Publications by xi'an
spacings on a torus
While in Brussels last week I noticed an interesting question on X validated that I considered in the train back home and then more over the weekend. This is a question about spacings, namely how long on average does it take to cover an interval of length L when drawing unit intervals at random (with a torus handling of the endpoints)? Which imme...
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a null hypothesis with a 99% probability to be true…
When checking the Python t distribution random generator, np.random.standard_t(), I came upon this manual page, which actually does not explain how the random generator works but spends instead the whole page to recall Gosset’t test, illustrating its use on an energy intake of 11 women, but ending up misleading the readers by interpreting a .00...
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Le Monde puzzle [#1048]
An arithmetic Le Monde mathematical puzzle: A magical integer m is such that the remainder of the division of any prime number p by m is either a prime number or 1. What is the unique magical integer between 25 and 100? And is there any less than 25? The question is dead easy to code primz=c(1,generate_primes(2,1e6)) for (y in 25:10000) if (m...
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Masterclass in Bayesian Statistics in Marseilles next Fall
This post is to announce a second occurrence of the exciting “masterclass in Bayesian Statistics” that we organised in 2016, near Marseilles. It will take place on 22-26 October 2018 once more at CIRM (Centre International de Recherches Mathématiques, Luminy, Marseilles, France). The targeted audience includes all scientists interested in le...
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a [Gregorian] calendar riddle
A simple riddle express this week on The Riddler, about finding the years between 2001 and 2099 with the most cases when day x month = year [all entries with two digits]. For instance, this works for 1 January, 2001 since 01=01 x 01. The only difficulty in writing an R code for this question is to figure out the number of days in a given month of...
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Le Monde puzzle [#1049]
An algorithmic Le Monde mathematical puzzle with a direct Alice and Bob play a game by picking alternatively one of the remaining digits between 1 and 10 and putting it in either one of two available stacks, 1 or 2. Their respective gains are the products of the piles (1 for Alice and 2 for Bob). The problem is manageable by a recursive functio...
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practical Bayesian inference [book review]
[Disclaimer: I received this book of Coryn Bailer-Jones for a review in the International Statistical Review and intend to submit a revised version of this post as my review. As usual, book reviews on the ‘Og are reflecting my own definitely personal and highly subjective views on the topic!] It is always a bit of a challenge to review introduc...
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Imperial postdoc in Bayesian nonparametrics
Here is another announcement for a post-doctoral position in London (UK) to work with Sarah Filippi. In the Department of Mathematics at Imperial College London. (More details on the site or in this document. Hopefully, the salary is sufficient for staying in London, if not in South Kensington!) The post holder will work on developing a novel Bay...
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the riddle of the stands
The simple riddle of last week on The Riddler, about the minimum number of urinals needed for n men to pee if the occupation rule is to stay as far as possible from anyone there and never to stand next to another man, is quickly solved by an R code: ocupee=function(M){ ok=rep(0,M) ok[1]=ok[M]=1 ok[trunc((1+M/2))]=1 while (max(diff((1:M)...
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maximal spacing around order statistics
The riddle from the Riddler for the coming weeks is extremely simple to express in mathematical terms, as it summarises into characterising the distribution of when the n-sample is made of iid Normal variates. I however had a hard time finding a result connected with this quantity since most available characterisations are for either Uniform or ...
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