mm-1848 === Given that p=sum of points on a roll of dice, s=number of faces on each die, and n=number of dice rolled, I know that k=floor((p-n)/s) sum(0,k) (-1)^k n!/((n-k)! k!) (p-sk-1)! /((p-sk-n)! (n-1)!) will give the number of combinations that will yield a particular sum. If you had an array of such dice, and summed the rows and columns, how would you calculate the total number of combinations that could yield that set of sums? For example, if the dice rolled and the sums were: 3 3 3 | 9 3 3 3 | 9 3 3 3 | 9 _____ 9 9 9 How would you calculate how many other combinations would also yield (9,9,9) and (9,9,9)? I know I could write a loop to just count the combinations, but for the numbers I am working with it is impractical, so I am looking for a mathimatical solution if there is one. -Michael VanDeMar posting-account=mmiamAwAAAATmtxVYi9NGy7tls83IKO3 Actually, it was not original. It goes by the name of the Meissel-Lehmer-Lagarias-Miller-Odlyzko Method, at least according to M. DELEGLISE AND J. RIVAT's COMPUTING pi(x): THE MEISSEL, LEHMER, LAGARIAS, MILLER, ODLYZKO METHOD, MATHEMATICS OF COMPUTATION, Volume 65, Number 213, January 1996, Pages 235-245, specifically the bottom half of page 236. I have repeatedly asked James Harris to explain why his method is substantially different from the one presented in that paper. The only difference is that he uses k instead of the kth prime, and he has never acknowledged this. --- Christopher Heckman Large number? It would be a step in the right direction if he could factor a small number. 15 has been a problem in the past, IIRC. Alan -- Defendit numerus !3KEIp?*w`|bL5qr,H)LFO6Q=qx~iH4DN;i;/yuIsqbLLCh/!U#X[S~(5eZ41to5f%E@'ELIi $t^ Uh, he is demonstrating his system by explaining away truths. -- David Kastrup, Kriemhildstr. 15, 44793 Bochum posting-account=Q2zO6wwAAABSLuGzZIjG0efOtB9n8fUY Some posters, mostly from sci.math, are going on and on about supposedly showing that the SFT doesn't work, but the problem is, you don't even have to check their math to know they're wrong because of the two square roots in the SFT. The first one which is the easy one is Az = Ax(Ax +/- sqrt((Ax - 2j^2)^2 + 4Tj^2))/(2Ax - 2M^2) and it's easy as you have Ax = +/- (k_1 + k_2) + 2j^2 where k_1 k_2 = - j^2 T, so you have that square root no problem. But notice, k_1 and k_2 are factors of Tj^2, as that's VERY important. That one is the easy square root. It's the second one that's problematic: b_2 f_1 = (-(Az - 2M^2)+/- sqrt((Az - 2M^2)^2 - 4TM^2))/2 as it requires you have factors of TM^2 to evaluate. But a sci.math poster claims to have evaluated and didn't use factors of TM^2, so what do you know? That poster is wrong. Now that's some easy mathematics, so how can even sci.math posters claim victory and go on and on as if they don't know very easy algebra? It's a mystery. For those of you who are a little lost, imagine you have something simpler, like sqrt(x^2 + 4M) and you wish to evaluate that square root, where x and M are integers. Well, you can't solve for it without having factors of M, like if f_1 f_2 = M you can let x = f_1 - f_2 and it evaluates as sqrt(x^2 + 4M) = f_1 + f_2 but you have to have factors of M. The quadratic b_2 f_1 = (-(Az - 2M^2)+/- sqrt((Az - 2M^2)^2 - 4TM^2))/2 is more complicated, but you still can't evaluate it without having factors of M, but a poster named Nora Baron claims to have done so, so what do you know? You know that person is wrong. It's not hard algebra. Now then, do you think that poster will come out and apologize or even admit being wrong? I hope so, as it's nice to hope for the best in people. After all, mathematics is not an area where it's always easy to just say something that's not true, as people can at times simply point out basic algebra that proves you're wrong, which is why mathematics is such a nice subject, for some people. Surrogate Factoring Theorem: Given M, a target natural number to be factored, and j, an integer b_2 f_1 = (-(Az - 2M^2)+/- sqrt((Az - 2M^2)^2 - 4TM^2))/2 where T = M^2 - j^2, and f_1 is a rational factor of T, and Az is given by Az = Ax(Ax +/- sqrt((Ax - 2j^2)^2 + 4Tj^2))/(2Ax - 2M^2) and Ax is given by Ax = +/- (k_1 + k_2) + 2j^2 where k_1 k_2 = -Tj^2, and k_1 and k_2 are rationals. James Harris posting-account=mmiamAwAAAATmtxVYi9NGy7tls83IKO3 You shouldn't be calling people liars who do your work for you. One of them showed that whenever you take square roots, you always end up with a rational number. You've never shown that. The SF Theorem certainly doesn't; it just shows that the equations give you a number. And it's not automatic; sqrt(1/3) is irrational. A theorem that specifies exactly when sqrt(x) is rational has real content to it. Infinitely more content than the SF Theorem. Actually, if you allow k_1 and k_2 to be negative, you can simplify that to Ax = k_1 + k_2 + 2 j^2. That depends on what you mean by evaluate. If you know Az, M, and T, you can evaluate the right-hand side of the equation by substituting those values. That is what most of the world means by evaluate: What number is this equal to? On the other hand, if you want to know what value of x makes an equation true, that's called solving the equation. Look it up in your lying^H^H^H^H^H math book if you don't believe me. I believe that poster is me. First of all, you should be THANKING me because I showed that SF wasn't worthless; I managed to get a non-trivial factor of 15 using SF. What I did, as a human being, was to pick f_1 = 1, which is certainly a factor of TM^2. Then I solved for b_2. The other poster (Decker? In any case, it's someone you should be THANKING as well, because he came up with an algorithm, something you haven't done) had come up with 8 possible values of b_2. In 2 of those cases, the numerator b_2 had a non-trivial factor of M in it. That's 2/8, not 0/8. Not only did I do YOUR work in finding ONE example where SF works, I found two, and showed that the rate of success for this example is 25%. It's not 50%, but it's a start. Or maybe you WANT SF to FAIL ... The mystery here is whether you're talking about the ones who said that SF will never work (which is not a correct description, since they only took positive square roots), or the ones who made SF work in one case. I assume you mean evaluate here, instead of solve for. There is no equation to solve; there's just an expression which evaluates to be a number. Not true. If M = 33 and x = 8, for instance, sqrt(x^2 + 4M) = sqrt(8^2 + 4 * 33) = sqrt (64 + 132) = sqrt(196) = 14. There. I never needed to factor 33. That is true, but you don't HAVE to do it. It just shows that if the value of x is special, then you can come up with an answer based on the factors of M. You don't have to actually FIND f_1 and f_2, though; that is, you don't need to know what number f_1 is equal to. It's called algebra, and it lets you work with unknown quantities. Your terminology is wrong. If you can't communicate, it's not other people's faults that they misinterpret what you say. It goes back to algebra; you don't need to actually know the values of the factors of M. Otherwise, you would be lying when you write an equation like p q = M (which you've done in the past). It also goes back to what she's proving: IF p and q are the factors of M, THEN (some variable equals some expression involving p and q). This is a different statement from (some variable equals some expression involving p and q). Of course, since you haven't taken a logic course, this is lost on you. It's the difference between the statements If x = 2, then 2 x = 4 and 2 x = 4. The first one is always true. The second isn't. Why do you think I haven't written you off as a crank? Same reason. Then why are you saying all mathematicians are liars? It must be hard for mathematicians to lie, and the fact that so many can is a miracle in itself ... Yes, you can point out where other people have gone wrong, but if they don't know enough about terminology and methodology, they'll not comprehend WHY it's wrong and simply repeat what they said before. Good example. --- Christopher Heckman posting-account=sg_iGAwAAAClZhnVQKakTFRnAjK0ujUn important. algebra? integers. No, I wouldn't agree with that. I showed that if k_1 k_2 = - j^2 T, and k_1 and k_2 are both integers, and you take the + square root in the expression for b_2 f_1, then you get b_2 f_1 = E / F, where E and F are both integers, with E = (k_1 + k_2)*j^2 + k_1 (k_1 + 3k_2) + 2 (k_1)^2 k_2/j^2 - (k_1 + k_2 + 2 j^2)*(k_1 + j^2) + 2M^2 (k_1 + k_2 + 2 j^2 - M^2), and F = 2 (k_1 + k_2 + 2 j^2 - M^2). You can verify this for yourself by letting M = 15, j = 17, T = M^2 - j^2 = 225 - 289 = -64. Since k_1 k_2 = -T * j^2 = 64 * 289, I can let k_1 = 289 * 32 = 9248, and k_2 = 2. In this case, E = (9248 + 2)*289 + 9248*(9248 + 3*2) + 2*9248^2*2/289 - (9248 + 2 + 578)*(9248 + 289) + 2*225*(9248 + 2 + 578 - 225) = 2673250 + 85580992 + 1183744 - 93729636 + 4321350 = 29700 F = 2 * (9248 + 2 + 578 - 225) = 19206 Thus, in lowest terms, E/F = 150/97. This is the same answer that C. Bond got by applying your theorem directly. You can check this by going through your own formulas, as follows: First note that Ax = (9248 + 2 + 578) = 9828. This yields Az = Ax(Ax +/- sqrt((Ax - 2j^2)^2 + 4Tj^2))/(2Ax - 2M^2 = 9828 (9828 + sqrt(9829 - 578)^2 - 4 * 31 * 256))/19206 = 9760.45360825. and this yields b_2 f_1 = (-(Az - 2M^2) + sqrt((Az - 2M^2)^2 - 4TM^2))/2 = 1.54639175 = 150/97. The agreement in fact is exact. The formula that I gave for the numerator of b_2 f_1, i.e., the term E above, gives exactly the same answer as your theorem. Agreed. even No - the formula that I gave for E in the expression b_2 f_1 = E / F is exactly correct (when the + sign is used in the square roots). Note that above, E = 29700, which is exactly divisible by M^2 = 225. Note also, that since in lowest terms, b_2 / f_1 = 150/97, the numerator, 150, is exactly divisible by M = 15 and not by any additional factors of M. So, in contrast to what you said, my formula arrives at the correct value for b_2 f_1 without any factorization of M. Sorry to disappoint. Do the arithmetic and see for yourself. out Right. See above. Nora B. given posting-account=Q2zO6wwAAABSLuGzZIjG0efOtB9n8fUY you of factors so, A single case. It's not too far-fetched to imagine that you've found an example to support your position. Now I could challenge on the use of integers only, except I don't see a problem with that, and I'll explain below. What you need to do Nora Baron is step out your calculations. Start from the beginning, and go through how you solve for b_2 f_1. If you do so, then I can show you your mistake, or find that I'm wrong. If you refuse, then I will challenge your use of single cases as single cases don't mathematically prove, and I have more to explain as to why I'm sure you have to be wrong. So? You can manufacture a formula to match at any number of single cases. 225. That shows naivette, which is why I left it in, as in fact, your formula would indicate that M is being factored trivially. The equation b_2 f_1 = (-(Az - 2M^2)+/- sqrt((Az - 2M^2)^2 - 4TM^2))/2 cannot be resolved without a factorization of TM^2, which is basic algebra, as I noted in the post that started this thread. If you are correct, then you have proven that the equations I use always trivially factor, which is why it's a big deal. However, the SFT connects all points on two hyperbolas, which contradicts with the possibility that only trivial factors are being used. You see, there are mysteries here. I don't trust you as I've watched you lie a lot, so you don't get the benefit of the doubt with me, and single cases do not prove in mathematics. Show your work Nora Baron, or you can debate as long as you like, and find that I'll simply point out simple algebra that proves you're wrong. For those still lost on that algebra, again, consider sqrt(x^2 + 4M) where M is a non-zero integer, not a square, and you wish that to be an integer. You MUST use a factorization of M. There simply is no choice in the matter as x must be the difference of integer factors of M. With the more complex square root in b_2 f_1 = (-(Az - 2M^2)+/- sqrt((Az - 2M^2)^2 - 4TM^2))/2 you MUST use some integer factorization of M, despite the fractions being used, and if Nora Baron is correct, then the equations I use rely on a trivial factorization of M, like M*1 = M but the problem there is, if the equations are hard-wired to trivially factor M, then that's what they'll do, so it'd never do anything else (except in some very special situations). There are several reasons why that's impossible. James Harris posting-account=sg_iGAwAAAClZhnVQKakTFRnAjK0ujUn posters something having a wrong. single why OK. You are at least focussing on the right question. The answer is not completely simple. Bear with me. First, I expected that you were going to object that Rick Decker's answer and my answer do not agree. Certainly they do not look the same. In fact they do agree, as you can see with the example I gave: M = 15, j = 17, T = -64, k_1 k_2 = -T j^2 = 64*189, and k_1 = 9248 and k_2 = 2. Rick says that b_2 f_1 = -k_1 + T or b_2 f_1 = T M^2 /(-k1 + T). Explicitly, doing the arithmetic, b_2 f_1 = -9312 or b_2 f_1 = - 14400/(-9312) = 150/97 = 27900/19206. The latter result is the same as my result. My formula for the numerator of b_2 f_1 is b_2 f_1 = E / F, where E = (k_1 + k_2)*j^2 + k_1 (k_1 + 3k_2) + 2 (k_1)^2 k_2/j^2 - (k_1 + k_2 + 2 j^2)*(k_1 + j^2) and F = 2 (k_1 + k_2 + 2 j^2 - M^2). So your question is really, how do I prove that this formula actually works ? It follows from an identity. There are several identities that one might apply here. One that *you* believe should work for the computation of b_2 f_1 is: (m - n)^2 + 4*n*m = (m + n)^2. Let me call this the +4 identity. Another related identity is: (m^2 - n^2)^2 + 4*m^2*n^2 = (m^2 + n^2)^2. This is the identity that is used to generate Pythagorean triples. I will call this the Pythagorean identity. Neither the +4 identity nor the Pythagorean identity apply to give the expressions that I gave above for E and F. There is instead another identity: Let U = c^2 (c + a)(2c + a + b) - 2(c^2 - ab)(c^2 + ac + bc + ab). Let V = 4 ab(c^2 - ab)(c^2 + ac + bc + ab)^2. Let W = (a + b)c^2 + a(a + 3b)c^2 + 2(a^2)bc. Then the identity is: U^2 + V = W^2. This holds for any positive numbers a, b, and c. I will call this the UVW identity. You can check that this identity is true by just expanding the left side and the right side and comparing the terms. Now, how do you apply this identity to derive the expressions I gave for E and F above? Let a = k_1, b = k_2, and c = M^2 = j^2 - (k_1 k_2)/j^2. Then you just crank it out. The +4 identity that you thought would work to give the result of your theorem does not work. The Pythagorean identity also does not work. The UVW identity does work. It is probably a new identity. I don't see it as particularly interesting by itself - not a publishable result - but it might fit into a larger pattern of identities, and it might be of interest if that is the case. In my view, this is the only nontrivial result to come out of your SFT. And it does not give any support for the efficacy of your brand of surrogate factoring. I didn't manufacture it. I derived it. It works for all the cases I have tried, which is quite a few. You could have tried it on multiple examples as well. It is easy to program. No, you're just wrong about this. The formula I gave above works, just as Rick Decker's also works, and it does not require factorization of M. No - the +4 identity that you think should apply here does not apply. No - the mysteries are all solved - Rick Decker and I have solved them differently, but they are solved. No mysteries are left. You didn't have to trust me. You could have tried it on any number of other examples. You could have tried to work through the algebra. Instead you chose to do nothing and call me a liar. and See above. Anyone can work out the details. an No, there are other ways to end up with a perfect square inside the square root that do not fit the x^2 + 4M pattern. Another identity than the one you were thinking of applies. trivially Nope, sorry, there are other possibilities than the one you have thought of. See above. Clearly there are no reasons why it's impossible. The formulas that I gave for E and F work. Nora B.