Le Monde puzzle [#1124]
A prime number challenge [or rather two!] as Le weekly Monde current mathematical puzzle: When considering the first two integers, 1 and 2, their sum is 3, a prime number....continue reading.
Author: xi'an
postdoc in Bayesian machine learning in Berlin [reposted]
The working group of Statistics at Humboldt University of Berlin invites applications for one Postdoctoral research fellow (full-time employment, 3 years with extension possible) to contribute to the research on...continue reading.
an arithmetic mean identity
A 2017 paper by Ana Pajor published in Bayesian Analysis addresses my favourite problem [of computing the marginal likelihood] and which I discussed on the ‘Og, linking with another paper...continue reading.
Le Monde puzzle [#1119]
A digit puzzle as Le weekly Monde current mathematical puzzle that sounds close to some earlier versions: Perfect squares are pairs (a²,b²) with the same number of digits such that...continue reading.
Galton’s board all askew
Since Galton’s quincunx has fascinated me since the (early) days when I saw a model of it as a teenager in an industry museum near Birmingham, I jumped on the...continue reading.
shortened iterations [code golf]
A codegolf lazy morning exercise towards finding the sequence of integers that starts with an arbitrary value n and gets updated by blocks of four as until the last term...continue reading.
Le Monde puzzle [#1115]
A two-person game as Le weekly Monde current mathematical puzzle: Two players Amaruq and Atiqtalik are in a game with n tokens where Amaruq chooses a number 1<A<10 and then...continue reading.
Le Monde puzzle [#1114]
Another very low-key arithmetic problem as Le Monde current mathematical puzzle: 32761 is 181² and the difference of two cubes, which ones? And 181=9²+10², the sum of two consecutive integers....continue reading.
Le Monde puzzle [#1112]
Another low-key arithmetic problem as Le Monde current mathematical puzzle: Find the 16 integers x¹,x²,x³,x⁴,y¹,y²,y³,y⁴,z¹,z²,z³,z⁴,w¹,w²,w³,w⁴ such that the groups x¹,y¹,z¹,w¹, &tc., are made of distinct positive integers, the sum of...continue reading.
poor statistics
I came over the weekend across this graph and the associated news that the county of Saint-Nazaire, on the southern border of Brittany, had a significantly higher rate of cancers...continue reading.
Le Monde puzzle [#1111]
Another low-key arithmetic problem as Le Monde current mathematical puzzle: Notice that there are 10 numbers less than, and prime with 11, 100 less than and prime with 101, 1000...continue reading.
Le Monde puzzle [#1110]
A low-key sorting problem as Le Monde current mathematical puzzle: If the numbers from 1 to 67 are randomly permuted and if the sorting algorithm consists in picking a number...continue reading.
R puzzle
Can you guess the meaning of the following R code “?”=`u\164f8ToI\x6Et`;’!’=prod;!{ y<-xtabs(~?readLines())}%in%{ z<-y[1]}&z>T##&[]>~48bEfILpu If not (!), the explanation is provided in Robin’s answer to a codegolf …continue reading.
R wins COPSS Award!
Hadley Wickham from RStudio has won the 2019 COPSS Award, which expresses a rather radical switch from the traditional recipient of this award in that this recognises his many contributions...continue reading.
Gibbs sampling with incompatible conditionals
An interesting question (with no clear motivation) on X validated wondering why a Gibbs sampler produces NAs… Interesting because multi-layered: The attached R code indeed produces NAs because it calls...continue reading.
CRAN does not validate R packages!
A friend called me the other day for advice on how to submit an R package to CRAN along with a proof his method was mathematically sound. I replied with...continue reading.
Le Monde puzzle [#1105]
Another token game as Le Monde mathematical puzzle: Archibald and Beatrix play with a pile of n>100 tokens, sequentially picking m tokens from the pile with m being a prime...continue reading.
Le Monde puzzle [#1104]
A palindromic Le Monde mathematical puzzle: In a monetary system where all palindromic amounts between 1 and 10⁸ have a coin, find the numbers less than 10³ that cannot be...continue reading.
another attempt at code golf
I had another lazy weekend go at code golf, trying to code in the most condensed way the following task. Provided with a square matrix A of positive integers, keep...continue reading.
biased sample!
A chance occurrence led me to this thread on R-devel about R sample function generating a bias by taking the integer part of the continuous uniform generator… And then to...continue reading.
