Archive for teaching

out of control…

Posted in Statistics with tags , , , , , , , , , on October 27, 2020 by xi'an

Nous continuerons, Professeur.

Posted in Kids, pictures with tags , , , , , , , , on October 24, 2020 by xi'an

“Nous continuerons, Professeur. Avec tous les instituteurs et professeurs de France, nous enseignerons l’histoire, ses gloires comme ses vicissitudes. Nous ferons découvrir la littérature, la musique, toutes les œuvres de l’âme et de l’esprit. Nous aimerons de toutes nos forces le débat, les arguments raisonnables, les persuasions aimables. Nous aimerons la science et ses controverses. Comme vous, nous cultiverons la tolérance. Comme vous, nous chercherons à comprendre, sans relâche, et à comprendre encore davantage cela qu’on voudrait éloigner de nous. Nous apprendrons l’humour, la distance. Nous rappellerons que nos libertés ne tiennent que par la fin de la haine et de la violence, par le respect de l’autre.”

Emmanuel Macron, 21 October 2020

hommage à Samuel Paty

Posted in Kids with tags , , , , , , , , , , , , on October 21, 2020 by xi'an

Toute notre communauté universitaire exprime sa plus vive émotion à la suite de l’assassinat de Samuel Paty, professeur dans un collège de Conflans Sainte-Honorine. Nous nous associons pleinement à la douleur de ses proches, de ses élèves et de ses collègues.

En tant qu’université, nos missions prolongent celles assumées par nos collègues de l’enseignement secondaire, dont nous sommes pleinement solidaires. Et nous tenons à rappeler, dans ces circonstances, les principes qui inspirent nos missions d’enseignement et de recherche : le respect de la liberté de penser, le goût du débat, le développement de l’esprit critique, la production de connaissance, tout cela dans le strict respect des lois de notre République.

Patrice Geoffron, Administrateur provisoire de l’Université Paris Dauphine-PSL  & Nicolas Péjout, Directeur Général des Services

errno EFBIG

Posted in Books, Kids, Linux, Statistics, University life with tags , , , , , , on October 12, 2020 by xi'an

MCMC, variational inference, invertible flows… bridging the gap?

Posted in Books, Mountains, Running, Statistics, Travel, University life with tags , , , , , , , , , , , , , , , , , on October 2, 2020 by xi'an

Two weeks ago, my friend [see here when climbing Pic du Midi d’Ossau in 2005!] and coauthor Éric Moulines gave a very interesting on-line talk entitled MCMC, Variational Inference, Invertible Flows… Bridging the gap?, which was merging MCMC, variational autoencoders, and variational inference. I paid close attention as I plan to teach an advanced course on acronyms next semester in Warwick. (By acronyms, I mean ABC+GAN+VAE!)

The notion in this work is that variational autoencoders are based on over-simple mean-field variational distributions, that usually produce a poor approximation of the target distribution. Éric and his coauthors propose to introduce a Metropolis step in the VAE. This leads to a more general notion of Markov transitions and a global balance condition. Hamiltonian Monte Carlo can be used as well and it improves the latent distribution approximation, namely the encoder, which is surprising to me. The steps of the Markov kernel produce a manageable transform of the initial mean field approximation, a random version of the original VAE. Manageable provided not too many MCMC steps are implemented. (Now, the flow of slides was much too fast for me to get a proper understanding of the implementation of the method, of the degree of its calibration, and of the computing cost. I need to read the associated papers.)

Once the talk was over, I went back to changing tires and tubes, as two bikes of mine had flat tires, the latest being a spectacular explosion (!) that seemingly went through the tire (although I believe the opposite happened, namely the tire got slashed and induced the tube to blow out very quickly). Blame the numerous bits of broken glass over bike paths.