## a memory called Empire [book review]

Posted in Books, Kids, pictures, Travel with tags , , , , , , , , , , , on June 6, 2020 by xi'an

A pleasant read for a few afternoon breaks (and vitamin D intake), that I chose as it was nominated for the Hugo and Nebula awards as well as a Not the Booker Prize Guardian choice. But not really worth the hype I think as the novel, A Memory Called Empire, is quite unidimensional (which is unfortunate for a space opera). In that the few characters that populate the book manage to move by themselves the political structure of the interstellar universe quite substantially. Within a few days. These characters are definitely attractive but somewhat too nice to be true and the way they bond and connect with one another is just implausible, even for a science fiction novel

“…no algorithm is innocent of its designersAn algorithm is only as perfect as the person designing it.”

The most interesting part in the story, although somewhat stretched too thin, is the conflict the central character feels between her attraction to the highly sophisticated culture of the Empire and the feeling that she will never be fully incorporated within that culture. Despite mastering the language and the societal codes well-enough to reach the upper spheres of society and impact them.

“…the real inspiration for the number-noun naming system comes from the naming practices of the Mixtec people of Oaxaca…” Arkady Martine

But, beside borrowing a lot to Japanese culture, and a wee bit to Maya or Aztec societies, the universe created by Arkady Martine is quite close to ours in its mundane aspects, including plastic spoons..! With very few truly novel technologies. But with email delivered on USB keys after travelling faster than light between star systems. The threat of an alien invasion is pending, by the end of the book, paving the way for an incoming second volume.To be read…

## Murderbot 2.0 [book review]

Posted in Books, Kids with tags , , , , , , , , , , , on May 30, 2020 by xi'an

After reading (for free) the (fab) four “murderbot diaries”, I got enough infected to fall for the fifth installment, Network Effect, and buy it upon release on May 5. This is definitely a continuation of the on-going development of the growth of the central character, SecUnit, a rogue android operating free-lance after it hacked its own OS. With private name Murderbot. And  with biological human parts and a more and more human way of thinking. Except it is faster and seriously multitasking. Characters that came to life in All Systems Red (an Amazon bestseller in Science Fiction!) and the following diaries are still around and active, including the super AI ART which is the closest to a friend Murderbot can think of. Corporate entities are still revolving around the story, with an unlimited greed that leads to catastrophes on new planets they turn into mines and often abandon if the economy does not come their way. As previously, a large part of the plot is hardwired in that it involves hacking, killerwares, unfortunate reboots, and hidden recovery files, which sounds like lazy plot lines at times but remains enjoyable. The fact (!) that some characters are androids means that they can even die and be rebooted if a safe copy of their OS is available. Which makes for a schizophrenic and hilarious inner dialogue at a point of the book. The part I found the least convincing cannot be divulged without being a spoiler, but it made the explanation for the bad guys being bad guys lame. And reminded of a terrible short story I had written in high school involving a sentient blurb which… (Well, it was getting worse from there!) But overall, this is quite a fun and enjoyable if rather geeky novel, with witty exchanges (although AIs with deep minds should have been able to come up with better ones!).

## Monte Carlo Markov chains

Posted in Books, Statistics, University life with tags , , , , , , , , , , , , , , , , , , , , , , on May 12, 2020 by xi'an

Darren Wraith pointed out this (currently free access) Springer book by Massimiliano Bonamente [whose family name means good spirit in Italian] to me for its use of the unusual Monte Carlo Markov chain rendering of MCMC.  (Google Trend seems to restrict its use to California!) This is a graduate text for physicists, but one could nonetheless expect more rigour in the processing of the topics. Particularly of the Bayesian topics. Here is a pot-pourri of memorable quotes:

“Two major avenues are available for the assignment of probabilities. One is based on the repetition of the experiments a large number of times under the same conditions, and goes under the name of the frequentist or classical method. The other is based on a more theoretical knowledge of the experiment, but without the experimental requirement, and is referred to as the Bayesian approach.”

“The Bayesian probability is assigned based on a quantitative understanding of the nature of the experiment, and in accord with the Kolmogorov axioms. It is sometimes referred to as empirical probability, in recognition of the fact that sometimes the probability of an event is assigned based upon a practical knowledge of the experiment, although without the classical requirement of repeating the experiment for a large number of times. This method is named after the Rev. Thomas Bayes, who pioneered the development of the theory of probability.”

“The likelihood P(B/A) represents the probability of making the measurement B given that the model A is a correct description of the experiment.”

“…a uniform distribution is normally the logical assumption in the absence of other information.”

“The Gaussian distribution can be considered as a special case of the binomial, when the number of tries is sufficiently large.”

“This clearly does not mean that the Poisson distribution has no variance—in that case, it would not be a random variable!”

“The method of moments therefore returns unbiased estimates for the mean and variance of every distribution in the case of a large number of measurements.”

“The great advantage of the Gibbs sampler is the fact that the acceptance is 100 %, since there is no rejection of candidates for the Markov chain, unlike the case of the Metropolis–Hastings algorithm.”

Let me then point out (or just whine about!) the book using “statistical independence” for plain independence, the use of / rather than Jeffreys’ | for conditioning (and sometimes forgetting \ in some LaTeX formulas), the confusion between events and random variables, esp. when computing the posterior distribution, between models and parameter values, the reliance on discrete probability for continuous settings, as in the Markov chain chapter, confusing density and probability, using Mendel’s pea data without mentioning the unlikely fit to the expected values (or, as put more subtly by Fisher (1936), “the data of most, if not all, of the experiments have been falsified so as to agree closely with Mendel’s expectations”), presenting Fisher’s and Anderson’s Iris data [a motive for rejection when George was JASA editor!] as a “a new classic experiment”, mentioning Pearson but not Lee for the data in the 1903 Biometrika paper “On the laws of inheritance in man” (and woman!), and not accounting for the discrete nature of this data in the linear regression chapter, the three page derivation of the Gaussian distribution from a Taylor expansion of the Binomial pmf obtained by differentiating in the integer argument, spending endless pages on deriving standard properties of classical distributions, this appalling mess of adding over the conditioning atoms with no normalisation in a Poisson experiment

$P(X=4|\mu=0,1,2) = \sum_{\mu=0}^2 \frac{\mu^4}{4!}\exp\{-\mu\}$,

botching the proof of the CLT, which is treated before the Law of Large Numbers, restricting maximum likelihood estimation to the Gaussian and Poisson cases and muddling its meaning by discussing unbiasedness, confusing a drifted Poisson random variable with a drift on its parameter, as well as using the pmf of the Poisson to define an area under the curve (Fig. 5.2), sweeping the improperty of a constant prior under the carpet, defining a null hypothesis as a range of values for a summary statistic, no mention of Bayesian perspectives in the hypothesis testing, model comparison, and regression chapters, having one-dimensional case chapters followed by two-dimensional case chapters, reducing model comparison to the use of the Kolmogorov-Smirnov test, processing bootstrap and jackknife in the Monte Carlo chapter without a mention of importance sampling, stating recurrence results without assuming irreducibility, motivating MCMC by the intractability of the evidence, resorting to the term link to designate the current value of a Markov chain, incorporating the need for a prior distribution in a terrible description of the Metropolis-Hastings algorithm, including a discrete proof for its stationarity, spending many pages on early 1990’s MCMC convergence tests rather than discussing the adaptive scaling of proposal distributions, the inclusion of numerical tables [in a 2017 book] and turning Bayes (1763) into Bayes and Price (1763), or Student (1908) into Gosset (1908).

[Usual disclaimer about potential self-plagiarism: this post or an edited version of it could possibly appear later in my Books Review section in CHANCE. Unlikely, though!]

## Gideon the Ninth [book review]

Posted in Statistics with tags , , , , , , , , on May 8, 2020 by xi'an

After much hesitation and pondering, I eventually gave in and started reading Gideon the Ninth by Tamsyn Muir, and then rushed through it over the first of May extended weekend! Hesitation and pondering, because I am not particularly excited in zombie novels and animate skeletons literature and living dead books. However, since the book was getting a lot of praise from reading groups and ended up a Hugo Awards 2020 Nominee, I ordered the 2€ Kindle version and got to read it, being immediately caught by the irreverent tone of the main character and the punk style of the story, which mixes necromancy, death cults, living gods, space travel, chivalrous quest, sword mystique, AIs, deadly puzzles à la Hunger Games, and a whodunit à la Agatha Christie, Then There Were None on an island planet… (Although I have never been a fan of Christie’s novels either, reading some eons ago as an unsuccessful way to improve my appalling English skills in secondary school). The book gets addictive because of this highly unusual combination, plus the compelling story and relation of the two central teenage girls, turning away from murderous to loving, once all skeletons are out of the closet (literally). There are enough complex and un-charicatur-esque characters to make the structure and the whodunit puzzle very enjoyable, with unexpected twists and a massively enjoyable ending. To think that this is a first novel is staggering, with highly funny dialogues for Death believers. Definitely worth the read (and the vote for the Hugo Award!) And the second volume is coming out next August. (But the first Act is available for free on kindles.)

## Gagner la guerre

Posted in Books, pictures with tags , , , , , , , , , , , , , , , , on May 2, 2020 by xi'an

Within a few sunny days of being consigned at home [by the “war” against the epidemics], I went through Jaworski’s Gagner la Guerre [To the victors go the spoils], which I had discovered in the list of the 101 favourite novels of Le Monde readers (or rather of whoever replied to the call since the survey was not restricted to Le Monde subscribers).  While I still have no clue how the book ended up at the 67th position in the list (!), next to Yourcenar’s fabulous L’Œuvre au Noir, I am still glad that this list pointed out the very existence of this book. Although not much more enlightened as to whom would include it in the “best novels ever”. (Warning: As the novel has not been translated from French into other languages, the review  below may be of limited appeal to most readers!)

A possible explanation for this paradox is that Jaworski is originally a creator of role-playing games and hence famous among some role-playing communities as well, who could have mobilized efficiently enough to bring him within the 101. The plot shows some influence of this role-playing expertise as the central character, a despicable, violent, sexist, xenophobic, rapist, murderous, anti-hero Benvenuto, moves from one danger to the next, while visiting the continent imagined by the author and meets characters from one fantasy race after the other: elves, dwarfs, near-orcs. Reminding me very much of the races in Warhammer, since fighting styles associated with each conveniently identified the different parts of the country. The home town of Benvenuto is a mix of Italian Renaissance state-cities, between Sienna and Venezia. Run by a Senate of rich families, fighting a Southern kingdom closely resembling the Ottoman empire, as in Guy Gavriel Kay’s Children of Earth and Sky. If in a much grittier style. It also reminded me of the fabulous Scott Lynch’s Gentlemen Bastards series, incl. Republic of Thieves. Sorcery is also involved here, whose role only appears progressively throughout the novel. Despite my usual annoyance at this choice, the writing style of the author, who also is a teacher of French literature in high school, always a first person narrative, ends up being a strength of the book, involving a rich multitude of language levels, from the vernacular to the antique, revealing as well a multitude of layers in Benvenuto (who finds himself anything but welcome from most places he visits!, including my living-room!!). None of them palatable however. To be perfectly clear, the book is an addictive page turner, despite an accumulation of details that sometimes delay the action, but which are nonetheless essential to make the book universe more substantial and complex. Highly recommended for French-speaking fans of grimdark pseudo-historical fantasy (over the legal age)!