
Grothendieck talks
In 201718, the seminar Lectures grothendieckiennes took place at the ENS in Paris. Among the speakers were Alain Connes, Pierre Cartier, Laurent Lafforgue and Georges Maltsiniotis. Olivia Caramello, who also contributed to the seminar, posts on her blog Around Toposes that the proceedings of this lectures series is now available from the SMF. Olivia’s blogpost […]

Huawei and topos theory
Apart from the initiatives I mentioned last time, Huawei set up a long term collaboration with the IHES, the Huawei Young Talents Program. “Every year, the Huawei Young Talents Program will fund on average 7 postdoctoral fellowships that will be awarded by the Institute’s Scientific Council, only on the basis of scientific excellence. The fellows…

Huawei and French mathematics
Huawei, the Chinese telecom giant, appears to support (and divide) the French mathematical community. I was surprised to see that Laurent Lafforgue’s affiliation recently changed from ‘IHES’ to ‘Huawei’, for example here as one of the organisers of the Lake Como conference on ‘Unifying themes in geometry’. Judging from this short Huaweiclip (in French) he…

Lockdown reading : SNORT
In this series I’ll mention some books I found entertaining, stimulating or comforting during these Corona times. Read them at your own risk. This must have been the third time I’ve read The genius in by basement – The biography of a happy man by Alexander masters. I first read it when it came out…

Escher’s stairs
Stairways feature prominently in several drawings by Maurits Cornelis (“Mauk”) Escher, for example in this lithograph print Relativity from 1953. Relativity (M. C. Escher) – Photo Credit From its Wikipedia page: In the world of ‘Relativity’, there are three sources of gravity, each being orthogonal to the two others. Each inhabitant lives in one of…

Princeton’s own Bourbaki
In the first half of 1937, Andre Weil visited Princeton and introduced some of the postdocs present (notably Ralph Boas, John Tukey, and Frank Smithies) to Poldavian lore and Bourbaki’s early work. In 1935, Bourbaki succeeded (via father Cartan) to get his paper “Sur un théorème de Carathéodory et la mesure dans les espaces topologiques”…

Cambridge, spring 1939
One of the few certainties we have on the BourbakiPetard wedding invitation is that it was printed in, and distributed out of Cambridge in the spring of 1939, presumably around mid April. So, what was going on, mathematically, in and around Trinity and St. John’s College, at that time? Well, there was the birth of…

the Bourbaki code revisited
The fictitious life of Nicolas Bourbaki remains a source of fascination to some. A few weeks ago, Michael Barany wrote an article for the JStor Daily The mathematical pranksters behind Nicolas Bourbaki. Here’s one of the iconic early Bourbaki pictures, taken at the Dieulefitmeeting in 1938. More than a decade ago I discovered the exact…

Ghost metro stations
In the strange logic of subways I’ve used a small part of the Parisian metromap to illustrate some of the biHeyting operations on directed graphs. Little did I know that this metromap gives only a partial picture of the underground network. The Parisian metro has several ghost stations, that is, stations that have been closed…

Witt and his Niemeier lattices
Sunday, January 28th 1940, Hamburg Ernst Witt wants to get two papers out of his system because he knows he’ll have to enter the Wehrmacht in February. The first one, “Spiegelungsgruppen und Aufzählung halbeinfacher Liescher Ringe”, contains his own treatment of the root systems of semisimple Lie algebras and their reflexion groups, following up on…