Archive for Paul Langevin

BayesComp²⁰²⁷ mirror in Aussois

Posted in Mountains, Statistics, Travel, University life with tags , , , , , , , , , , , , , , , , , , , , on August 13, 2026 by xi'an

Here we go! We have just completed the webpage for the BayesComp 2027 mirror conference in Aussois, French Alps, and launched the call for contributions.

This meeting mirrors the main BayesComp 2027 conference, held in Texas on the same week. As such, it will broadcast live and delayed sessions from the main conference, including plenary sessions, host local talk and poster sessions (to be broadcasted), and more generally provide an alternative forum for researchers in Bayesian computational statistics who cannot attend BayesComp 2027. As discussed earlier on the ‘Og, and following a debate launched at the ISBA 2024 World Meeting in Venezia, ISBA is now considering mirror (or multi-hub) meetings as a possible way to address accessibility, sustainability, and inclusiveness issues in its scientific meetings. 

The scientific committee will select presentations soon after the submission deadline, on 30 November 2026. Note that due to the capacity of the CAES Paul Langevin conference centre in Aussois the number of participants will be capped at 200. (Travel to Aussois by train to Modane is easy, thanks to direct, fast trains from Paris (4h), Torino (1h), and Lyon (2h). And by car if need be, since Modane is the French exit of the Tunnel du Fréjus (aka Traforo Alpino del Fréjus) linking France and Italy, the Italian exit being Bardonecchia.)

Important Dates

off to [ML@]Aussois

Posted in Books, Kids, Mountains, Running, Statistics, Travel, University life with tags , , , , , , , , , , , , , , , , , , on November 14, 2025 by xi'an

 

Borel and Langevin jailed [in 1941]

Posted in Books, Kids, pictures, Statistics, University life with tags , , , , , , , , , , , , , , , , , on December 1, 2024 by xi'an

When attending the Le Cam 100th anniversary day at IHP, I learned from Laurent Mazliak’s talk that Émile Borel  Borel (then in his 70’s and a member of the French Académie des Sciences) was arrested and jailed for a few weeks in 1941, as well as Paul Langevin (both in 1940 and 1941), for political (left-wing) reasons (?), by German security services (Abwehr), with no involvement of the French collaborationist authorities who rather intervened towards their release (along with the German Navy!, unlikely connected with Borel being the minister of the French Navy in 1924!!). Possibly from denunciations sent to German forces. Possibly as a show of power by the occupying forces towards the Vichy government and Philippe Pétain. The fact that Borel and his wife, Camille Marbo, were actually engaged in the French Resistance at least from 1942 fortunately did not come to the knowledge of French police or German security. (Langevin was one of the founders of the 1934  Comité de vigilance des intellectuels antifascistes. In 1941, his son-in-law, Jacques Solomon, a physicist, got arrested and executed for founding a clandestine newspaper, l’Université libre. His daughter Hélène Solomon-Langevin got deported but survived several deportation camps.)

scalable Langevin exact algorithm [Read Paper]

Posted in Books, pictures, Statistics, University life with tags , , , , , , , , , , , , , , , , on June 23, 2020 by xi'an


Murray Pollock, Paul Fearnhead, Adam M. Johansen and Gareth O. Roberts (CoI: all with whom I have strong professional and personal connections!) have a Read Paper discussion happening tomorrow [under relaxed lockdown conditions in the UK, except for the absurd quatorzine on all travelers|, but still in a virtual format] that we discussed together [from our respective homes] at Paris Dauphine. And which I already discussed on this blog when it first came out.

Here are quotes I spotted during this virtual Dauphine discussion but we did not come up with enough material to build a significant discussion, although wondering at the potential for solving the O(n) bottleneck, handling doubly intractable cases like the Ising model. And noticing the nice features of the log target being estimable by unbiased estimators. And of using control variates, for once well-justified in a non-trivial environment.

“However, in practice this simple idea is unlikely to work. We can see this most clearly with the rejection sampler, as the probability of survival will decrease exponentially with t—and thus the rejection probability will often be prohibitively large.”

“This can be viewed as a rejection sampler to simulate from μ(x,t), the distribution of the Brownian motion at time  t conditional on its surviving to time t. Any realization that has been killed is ‘rejected’ and a realization that is not killed is a draw from μ(x,t). It is easy to construct an importance sampling version of this rejection sampler.”