Schlomo Cohen

Quite a few years back, when I was finishing the (in)famous Classes préparatoires, I started writing a series of stories entitled Les fabuleuses aventures de Schlomo Cohen le Mathématicien détective (“The Wonderlous Adventures of Schlomo Cohen, Detective-Mathematician”); after finishing four texts ranging in length from a short story to a modestly-sized novel, this ended around 1994 when I really didn’t have time anymore for the type of imaginative concentration needed for even my level of fiction-writing.

As the title already suggests, there was a strong influence of British-style super-detective crime fiction when I started, based on reading too much Sherlock Holmes and Agatha Christie when I was a few years younger. Indeed, Schlomo Cohen is said to be “the best non-fictional private detective in London”. However, the third, and longest, story, concludes in Los Angeles with a clear debt to R. Chandler, since P. Marlowe makes his appearance, showing at least some improvement in stylistic debt over the years, and the last one is full of direct or indirect quotations of “The Waste Land”…

The other two obvious characteristics are that the hero, the superior detective S. Cohen, is (1) a mathematician; (2) Jewish. The second part may seem somewhat strange (I am not Jewish myself), and is due mostly to the twin influences of I. Bashevis Singer and W. Allen when I started writing the stories (in fact, S. Cohen is theoretically quite orthodox, quoting the Talmud and other sacred texts rather freely, and his mother, Masha Cohen, plays a big part in the last three stories).

The first characteristic (mathematics) is of course more understandable, and was for me the source of much of the fun in writing the stories. The first idea, as far as I remember, was to use sophisticated plots carefully designed so that insights from great theorems and their proofs would be genuinely useful to solve the mysteries S. Cohen was confronted with. This was quickly replaced with essentially completely random associations d’idées, which (quite obviously) make no sense whatsoever, but which nevertheless lead S. Cohen to the guily partie(s).

Here are the main mathematical results Schlomo Cohen claims led him to solve the outstanding problems of the age:

  • Some theorems of Church on ultrapowers (which I don’t remember at all!) in Le vol du traité secret (“The theft of the secret treaty”);
  • The Hahn-Banach theorem in De la banane dans le Bourgogne (“Banana in Burgundy”);
  • The theory of Lefschetz pencils, van der Waerden’s theorem on finite colorings of the integers, Riemannian geometry, in Schlomo Cohen contre les maîtres criminels (“Schlomo Cohen against the master criminals”);
  • Non-euclidean geometry, in Le traducteur subreptice (“The surreptitious translator”).

Quite a few other results are discussed, and they mostly show what type of mathematics I was learning (and finding striking!) at the time.

I am mentioning this today mostly because I have just discovered that the second story (“Banana in Burgundy”) has become part of a (semi?) official bibliography of works about Bourbaki (look at “Anonymes” as author). The point is that, in this particular story, I envision Schlomo Cohen as a great friend of André Weil, so much so that he is invited to attend the first Bourbaki Congress, in Burgundy. There, terrible events occur, involving a conspiration against the wines of Burgundy, the French constabulary, and the transformation of all but one of the Bourbakists into amateur detectives…

People more knowledgeable about the history of Bourbaki than I was at the time will of course realize that the date, place and much else doesn’t make any sense at all, but still, even today, I find pleasure in re-reading the exchanges I wrote between mathematicians, and I think they are quite realistic in a way. Indeed, I feel flattered that the bibliography above says that the story is a Récit plaisant et fantaisiste qui décrit tout de même le groupe Bourbaki de façon réaliste (“A pleasant whimsical story which nevertheless describes realistically the Bourbaki group”).

The story, if you want to read it (it’s in French), is online here (search for “Humour”). Note that most of it does not involve Bourbaki at all; for the best parts, you can look around page 26, up to 44 or 45.

I should say that I had put the stories anonymously on the internet a few years ago (except the first one, which was really too embarrassing to my mind), and this is where the authors of the bibliography must have found it. The third story is therefore also available on this original site (if you look for it a bit)… But from a literary point of view, and indeed also plot-wise, the fourth and last one, Le traducteur subreptice is by far the best. There one finds all ingredients for a smashing hit: Masha Cohen’s theory of “Golems of the second kind”; Schlomo’s monograph on “The babylonian Talmud considered as a formal system”; the beautiful daughter of a mysterious Jesuit Father and her sulfurous thesis, “The judicial arsenal of the Spanish Inquisition”; the Vermont senator Philip P. Mark and his erstwhile English revolutionary friends; and the mysterious criminal of the title, whose devious deed is to replace the original manuscript of “The Waste Land” with a French translation… (One also learns in passing that S. Cohen wrote his thesis under the direction of J.E. Littlewood, on “A refinement of the circle method with applications to Waring’s problem”; in “Banana in Burgundy”, on the other hand, he is said to have interesting results concerning torsion points of elliptic curves).

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I am a professor of mathematics at ETH Zürich since 2008.

4 thoughts on “Schlomo Cohen”

  1. If I may recommend a book for someone who read this novel and liked it, that would be : “Leeches” of David Albahari, a french translation is published by Gallimard. Both have many subjects in common, but I must admit that the later is much more versed in psychology /self introspection, and has very little if not erroneous mathematical references.

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