off to Luminy!!!

off to Luminy!!!

CIRM in dire need of help

The International Mathematics Conference Centre, CIRM, located in Luminy, Marseille, France, has been deeply disrupted by the COVID-19 pandemic. Up to 60 % of the events planned there have been cancelled so far and all remaining conferences have gone virtual or at best hybrid, open to a remote audience, including in an interactive way. This has required important and unexpected investments. Furthermore, this crisis happened at the worst possible moment as CIRM had just finished doubling its infrastructure capacities. This is why I strongly support the call from the French Mathematical Society (SMF) to make a donation to CIRM before the end of the year, especially from researchers who benefited from its hospitality and unique environment.

Big Bayes goes South

At the Big [Data] Bayes conference this week [which I found quite exciting despite a few last minute cancellations by speakers] there were a lot of clustering talks including the ones by Amy Herring (Duke), using a notion of centering that should soon appear on arXiv. By Peter Müller (UT, Austin) towards handling large datasets. Based on a predictive recursion that takes one value at a time, unsurprisingly similar to the update of Dirichlet process mixtures. (Inspired by a 1998 paper by Michael Newton and co-authors.) The recursion doubles in size at each observation, requiring culling of negligible components. Order matters? Links with Malsiner-Walli et al. (2017) mixtures of mixtures. Also talks by Antonio Lijoi and Igor Pruenster (Boconni Milano) on completely random measures that are used in creating clusters. And by Sylvia Frühwirth-Schnatter (WU Wien) on creating clusters for the Austrian labor market of the impact of company closure. And by Gregor Kastner (WU Wien) on multivariate factor stochastic models, with a video of a large covariance matrix evolving over time and catching economic crises. And by David Dunson (Duke) on distance clustering. Reflecting like myself on the definitely ill-defined nature of the [clustering] object. As the sample size increases, spurious clusters appear. (Which reminded me of a disagreement I had had with David McKay at an ICMS conference on mixtures twenty years ago.) Making me realise I missed the recent JASA paper by Miller and Dunson on that perspective.

Some further snapshots (with short comments visible by hovering on the picture) of a very high quality meeting [says one of the organisers!]. Following suggestions from several participants, it would be great to hold another meeting at CIRM in a near future.

bonjour Marseille [jatp]