Archive for Canada

journal of the [second] plague year [away]

Posted in Books, Kids, Mountains, pictures, Travel, University life, Wines with tags , , , , , , , , , , , , , , , on June 12, 2021 by xi'an

Read Fred Vargas’s Seeking Whom He May Devour (L’Homme à l’envers), which I found on a bookshelf of our vacation rental in Annecy. And got more quickly bored by the story as it is plagued with the same defects as the ones I read before, from a definitive issue with Canadians (!), to an attempt to bring supernatural causes in the story and reveal them as fake by the end of the book, to a collection of implausible and caricaturesque characters surrounded by the usual backcountry morons that would rather fit a Paasilinna novel, and to the incomprehensible intuitions of Inspector Adamsberg. I also went through the sequel to Infomocracy, Null states, albeit this was a real chore as it lacked substance and novelty (the title by itself should have been a warning!).

Watched Night in Paradise (낙원의 밤), another Korean gangster movie, which seems to repeat the trope of bad-guy-on-the-run-meets-lost-girl found in my previously watched Korean Jo-Phil: The Dawning Rage, where the main character, a crooked police officer is radically impacted after failing to save a lost teenager.  (And also in the fascinating The Wild Goose Lake.) The current film is stronger however in creating the bond between the few-words gangster on the run and the reluctant guest Jae-yeon who is on a run of a different magnitude. While the battle scenes are still grand-guignolesque (if very violent) in a Kill Bill spirit, and the gang leaders always caricaturesque, the interplay between the main characters makes Night in Paradise a pretty good film (and explains why it got selected for the Venice Film Festival of 2020). Also went through the appalling Yamakasi by Luc Besson, a macho, demagogical, sexist, simplist, non-story…

parallel tempering on optimised paths

Posted in Statistics with tags , , , , , , , , , , , , , , , on May 20, 2021 by xi'an


Saifuddin Syed, Vittorio Romaniello, Trevor Campbell, and Alexandre Bouchard-Côté, whom I met and discussed with on my “last” trip to UBC, on December 2019, just arXived a paper on parallel tempering (PT), making the choice of tempering path an optimisation problem. They address the touchy issue of designing a sequence of tempered targets when the starting distribution π⁰, eg the prior, and the final distribution π¹, eg the posterior, are hugely different, eg almost singular.

“…theoretical analysis of reversible variants of PT has shown that adding too many intermediate chains can actually deteriorate performance (…) [while] on non reversible regime adding more chains is guaranteed to improve performances.”

The above applies to geometric combinations of π⁰ and π¹. Which “suffers from an arbitrarily suboptimal global communication barrier“, according to the authors (although the counterexample is not completely convincing since π⁰ and π¹ share the same variance). They propose a more non-linear form of tempering with constraints on the dependence of the powers on the temperature t∈(0,1).  Defining the global communication barrier as an average over temperatures of the rejection rate, the path characteristics (e.g., the coefficients of a spline function) can then be optimised in terms of this objective. And the temperature schedule is derived from the fact that the non-asymptotic round trip rate is maximized when the rejection rates are all equal. (As a side item, the technique exposed in the earlier tempering paper by Syed et al. was recently exploited for a night high resolution imaging of a black hole from the M87 galaxy.)

Mission implausible

Posted in Books, Kids, pictures with tags , , , , , , , , , , , , , , , , on March 28, 2021 by xi'an

I watched two movies with the same starting point, namely an old man being forced to take care of an unknown girl, despite his lack of fatherhood experience and no initial inclination to do so, while later defying odds and surviving together… One is News of the World (absurdly translated as The Mission in French, hence my poor pun) with Tom Hanks and (fabulous!) Helena Zengel, the other is Midnight Sky, with the improved French title of Midnight in the Universe, with George Clooney and Caoilinn Springall. The first one is a (modern) Western, set in Texas right after the Civil War and sometimes presented as a modern (and over-washed) version of Ford’s The Searchers, while the second one is an ecological science-fiction film, set in 2049, as the Earth is collapsing under an unspecified but all encompassing disaster. The first is passable if implausible, the second one is a disaster at all levels.

In News of the World Tom Hanks is again doing his Jimmy Stewart impersonation, always doing the “right” thing even when this is rather implausible. The fact that no-one seems to care that a stranger goes away with a young girl may be plausible in the late 1800’s Texas, although I am surprised none of the very few women in the story, one of them the girl’s own aunt, does even object. On the other hand, the motive for the compulsory gun duel sounds very weak if darker than the rest of the story (and is there any chance a shotgun cartridge filled by coins (of the right diameter!) can fly true to its target?!) The choice of depicting Kiowa Indians as silent spectres walking away may be artistically motivated but it does not carry much weight, just like Hank in the movie is not making much progress in denunciation of slavery and genocide, besides keeping his own decency.

In Midnight Sky, George Clooney is a grumpy old scientist stuck in a Far North observatory, in terminal phase of a blood disease and who is gradually revealed as having always failed on the personal relation side. [Anyone wondering at the scientific pertinence of the presence of a most traditional observatory [incl. manual orienteering] at this latitude? Although I found that Canada has recently set an observatory on Ellesmere Island, Nunavut.] As Earth is collapsing under deadly radiation, Clooney finds himself alone until he discovers a little girl conveniently left behind during the evacuation of the station. As a space ship is returning to Earth, unaware of the disaster, the pair sets on an impossible mission to reach a better communication station. first on a snowmobile, then on foot!, with no goggles and a woolen hat in a snow storm!, just to make sure we can recognise Clooney!, while the disaster that see the pair stranded with only their clothes on a frozen tundra makes no sense. For instance, falling into Arctic water has a very low survival probability, esp. for a a sick and old man. And the part taking place on the very-low-tech space ship is light-years away from anything remotely realistic. Ending up (spoiler!) with the ship turning back to this habitable moon of Jupiter as if this would make any difference… Have a safe trip!

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…)

Don Fraser (1925-2020)

Posted in Books, Statistics, University life with tags , , , , , , , , , , , , , , , on December 24, 2020 by xi'an

I just received the very sad news that Don Fraser, emeritus professor of statistics at the University of Toronto, passed away this Monday, 21 December 2020. He was a giant of the field, with a unique ability for abstract modelling and he certainly pushed fiducial statistics much further than Fisher ever did. He also developed a theory of structural  inference that came close to objective Bayesian statistics, although he remained quite critical of the Bayesian approach (always in a most gentle manner, as he was a very nice man!). And most significantly contributed to high order asymptotics, to the critical analysis of ancilarity and sufficiency principles, and more beyond. (Statistical Science published a conversation with Don, in 2004, providing more personal views on his career till then.) I met with Don and Nancy rather regularly over the years, as they often attended and talked at (objective) Bayesian meetings, from the 1999 edition in Granada, to the last one in Warwick in 2019. I also remember a most enjoyable barbecue together, along with Ivar Ekeland and his family, during JSM 2018, on Jericho Park Beach, with a magnificent sunset over the Burrard Inlet. Farewell, Don!