Archive for Calgary

a journal of the wars year

Posted in Books, Kids, Mountains, pictures, Travel, Wines with tags , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , on July 18, 2025 by xi'an

 Read Patrick Dewdney’s La Maison des Veilleurs, the fourth volume in this fantastic fantasy series. Only to realise by the end that this was not the end! The setting is the same as in the previous volumes, which makes this one less exciting and prone to extended lazy episodes. The main character, Syffe, keeps puzzling about his destiny and culpability in past events, and it took me a while to get re-hooked, but this remains a remarkable creation. Hopefully soon to be completed! During my Singaporean trip, I also read Sayaka Murata’s Earthlings which is a short fantasy in the Murakami sense, a disrupting mixture of realism (and nostalgia of childhood days) and of unreal behaviours of the characters. The story revolves around mental and sexual aggressions of the main character as a pre-teen, from a paedophile teacher as well as an abusive mother and a transparent father. The story gradually turns away from any pretence to realism and the end is a wee bit of a disappointment. Still worth reading imho. As well as Graham Greene’s The Man Within, which I had not read before (during an episode of intense exploration of his work, following the discovery of The End of the Affair and Brighton Rock). This is one of the earliest Greene’s, and it does contain many hints and premises of the great books to come, with the themes of pursuit, guilt, salvation already there, but as such, the story is rather awkward and contrived, with unnatural dialogues, inner thoughts revolving in circles, and a complete lack of realism in the scenario. The style itself is definitely Greene’s, with beautiful descriptions of the landscape. (I wonder why the cover features the famous Preikestolen cliff on the Lysefjord  rather than the more sedate Shoreham downs, where smuggling French alcohols makes sense!)

Made no cooking for an entire week but enjoyed the almost infinite variety of Singaporean cuisines, with some nice discoveries. If missing the chili crab session on two consecutive nights! (And, coïncidence!, sat next to the same passenger on both flights between Paris and Singapore. If not the same crew as it happened once between Amsterdam and Calgary.) Had a weekend to recover and make most of my “classics”, incl. the weekly whey buckwheat galettes. And missing once again to keep an aquafaba mousse mouss-y enough!

Watched one episode of When Life Gives You Tangerines, which features Jeju women (haenyeo) diving for abalone harvesting (which I tasted in Singapore, if not likely from Jeju). And (at last) Oppenheimer on my flight back, as a way to fight sleep towards resetting my internal clock. Which I mostly enjoyed, despite some awkwardness in the scenario and an old-fashioned way of flipping between different eras, with black and white episodes in case one does not notice. And a very poor treatment of female characters. The ghastly moments when the team celebrates the destruction of Nagasaki and Hiroshima or when officials refuse to drop from the nuclear arm race are quite strong, especially these days. Among the MCMC originators, only Edward Teller is involved in the story, from his obsession with the H bomb to his testimony against Oppenheimer at the high of the McCarthy Red Scare… I also sped through Companion, a lame movie about support robots turning into killers that offers little in either thriller or comic perspectives. Possibly written by ChatGPT?!

off to Banff [17w5024]

Posted in Mountains, pictures, Running, Statistics, Travel, University life with tags , , , , , , on February 18, 2017 by xi'an

Today, I fly from Paris to Amsterdam to Calgary to attend the ABC’ory workshop (15w2214) at the Banff International Research Station (BIRS) that Luke Bornn, Jukka Corander, Gael Martin, Dennis Prangle, Richard Wilkinson and myself built. The meeting is to brainstorm about the foundations of ABC for statistical inference rather than about the computational aspects of ABC, but the schedule is quite flexible for other directions!

asynchronous distributed Gibbs sampling

Posted in Books, Statistics, Travel, University life with tags , , , , , , , on October 13, 2015 by xi'an

Alexander Terenin, Dan Simpson, and David Draper just arXived a paper on an alternative brand of Gibbs sampler, which they think can revolutionise the sampler and overcome its well-known bottlenecks. David had sent me the paper in advance and thus I had time to read it in the plane to Calgary. (This is also the very first paper I see acknowledging a pair of trousers..! With no connection whatsoever with bottlenecks!)

“Note that not all updates that are sent will be received by all other workers: because of network traffic congestion and other types of failures, a significant portion of the updates will be lost along the way.”

The approach is inherently parallel in that several “workers” (processors or graphical units) run Gibbs samplers in parallel, using their current knowledge of the system. This means they update a component of the model parameter, based on the information they have last received, and then send back this new value to the system. For physical reasons, there is not instantaneity in this transmission and thus all workers do not condition on the same “current” value, necessarily. Perceiving this algorithm as a “garden of forking paths” where each full conditional uses values picked at random from a collection of subchains (one for each worker), I can see why the algorithm should remain valid.

“Thus, the quality of this [ABC] method rises and falls with the ingenuity of the user in identifying nearly-sufficient statistics.”

It is also clear that this approach allows for any degree of parallelisation. However, it is less clear to me why this should constitute an improvement. With respect to the bottlenecks mentioned at the beginning of the paper, I do not truly see how the large data problem is bypassed. Except in cases where conditionals only depend on small parts of the data. Or why large dimensions can be more easily managed when compared with a plain Gibbs sampler or, better, parallel plain Gibbs samplers that would run on the same number of processors. (I do not think the paper runs the comparison in that manner, using instead a one-processor Gibbs sampler as its benchmark. Or less processors in the third example.) Since the forking paths repeatedly merge back at aperiodic stages, there is no multiplication or clear increase of the exploratory abilities of the sampler. Except for having competing proposed values [or even proposals] selected randomly. So maybe reaching a wee bit farther from time to time.

a weekend in Banff

Posted in Mountains, pictures, Running, Statistics, Travel, University life with tags , , , , , , on September 26, 2015 by xi'an

Yesterday, I flew from Amsterdam to Calgary to attend the Canadian Statistical Sciences Institute Leadership Retreat (15w2214) at the Banff International Research Station (BIRS). The point of this meeting is to brainstorm towards building a research policy and strategy for the newly created CANSSI. To which scientific advisory committee I joined last semester. I just hope my brain will remain functional enough to contribute to the discussion, if not to storm, despite the eight hour time lag! (The drive from Calgary to Banff was beautiful, with flashy yellow bursting from the green landscape: Fall is coming.)