Archive for Chennai

a journal of the cha(ca)os (and fig) year

Posted in Books, Kids, Mountains, pictures, Travel, Wines with tags , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , on October 1, 2025 by xi'an

 Read the last part of The Thousand Autumns of Jacob de Zoet by David Mitchell, which still  takes place in the early 1800’s at the Dutch East India Company trading post Dejima in Nagasaki, as the historical aspects—like the attempt by a British ship to take over the outpost—beat the weakest features of the story. The end does feel rushed.

I made my first attempt at a chocolate tablet by mixing the cocoa—cacao in French—paste (kako in Créole) I brought back from Guadeloupe—made from the cocoa seeds I had bought at the market, roasting and crushing them—with crushed biscuits and a tiny bit of butter. The result was keeping with the bitter chocolate flavour I enjoy in 100% cocoa tablets, if presumably richer in fat and sugar, and more on the chocolate biscuit side! As the fig tree is now delivering at full speed, I am making compotes and office deliveries on most days, along with picking great tomatoes (which survived the heat waves) and the second chili pepper that grew from the chili tree this summer—sadly so low on the Scoville scale that it didn’t much differ from the peppers that also grew there—. In a bountiful year, the only failure was the buckwheat attempt, since no single flower came to deliver. Expert advice is thus sought for next year! This did not prevent me from resuming cooking whey (from skyr) and buckwheat, rye, or chestnut crêpes (on the Amazon iron griddle that no longer sticks!).

Watched and enjoyed the series Dept. Q, a gritty, depressing, and engrossing detective story that mixes cold cases, domestic violence, PTSD, sexism, several levels of guilt, and a variety of Scottish accents, from Edinburgh to the Western Isles. Despite the captivity thread in the scenario that I always dislike as a weak option in this kind of story, albeit making more sense as the episodes unfold. The grey areas surrounding most characters keeps the series at quite an acceptable level of engagement, as does the range of personalities thus displayed. This includes most victims that could have fallen into the poor-dear trap, but remain ambiguous and equally guilty to maintain the balance. Looking forward new seasons (not in the Scottish sense, where most days usually cover all four of them!). Also watched the second season of Wednesday, enjoyable enough if on the light and repetitive side. With Jenna Ortega still running the show, along with a stronger presence of Catherine Zeta-Jones. Just missing the Cramps moment of Season 1!

fishing boats, Mahabalipuram [jatp]

Posted in pictures, Travel, University life with tags , , , , , , , , , , , , , , , on August 19, 2025 by xi'an

André ou Jean Ville (1910-1989)

Posted in Books, pictures, Travel, University life with tags , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , on August 12, 2025 by xi'an

Throughover the workshop in Chennai floated (!) the figure of Jean/André Ville, with his inequality generalising Markov’s, who invented martingales. He is not such a well-known figure in France—at least to me!—, despite having led a rather exceptional life, from being a visiting scholar in Berlin (in the Maison académique de Berlin, along with a certain Jean-Paul Sartre) and Vienna in the 1930s, to his wife being (in Berlin) one of the many (disposable and despised) lovers of JP Sartre (to whom an open-minded or clueless Ville later sent his thèse d’université on martingales and collectives, a much more substantial piece of work than the current PhD), to him working with German and Austrian mathematicians and logicians, such as Popper, Gödel, and Wald–who, what a coïncidence!, died in India from a plane crash in 1950 that had left from Chennai–and being impressed enough by the latter to passing an economics degree in the Sorbonne when back in Paris, establishing a minimax result for a zero-sum matrix game with two players, to his counter-example to von Mises’ kollectiv, to his nickname of the King of Counterexamples in the Viennese mathematics seminar, to him operating the first (Bull) computer at the Université de Paris. (Glenn Shafer wrote a detailed accounting of his youth, on which this post is based, up to his thesis defence but a few days from France mobilising for war–where his collegue Wolfgang Doeblin would kill himself the year after, to avoid capture–. With Bernard Bru, Edmond Malinvaud and Alain Trognon among the people who helped.) After the war, he worked several years as a prépa maths teacher before working for a French State electricity companion on signal theory and Monte Carlo methods, and then returning to Université de Paris as a professor in 1957.

on stopping rules

Posted in Books, Statistics with tags , , , , , , , , , , , , , , , , , on August 3, 2025 by xi'an

The workshop in Chennai and its focus on sequential procedures made me realise (among other things) I had never read Cornfield’s 1966 TAS paper on sequential testing and the likelihood principle:

“By sequential analysis I mean any form of analysis in which the conclusion depends not only on the data, but also on the stopping rule.”

Written with little maths and formalism, this paper argues that keeping a fixed critical level amounts to keeping a fixed amount of evidence. Hence constituting an early critique of p-values even though not expressed in such terms. The part of the paper related with the likelihood principle does not address testing or evidence in a Bayesian way. As a side (late awakening) remark, iid observations in sequential settings are not longer independent, conditional on the stopping rule realisation N=n, since they are constrained by the fact that the stopping rule realisation is n and not n-1, n-2, …  For a short while, I thought it was in turn impacting the distribution of any “sufficient” statistic one may propose, with a normalising constant that depends on the unknown parameter and hence cannot be neglected. Over all those years, I had never though of the modification of sufficiency characteristics in such contexts. But in fine the pair made of the value of the stopping rule and of the unsequential sufficient statistics proves enough. And the normalisation constant is the probability that the stopping rule.. stops!, which is equal to one! For the same short while, I was then wondering that the stopping rule principle!

“my second line of argument that there is a reasonable alternative explication of the idea of inference and one which leads to the rejection of sequential analysis. This explication is provided by the likelihood principle—which states that all observations leading to the same likelihood function should lead to the same conclusion.”

I thus went back to the fundamentals (!), namely [freely available] Bernardo’s and Smith’s Section 5.1.4 (reproduced in EJ’s Stopping rule appendix, also citing Cornfield at length), where the likelihood is properly defined by the joint density of the stopping rule τ and the attached sample at their realised values. And failing in the end (and a discussion with Judith)nto spot a missing normalisation constant.

a journal of the chaos (and rhubarb) year

Posted in Books, Kids, Mountains, pictures, Travel, Wines with tags , , , , , , , , , , , , , , , , , , , , , , , , , , , , on July 30, 2025 by xi'an

 Read Fjellet, geværet, vannet (A mountain, a gun, a lake) by Lars Ramslie (in French, published by the Chamonix based Paulsen editions). A perturbing recollection of a broken childhood between the Norwegian outdoors and violent parenting, in the shadow of an out-of-control father. To the point I found it rather hard to finish the book, the author (and son) being often borderline apologetic for his father’s violent outbursts. That he survived such a trauma is astounding. That local social services could not keep his father away is a shame… I also read E.M. Forster’s A Passage to India classic, while travelling to Chennai, which already reviewed in a separate post.

Beyond indulging in South Indian dishes and a never ending range of appams and local fruits, I made rhubarb preserve from a home-grown rhubarb planting, sometime supplemented with the first figs from our fig-tree and sometime augmented by farmer market sticks. Picked too hot a day to make a ceviche, despite a quick dip in lemon as I returned from the market. (No aftereffect, it just did not taste nice.) And panned an experimental monkfish liver that proved nice and ejnoyable (and with a very mild taste compared with the veal liver I had to eat once a week as a child).

Watched nothing on the flights to and from India. Not even my neighbours’ screens! But watched the Japanese TV series The Hot Spot that is rather funny if not hilarious, and on the lengthy side (esp. all the lunch meetings in Mont Blanc (!) restaurant). Still, the mundane lives of all characters, including the alien—who suffers from all too human shortcomings!—, and  the ever-present backdrop of Mount Fuji make the show worth watching for a while. (A second season feels superfluous, mind.)