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$\aleph$ looks like $\mathbb N$?
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18 votes

According to not necessarily reliable internet sources, Georg Cantor "told his colleagues and friends that he was proud of his choice of the letter aleph to symbolize the transfinite numbers, since ...

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The geometric-mean factorial
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15 votes

looks like Somos's quadratic recurrence constant

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A continuous function for defining unique values to a 1024x1024 image with a 24 bit 3 color channel image
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7 votes

This problem is very roughly analogous to having a square piece of paper and you want to fold it so that it fits into a cube, except both the paper and cube are discrete, and the folds of the paper ...

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Are there any fast algorithms for factoring integers that don't work by searching for smooth numbers?
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7 votes

This paper explains why smooth numbers play a key role in almost every modern integer factorization algorithm. Maybe it lists the exceptions, but I couldn't find them. http://www.math.dartmouth.edu/~...

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limiting empirical spectral distribution of the Laplacian matrix on an Erdos-Renyi graph?
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4 votes

Maybe relevant: "Lifshitz tails for spectra of Erdős–Rényi random graphs" Oleksiy Khorunzhiy, Werner Kirsch, and Peter Müller "We consider the discrete Laplace operator (the graph Laplacian) on ...

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Simple example of why Differential Equations can be NP Hard
3 votes

Slides 58--72 here show a SAT reduction.

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Authorship, and order of authors
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3 votes

If they are co-authors on the paper then add them alphabetically as is customary for math journals. Otherwise if they are not co-authors then just mention them in acknowledgements. If you want to ...

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Stationary distribution in general Markov Chains
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3 votes

I call a Strongly Connected Component (SCC) "ergodic" if we cannot get out of it, and "transient" otherwise. It suffices to compute the probability ρ(C) to end up in each ergodic ...

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Ruin time for a two-input "risk only" slot machine
3 votes

This isn't an answer so please vote it down, but if you want a closed-form approximation then you can say that you begin with some finite distribution of coin amounts, so instead of saying you start ...

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Eigenvalues of a matrix constructed with simple logic
2 votes

I am poking around at a large matrix (with dimension 2^N×2^N). The matrix is made up of ... corresponding to specific interactions is it thus possible to implicitly find Eigenvalues of it, without ...

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QR alogrithm for eigenvalue problem
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2 votes

This example is explained in section 11.5 here.

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Position likelihood in a 2D graph
1 votes

You can use a Markov chain on the positions. In ten moves you can't get too far, so you can use a finite grid. In your specific example, the probability of ending up at least 4 blocks away is about 0....

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How to construct a semi-positive definite matrix in this form: (L=D-A')
1 votes

If you adjust the diagonal accordingly then yes, because it would correspond to the Laplacian matrix of a slightly different edge-weighted graph.

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Estimating the Variance of a Discrete Normal Distribution
1 votes

If X is the continuous normal random variable and you write the discretized random variable Z as X + Y, then Var(Z) = Var(X) + Var(Y) + 2 Cov(X, Y). When sigma is large enough that Y becomes almost ...

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How to estimate the entropy of a distribution on a power set?
1 votes

This paper explains entropy estimation without distribution estimation in the undersampled regime.

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Random planar, bipartite graphs
1 votes

Use whatever random planar graph sampler to get a planar graph with blue vertices. Put a red vertex on each edge.

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Third order central moment of a positive linear combination of log-normal random variables
0 votes

I am looking for a general case. It seems to be a folk-lore that the skewness of one sided distributions (say positive sided) is positive. I am looking for a formal argument for/against it. This ...

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Is there an oscillating analog of the Gaussian distribution?
0 votes

I would guess sinc.${}{}{}{}{}{}{}{}{}{}{}$

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