Publications by xi'an
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: library(pracma) foundsol=TRUE N=2 while (foundsol){ N=N+1 noseq=TRUE uplim=10^6 t=0 whil...
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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, R, Statistics, University life Tagged: Buf...
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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 abstrac...
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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 year...
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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 the four dates is at most 3, not 4...
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Le Monde puzzle [#842]
An easily phrased (and solved?) Le Monde mathematical puzzle that does not [really] 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 E1 is a brute-force sol...
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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 [from 4% to 8% on the sales] if a purchase is made by the reader in the 24 hours following the entry on Amazon through this link, thanks to th...
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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): > printSudoku(readSudoku("libe.dk")) +-------+-------+-------+ | 4 6 | 2 | 3 9 | | 3 | | 2 | | 7 2 | | 5 6 | +-------+-------+-------+ | | 9 4 5 | | | 5 ...
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Le Monde puzzle [#843]
A straightforward Le Monde mathematical puzzle: Find integers x with 4 to 8 digits which are (a) perfect squares x=y² such that [x/100] is also a perfect square; (b) perfect cubes x=y³ such that [x/1000] is also a perfect cube; (c) perfect cubes x=y³ such that [x/100] is also a perfect cube (where [y] denotes here the integer part). I first ...
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MCMSki IV, Jan. 6-8, 2014, Chamonix (news #14)
The programs of the talks, posters and workshop are now printed and available on Speaker Deck (talks, posters, workshop). Please let me know if you spot anything wrong (even though it will not be reprinted!). This is presumably the last news item till Jan. 5 as I am almost off to Chamonix for a week of hard work preparing the conference skiing wi...
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