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seen May 9 '12 at 2:58

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Dec
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comment Algorithm for scrolling through different orbits in a permutation group
@JoelCohen, you are slightly off on your description of $C_\pi$. Specifically, $C_\pi$ also contains those permutations which map equal-sized cycles in $\pi$ to each other. For example, the centralizer of $(1,2)(3,4)$ in $S_4$ contains $(1,3)(2,4)$. I believe this does give you a full list of generators of $C_\pi$ -- 1) cycles in $\pi$, 2) permutations of the fixed points of $\pi$, and 3) order-preserving swaps of the cycles of a given size in $\pi$. I might be missing something though regarding more complicated actions within each cycle of a given size.
Dec
16
answered Expectation of function of random variable?
Dec
15
comment Problem about the sum of independent exponential variable
i.i.d., centered and has variance 1. The results then follow from the Central Limit Theorem. Of course, this is an approximation that only holds for large $n$...
Dec
9
answered Theorem for a $2$-dimensional (easy) integral with variable boundary
Nov
29
comment How is a Halton sequence related to a Latin hypercube?
Another drawback of both techniques is whenever you want to look at multi-point correlations -- both techniques don't let the points cluster as much as a truly random selection would. I believe the Halton sequence does better.
Nov
15
comment Planar kelvin problem
I think you got the maximal side length wrong. If the side of the hexagon is $s$, the area is $A = 3\sqrt{3}s^2/2$, so the maximal sidelength is $\sqrt{2A/3\sqrt{3}}$.
Nov
15
answered Exciting games and material to motivate children to math
Nov
15
answered A subtle modification to the $t$ distribution
Nov
8
answered $\sin(A)$, where $A$ is a matrix
Nov
7
comment A function of two functions that loses dependence on an argument
Formally, $h$ does require $u$, as the product on the right hand side is undefined when $u=0$.
Nov
6
comment Solve $\displaystyle\int_{0}^a \left(3^{\frac{1}{3} \left( x^3 - 3x \right) }-1\right)\, dx = 0$ using elementary methods
Are you trying to solve for $a$? In that case the only answer is $a=0$, since $3^z$ is positive for all real $z$.
Nov
4
comment Probability question: optimal strategy
@RossMillikan: That's an unstable equilibrium, as each is indifferent between firing at time $x^*$ and not firing, knowing that the other one will.
Nov
4
comment Probability question: optimal strategy
Ross, there is one issue -- if A does not fire at this time $x^*$, B doesn't know what A's $\Delta t$ is, so he can't fire at $x^* + \Delta t/2$. This is why I think both adopt a mixed strategy.
Nov
4
comment Probability question: optimal strategy
My suspicion is that the correct answer is a mixed strategy. Each has some probability distribution of when they will shoot given that the other has not yet shot. Now how to determine said distribution... I'm still thinking about it.