Le Monde puzzle [#1045]

Posted in Books, Kids with tags , , , on March 19, 2018 by xi'an

An arithmetic Le Monde mathematical puzzle of limited proportions (also found on Stack Exchange):

  1. If x,y,z are distinct positive integers such that x+y+z=19 and xyz=p, what is the value of p that has several ordered antecedents?
  2.  If the sum is now x+y+z=22, is there a value of p=xyz for which there are several ordered antecedents?
  3. If the sum is now larger than 100, is there a value of p with this property?

The first question is dead easy to code

for (y in 1:5) #y<z<x
for (z in (y+1):trunc((18-y)/2))
 if (19-y-z>z) entz=c(entz,y*z*(19-y-z))

and return p=144 as the only solution (with ordered antecedents 2 8 9 and 3 4 12). The second question shows no such case. And the last one requires more than brute force exploration! Or the direct argument that a multiple by κ of a non-unique triplet produces a sum multiplied by κ and a product multiplied by κ³. Hence leads to another non-unique triplet with an arbitrary large sum.

Picus viridis [jatp]

Posted in pictures with tags , , , , on March 18, 2018 by xi'an

a faint memory of ice

Posted in Books, Mountains, pictures, Running, Travel with tags , , , , , , , , , , , , , , on March 17, 2018 by xi'an


During the past week of vacations in Chamonix, I spent some days down-hill skiing (which I find increasingly boring!), X-country skiing (way better), swimming (indoors!) and running, but the highlight (and the number one reason for going there!) was an ice cascade climb with a local guide, Sylvain (from the mythical Compagnie des Guides de Chamonix). There were very options due to the avalanche high risk and Sylvain picked a route called Déferlante at the top of Les Grands Montets cabin stop and next to the end of a small icefield, Glacier d’Argentière. We went there quite early to catch the first cabin up, along a whole horde of badasss skiers and snowboarders, and reached the top of the route by foot first, a wee bit after 9 pm. A second guide and a client appeared before we were ready to abseil down, and two more groups would appear later. On touring skis. Continue reading

and here we go!

Posted in Books, Running, Statistics, University life with tags , , , , , on March 16, 2018 by xi'an

On March 1, I have started handling papers for Biometrika as deputy editor, along with Omiros Papaspiliopoulos. With on average one paper a day to handle this means a change in my schedule and presumably less blog posts about recent papers and arXivals if I want to keep my daily morning runs!

Brussels skyline [jatp]

Posted in pictures, Running, Travel, University life with tags , , , , , , , on March 15, 2018 by xi'an

another instance of a summer of Bayesian conferences

Posted in pictures, Statistics, Travel, University life with tags , , , , , , , , , on March 15, 2018 by xi'an

As it happens, the next MaxEnt conference will happens in London, on 2-6 July, at the Alan Turing Institute, which makes it another perfect continuation of the ISBA meeting in Edinburgh, or of the Computational Statistics summer school in Warwick the week after. But in competition with BAYsm in Warwick and MCqMC in Rennes. I once attended a MaxEnt meeting in Oxford. (Oxford, Mississippi!) Which was quite interesting in the audience it attracted and the focus of the discussions, some of which were exhilaratingly philosophical!

Stephen Hawking (1942-2018)

Posted in Books, University life with tags , , , , , , on March 14, 2018 by xi'an

“I have lived with the prospect of an early death for the last 49 years. I’m not afraid of death, but I’m in no hurry to die. I have so much I want to do first. I regard the brain as a computer which will stop working when its components fail. There is no heaven or afterlife for broken down computers; that is a fairy story for people afraid of the dark.”