Blog Archives

sudoku break

December 12, 2013
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sudoku break

While in Warwick last week, one evening after having exhausted my laptop battery, I tried the following Sudoku (from Libération): and could not even start. As it happened, this was a setting with no deterministic move, i.e. all free/empty entries had multiple possible values. So after trying for a while and following trees to no

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amazonly associated thanks (& warnin’)

December 8, 2013
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amazonly associated thanks (& warnin’)

Following a now well-established pattern, let me (re)warn (the few) unwary ‘Og readers that the links to Amazon.com and to Amazon.fr found on this blog are actually susceptible to earn me a monetary gain if a purchase is made by the reader in the 24 hours following the

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Le Monde puzzle [#843]

December 6, 2013
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Le Monde puzzle [#843]

A Le Monde mathematical puzzle of moderate difficulty: How many binary quintuplets (a,b,c,d,e) can be found such that any pair of quintuplets differs by at least two digits? I solved it by the following R code that iteratively eliminates quintuplets that are not different enough from the first ones, for a random order of the

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Le Monde puzzle [#842]

November 29, 2013
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Le Monde puzzle [#842]

An easily phrased (and solved?) Le Monde mathematical puzzle that does not require an R code: The five triplets A,B,C,D,E are such that and Given that find the five triplets. Adding up both sets of equations shows everything solely depends upon E1… So running an R code that checks for all possible values of

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Unusual timing shows how random mass murder can be (or even less)

November 29, 2013
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Unusual timing shows how random mass murder can be (or even less)

This post follows the original one on the headline of the USA Today I read during my flight to Toronto last month. I remind you that the unusual pattern was about observing four U.S. mass murders happening within four days, “for the first time in at least seven years”. Which means that the difference between

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Importance sampling schemes for evidence approximation in mixture models

November 26, 2013
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Importance sampling schemes for evidence approximation in mixture models

Jeong Eun (Kate) Lee and I completed this paper, “Importance sampling schemes for evidence approximation in mixture models“, now posted on arXiv. (With the customary one-day lag for posting, making me bemoan the days of yore when arXiv would give a definitive arXiv number at the time of submission.) Kate came twice to Paris in the past

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MCMSki IV, Jan. 6-8, 2014, Chamonix (news #12)

November 26, 2013
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MCMSki IV, Jan. 6-8, 2014, Chamonix (news #12)

We are converging towards MCMSki IV getting closer and closer to the conference! I hope that by now all intended participants have registered (registration is still open!), found a place where to stay during and around the conference (still feasible!), and booked their flight to Geneva (or nearby). First, please send me asap the  poster abstract

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Buffon needled R exams

November 24, 2013
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Buffon needled R exams

Here are two exercises I wrote for my R mid-term exam in Paris-Dauphine around Buffon’s needle problem. In the end, the problems sounded too long and too hard for my 3rd year students so I opted for softer questions. So recycle those if you wish (but do not ask for solutions!) Filed under: Books, Kids,

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Le Monde puzzle [#840]

November 22, 2013
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Le Monde puzzle [#840]

Another number theory Le Monde mathematical puzzles: Find 2≤n≤50 such that the sequence {1,…,n} can be permuted into a sequence such that the sum of two consecutive terms is a prime number.  Now this is a problem with an R code solution: which returns the solution as and so it seems there is no solution beyond N=12…

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On the use of marginal posteriors in marginal likelihood estimation via importance-sampling

November 19, 2013
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On the use of marginal posteriors in marginal likelihood estimation via importance-sampling

Perrakis, Ntzoufras, and Tsionas just arXived a paper on marginal likelihood (evidence) approximation (with the above title). The idea behind the paper is to base importance sampling for the evidence on simulations from the product of the (block) marginal posterior distributions. Those simulations can be directly derived from an MCMC output by randomly permuting the

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