Posts Tagged ‘ congruence ’

Le Monde puzzle [#29]

July 28, 2011
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Le Monde puzzle [#29]

This week, the puzzle from the weekend edition of Le Monde was easy to state: in the sequence (8+17n), is there a 6th power? a 7th? an 8th? If so, give the first occurrence. So I first wrote an R code for a function testing whether an integer is any power: (The function returns the

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Parallel computation [permutations]

February 19, 2011
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Parallel computation [permutations]

François Perron is visiting me for two months from Montréal and, following a discussion about the parallel implementation of MCMC algorithms—to which he also contributed with Yves Atchadé in 2005—, he remarked that a deterministic choice of permutations with the maximal contrast should do better than random or even half-random permutations. Assuming p processors or

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