Recent content by bpet
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Undergrad How to determine if a set is a semiring or a ring?
In order to determine if the set is a semiring you first need to specify exactly what are the addition and multiplication operations.- bpet
- Post #2
- Forum: Set Theory, Logic, Probability, Statistics
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Undergrad Write probability in terms of shape parameters of beta distribution
It's not quite a beta-binomial distribution. However you can do a similar integral $$\int_0^1 P(A_{wins}\cap y|\alpha,\beta)Beta(p|\alpha,\beta)$$. Note also that the expression for P further simplifies before you do the integral.- bpet
- Post #2
- Forum: Set Theory, Logic, Probability, Statistics
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Challenge Math Challenge - March 2021
Thanks for writing up the details. Note that only the one S-polynomial needs to be computed if we do the reductions on all polynomials immediately.- bpet
- Post #42
- Forum: Math Proof Training and Practice
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Challenge Math Challenge - March 2021
Ok so I used Buchberger’s algorithm https://en.m.wikipedia.org/wiki/Buchberger%27s_algorithm, only one polynomial was added to the basis as described in the previous post and this reduced to x+1, then the original polynomials reduced to 0 and y^2-1 trivially. As for the irreducible components...- bpet
- Post #40
- Forum: Math Proof Training and Practice
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Challenge Math Challenge - March 2021
Which bit would you like me to explain further? Keep in mind I’m tapping this out on a phone here. Cheers- bpet
- Post #35
- Forum: Math Proof Training and Practice
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Challenge Math Challenge - March 2021
ok so the reduced Groebner basis is (x+1) and (y^2-1) obtained from computing y(x^2y+xy)-x(xy^2-1) and reducing several times. That would mean, if I understand the definitions correctly, there are 3 irreducible components corresponding to y=1, y=-1 and x=-1.- bpet
- Post #32
- Forum: Math Proof Training and Practice
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Can Cryptographic Methods Help Solve Quadratic Diophantine Equations?
This page has some theory for this type of equation: Quadratic residue - Wikipedia- bpet
- Post #11
- Forum: Calculus and Beyond Homework Help
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High School The CDF of the Sum of Independent Random Variables
There is a more general formula for when the variable can be either discrete, continuous, or a mixture of the two (or even singular if you wish). We have P[X+Y\le x] = P[X\le x-Y] = E[F_X(x-Y)] = \int F_X(x-y)dF(y) The integral above is a Stieltjes integral so we recover the standard...- bpet
- Post #11
- Forum: Set Theory, Logic, Probability, Statistics
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Challenge Micromass' big series challenge
Substitute $$\tan(x)=\frac{2\sin^2(x)}{\sin(2x)}$$ so the product telescopes down to $$\frac{2^{\frac{1}{2}+\frac{1}{4}+\ldots}|\sin(1)|}{\lim_{n\to\infty}\sqrt[2^{n+1}]{|\sin(2^{n+1})|}} = 2\sin(1)\approx 1.68294196962$$ For a proof that the limit in the denominator is 1 see Agnew, R. P. and...- bpet
- Post #34
- Forum: Math Proof Training and Practice
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Undergrad What Is the Probability of Rolling Pairs That Sum to Seven with n Dice?
Let p_k(n) be the probability that case k has occurred after n dice have been thrown. It is not hard to show that these probabilities satisfy a recurrence relation \begin{pmatrix}p_1(n+1) \\ p_2(n+1) \\ p_3(n+1) \end{pmatrix} = \begin{pmatrix} \frac{1}{6} & 0 & 0 \\ \frac{2}{3} & \frac{1}{3} & 0...- bpet
- Post #6
- Forum: Set Theory, Logic, Probability, Statistics
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Is My Card Game Probability Calculation Correct?
I would have thought that since one player has two cards of type A then the answer would simply be (1/6)*(1/5)*(1/4)*(1/3)- bpet
- Post #2
- Forum: Set Theory, Logic, Probability, Statistics
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HMM with continuous observation - PDFs to probabilities
That doesn't quite sound right, can you give an example?- bpet
- Post #2
- Forum: Set Theory, Logic, Probability, Statistics
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First passage time for Kinetic Monte Carlo model
I can't say much without seeing more details but the transition matrix of the modified process should be the same except with a row of zeros for the absorbing state - that shouldn't break the law of conservation of probability.- bpet
- Post #7
- Forum: Set Theory, Logic, Probability, Statistics
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Probability problem - from another forum
Using the Negative Binomial CDF this can be expressed in terms of the regularised incomplete Beta function 1-I_{P_t}(100,100)=I_{P_h}(100,100)- bpet
- Post #5
- Forum: Set Theory, Logic, Probability, Statistics
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What is the distribution of the sum of two random vectors?
Standard convolution formulas are not likely to be of much use for this approach because X and Y are dependent. Also don't worry about the PDF just yet, it's trivial to calculate (if it exists) once you've got the CDF. A CDF can be written as the expected value of a Boolean indicator...- bpet
- Post #5
- Forum: Set Theory, Logic, Probability, Statistics