Archive for chess

a journal of the plague year [soon to turn one…]

Posted in Books, Kids, Mountains, pictures, Travel with tags , , , , , , , , , , , , , , , , , , , , , , , on March 6, 2021 by xi'an

Read in a few Sunday hours Living proof by John Harvey, a 1995 novel that I had found in the book exchange section of our library. A very easy read but rather enjoyable with several stories within stories and books within books. The resolution of the main murder mystery was disappointing but I enjoyed the inclusion of real artists like Ian Rankin and Mark Timlin. With a pastiche of P.D. James. And plenty of jazz references. Plus two characters meeting while studying at Warwick. And some shared glimpses of Nottingham like the statue of Robin Hood and the troglodyte Ye Olde Trip to Jerusalem. where I was once  invited for a pint… The story takes place during and around Nottingham’s Shots in the Dark festival. I hence grabbed another volume in the library in prevision of another lazy afternoon!

Baked rather decent chapattis for a take-home Bengali dinner but ruined the pan and started the fire alarm! Also tried to bake tortillas but mixed up the proportions of flour and water, ending up with a type of galette or injera instead (which worked as a container for the fajitas!).

Eventually watched the last two episodes of the Queen’s Gambit, but found them somewhat disappointing, between the main characters’ attitude that did not feel in tune with the 1960’s, the French femme fatale who cannot pronounce Jardins du Luxembourg, and the somewhat rosy tale of two orphans achieving financial freedom and professional success before their majority. Also watched the Korean Space Sweepers after an exhausting day, with a very shallow plot and a complete disregard for physics.

Read the duology of Six of Crows and Crooked Kingdom, by Leigh Bardugo, set in the same universe as the Grisha novels. Which I had read five years ago and somewhat forgotten than these novels were written as young adult books, with a resulting shallow plot, so full of sudden changes of fortune that any worry for the (caricaturesque) characters vanishes (till the one point when one should have) in a definitive suspension of suspense. (The Guardian reviewed Six of Crows in the Children’s book review section, which feels rather inappropriate given the degree of abuse the teens in the novels are submitted to, with two girls surviving sexual enslavement in the local brothels.) Just like the Grisha novels were set in a postcard version of Russia, these novels are taking place in a similarly thin (pannenkoek) version of Amsterdam (with waffles as the only culinary delicacy!). I do realise these series have a huge fan base, to the point of leading to an incoming Netflix series. But I found the more elaborate Ninth House much more enjoyable… (In tune with this series of reviews, the second book includes a plague episode with a modicum of realism, at least in its early stages.)

monomial representations on Netflix

Posted in Books, Kids, pictures, Travel with tags , , , , , , , , , , , , on February 16, 2021 by xi'an

When watching the first episode of Queen’s Gambit, following the recommendations of my son, I glimpsed the cover of a math thesis defended at Cornell by the mother of the main character..! Prior to 1957, year of her death. Searching a wee bit further, I found that there exists an actual thesis with this very title, albeit defended by Stephen Stanley in 1998 at the University of Birmingham. that is, Birmingham, UK [near Coventry]. Apart from this amusing trivia piece, I also enjoyed watching the first episodes of the series, the main actor being really outstanding in her acting, and the plot unfolding rather nicely, except for the chess games that are unrealistically hurried, presumably because watching people thinking is anathema on TV! The representation of misogyny at the time is however most realistic (I presume|!) and definitely shocking. (The first competition game when Beth Hamon loses is somewhat disappointing as failing to predict a Queen exchange is implausible at this level…) However, the growing self-destructive behaviour of Beth made me cringe to the point of stopping the series. The early episodes also reminded me of the days when my son had started playing chess with me, winning on a regular basis, had then joined a Saturday chess nearby, was moved to the adult section within a few weeks, and … stopped altogether a few weeks later as he (mistakenly) thought the older players were making fun of him!!! He never got to any competitive level but still plays on a regular basis and trashes me just as regularly. Coincidence or not, the Guardian has a “scandalous” chess story to relate last week,  when the Dutch champion defeated the world top two players, with one game won by him having prepared the Najdorf Sicilian opening up to the 17th round! (The chess problem below is from the same article but relates to Antonio Medina v Svetozar Gligoric, Palma 1968.)

Le Monde puzzle [#1141]

Posted in Kids, pictures, R, University life with tags , , , , , , , , on May 4, 2020 by xi'an

The weekly puzzle from Le Monde is in honour of John Conway, who just passed away, ending up his own game of life:

On an 8×8 checker-board, Alice picks n squares as “infected”. She then propagates the disease by having each square with least two infected neighbours to become infected as well. What is the minimal value of n for the entire board to become infected? What if three infected neighbours are required?

A plain brute force R random search for proper starting points led to n=8 (with a un-code-golfed fairly ugly rendering of the neighbourhood relation, I am afraid!) with the following initial position

With three neighbours, an similar simulation failed to return anything below n=35 as for instance:

oops, n=34 when running a little longer:

which makes sense since an upper bound is found by filling one square out of two (32) and adding both empty corners (2). But this upper bound is only considering one step ahead, so is presumably way too large. (And indeed the minimal value is 28, showing that brute force does not always work! Or it may be that forcing the number of live cells to grow at each step is a coding mistake…)

value of a chess game

Posted in pictures, Statistics, University life with tags , , , , , , , , , , , , on April 15, 2020 by xi'an

In our (internal) webinar at CEREMADE today, Miguel Oliu Barton gave a talk on the recent result his student Luc Attia and himself obtained, namely a tractable way of finding the value of a game (when minimax equals maximin), result that got recently published in PNAS:

“Stochastic games were introduced by the Nobel Memorial Prize winner Lloyd Shapley in 1953 to model dynamic interactions in which the environment changes in response to the players’ behavior. The theory of stochastic games and its applications have been studied in several scientific disciplines, including economics, operations research, evolutionary biology, and computer science. In addition, mathematical tools that were used and developed in the study of stochastic games are used by mathematicians and computer scientists in other fields. This paper contributes to the theory of stochastic games by providing a tractable formula for the value of finite competitive stochastic games. This result settles a major open problem which remained unsolved for nearly 40 years.”

While I did not see a direct consequence of this result in regular statistics, I found most interesting the comment made at one point that chess (with forced nullity after repetitions) had a value, by virtue of Zermelo’s theorem. As I had never considered the question (contrary to Shannon!). This value remains unknown.

Death won the last chess game [but it took a while]

Posted in Statistics with tags , , , , , , , , on March 30, 2020 by xi'an