Archive for hidden networks

JSM 2024, Portland, Day 2

Posted in pictures, Running, Statistics, Travel, University life with tags , , , , , , , , , , , , , , , , , , , , , , , , , , , on August 7, 2024 by xi'an

By happenstance, I started my day in the cybersecurity session. With (again) hardly a soul in the room… A first talk on avoiding herding and achieving asymptotic truth learning (about a binary outcome) in a graph by putting constraints on the graph structure, without any clear connection with statistics or cybersecurity. Even less for the second talk on optimising masks. Only with the third one came cybersecurity motivations, the focus being on a two-player Stackelberg game already used in this framework. The result proper was about estimating the parameter of a (rather unrealistic) posited model reproducing the adversarial actions. The last talk about jailbreak attacks was again off-field by miles.


Then attended (as intended!) the 2024 Blackwell-Rosenbluth Award session, featuring the nominees Sharmistha Guha (Texas A&M) on multiple network inference, Simon Mak (Duke) on using Bayesian surrogate models, Guanyang Wang (Rutgers) who recently spoke at our mostly Monte Carlo seminar, Akihiko Nishimura (John Hopkins) on a unification of HMC and PDMPs, most appropriate when located next to Mount Hamilton and the Zigzag river!, and Maria Skoularidou (MIT) on evolutionary Monte Carlo for gene expression. Alas with hardly anyone in the room.

In the afternoon, I went to the (very well-attended this time!, with no seat available for many attendees, incl. yours truly!) COPSS Elizabeth L. Scott Lecture by my friend from Rutgers, Regina Liu, on the highly relevant challenge of combining inferences from diverse data sources. Using the (definitely Rutgerian!) approach of confidence distributions!

Last (late) afternoon, I went swimming from Kevin Duckworth dock, just below the conference centre. Water was quite warm (and green), with a few other swimmers, and no stomachical after-effect, so far. Hence I returned there once again this afternoon.

clustering dynamical networks

Posted in pictures, Statistics, University life with tags , , , , , , , , , , on June 5, 2018 by xi'an


Yesterday I attended a presentation by Catherine Matias on dynamic graph structures, as she was giving a plenary talk at the 50th French statistical meeting, conveniently located a few blocks away from my office at ENSAE-CREST. In the nicely futuristic buildings of the EDF campus, which are supposed to represent cogs according to the architect, but which remind me more of these gas holders so common in the UK, at least in the past! (The E of EDF stands for electricity, but the original public company handled both gas and electricity.) This was primarily a survey of the field, which is much more diverse and multifaceted than I realised, even though I saw some recent developments by Antonietta Mira and her co-authors, as well as refereed a thesis on temporal networks at Ca’Foscari by Matteo Iacopini, which defence I will attend in early July. The difficulty in the approaches covered by Catherine stands with the amount and complexity of the latent variables induced by the models superimposed on the data. In her paper with Christophe Ambroise, she followed a variational EM approach. From the spectator perspective that is mine, I wondered at using ABC instead, which is presumably costly when the data size grows in space or in time. And at using tensor structures as in Mateo’s thesis. This reminded me as well of Luke Bornn’s modelling of basketball games following each player in real time throughout the game. (Which does not prevent the existence of latent variables.) But more vaguely and speculatively I also wonder at the meaning of the chosen models, which try to represent “everything” in the observed process, which seems doomed from the start given the heterogeneity of the data. While reaching my Keynesian pessimistic low- point, which happens rather quickly!, one could hope for projection techniques, towards reducing the dimension of the data of interest and of the parameter required by the model.