Archive for Tokyo

approximate Bayesian inference [survey]

Posted in Statistics with tags , , , , , , , , , , , , , , , , , , on May 3, 2021 by xi'an

In connection with the special issue of Entropy I mentioned a while ago, Pierre Alquier (formerly of CREST) has written an introduction to the topic of approximate Bayesian inference that is worth advertising (and freely-available as well). Its reference list is particularly relevant. (The deadline for submissions is 21 June,)

γ-ABC

Posted in Statistics with tags , , , , , , , on March 24, 2021 by xi'an

An AISTATS 2021 paper by Masahiro Fujisawa,Takeshi Teshima, Issei Sato and Masashi Sugiyama (RIKEN, Tokyo) just appeared on arXiv.  (AISTATS 2021 is again virtual this year.)

“ABC can be sensitive to outliers if a data discrepancy measure is chosen inappropriately (…) In this paper, we propose a novel outlier-robust and computationally-efficient discrepancy measure based on the γ-divergence”

The focus is on measure of robustness for ABC distances as those can be lethal if insufficient summarisation is used. (Note that a referenced paper by Erlis Ruli, Nicola Sartori and Laura Ventura from Padova appeared last year on robust ABC.) The current approach mixes the γ-divergence of Fujisawa and Eguchi, with a k-nearest neighbour density estimator. Which may not prove too costly, of order O(n log n), but also may be a poor if robust approximation, even if it provides an asymptotic unbiasedness and almost surely convergent approximation. These properties are those established in the paper, which only demonstrates convergence in the sample size n to an ABC approximation with the true γ-divergence but with a fixed tolerance ε, when the most recent results are rather concerned with the rates of convergence of ε(n) to zero. (An extensive simulation section compares this approach with several ABC alternatives, incl. ours using the Wasserstein distance. If I read the comparison graphs properly, it does not look as if there is a huge discrepancy between the two approaches under no contamination.) Incidentally, the paper contains a substantial survey section and has a massive reference list, if missing the publication more than a year earlier of our Wasserstein paper in Series B.

a journal of the plague year [are we there yet?!]

Posted in Books, Kids, Mountains, pictures, Travel with tags , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , on March 20, 2021 by xi'an

Read the next volume of the Witcher series, Baptism of Fire, with even less enthusiasm than for the previous one, as the momentum of the series seems to have stalled… (Despite reading some highly positive reviews.) Some dialogues are funny enough, along with progressive views not particularly common in fantasy, like the support of reproductive rights, incl. abortion (and even less supported in the home country of the author, Andrzej Sapkowski!). But overall, not much happening and too much infodump!

Baked Ethiopian lentils & spinach mix, to get along with a slow cooking Ethiopian beef stew. And cooked more Venetian dishes. And had a great Korean streetfood dinner at (or from) MamiBaba by Quinsou, near Montparnasse, with pajeon (the cousin to okonomiyaki!) and kimchee. Accompanied by a first attempt at baking a chocolate pie.

Watched a few episodes of Alice in Borderland, vaguely suggested as hearsay by my daughter, but despite the fascinating scenes of an empty Tokyo, the plot is not particularly engaging, the tricks towards solving the game often lame, and the characters are not developed at all. Then watched Kurosawa’s Creepy, a gripping if not particularly realist psychological thriller that was premiered at the 2016 Berlin Film Festival. And reminded me of the much more disturbing Losey’s The Servant

Read two further volumes of John Harvey’s Charlie Resnick, in a random order, volumes that I found in and returned to the exchange section in front of our library as usual. And which I found almost as good as the first one, with its insistence on the humanity of each of the characters rather than indulging in manicheism. References to jazz pieces got a wee bit annoying by the third volume… And there is a maximal number of rye bread sandwiches with Polish pastrami I can swallow!

Watched also for the first time the fascinating The Wild Goose Lake (南方车站的聚会 which translates as A Rendez-Vous at a Station in the South), by Diao Yinan, a 2019 Cannes Festival selection, a psychological and violent noir film taking place in Wuhan among local gangs, when a gang boss kills by mistake a policeman after a very gory episode. The classical story line of the chase à la A bout de souffle is both tenuous and gripping, with an painful attention to colour and lightings, most scenes taking place at night with ghastly lights, with an intentional confusion between gangs of criminals and groups of cops, the final scene in full daylight making everything else sounding like a bad dream. The two main characters are striking, with an outlandish swan-like actress Gwei Lun-Mei. This also led me to watch the earlier Black Coal Thin Ice, which I also found impressive in terms of filming [that makes the cold and snow in this Northern city almost perceptible!] and definition of characters, once again involving Gwei Lun-Mei as the central, almost mute, and doomed, woman, but puzzling in terms of psychology and scenarios. (The shootout in the gallery is plain ridiculous imho.)

Keith Jarrett’s left hand

Posted in Travel with tags , , , , on November 7, 2020 by xi'an

Just read in the NYT the sad news that the outworldly pianist Keith Jarrett is unlikely to perform ever again, following strokes that left him partly paralyzed. His legacy will endure, including this “last solo”:

Infomocracy [book review]

Posted in Books, Travel with tags , , , , , , , , , on June 17, 2017 by xi'an

Infomocracy is a novel by Malka Older set in a near future where most of the Earth is operating under a common elective system where each geographical unit of 100,000 people elect a local representative that runs this unit according to the party’s program and contributes to elect a Worldwide government, except for some non-democratic islets like Saudi Arabia. The whole novel revolves around the incoming election, with different parties trying to influence the outcome in their favour, some to the point of instating a dictature. Which does not sound that different from present times!, with the sligth difference that the whole process is controlled by Information, a sort of World Wide Web that seems to operate neutrally above states and parties, although the book does not elaborate on how this could be possible. The story is told through four main (and somewhat charicaturesque) characters, working for or against the elections and crossing paths along the novel. Certainly worth reading if not outstanding. (And definitely not “one of the greatest literary debuts in recent history”!)

The book is more interesting as a dystopia on electoral systems and the way the information revolution can produce a step back in democracy, with the systematisation of fake news and voters’ manipulation, where the marketing research group YouGov has become a party, than as a science-fiction (or politics-fiction) book. Indeed, it tries too hard to replicate The cyberpunk reference, William Gibson’s Neuromancer, with the same construct of interlacing threads, the same fascination for Japan, airports, luxury hotels, if not for brands, and a similar ninja-geek pair of characters. And with very little invention about the technology of the 21st Century.  (And a missed opportunity to exploit artificial intelligence themes and the prediction of outcomes when Information builds a fake vote database but does not seem to mind about Benford’s Law.) The acknowledgement section somewhat explains this imbalance, in that the author worked many years in humanitarian organisations and is currently completing a thesis at Science Po’ (Paris).