Archive for Cryptonomicon

space opera by John Scalzi [book review]

Posted in Books, pictures, Travel with tags , , , , , , , , , , , , , , , , , on June 15, 2019 by xi'an

John Scalzi, author of the memorable Old Man’s War, has started a trilogy of which I only became aware recently (or more precisely became re-aware!), which has the perk of making two of the three books already published and hence available without a one or two year break. And having the book win the 2018 Locus Award in the meanwhile. This new series is yet again a space opera with space travel made possible by a fairly unclear Flow that even the mathematicians in the story have trouble understanding. And The Flow is used by guilds to carry goods and people to planets that are too hostile an environment for the “local” inhabitants to survive on their own. The whole setup is both homely and old-fashioned: the different guilds are associated with families, despite being centuries old, and the empire of 48 planets is still governed by the same dominant family, who also controls a fairly bland religion. Although the later managed to become the de facto religion.

“I’m a Flow physicist.  It’s high-order math. You don’t have to go out into the field for that.”

This does not sound much exciting, even for space operas, but things are starting to deteriorate when the novels start. Or more exactly, as hinted by the title, the Empire is about to collapse! (No spoiler, since this is the title!!!) However, the story-telling gets a wee bit lazy from that (early) point. In that it fixates on a very few characters [among millions of billions of inhabitants of this universe] who set the cogs spinning one way then the other then the earlier way… Dialogues are witty and often funny, those few characters are mostly well-drawn, albeit too one-dimensional, and cataclysmic events seem to be held at bay by the cleverness of one single person, double-crossing the bad guys. Mostly. While the second volume (unusually) sounds better and sees more action, more surprises, and an improvement in the plot itself, and while this makes for a pleasant travel read (I forgot The Collapsing Empire in a plane from B’ham!), I am surprised at the book winning the 2018 Locus Award indeed. It definitely lacks the scope and ambiguity of the two Ancillary novels. The convoluted philosophical construct and math background of Anathem. The historical background of Cryptonomicon and of the Baroque Cycle. Or the singularity of the Hyperion universe. (But I was also unimpressed by the Three-Body Problem! And by Scalzi’s Hugo Award Redshirts!) The third volume is not yet out.

As a French aside, a former king turned AI is called Tomas Chenevert, on a space-ship called Auvergne, with an attempt at coming from a French speaking planet, Ponthieu, except that is should have been spelled Thomas Chênevert (green oak!). Incidentally, Ponthieu is a county in the Norman marches, north of Rouen, that is now part of Picardy, although I do not think this has anything to do with the current novel!

Turing’s Bayesian contributions

Posted in Books, Kids, pictures, Running, Statistics, University life with tags , , , , , , , , , , , , on March 17, 2015 by xi'an

Following The Imitation Game, this recent movie about Alan Turing played by Benedict “Sherlock” Cumberbatch, been aired in French theatres, one of my colleagues in Dauphine asked me about the Bayesian contributions of Turing. I first tried to check in Sharon McGrayne‘s book, but realised it had vanished from my bookshelves, presumably lent to someone a while ago. (Please return it at your earliest convenience!) So I told him about the Bayesian principle of updating priors with data and prior probabilities with likelihood evidence in code detecting algorithms and ultimately machines at Bletchley Park… I could not got much farther than that and hence went checking on Internet for more fodder.

“Turing was one of the independent inventors of sequential analysis for which he naturally made use of the logarithm of the Bayes factor.” (p.393)

I came upon a few interesting entries but the most amazìng one was a 1979 note by I.J. Good (assistant of Turing during the War) published in Biometrika retracing the contributions of Alan Mathison Turing during the War. From those few pages, it emerges that Turing’s statistical ideas revolved around the Bayes factor that Turing used “without the qualification `Bayes’.” (p.393) He also introduced the notion of ban as a unit for the weight of evidence, in connection with the town of Banbury (UK) where specially formatted sheets of papers were printed “for carrying out an important classified process called Banburismus” (p.394). Which shows that even in 1979, Good did not dare to get into the details of Turing’s work during the War… And explains why he was testing simple statistical hypothesis against simple statistical hypothesis. Good also credits Turing for the expected weight of evidence, which is another name for the Kullback-Leibler divergence and for Shannon’s information, whom Turing would visit in the U.S. after the War. In the final sections of the note, Turing is also associated with Gini’s index, the estimation of the number of species (processed by Good from Turing’s suggestion in a 1953 Biometrika paper, that is, prior to Turing’s suicide. In fact, Good states in this paper that “a very large part of the credit for the present paper should be given to [Turing]”, p.237), and empirical Bayes.


Posted in Books, University life with tags , , , , , , , , , , , on November 20, 2010 by xi'an

One colleague of mine in Dauphine gave me Anathem to read a few weeks ago. I had seen it in a bookstore once and planned to read it, so this was a perfect opportunity. I read through it slowly at first and then with more and more eagerness as the story built on, spending a fair chunk of the past evenings (and Metro rides) into finishing it. Anathem is a wonderful book, especially for mathematicians, and while it could still qualify as a science-fiction book, it blurs the frontiers between the genres of science-fiction, speculative fiction, documentary writings and epistemology… Just imagine any other sci’fi’ book being reviewed in Nature! Still, the book was awarded the 2009 Locus SF Award. So it has true sci’fi’ characteristics, including Clarke-ian bouts of space opera with a Rama-like vessel popping out of nowhere. But this is not the main feature that makes Anathem so unique and fascinating.

“The Adrakhonic theorem, which stated that the square of a right triangle hypotenuse was equal to the sum of the squares of the other two sides…” (p. 128)

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