Archive for Paris

a journal of the COVID²⁵ year

Posted in Books, Statistics, Travel with tags , , , , , , , , , , , , , , , , on September 14, 2025 by xi'an

 Last week, I got COVID for the very first (detected) time! Although it took a while to realise this was COVID and not the common cold. It started with an overnight runny nose that I attributed to swimming outside the previous and cool morn, a minor temperature shock compared with the previous week in Guadeloupe. And did not spot the unusually high heart rate that night… The next afternoon, I was feeling a bit feverish (with no fever!) and definitely tired, but again attributed the feeling to faster bike rides to and from Paris Dauphine and the after-effect of Caribean jetlag. I then had a very long night and definitely felt okay the morning after (with nightly heart rate back to normal). It is only when my wife starting showing the same symptoms that I suspected more than a common cold. With confirmation from a COVID test two days later. By then I had unfortunately contaminated a few other people,  all of whom recovered reasonably fast (phew!). I have since taken back to wear a face mask in any close encounter and warned my students. I wonder if I got it in the plane back or at Dauphine on the opening day. Definitely planning the continuation of my yearly vaccine next November!!!

Stéphane Mallat awarded CNRS Gold Medal

Posted in Books, pictures, Statistics, University life with tags , , , , , , , , , , , , , on September 12, 2025 by xi'an

a week of causality and explainable [p]A[r]I[s] (20-24 Oct 2025)

Posted in Statistics, Travel, University life with tags , , , , , , , , on September 8, 2025 by xi'an

not-so-new bike!

Posted in pictures, Travel with tags , , , , , , , , , , on August 23, 2025 by xi'an

André ou Jean Ville (1910-1989)

Posted in Books, pictures, Travel, University life with tags , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , on August 12, 2025 by xi'an

Throughover the workshop in Chennai floated (!) the figure of Jean/André Ville, with his inequality generalising Markov’s, who invented martingales. He is not such a well-known figure in France—at least to me!—, despite having led a rather exceptional life, from being a visiting scholar in Berlin (in the Maison académique de Berlin, along with a certain Jean-Paul Sartre) and Vienna in the 1930s, to his wife being (in Berlin) one of the many (disposable and despised) lovers of JP Sartre (to whom an open-minded or clueless Ville later sent his thèse d’université on martingales and collectives, a much more substantial piece of work than the current PhD), to him working with German and Austrian mathematicians and logicians, such as Popper, Gödel, and Wald–who, what a coïncidence!, died in India from a plane crash in 1950 that had left from Chennai–and being impressed enough by the latter to passing an economics degree in the Sorbonne when back in Paris, establishing a minimax result for a zero-sum matrix game with two players, to his counter-example to von Mises’ kollectiv, to his nickname of the King of Counterexamples in the Viennese mathematics seminar, to him operating the first (Bull) computer at the Université de Paris. (Glenn Shafer wrote a detailed accounting of his youth, on which this post is based, up to his thesis defence but a few days from France mobilising for war–where his collegue Wolfgang Doeblin would kill himself the year after, to avoid capture–. With Bernard Bru, Edmond Malinvaud and Alain Trognon among the people who helped.) After the war, he worked several years as a prépa maths teacher before working for a French State electricity companion on signal theory and Monte Carlo methods, and then returning to Université de Paris as a professor in 1957.