Archive for Montréal

a journal of the plague year [post-december reviews]

Posted in Books, Kids, pictures, Travel with tags , , , , , , , , , , , , , , , , , , , , , , , , , , , , , on February 13, 2021 by xi'an

Read a (French) novel by Fred Vargas, Sous les Vents de Neptune, after finding it in the book depository near my office. And enjoyed it very much, partly because it was partly taking place near Ottawa [which I visited many times while my wife was completing her EE Master there] and partly because of the author’s ability to make us doubt the main character and to keep the suspense tight enough for most of the book. There are a trip to Montréal to attend a concert and a journey to Detroit and back to find a lost relation, both reminding me of drives on these roads more than 30 years ago. What annoyed me though was the caricaturesque depiction of the locals, with a Québecois French that sounded overdone. Checking for a local perspective on that aspect, I found a book review in Le Devoir of 2004 sharing the reservation on that aspect, if with humour.  (I would also have rather done without the super-hacker character à la Lisbeth Salander.)

Watched Still Life (三峡好人) a 2006 film by Jia Zhangke, as it was proposed in the list of my local cinema (which I support during the endless lockdown of cinemas and theatres in France). This is an amazing film, which at the same time feels incredibly remote or alien… It follows two characters arriving by boat on the at the Three Gorges Dam under construction in search of a runaway spouse. The search for their respective spouse takes place among the demolition of the old Fengjie, soon to be drowned under 150 meters of dam water. This demolition makes for a unique soundtrack, workers hammering in cadence as blurred black shades against the sky. The dialogues are full of long silences, except for the background hammering, and it often feels theatrical. But the characters maintain a strong dignity throughout the film and the depiction of the last days of Fengjie is gripping. The film received the 2006 Venezia Golden Lion.

Cooked a few Venetian dishes from a Venetian cookbook that was my Xmas gift. And finished that way past-the-date polenta boxes. Managed to escape unscathed from both the bûche and galette weeks! And found that cooking spelt bread with spelt yeast was unbelievably easy, taking less time to work on the dough than to reach the closest bakery!

Could not manage to achieve a coherent discussion with some anti-vaxxer relatives over the Xmas break. And gave up, still hoping they would change their mind.

Watched the first episodes of The Expanse, which started as a collection of eight novels and eight shorter works, before turning into a TV series which won the 2020 Hugo Award. Enjoyable if a rather conventional setting, with the usual disregard for space physics! Reminded me very much of the Takeshi Kovacs novels.  To quote from Wikipedia, “Ty Franck began developing the world of The Expanse initially as the setting for a MMORPG and, after a number of years, for a tabletop roleplaying game.” Some of the actors are terrific (even though Steven Strait’s Holden painfully reminds me of Kit Harrington’s Jon Snow, to the point I wondered for a while if they were the same actor…)

non-uniform Laplace generation

Posted in Books, pictures, Statistics, University life with tags , , , , , , , , , on June 5, 2019 by xi'an

This year, the French Statistical Society (SFDS) Prix Laplace has been granted to Luc Devroye, author of the Non-Uniform Random Generation bible. among many achievements!, prize that he will receive during the 2019 meeting in Nancy, this very week.

the Montréal declarAIon

Posted in University life with tags , , , , , , , , , , , , on April 27, 2019 by xi'an

In conjunction with Yoshua Bengio being one of the three recipients of the 2018 Alan Turing award, Nature ran an interview of him about the Montréal Déclaration for a responsible AI, which he launched at NeurIPS last December.

“Self-regulation is not going to work. Do you think that voluntary taxation works? It doesn’t.”

Reflecting on the dangers of abuse of and by AIs, from surveillance, to discrimination, but being somewhat unclear on the means to implement the ten generic principles listed there. (I had missed the Declaration when it came up.) I agree with the principles stressed by this list, well-being, autonomy, privacy, democracy, diversity, prudence, responsability, and sustainability, it remains to be seem how they can be imposed upon corporations whose own public image puts more restraint on them than ethics or on governments that are all too ready to automatise justice, police, and the restriction of citizen’s rights. Which makes the construction of a responsible AI institution difficult to imagine, if the current lack of outreach of the extra-national institutions is the gauge. (A striking coincidence is that, when  Yoshua Bengio pointed out that France was trying to make Europe an AI power, there was also a tribune in Le Monde about the lack of practical impact of this call to arms, apart from more academics moving to half-time positions in private companies.) [Warning: the picture does not work well with the dark background theme of this blog.]

ISBA World meetings to come

Posted in pictures, Statistics, Travel, University life with tags , , , , , , , on January 27, 2019 by xi'an

June 2020: Kumming, Yunnan, China

June 2022: Montréal, Québec, Canada

June 2024: Venezia, Veneto, Italy

a question from McGill about The Bayesian Choice

Posted in Books, pictures, Running, Statistics, Travel, University life with tags , , , , , , , on December 26, 2018 by xi'an

I received an email from a group of McGill students working on Bayesian statistics and using The Bayesian Choice (although the exercise pictured below is not in the book, the closest being exercise 1.53 inspired from Raiffa and Shlaiffer, 1961, and exercise 5.10 as mentioned in the email):

There was a question that some of us cannot seem to decide what is the correct answer. Here are the issues,

Some people believe that the answer to both is ½, while others believe it is 1. The reasoning for ½ is that since Beta is a continuous distribution, we never could have θ exactly equal to ½. Thus regardless of α, the probability that θ=½ in that case is 0. Hence it is ½. I found a related stack exchange question that seems to indicate this as well.

The other side is that by Markov property and mean of Beta(a,a), as α goes to infinity , we will approach ½ with probability 1. And hence the limit as α goes to infinity for both (a) and (b) is 1. I think this also could make sense in another context, as if you use the Bayes factor representation. This is similar I believe to the questions in the Bayesian Choice, 5.10, and 5.11.

As it happens, the answer is ½ in the first case (a) because π(H⁰) is ½ regardless of α and 1 in the second case (b) because the evidence against H⁰ goes to zero as α goes to zero (watch out!), along with the mass of the prior on any compact of (0,1) since Γ(2α)/Γ(α)². (The limit does not correspond to a proper prior and hence is somewhat meaningless.) However, when α goes to infinity, the evidence against H⁰ goes to infinity and the posterior probability of ½ goes to zero, despite the prior under the alternative being more and more concentrated around ½!