Category: stories

  • Cambridge, spring 1939

    One of the few certainties we have on the Bourbaki-Petard 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 Dieulefit-meeting 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 metro-map to illustrate some of the bi-Heyting operations on directed graphs. Little did I know that this metro-map 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…

  • the bongcloud attack

    In this neverending pandemic there’s a shortage of stories putting a lasting smile on my face. Here’s one. If you are at all interested in chess, you’ll know by now that some days ago IGMs (that is, international grandmasters for the rest of you) Magnus Carlsen and Hikaru Nakamura opened an official game with a…

  • Teapot supremacy

    No, this is not another timely post about the British Royal family. It’s about Richard Borcherds’ “teapot test” for quantum computers. A lot of money is being thrown at the quantum computing hype, causing people to leave academia for quantum computing firms. A recent example (hitting the press even in Belgium) being the move of…

  • Lockdown reading : Penumbra

    In this series I’ll mention some books I found entertaining, stimulating or comforting during these Corona times. Read them at your own risk. It’s difficult to admit, but Amazon’s blurb lured me into reading Mr. Penumbra’s 24-Hour Bookstore by Robin Sloan: “With irresistible brio and dazzling intelligence, Robin Sloan has crafted a literary adventure story…

  • The strange logic of subways

    “A subway is just a hole in the ground, and that hole is a maze.” “The map is the last vestige of the old system. If you can’t read the map, you can’t use the subway.” Eddie Jabbour in Can he get there from here? (NYT) Sometimes, lines between adjacent stations can be uni-directional (as…

  • Lockdown reading : the Carls

    In this series I’ll mention some books I found entertaining, stimulating or comforting during these Corona times. Read them at your own risk. An Absolutely Remarkable Thing (AART for the fans) by Hank Green came out in 2018, and recently I reread it when its sequel A Beautifully Foolish Endeavor appeared last summer. “Protagonist April…

  • Richard Borcherds on Witt and the Leech lattice

    A rare benefit of the Covid-situation is that Richard Borcherds decided to set up a YouTube channel with recordings of his online lectures. Plenty of gems to be discovered there, including a talk on Monstrous Moonshine, and a talk he gave for the Archimedeans about the Sporadic Groups. As part of his History of Science-course…