. There is an universal machine somewhere in the list that > > > > > will try to emulate all the other machines in the list and add 1 mod b. > > > > > It will be on line i. When it comes to computing the i-th digit of the > > > > > diagonal it will call itself and go into an infinite regression. > > > > > > > > > > > > If you only believe in computable reals, I don't think you should say > > > > > There are only countably many reals unless you can find an effective > > > > > enumeration of the computable reals. As Cantor's argument proves, there > > > > > is no such enumeration. > > > > > > > > I think you have it all backwards. As I have shown above the diagonal > > > > argument does not go through if you restrict yourself to computable > > > > reals. The totality of the function is required for the argument to go > > > > through. It serves no other purpose. > > > > > > > > > > > If you require your reals to be computable, you should also require > > > > your enumerations to be effective. > > > > > > I do not see the connection. All the the Turing machines are countable > > > > and so are their inputs N. Effective enumeration is the range of one of > > > > them. > > > > > > > > > And a non-effective enumeration isn't. And I can't think of any good > > > > reason for rejecting non-computable reals which wouldn't also be a > > > > reason for rejecting non-effective enumerations. They are pretty much > > > > the same kind of thing. An enumeration of the reals can be coded by a > > > > real, and the real will be computable if and only if the enumeration is > > > > an effective enumeration of a subset of the computable reals. If you > > > > don't believe in non-computable reals, you shouldn't believe in any > > > > enumerations that aren't effective enumerations of a subset of the > > > > computable reals. > > > > > > I think what you are trying to tell ma that you want the diagonal > > > argument to stand. For that you need a total function. Therefore I > > > should also accept the requirement that the function be total. But it > > > is a contrived case considering that for a given general recursive > > > function you cannot even tell if it is total or not. > > > > > > > > I don't think you should call it an enumeration of the reals if the > > > function is not total. Because I don't think a Turing machine really > > > computes a real if it won't ever tell you what the value of a > > > particular digit is. If we happen to know that the Turing machine > > > doesn't halt on this particular digit, then we can come up with a > > > different Turing machine which does halt on every digit and say this > > > is the real that the first Turing machine computes. But there's no > > > effective procedure for coming up with such a Turing machine. You're > > > saying, take the list where the n-th real is the real computed by the > > > n-th Turing machine, where in the case where the Turing machine doesn't > > > halt for some particular digit you're appealling to the fact that we > > > can find another Turing machine which goes on producing zeroes forever > > > after the point where the first Turing machine doesn't halt. But this > > > is cheating, you're evading the fact that there's no effective > > > procedure for finding such a Turing machine. What you've got doesn't > > > deserve to be called an effective enumeration of all the reals, because > > > there's no effective procedure for finding the m-th digit of the n-th > > > real. > > > > Correct. That is what's wrong with the diagonal argument. The matrix > > > will in fact be full of holes. Some of them will be on the diagonal, so > > > the anti-diagonal is not computable. > > > > > > There's nothing wrong with the diagonal argument as long as you're > > > clear about what it purports to show. There is a non-effective > > > enumeration of the computable reals, yes, this in no way contradicts > > > the diagonal argument, and does not deserve to be paraphrased as The > > > reals are countable. You're assuming the matrix with its holes in it > > > actually exists. There's no effective way of telling whether a given > > > entry in the matrix will have a hole in it or not, so to assume that > > > the matrix somehow exists as a determinate object is on a par with > > > assuming the existence of a non-computable real. > > > > > > > The diagonal argument does show that there can be no effective > > > enumeration of the set of all computable reals. What you've got, I > > > claim, should be called a non-effective enumeration. > > > > It is still an enumeration. > > > > > And since I can't > > > see any good reason to reject non-computable reals that doesn't also > > > lead to rejecting non-effective enumerations, I don't accept that > > > you've given me a reasonable stance which justifies the statement The > > > reals are countable. > > > > I will give you a couple of reasons: > > > 1) What happens in infinity is beyond the realm not only of observable > > > but even imaginable phenomena. Hence any statements about infinity > > > (such as one infinity is greater than another) are meaningless. > > > > Is the statement The computable reals are not effectively countable > > > meaningless? > > > > Maybe not, but P(N) > N is. > > > > > Why? It says there's an injection from N into P(N) and no bijection > > from N onto P(N). Seems to me I understand it perfectly well. > > Can you picture one infinity greater than another? > > > Can you picture four-dimensional space? > > No. Can you? That is I cannot picture a four-dimensional gemetric space > as oppose to algebraic space defines as R x R X R x R. > > No, I can't, but that obviously has no bearing on what mathematical > practice should be. So I was wondering why you thought it was relevant > to ask whether I can picture one infinity greater than another, > whatever that means. > > I don't know what this question > > means. It's irrelevant. I understand the meaning of the statement > > perfectly well. > > If you cannot imagine what |R| > |N| means nothing. > > Well, that's an ill-formed sentence and it's hard to tell what you > meant to say. I know perfectly well what |R|>|N| means. > > > > > > > 2) Actual infinity (that is finished infinity) is a contradiction in > > > terms > > > 3) Infinite, incompressible strings carrying infinite amount of > > > information cannot exist for reasons 1) and 2). > > > > So why do you believe your enumeration, which you conceded was > > > non-effective, exists? > > > > I never said I believed in any enumeration. > > > > > Good. So presumably you won't claim that the reals are countable. > > I do not believe that that there are more reals than natural numbers. > > > So you either reject the claim that the naturals can be injected into > > the reals, or you claim that the naturals can be bijected onto the > > reals. Somehow I doubt the former. So how does this square with your > > saying I never said I believed in any enumeration? > > I said effective enumeration of real numbers was not necessary. > > Well, that's just as well because it's impossible. So what exactly are > you trying to prove? > > I also > said that all the Turing machines that compute real numbers can be > effectively enumerated. > > Well, that's actually not true. > > I also said that I did not see any reason why > we needed a subset of the machines that compute infinite strings as > 3.14 is a real number just as 3.14000000...... > > Because if we allow the Turing machines which don't halt, there will be > no effective procedure for determining the real number they compute to > an arbitrary level of accuracy. > > > > > > > 4) in a finite binary tree the ratio of edges to paths is (2*2^n - > > > 2)/2^n. In an infinite tree the ratio is lim{n-->oo} (2*2^n - 2)/2^n = > > > 2. > > > > Wrong, in an infinite tree it's not defined. > > > > Is it true that lim{n-->oo}(2*2^n - 2)/2^n = 2? > > > > Yes. > > > > is it true that we indexed all the layers by integers? > > > > Don't understand this one. You seem to be missing my point. > > Here is the point. lim{n-->oo}(2*2^n - 2)/2^n = 2 applies to the > > INFINITE tree because there are infinitely many integers. > > > Look, this is just drivel. You've given no reason for thinking this > > limit has anything to do with anything. > > Hm ... So do you agree that (2*2^n - 2)/2^n is the ratio of edges to > paths in a finite binary tree? What then is your interpretation of > lim{n-->oo}(2*2^n - 2)/2^n? > > It's just an expression which you came up with. It's mathematically > well-formed but you have given me no reason to think it has anything to > do with anything. What then is your interpretation of lim{n-->oo}(2*2^n - 2)/2^n? > It is the unique numer x, if it exists, such that for all positive real > numbers epsilon, there exists a positive integer N, such that for all > n>N, |x-((2*2^n-2)/2^n)|= 1)? Is it true that An(#eges/#path >= 1)? > > > > > Is it true that > > N is infinite? > > > > > Yes. > > > > > > It contradicts Cantor's result that the cardinality of the paths is > > > greater than the number of the edges. > > > 5) The diagonal argument shows that for any matrix of size n there is a > > > string of size n that is not in the matrix. Yet for any n such a string > > > can be generated and added to the list. You could as well have counters > > > A and B with values v(B) and v(A) such that vhen v(A) = n then v(B) = > > > n+1. You could keep incrementing these counters till infinity and find > > > that for any n v(B) > v(A). Yet it would be absurd to argue that in > > > infinity B > A. But the Cantorists do precisely that arguing that they > > > can always find one more antidiagonal that is not on the list yet. > > > > We say that one infinite set is of larger size than another when the > > > latter can be injected into the former but not bijected onto the > > > former. Cantor proves this is the case for the set of real numbers and > > > the set of natural numbers. > > > > You missed the point. I am saying that any time you find the > > anti-diagonal I can put back on the list. What leads you to believe > > that once we reach infinity there will be one outstanding anti-diagonal > > left before I have a chance to put it in the list. > > > > > Given any countable set of real numbers, there is a real number not in > > the set. That shows that the set of real numbers is not countable. > > Any real that is not on the list can be added to the list. > > > So what? > > So all the reals will be on the list. > > Wrong. > > > > > > > When > > > you observe a dog chasing its tail you do not conclude that one > > > infinity is greater than another. > > > > > > > Secondly procedures that are not total are still considered effective. > > > Case in point is my example of a list of modified Turing machines. It > > > does not matter one iota if any given machine will terminate or not > > > because in either case it will compute a real number. And there no more > > > computable real numbers than there are modified Turing machines. > > > > > > > > You are not justified in saying the real numbes are countable from your > > > standpoint unless you can give an effective enumeration of the > > > computable reals, which gives an effective procedure for finding the > > > m-th digit of the n-th real. > > > > You added this arbitrary condition to preserve the diagonal argument. > > > > > > It's no more arbitrary than the requirement that reals be computable. > > > > If the enumeration you've given is good > > > enough to be called an enumeration, why shouldn't I take the > > > anti-diagonal for it and say that's good enough to be called a real > > > number? > > > > Because the diagonal will have holes. > > > > > > When I objected to you that the enumeration will have holes, you said, > > > Fine, get rid of the holes > > > > I do not recall saying this. > > > > I could not find the quote there. > > > > `It does not need to. 3.14 is a real number just as > > 3.140000000000........' > > You're saying the fact that there are holes doesn't matter. You > > advocate replacing 3.14 followed by an infinite string of holes with > > 3.1400000000...... > > No, I am not advocating that. Quite the contrary. I am saying that 3.14 > stands on its own. > > Well, it doesn't, because you have know way of knowing what it is. You > know it starts with 3.14, and that's all you know. You don't know > whether there are any more digits. Why do I need to know how many more digits? All i want to know is if it > is a real, and a real it is. > But you don't know which real it is. If you're saying you can have a > list of reals where there's no effective procedure for telling what the > n-th real is, then why don't you allow a real where there's no > effective procedure for telling what the n-th digit is? I do. > > > > without worrying about the fact that > > > there's no effective procedure for doing so. You still thought this was > > > a good enough reason to call it an enumeration. Why shouldn't I do the > > > same thing here and say that the anti-diagonal with the holes removed > > > deserves to be called a real, even though it's not computable? > > > > > > > Whatever. It doesn't really matter. As long as you translate your claim > > > into my language I'll agree with you. Just say The computable reals > > > are non-effectively countable. > > > > OK, they are not effectiveky countable. > > > > > > Good. Also, there is nothing wrong with the diagonal argument, and you > > > cannot justify saying The reals are countable without twisting the > > > meanings of words in totally arbitrary ways. > > > > That's fine. I think that to paraphrase > > > this as The real numbers are countable is silly, that's what I object > > > to. > > > > Countable means the same cardinality as N. > > > > > > And same cardinality means there exists a bijection. Why am I > > > supposed to accept the existence of the bijection but not the > > > anti-diagonal? > > > > I thought the anti-diagonal was supposed to prove that there was no > > bijection. > > > > > It does. You are telling me the enumeration exists but not the > > anti-diagonal, therefore the enumeration is a bijection. I see no good > > reason for accepting the existence of the enumeration but not the > > anti-diagonal. > > > > It's not good enough to say the anti-diagonal will have > > > holes. You can only justify your claim that the bijection exists by > > > getting rid of the holes (in a necessarily non-effective way). > > > > Obviously there is bijection between Turing machines and N, holes or > > not. > > > > > Well, yes, I think it's obvious, but I also think it's obvious that the > > anti-diagonal exists. I don't think you can have one without the other. > > If some of the (countable many) Turing machines go into infinite loop > > or infinite recursion then the diagonal will not be computable. > > > That's right, the enumeration will not be effective, and the diagonal > > will not be computable. I don't understand why you believe in the > > enumeration but not the diagonal. > > I believe that the set of machines that compute infinitely long real > numbers is smaller than the set of machines that compute all the real > numbers. The set that computes all the real numbers is definitely > denumerable, even effectively enumerable. > > But this is no good to you because for some of these machines you don't > know which real number they compute. You just said which real number. So you know it is a real number > after all. > Yes, *I* know it's a real number. But I believe in non-computable reals > as well. I don't think you should allow yourself to speak of a list of > real numbers where you don't know what the n-th real number is if you > won't allow yourself to speak of a real where you don't know what the > n-th digit is. I am a bit lost here. Are you saying that if you do not know whether the machine will compute the next digit then the real is not computable? That doesn't deserve to be called > an effective enumeration of the computable reals. If you do not like to call it an effective enumeration of the > computable reals I am OK with that. > Good. Now, if you don't believe in non-computable reals, why do you > believe in non-effective enumerations? Or, if you don't believe in > non-effective enumerations, why do you say the reals are countable? Because I have no reason to believe they are uncountable. > Regarding a given > Turing machine such that we don't know whether it halts for every digit > or not, I don't see how you could justify the claim This Turing > machine definitely computes some real number What do you think it could possibly compute. Could it compute something > that is not a real number? > As a matter of fact, if it doesn't halt for every digit I don't think > it computes anything. If it computes 3.14 then it looks like a perfectly good number to me. > You say even in that case it still computes a > real number, but you can only justify that by implicitly appealing to > an oracle machine that can see for which digits the Turing machine > won't halt. Not really. I am saying that whether it halts or not whatever it will compute is a real. No oracle is required. If you accept such a real number as an entry in your list, > saying in principle we could get rid of the holes, I am definitely not saying that. The holes are there to stay. > then I think you > should accept the anti-diagonal for the list as well. If you say ah, > but we can't form the anti-diagonal because of the holes then I say > we can't even form the list in the first place because of the holes. Let's say we cannot form a list. But we do not have any reason to say that the reals are uncountable either. > from a constructivist > standpoint. You're trying to sneak in non-constructivist assumptions > when it suits you, but you won't allow non-computable reals. Are you saying that Turing machines that do not halt are not > constructivist? If non-computable reals are not constructivist, then non-effective > lists of reals are not constructivist either. (Actually, we can justify > talking about non-computable reals perfectly well from a constructivist > standpoint, but you and |-|erc are ignoring that fact so I'm ignoring > it too for the sake of argument). Well maybe, it is a question of terminology. I am not > necessarily advocating one label or another. All I am saying is that > you can enumerate all the machines that will compute real numbers But you can't. If it deserves to be called an enumeration, then the > anti-diagonal deserves to be called a real. Is it your position that if the machine does not compute infinitely many digits then it is not a real number? and > that I do not care if any of those machines halts or not because > whatever it computes can be nothing but a real. > > > > So I > > > should be allowed to do the same with the anti-diagonal and say Here > > > is a non-computable real number. > > > > What justifies saying that it exists? > > > > > What justifies saying that the enumeration exists? If it does, the > > anti-diagonal should exist too. > > If the enumeration does not exist then there is no diagonal. > > > True. The nonexistence of the enumeration is the point of Cantor's > > argument. > > > > > > > > > > > > > And in that case the argument works > > > > fine. > > > > > > Are you suggesting that there is some contradiction in recognizing only > > > > countable reals? > > > > > > No, countable reals doesn't mean anything. If you substitute > > > > computable reals, I suggested no such thing. > > > > > > Hardly. You only need to drop the axiom of extent > > > > > > There is no axiom of extent. > > > > > > I meant axiom of comprehension. > > > > > > > > > or > > > > the the power set axiom and the diagonal argument will not go through. > > > > > > Yes, it will, it will show that there is no countable set containing > > > > all the reals. > > > > > > No, it will not. If there is no power sat then you cannot show that it > > > is greater than N. > > > > > > > > > And since you believe that ZFC is consistent then a weaker system is > > > > even more consistent. > > > > > > > > > There are subtheories of ZFC in which the diagonal argument doesn't go > > > > through. That is no objection to the diagonal argument. Your job is to > > > > find a consistent theory in which the reals are countable (which > > > > necessarily won't be a subtheory of ZFC), and convince me that I should > > > > accept this theory. I expect you could do the former, but I doubt you > > > > can do the latter. > > > > > > I already told how to construct a consistent theory where the diagonal > > > argument will not go through. Drop the axiom of comprehension or drop > > > the power set axiom. > > > > > > That of course is not entirely satisfactory theory. So I propose adding > > > the axiom: A class x is set only if x is definable. This will result in > > > proving that > > > B = {x e N| x ~e phi(x)}, phi:N --> P(N) > > > is not a set. After all B is just Russell's set in blue. > > > > > > > > > And not knowing which Turing machine will halt how can you specify a > > > > total function? > > > > > > > > > Don't understand this point. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > and it's not a > > > > > > > > computable matter to decide which do and which don't. === Subject: Re: Uncomputable numbers are all in your head > > Given any countable set of real numbers, there is a real number not in >> > the set. That shows that the set of real numbers is not countable. >> > Any real that is not on the list can be added to the list. >> > So what? >> So all the reals will be on the list. >> Are you joking or are you serious? You prove that the reals are >> uncountable. You take a list. You find a real not on it. So, you add the >> new real to the list to create another list. Of course, the proof still >> works, so there is a real not on the second list. But I can add the second anti-diagonal immediately to the second list. How many reals do you >> think you need to add to the list until they are all there? Infinitely many. Yes, but only a countable infinity. There are uncountably many numbers to be > added. Are you saying that you can generate uncountably many anti-diagonals, but I can put only countably many back on the list? > -- > Dave Seaman > U.S. Court of Appeals to review three issues > concerning case of Mumia Abu-Jamal. > === Subject: Re: Uncomputable numbers are all in your head > Yes, but only a countable infinity. There are uncountably many numbers to be > added. Are you saying that you can generate uncountably many anti-diagonals, > but I can put only countably many back on the list? Depends what you mean by can generate. If you give us uncountably many lists, we can certainly generate an antidiagonal for each one. However, the main thing that we are saying is that there are uncountably many reals, but a list can only contain a countable number of items (the latter is pretty much by definition of what a list is). -- === Subject: Re: Uncomputable numbers are all in your head > Any real that is not on the list can be added to the list. > > So what? > > So all the reals will be on the list. > > Are you joking or are you serious? You prove that the reals are > uncountable. You take a list. You find a real not on it. So, you add the > new real to the list to create another list. Of course, the proof still > works, so there is a real not on the second list. But I can add the second anti-diagonal immediately to the second list. Ye gods. Of course you can re-iterate the diagonal construction, at > each point constructing a new countable list, and then diagonalizing to > define a new number not on that list, we which can add to get an > extended list. But you will never get *all* real numbers that, only a > countably infinite subset of them. I am proposing to put ALL the anti-diagonals on the list one by one. === Subject: Re: Uncomputable numbers are all in your head > > > Any real that is not on the list can be added to the list. > > So what? > > So all the reals will be on the list. > > Are you joking or are you serious? You prove that the reals are > uncountable. You take a list. You find a real not on it. So, you add the > new real to the list to create another list. Of course, the proof still > works, so there is a real not on the second list. > > But I can add the second anti-diagonal immediately to the second list. Ye gods. Of course you can re-iterate the diagonal construction, at > each point constructing a new countable list, and then diagonalizing to > define a new number not on that list, we which can add to get an > extended list. But you will never get *all* real numbers that, only a > countably infinite subset of them. I am proposing to put ALL the anti-diagonals on the list one by one. What makes you think you can do that? Aren't you just assuming what you want to show? You want to show the reals are countable. This means you want to show that you can put them on a list. And, you are proposing to do this one by one, which seems to be just a different way of saying that the reals can be put on a list. But, you haven't yet shown that the reals can be put on a list. And, in fact, we have proved that the reals can't be put on a list. So, this seems to boil down to the following: Theorem. The reals are countable. Proof: The reals can be put on a list. QED -- === Subject: JSH All Your Base Belong To Me. All Your Ass Belong To Me Too. You guys are a bunch of sissies. None of you can successfully argue against Harris's mathematical Theory of Triviality and QG. You are all a bunch of pussies. Harris's Theorem The Existence of a Trivial is Indeterminate. === Subject: Re: Kant - why knucmo and i really agree (but argue because he is wrong) > Knucmo, I think we both agree that the fundamental-most categories > we use to interpret our world are strongly inherent to our > being. I have said that in many of my posts on the topic, > and you have argued that is Kant's position. You have also > allowed Kant's position the possibility of corporeal being, > and contingency. Sir Frederick and other regular posters, as well as numerous > other modern philosophers, have covered theories of truth in > the brain. How we pattern recognise, the process of > categorisation, what we remember and why. If you are a realist, mind is corporeal and ontogenic and > phylogenic learning are the only forms of knowledge. > Phylogenic learning, or evolution, gives us our mostly- > common categories, the basis on which language, logic, and > our mathematics are built. They make the game possible. Where we differ, Knucmo, is in the role Kant plays in this > description. You believe that he intends a priori to > allow for contingent facts, that the synthetic a priori that > he founds his metaphysics on is not necessarily absolute. You have stated in other leaves that you do believe there > is some absolute truth. 1 + 1 = 2. That is the type of > thing Kant believed, and I will agree with you if you > characterise him so. But he also believed a lot more was > absolute. I have given many quotations of Kant where he details the > extent of the necessity he felt his foundations provided. > They were necessary because they involved his fundamental > questions, which he (again as I have quoted) are to be > made absolute. Mathematics? Absolute. > Science and a foundation of absolute, to interpret the contingent. > Metaphysics from transcendant truth. > Kant speaks for himself, here; V. IN ALL THEORETICAL SCIENCES OF REASON SYNTHETIC A PRIORI JUDGMENTS ARE CONTAINED AS PRINCIPLES 1. All mathematical judgments, without exception, are synthetic. This fact, though incontestably certain and in its consequences very important, has hitherto escaped the notice of those who are engaged in the analysis of human reason, and is, indeed, directly opposed to all their conjectures. For as it was found that all mathematical inferences proceed in accordance with the principle of contradiction (which the nature of all apodeictic certainty requires), it was supposed that the fundamental propositions of the science can themselves be known to be true through that principle. This is an erroneous view. For though a synthetic proposition can indeed be discerned in accordance with the principle of contradiction, this can only be if another synthetic proposition is presupposed, and if it can then be apprehended as following from this other proposition; it can never be so discerned in and by itself. First of all, it has to be noted that mathematical propositions, strictly so called, are always judgments a priori, not empirical; because they carry with them necessity, which cannot be derived from experience. If this be demurred to, I am willing to limit my statement to pure mathematics, the very concept of which implies that it does not contain empirical, but only pure a priori knowledge. We might, indeed, at first suppose that the proposition 7 & 5 = 12 is a merely analytic proposition, and follows by the principle of contradiction from the concept of a sum of 7 and 5. But if we look more closely we find that the concept of the sum of 7 and 5 contains nothing save the union of the two numbers into one, and in this no thought is being taken as to what that single number may be which combines both. The concept of 12 is by no means already thought in merely thinking this union of 7 and 5; and I may analyse my concept of such a possible sum as long as I please, still I shall never find the 12 in it. We have to go outside these concepts, and call in the aid of the intuition which corresponds to one of them, our five fingers, for instance, or, as Segner does in his Arithmetic, five points, adding to the concept of 7, unit by unit, the five given in intuition. For starting with the number 7, and for the concept of 5 calling in the aid of the fingers of my hand as intuition, I now add one by one to the number 7 the units which I previously took together to form the number, and with the aid of that figure [the hand] see the number 12 come into being. That 5 should be added to 7, I have indeed already thought in the concept of a sum = 7 & 5, but not that this sum is equivalent to the number 12. Arithmetical propositions are therefore always synthetic. This is still more evident if we take larger numbers. For it is then obvious that, however we might turn and twist our concepts, we could never, by the mere analysis of them, and without the aid of intuition, discover what [the number is that] is the sum. Just as little is any fundamental proposition of pure geometry analytic. That the straight line between two points is the shortest, is a synthetic proposition. For my concept of straight contains nothing of quantity, but only of quality. The concept of the shortest is wholly an addition, and cannot be derived, through any process of analysis, from the concept of the straight line. Intuition, therefore, must here be called in; only by its aid is the synthesis possible. What here causes us commonly to believe that the predicate of such apodeictic judgments is already contained in our concept, and that the judgment is therefore analytic, is merely the ambiguous character of the terms used. We are required to join in thought a certain predicate to a given concept, and this necessity is inherent in the concepts themselves. But the question is not what we ought to join in thought to the given concept, but what we actually think in it, even if only obscurely; and it is then manifest that, while the predicate is indeed attached necessarily to the concept, it is so in virtue of an intuition which must be added to the concept, not as thought in the concept itself. Some few fundamental propositions, presupposed by the geometrician, are, indeed, really analytic, and rest on the principle of contradiction. But, as identical propositions, they serve only as links in the chain of method and not as principles; for instance, a = a; the whole is equal to itself; or (a & b) a, that is, the whole is greater than its part. And even these propositions, though they are valid according to pure concepts, are only admitted in mathematics because they can be exhibited in intuition. 2. Natural science (physics) contains a priori synthetic judgments as principles. I need cite only two such judgments: that in all changes of the material world the quantity of matter remains unchanged; and that in all communication of motion, action and reaction must always be equal. Both propositions, it is evident, are not only necessary, and therefore in their origin a priori, but also synthetic. For in the concept of matter I do not think its permanence, but only its presence in the space which it occupies. I go outside and beyond the concept of matter, joining to it a priori in thought something which I have not thought in it. The proposition is not, therefore, analytic, but synthetic, and yet is thought a priori; and so likewise are the other propositions of the pure part of natural science. 3. Metaphysics, even if we look upon it as having hitherto failed in all its endeavours, is yet, owing to the nature of human reason, a quite indispensable science, and ought to contain a priori synthetic knowledge. For its business is not merely to analyse concepts which we make for ourselves a - priori of things, and thereby to clarify them analytically, but to extend our a priori knowledge. And for this purpose we must employ principles which add to the given concept something that was not contained in it, and through a priori synthetic judgments venture out so far that experience is quite unable to follow us, as, for instance, in the proposition, that the world must have a first beginning, and such like. Thus metaphysics consists, at least in intention, entirely of a priori synthetic propositions. http://www.arts.cuhk.edu.hk/Philosophy/Kant/cpr/ http://www.bright.net/~jclarke/kant/ http://en.wikipedia.org/wiki/Critique_of_Pure_Reason > I have given quotations like: > Here is a great and established branch of knowledge, encompassing > even now a wonderfully large domain and promissing an unlimited > extension in the future, yet carrying with it thoroughly apodictic > certainty, that is, absolute necessity, and therefore resting upon > no empirical grounds. Kant was monovalent. He was an apologist for monotheism. This is > why I have such a negative view of Kant, and why I think others > may have a more positive view. This belief in one truth. When I quote him waxing on the geometrically absolute qualities > of space and implying that the inverse square law is necessary, > as I have done, it is because it illustrates the error. if (KantsProgrammeSuccessful) then (SomePhenomenologicalStatement) > ~(SomePhenomenologicalStatement) > ---- > ~(KantsProgrammeSuccessful) You, Knucmo, have claimed this syllogism invalid. You seem to > claim the error lies in the first step, that no implication is > possible. But you do not answer why the quotes I have given > claim otherwise, in Kant's own words. You see, I dislike Kant's programme because I believe he is > strongly monovalent. I believe he claims this in a number of > places, and uses it to found his theory of morality. He makes > numerous claims that the universality of morality is founded > in the absolute necessity of the categorical imperative. So, as with your 1 + 1 = 2, he believes there is an absolutely > unquestionable core to rational thought that determines not > only what we perceive but what we ought decide to do. It is > a strange interpretation of Kant in my eyes to believe he > accepts an evolutionary a priori that is contingent but still > reveals absolute imperatives to the intuition, and one that > Kant himself denies. Kant is not to be credited for simply saying that we order our > perceptions and give structure to the senses. That is old and > common to many traditions, to very old ones (Buddhism and > Stoicism) which I have mentioned and you have yet to respond to, > Knucmo. In fact, in a response to Fernando Revilla in the > kant thread, I mentioned in passing Ratnakirti, who even > specifically pointed to antinomies in designating boundaries > for concepts, hundreds of years prior to Kant. Chryssipus > was But the nominalist schools of Buddhism and the Stoic schools of > classic philosophy both have extensive theories of human error. > Kant was often quite explicit that his intensions were to explain > the basis of human certainty. When pressed, many with Kantian > tendencies will claim an absolute, like your 1 + 1 = 2. My > objection is when the absolute is denied and Kant's own > statements ignored. You could answer my quotes, which I entered in by hand from > source material, Knucmo. Or you could read some of the available information out there, > like http://post.queensu.ca/~miller/Papers/Innate%20ideas.pdf and other professional journal content. But instead of confronting the issues raised and avoiding > acknowledging the quotes, you have decided to post some juvenile > remarks and belittle me by your Hes. I do not know if I can get any resolution. Perhaps my mind is > too much made up. I had thought someone could explain the > quotes, which seem explicit to me. Particularly: If we consider the properties of the circle, by which this figure > combines in itself so many arbitrary determinations of space > in a universal rule, we cannot avoid attributing a constitution > to this geometrical thing. Two straight lines, for example, which > intersect each other and the circle, howsoever they may be > drawn, are always divided so that the rectangle constructed > with the segments of the one is equal to that constructed with > the segments of the other. The question now is: Does this > law lie in the circle or the understanding? That is, does this > figure, independently of the understanding, contain in itself the > ground of the law; or does the understanding, having constructed > according to its concepts (of the equality of the radii) the figure > itself, introduce into it this law of the chords intersecting in > geometrical proportion? When we follow the proofs of this law, > we soon perceive that it can only be derived from the condition > on which the understanding founds the construction of this > figure, namely, the concept of the equality of radii. But if we > enlarge this concept to pursue further the unity of various > properties of geometrical figures under the common laws and > consider the circle as a conic section, which of course is > subject to the same fundamental conditions of construction as > other conic sections, we shall find that all the chords which > intersect within the ellipse, parabola, and hyperbola always > intersect so that the rectangles of segments are not indeed > equal but always bear a constant ratio to one another. If we > proceed still farther to the fundamental teachings of astronomy, > we find a physical law of reciprocal attraction applicable to > all material nature, the rule of whichis that it decreases > inversely as the square of its distance from each attracting > point, that is, as the spherical surfaces increases over which > this force spreads, which law seems to be necessarily inherent > in the very nature of things, and hence is usually propounded as > knowable a priori. Simple as the sources of this law are, > merely resting on the relation of spherical surfaces of different > radii, its consequences are so valuable with regard to the > variety and simplicity of their agreement that not only are all > possible orbits of the celestial bodies conic sections, but > such a relation of these orbits to one another results that no > other law of attraction than that of inverse square of the distance > can be imagined as fit for a cosmical system. Here accordingly is nature, which rests upon laws the understanding > knows a priori, and chiefly from the universal principles of the > determination of space. -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- > galathaea: prankster, fablist, magician, liar === Subject: Re: Cantor Confusion Nntp-Posting-Host: apps.cwi.nl > No, that does AC (although the statement is indirectly). V=L is the axiom > of constructibility and states that every set is constructible. Most > mathematicians think it is false, but it can not be disproven and is > consistent with ZF. It *gives* a construction. > > But, alas, this construction cannot be communicated. It is and remains > a top secret. Otherwise most mathematicians could easily be proved > wrong by simply constructing a well-ordering of R. It can be communicated. But you are not even willing to look at the axiom and its consequences. > > Eh? As I understand it, there is only one union. But, what is the > > relevance? > > > > There is a union of paths for every path. > > How do you define a union of paths? > > For example: the infinite union of {0.01} and {0.010} and {0.0101} ... > yields the path corresponding to 1/3. I asked for a definition, not an example. How do you define the union of paths? What (for instance) is the union of {0.1111} and {0.1011}? > > Every node which is placed on a finite level (= every digit with a > > finite index) is in the union of all finite trees. Therefore every path > > containing nodes on a finite level (= every sequence of digits at > > places with finite indexes) is in the union of finite trees. There is > > nothing remaining! > > But that does *not* mean that the set of paths is the union of the sets of > paths in the finite trees. > > If the tree is complete with respect to edges, then it cannot be > completed any further. Makes no sense. It does not even refute my statement. > You are again, *not* talking about the union of sets of paths. So what is > the relevance? > > If the tree is complete with respect to edges, then it cannot be > completed any further. And again, *not* talking about the union of sets of paths. So what is the relevance? > > Nevertheless, the representations in the union of all finite trees are > > countable as the countable union of finite sets. > > A new term again. What are the representations? > > The paths are representations of real numbers. Oh. Perhaps. Pray define. -- dik t. winter, cwi, kruislaan 413, 1098 sj amsterdam, nederland, +31205924131 home: bovenover 215, 1025 jn amsterdam, nederland; http://www.cwi.nl/~dik/ === Subject: Re: Cantor Confusion Nntp-Posting-Host: apps.cwi.nl > > What is a ghost path? > > A ghost path is a path which does not exist in a tree which contains > the paths of all real numbers the bits of which can be indexed by > natural numbers. That is something I do not understand. Please elaborate. > > The union of all finite trees is also the union of all last levels. > > That is the union of all levels. If some path is missing, then it must > > stretch over more than all levels indexed by natural numbers. > > Ah, again about that diagonal. No, you are wrong. > > All path the bits of which can be indexed by natural numbers are in the > union of all finite trees. But *not* in the union of the sets of paths in the finite tree. > You know it. You cannot point to a bit of any number of [0, 1] which is > missing. But you claim there were further numbers. > > Try to complete the union of all finite trees to the complete infinite > tree. Which level, node or edge would you add? Pray, properly define the union of trees. In my opinion a tree consists of three sets. First the set E of edges, next the set N of nodes and finally the set P of paths. What is the union of two trees? > Why was it not a proof? > > Because you used crippled plants which are not under discussion in a > forest of well grown trees. My proof was about the set of paths in the union of finite trees not being the union of the sets of paths in the finite trees. What was wrong about that proof? Please, once come up with a proper definition of the union of two trees. Before you come up with such a definition it is impossible to even entertain a discussion. > I am talking about the union of *sets* of paths, not the union of paths. > Do you not see the difference? How do you define the union of paths? > And how do you define the union of the *sets* of paths that are in the > finite trees? > > Which edge of any infinite path is missing? Which bit could be added to > one of the numbers represented? What is the relevance? If you cna state that there is some infinite path in the union of the *sets* of paths in finite trees, you should also be able to point to a finite tree that contains that infinite path. There is no edge missing, it is only that your infinite path is not a path in any of the finite trees, so it is not in the union of the sets of paths in finite trees. > Ok, so you do *not* use the union of the sets of paths but something else. > > The material from which the paths are constructed. Makes no sense. > Indeed, you actually do not use those sets at all in forming your union. > Nevertheless you want to draw conclusions about the cardinality of the > *set* of paths in that union from the cardinalities of the *sets* of > paths in the finite trees. > > The completeness of U{n e N} {1,2,3,...n} = N is the same as the > completeness of the union of all levels of the infinite tree, and that > is the same as the union of all finite trees. And all these unions are > counatble. As you still fail to provide proper definitions of unions of trees, I wonder. > How do you *define* the union of two trees? > I saw a tree as consisting of three sets: E, N and P for edges, nodes > and paths. > > You can also unify the levels. Eh. Pray expand. > And I defined the union of two trees T1 and T2 as: > [ {E1, E2}, {N1, N2}, {P1, P2} ] > (where those unions are sets, so duplicated elements can be elided). > > It is sufficient to build the union of all finite trees, or of all > levels, or of all edges, or of all nodes. This union is an infinite > tree. An infinite tree cannot be surpassed (by another tree with > naturally indexed levels). Therefore the union is *the* infinite tree > and, hence, it contains all possible paths. Again, no definition, only assertions. -- dik t. winter, cwi, kruislaan 413, 1098 sj amsterdam, nederland, +31205924131 home: bovenover 215, 1025 jn amsterdam, nederland; http://www.cwi.nl/~dik/ === Subject: Re: Cantor Confusion Nntp-Posting-Host: apps.cwi.nl ... > > Ok? Every infinite tree, which contains all levels enumerated with > > natural numbers, contains all possible paths and, therefore, contains > > the representations of all real numbers of [0, 1]. > > In that case the set of paths in the infinite tree is not the union of the > sets of paths in the finite trees. > > The union of all finite trees (= union of all levels) of the tree > automatically contains all paths, because there is no path or part of a > path outside of this union. And again, in that case the set of paths in the union is not the union of the sets of paths. I did show that with a finite graph. So I wonder why you think it holds for an infinite graph (which a tree is)? > > The union of all finite initial segments {1,2,3,...n} is the infinite > > initial segment N. So the infinite tree is the union of all finite > > trees. > > Yes, so what? I repeat that I am talking about the union of the sets of > paths. > > The union of all finite trees (= union of all levels) of the tree > automatically contains all paths, because there is no path or part of a > path outside of this union. Yes, but that does *not* make the *set* of paths the union of the *sets* of paths in the finite trees. > No, because I do not state that. I only state (I repeat): > there is no infinite number in the union of initial segments > and that means that N does not contain an infinite number. It contains > only finite numbers (but infinitely many). And the union of all finite > initial segments *is* N. > > Correct. As the union of all finite paths turning always right is > 0.111... . Pray, define the union of paths. But I am talking about *sets* of paths. > U{n is natural} {n} = N. Because every k in N is in one of the sets used > in the union, namely {k}. {0.111...} is *not* in > U[ {0.1}, {0.11}, {0.111}, ...} ] because it is in *none* of the sets > used in the union. > > But {0.111...} is {{0.1}, {0.11}, {0.111}, ...} (see below). Oh. > The union of {0.1}, {0.11}, {0.111}, ..., is *not* {0.111...}, it is: > {0.1, 0.11, 0.111, 0.1111, ...}. Remember: unions are defined for *sets*. > I do not know any definition of union for numbers as these. > > And what is the set {0.1, 0.11, 0.111, 0.1111, ...}, or, translated to > digits, the set {1,2,3,...}? Is it not {0.111...} or, translated to > digits, N (or omega)? Perhaps. But what is the relevance? How about the set {0.1, 0.10, 0.101, 0.1010, ...}? How do you define the *union* of paths? In a level three tree I can encounter the paths 0.111 and 9.101. What is their union? > So we go a bit abstract already. > > So consider the circles below. Their meaning should be unique. For you, apparently. > > > They will understand, at least by experiment, > > > > > > oo > > > ooo > > > _____ > > > ooooo > > > > You apparently have not done the experiment. No, they will not > > understand, and such experiments have been done. > > > > Depends on their intelligence, which I don't know. > > It has nothing to do with intelligence. In their culture they do not use > *any* abstraction. They do everything with concrete things only. > > In above circles there is no abstraction. You think so. I see (in my non-abstracted view) a line with circles, beneath it another line of circles, a dash and a third line of circles. I have no idea what the meaning of that is. A picture, apparently. Looks nice. But what is the meaning? -- dik t. winter, cwi, kruislaan 413, 1098 sj amsterdam, nederland, +31205924131 home: bovenover 215, 1025 jn amsterdam, nederland; http://www.cwi.nl/~dik/ === Subject: (i) = 1000...0000, (e)= -1, pi = 3 solves the old beautiful equation e^(pi*i)= -1 > So if ....88888 has a square root then they could be ....2xyz or > > ....9xyz but apparently as you point out above they can be neither. > > Natural Numbers may or may not have square roots but they are between > > perfect squares. > > The number .....999999 does have a square root and it either ends in 7 > > or 3 > > Apparently it is the number ....31xyz....7 or ....31xyz....3 It is neither. > ...03 * ...03 = ...09 ...07 * ...07 = ...49 > ...13 * ...13 = ...69 ...17 * ...17 = ...89 > ...23 * ...23 = ...29 ...27 * ...27 = ...29 > ...33 * ...33 = ...89 ...37 * ...37 = ...69 > ...43 * ...43 = ...49 ...47 * ...47 = ...09 > ...53 * ...53 = ...09 ...57 * ...57 = ...49 > ...63 * ...63 = ...69 ...67 * ...67 = ...89 > ...73 * ...73 = ...29 ...77 * ...77 = ...29 > ...83 * ...83 = ...89 ...87 * ...87 = ...69 > ...93 * ...93 = ...49 ...97 * ...97 = ...09 > none of them ends with 99. At first I thought a carryover would save this number 31...3 but there is no more carryover. So I have to resort to (i) as either 1000....0000 or -1000....00000 I typed this post earlier today but Google was having troubles so it may appear later. Now the biggest number in Natural Numbers is ....999999 and it resembles the number -1. It is not -1 but can substitute for -1. Now the number 1000....00000 has an automatic square root identical to itself as 100....0000 but can this number be -1???? It can if we consider and hold true that 999....9999 is the largest number to exist. And thus if we demand 9999....999 the largest number when we subtract 10000....00000 from 9999....99999 we have -1 So for our equation that we wish to solve of e^(i*pi) = -1 we can rewrite as: e^ (100...000 x pi) = -1 Now I am still searching to find what the variable of e ranges over. The variable of pi, (pi not in Euclidean geometry but pi in Riemann geometry varies over 2 to 3.14159.....) that I will use pi as ......000003 or simply 3 So the above becomes this equation: e^ (100...000 x 3) = -1 So, now all I have to take care of is the number (e). A geometrical interpretation of (e) is that it is a number for which a geometrical object is growing in a Eucl. or Riem or Loba space for which the object remains in a state of constant proportionality. Analogy: is the seashell as it grows looks the same when small as when it grows to full maturity. Another example is the onion which remains in a constant proportionality of its parts as it grows from small to large. So, what is the range of values that (e) has in Euclidean geometry and the answer is that it has only the value of 2.71828..... But the value of (e) in Riemannian geometry I think ranges from +1 to that of +2.71828..... And most important of all, what is the range of value of (e) in Lobachevskian geometry and my intuition tells me it is -1 to -2.71828....... So I need to verify these claims. But am pretty confident they are true. And I would be astounded if I were the first mathematician in history to realize that e is a variable that has the range of the above listed. Then the mathematics community was asleep at the helm. So, now, I have all the values to solve for the ages old beautiful equation of e^(pi*i)=-1 When I replace the number (e) with -1 I get this: (-1)^(3* 1000....0000) = -1 And that does it, that solves the beautiful ages old equation of e^(pi*i) = -1 It solves it because the exponent of pi x i is a odd number of 30000....00000 which since 1000....0000 is -1 that 3000....0000 is -3 and so -1^ -3 is still -1. Now I am a bit uneasy about that and not extremely satisfied since I have changed the values repeatedly over the past few days. But it is nonetheless the world's first valued filled equation which is probably the world's most beautiful and mysterious of equations. And even though there were many changes to reach this point, it must be seriously examined as the first time anyone has satisfied that equation with numeric values. Now what is the geometrical interpretation of the above. That is easy for me with the Atom Totality theory. It says the Universe itself is one big atom and that humanity is viewing the last six electrons of the Atom Totality where galaxies are tiny pieces of the last 6 electrons. So we are inside a huge Lob of the 5f6 of the Atom Totality. We are in a Lobachevskian geometry as the inside of an electron-lob. And the value for e would be -1 and the value for pi would be 3 and the value for i would be 1000....00000. P.S. If 1000....0000 does not work out, well, I have only one last straw up my sleeve--- -1000.....000000, at least for the time being. Archimedes Plutonium www.iw.net/~a_plutonium whole entire Universe is just one big atom where dots of the electron-dot-cloud are galaxies === Here is a short course, enjoyment and fun: Audio speech by Benjamin Freedman in his own voice you can hear here : Free Science History Ebook: THE MANUFACTURE AND SALE of Saint Einstein The following passage by Benjamin Disraeli (who has very interesting quotes in the searcheable free pdf book) at http://jewishracism.com/SaintEinstein.htm After Hechler came David Ben-Gurion, who stated, The First World War brought us the Balfour Declaration. The Second ought to bring us the Jewish State.1772 .......... read the book === Subject: Why some mathematical ancestry in U.S. trace back to Germany? Recently I have been searching for mathematical ancestries of all mathematicians that I person know on the Mathematics Genealogy website (which tells you who's whose doctoral adviser). These mathematicians that I searched for are mostly in U.S., but it seems trace back several generation (in student-adviser sense) it always end up in Germany. === Subject: Re: Can ZFC prove Addition is Associative? >> >On Tue, 09 Jan 2007 10:41:23 +0100, Han de Bruijn >> > schreef: >Uh, that's correct. In an informal sense the probability of a random >integer being even is 1/2, but if we're talking carefully about >probability the way it is formulated mathematically then there >is no such probability (because there is no uniform probability >measure on the integers). >>Uh, and THAT is only because you are able to talk about THE integers. >>With any finite set of integers N = {1,2,3, .. ,n} there is no problem. >> >The question I was talking about was whether it's correct to say >that the probability that a random natural number is even is 1/2. >You appeared to be saying something about that question as well, >in particular you seemed to be suggesting that it was _correct_ >to say that, since the density of the evens is 1/2. >> >You're talking about the set of all natural numbers as well. >With any finite set {1,...n} we're talking about a different question. >> >> This is an example of the absurdity of Han's position. He >> does not believe in the set {1, 2, 3, .... }, yet he objects >> to the fact that according to the standard definitions >> there does not exist a uniform probability measure on {1, 2, 3, .... }. > The explanation is in the fact that my set {1, 2, 3, .... } is quite > different from yours. It isn't there as a whole (: actual infinity). > But we have gone through all this, haven't we? Yes, your set {1, 2, 3, ... } is quite different. So why do you insist that what is true of your set {1, 2, 3, ... } should be true of the standard set {1, 2, 3, ... }? They are different sets. You know that, yet you try to pretend that they are the same set when it suits your rants. Your contradiction is simply a result of switching which set your are talking about in the middle of your argument. Stephen === Subject: Re: Size of equivalence class of Cauchy sequences <45A5E7DD.4020507@netscape.net >Given a rational number, r, how many Cauchy sequences >converge to r? c, the cardinality of the reals. So, let me see if I understand correctly: If we use the equivalence classes of Cauchy sequences method to define real numbers, then each real number is itself a set with cardinality that of the set of real numbers. If we use the Dedekind cut method to define real numbers, then each real number is a denumerable set. (?) Moeblee === Subject: Re: Could you help me with complex numbers? David Ullrich gave great answers to your questions, so I won't repeat them other than to second his suggestion that you roundly ignore whoever told you that 15-year-old girls have no business being interested in complex numbers (or anything else that piques your intellectual curiosity). On second thought I have given a partial answer to your question about what complex numbers measure, see below. > math and try to study a bit more thn required by my school. The complex > numbers have always made me curious, so I tried to understand them to > the extent it's possible for someone my age. Formal education will try to distill this natural and healthy impulse to learn out of you. Don't let it! > At first, I was introduced to the misteryous i = sqrt(-1), something > really kabbalistic to me. Then, I got to know what mathematicians did > was extend those algebraic laws of the real field (I've read something > about groups, rings and fields) to the vector space R^2. Not sure if > this is correct, but that's what I think. In R^2 we can add and > multiply by a scalar, but we can't multiply, for example, (2,3) and > (3,7). But then it was defined that, in the complex plane, (Argand > Gauss plane, right?) (a,b) * (c,d) = (ac - bd , ad + bc). So, it seems > to me that, just like R^2, the complex plane C is formed by orderd > pairs of elements extracted from the real line. And the only difference > between them is that R^2 doesn't have all of those algebraic laws and C > does. In other words, C is a field and R^2 is not. It can't be that > simple, of course there's something I don't gather, I don't > understand. But thats my perception. If I'm right, and probably I'm > wrong, if we see R^2 and C just like sets and dont take into account > those field operations, then apparently they are exactly the same set. As David suggested elsewhere in this thread, the distinction is entirely a matter of point of view. You are entirely correct. Most mathematicians use R^2 to denote a two dimensional real vector space and C to denote the field, but one can set everything up so that they have the same underlying set. You may be interested to know that there are theorems about R and C that guarantee that even if you have a different construction of C (or R) in mind than I do, we are still talking about fundamentally the same objects: all of the a priori different things that get called C are isomorphic to each other. > So, whast's the difference between, for example (2,3) and 2 + 3i? 2 + > 3i suggests a vector notation, as though we could see the complex > numbers as vectors on the plane, like those we study in Physics, like > forces, velocities, etc. Are the complex numbers actual numbers or are > they vectors? That is, does it make sense to measure something in > complex numbers. Sorry for my stupid question, but does it make any > sense to say you bought something for (30 + 50 i) US$ ? If instead of > money it was say, distance, I could understand, since the real axis may > be seen as the horizontal axis and the imaginary axis stands for the > vertical axis. There is one thing that comes to mind, for what it's worth: in the theory of AC electrical circuits, the quantity of _impedance_ is represented as a complex number. http://en.wikipedia.org/wiki/Electrical_impedance This may not be very enlightening but at least it is a partial answer to the question can complex numbers measure things? Perhaps not in the sense of rulers or voltmeters, but it is very useful to be able to imagine them doing so in a way consistent with the theory. > It seems to me that the complex numbers are somwhat artificial, > because from what I could read they were say constructed. I mean, fisrt > you have the natural numbers {1,2,3....} and you always could add but > subtraction was impossible if n < m. Then the negative integers were > created and solved this problem, the set Z of all the integers became > available. But then division was not always possible and the set of the > rationals Q was created. But then you couldn't compute things like > sqrt(2) and so came the irrationalls. That is, so far you solved the > problems, but with the complexes, didn't matematician just construct > something rather artificial? They got out of the real line. They did get out of the real line, but in a natural extension of the process you describe. The desire for solutions to k = m - n (or, if you like, m + n = 0) for arbitrary positive integer m and n leads to the negative integers in a way similar to the way that the desire for solutions to z^2 + x = 0 for arbitrary real numbers x leads to the complex numbers. It is a bit surprising when first meeting these objects when one realizes that the expansion of the system of the real numbers that allows for solutions to x^2 + 1 = 0 actually allows you to solve ALL polynomial equations a_n x^n + ... + a_1 x + a_0 = 0, even when the a's are complex! See Fundamental Theorem of Algebra. You may be interested in further progress in this direction. Google for quaternions, octonions, normed division algebra, and, if you're feeling particularly enthusiastic, Clifford algebra. Given what you say in your post, I should not think an understanding of the basics of any of these ideas to be beyond you (with the possible exception of the Clifford algebras, at least without some more reading). At the worst it will be confusing; at best it will introduce you to some of the most beautiful and fascinating mathematics around. http://en.wikipedia.org/wiki/Quaternion http://en.wikipedia.org/wiki/Octonion http://en.wikipedia.org/wiki/Normed_divison_algebra http://en.wikipedia.org/wiki/Clifford_algebra > Well, thank you all and sorry, I know a 15 yo girl is not supposed to > ask such silly questions to the top dogs of Math, but I'm really > curious. Ha. Ask whatever you like, we're happy to help. We like math so much that many of us do it for a living and all of us kill time on sci.math. At least in part we are here because we (sadly) talk to relatively few people in real life who express such interest in the things that also interest us. > (Dont get me wrong, though I like Math I'm a normal 15 yo girl) I venture to suggest the two ought not to be thought mutually exclusive. Best, -dave *********************************************************** Papa, can you multiply triples? No, I can only add and subtract them. -an (apocryphal) conversation between W.R. Hamilton and his young son *********************************************************** === Subject: Re: Irrational numbers questions <636a1$45a4e0bf$82a1e228$26741@news1.tudelft.nl> <878xgbj99y.fsf@phiwumbda.org> <87irfeimw0.fsf@phiwumbda.org> <64114$45a65bf9$82a1e228$1014@news1.tudelft.nl> <87d55lh7ta.fsf@phiwumbda.org> Jesse F. Hughes schreef: >> On Wed, 10 Jan 2007 16:37:35 -0500, Jesse F. Hughes > meant irrational? >> No, if we assume his post was in good faith he didn't mock me for >> the typo, he was too stupid to realize it _was_ a typo. False accusation. You mean he *shouldn't* have assumed that you were being honest when > you mistook a typo for a more egregious error? Uhm, right, silly word games to win a silly debate. Han de Bruijn === Subject: Re: Irrational numbers questions Not a proof that gamma is irrational The Euler-Mascheroni constant called 'gamma' is defined by: lim (n -> oo) [ sum(k = 1..n) 1/k - ln(n) ] It's value is, approximately, given by: 0.577215664901532860606512090082402431042 It is hitherto unknown whether 'gamma' is an irrational number or not. The following is NOT a proof of a conjecture that the Euler-Mascheroni constant, called 'gamma', would be an _irrational_ number. A method is implemented by the following algorithm: start walking down through the Stern-Brocot tree in the first place. Which is implemented in the accompanying program as the 'while true do' loop. See: http://en.wikipedia.org/wiki/Stern-Brocot_tree At each stage in the tree, consider the approximation which is made possible by R.M. Young's theorem, as has been explained in: Namely: L(n) < gamma < R(n) . Where L(n) is monotonically increasing towards gamma, while R(n) is monotonically decreasing towards gamma. The width of the interval which delimits the approximation for gamma is: G(n)-1/(2(n+1)) - [ G(n)-1/(2.n) ] = 1/(2.n(n+1)) Where: G(n) = [ sum(k = 1..n) 1/k - ln(n) ] . Make certain that lower bound L(n) as well as the upper bound R(n) are well _within_ the intervals, as defined by subsequent fractions in the Stern-Brocot tree. This can always be done, because the abovementioned width of R.M. Young's interval can be made as small as desired: being implemented in the accompanying program as the 'while not OK do' loop. The bounds L,R can never be _equal_ to these fractions, because there is a natural logarithm ln(N) in them. And this logaritm is irrational, hence the bounds L,R are also irrational themselves. This proves that any bounds to gamma are never fractions in the tree. But the tree exhausts all fractions. And gamma is within these bounds. But, uhm .. suppose that gamma actually _is_ a fraction F . Then, at a certain place in the Stern-Brocot tree, L(n) < F < R(n). And this will will remain so, no matter how the interval [ L(n) , R(n) ] is squeezed to zero. Meaning that the 'while not OK do' loop is never ending. That is why the above is NOT a proof that gamma itself would be irrational. But perhaps we can not _prove_ that the Euler-Mascheroni constant gamma is irrational, but we _can_ determine approximations for its Simplicity for sure. This is done in the following program, where it is determined that the simplest simplicity of gamma is less than: 1/13 . Therefore it cannot be concluded that gamma is quite close to irrational, mainly due to software limitations: _insufficient precision_. Software limitations can be overcome however, so I expect that better estimates can be found. ---------------------------------------------------------------------- program Macaroni; { Gamma as a Path in the Stern-Brocot Tree http://en.wikipedia.org/wiki/Stern-Brocot_tree } const tol : double = 1.E-11; gamma : double = 0.577215664901532860606512090082402431042; procedure Young(eps : double); { Walk through the tree all along until gamma } var m1,m2,n1,n2,N : Longint; L,U,som,G : double; tel,boven,onder,min : integer; function OK : boolean; begin OK := (((n1+n2)*U < m1+m2) and (n1*L > m1)) or (((n1+n2)*L > m1+m2) and (n2*U < m2)); end; begin Writeln; { Initialize tree } m1 := 0; n1 := 1; m2 := 1; n2 := 0; { # iterates } tel := 0; N := 1; som := 1; G := som - ln(N); L := G - 1/(2*n); U := G - 1/(2*(n+1)); boven := 0; onder := 0; while true do begin tel := tel + 1; { if gamma not in between approximating fractions } while not OK do begin N := N + 1; som := som + 1/N; G := som - ln(N); L := G - 1/(2*n); U := G - 1/(2*(n+1)); end; if (n1+n2)*U < (m1+m2) then { Tightening } begin Write('U'); { Upper Bound } m2 := m1+m2; n2 := n1+n2; boven := boven + 1; end else begin Write('L'); { Lower Bound } m1 := m1+m2; n1 := n1+n2; onder := onder + 1; end; { Think about this: } if eps*n1*n2 > 1 then Break; end; Writeln; Writeln(' ',G,' '); Writeln(' ',m1/n1,' < ',L); Writeln(' < ',gamma,' < '); Writeln(' ',U,' < ',m2/n2); Writeln(' +/- ',eps:1); Writeln(' ',m1,' / ',n1,' < gamma < ',m2,' / ',n2); Writeln(' ',tel,' iterations < ',Round(ln(eps)/ln(gamma))); min := boven; if onder < boven then min := onder; Writeln(' Simplest Rational Simplicity = 1/',min); end; begin Young(tol); end. ---------------------------------------------------------------------- Output: ULUULUULUUUULLLUUUUUUUUUUUUULLLLLULUUUUUUUUL 5.77216947247995E-0001 5.77215664900508E-0001 < 5.77215664900787E-0001 < 5.77215664901533E-0001 < 5.77215664904075E-0001 < 5.77215664904076E-0001 +/- 1.0E-0011 323007 / 559595 < gamma < 289166 / 500967 44 iterations < 46 Simplest Rational Simplicity = 1/13 ---------------------------------------------------------------------- Disclaimer: the program defines the algorithm, illustrates the proof, but is not itself evidence. Note however that there are long sequences of U(pper) bound adaptions while executing the program. This behaviour is typical for fractions. Meaning that gamma is quite alike a fraction - while being found eventually being irrational. This might be kind of an explanation why the irrationality of gamma is so hard to prove. But oh well, the same kind of behaviour is found for Pi ... For what it is worth. Han de Bruijn