day three at ISBA 22

Still woke up early too early [to remain operational for the poster session], finalised the selection of our MASH 2022/3 students, then returned to the Jean-Drapeau pool, which was  even more enjoyable in a crisp bright blue morning (and hardly anyone in my lane).

Attended a talk by Li Ma, who reviewed complexifying stick-breaking priors on the weights and introduced a balanced tree stick mechanism (why same depth?) (with links to Jara & Hanson 2010 and Stefanucci & Canale 2021). Then I listened to Giovanni Rebaubo creating clustering Gibbs-type processes along graphs, I sorted of dozed and missed the point as it felt as if the graph turned from a conceptual connection into a physical one! Catherine Forbes talked about a sequential version of stochastic variational approximation (published in St&Co) exploiting the update-one-at-a-time feature of Bayesian construction, except that each step relies on the previous approximation, meaning that the final—if fin there is!—approximation can end up far away from the optimal stochastic variational approximation. Assessing the divergence away from the target (in real time and tight budget would be nice).

After a quick lunch where I tasted seaweed-shell gyozas (!), I went to the generalised Bayesian inference session on Gibbs posteriors, [sort of] making up for the missed SAVI workshop! With Alice Kirichenko (Warwick) deriving information complexity bounds under misspecification, plus deriving an optimal value for the [vexing] coefficient η [in the Gibbs posterior], and Jack Jewson (ex-Warwick), raising the issue of improper models within Gibbs posteriors, although the reference or dominating measure is a priori arbitrary in these settings. But missing the third talk, about Gibbs posteriors again, and Chris Homes’ discussion, to attend part of the Savage (thesis) Award, with finalists Marta Catalano (Warwick faculty), Aditi Shenvi (Warwick student), and John O’Leary (an academic grand-children of mine’s as Pierre Jacob was his advisor). What a disappointment to have to wait for Friday night to hear the outcome!

I must confess to some  (French-speaker) énervement at hearing Mon(t)-réal massacred as Mon-t-real..! A very minor hindrance though, when put in perspective with my friend and Warwick colleague Gareth Roberts forced to evacuate his hotel last night due to a fire in basement, fortunately unscathed but ruining Day 3 for him… (Making me realise the conference hotel itself underwent a similar event 14 years ago.)