
Grothendieck’s gribouillis (4)
Fortunately, there are a few certainties left in life: In spring, you might expect the next instalment of Connes’ and Consani’s quest for Gabriel’s topos. Here’s the latest: $\overline{\mathbf{Spec}(\mathbb{Z})}$ and the Gromov norm. Every half year or so, Mochizuki’s circleoffriends tries to create some buzz announcing the next IUTeichworkshop. I’ll spare you the link, if […]

the Riemann hypothesis and 5040
Yesterday, there was an interesting post by John Baez at the ncategory cafe: The Riemann Hypothesis Says 5040 is the Last. The 5040 in the title refers to the largest known counterexample to a bound for the sumofdivisors function \[ \sigma(n) = \sum_{d  n} d = n \sum_{d  n} \frac{1}{d} \] In 1983,…

G+ recovery 6 : mathhistory
In April my Google+ account will disappear. Here I collect some G+ posts, in chronological order, having a common theme. Today, mathhistory (jokes and puns included). September 20th, 2011 Was looking up pictures of mathematicians from the past and couldn’t help thinking ‘Hey, I’ve seen this face before…’ Leopold Kronecker = DSK (2/7/2019 : DSK…

G+ recovery 5 : #IUTeich (3)
The final part, starting with a reaction of Mochizuki himself on my previous IUTeichposts. July 7th, 2013 Mochizuki update While i’ve been away from G+, someone emailed Mochizuki my last post on the problem i have with Frobenioids1. He was kind enough to forward me M’s reply: “There is absolutely nothing difficult or subtle going…

G+ recovery 4 : #IUTeich (2)
Here’s batch 2 of my old google+ posts on ‘Inter Universal Teichmuller theory’, or rather on the number theoretic examples of Frobenioids. June 5th, 2013 Mochizuki’s categorical prime number sieve And now for the interesting part of Frobenioids1: after replacing a bunch of arithmetic schemes and maps between them by a huge category, we will…

G+ recovery 3 : #IUTeich (1)
Perhaps the ‘hottest’ topic I got involved with on Google+ was Mochizuki’s (claimed) proof of the ABCconjecture. Rereading these posts in chronological order shows my changing attitude to this topic, from early skepticism, over attempts to understand at least one preIUTeich paper (Frobenioids 1) to a level of belief, to … resignation. Here’s the first…

G+ recovery 2 : Grothendieck
My Google+ account is going away on April 2, 2019, so i’ll try to rescue here some posts, in chronological order and around one theme. Here’s Grothendieckstuff, part two. March 18th, 2014 crowdfunding Grothendiecks biography? +John Baez has a post out at the ncatcafe on Leila Schneps’s quest to raise $6000 to translate Scharlau’s 3volume…

G+ recovery 1 : Grothendieck
My Google+ account is going away on April 2, 2019, and all attempts to automatically backup my G+ posts seem to fail so far. So i’ll try to rescue here some of them, in chronological order and around one theme. Today, Grothendieckstuff, part one. May 30th, 2013 Recordings of a 1972 talk by Grothendieck at…

Rarer books: Singmaster’s notes
David Singmaster‘s “Notes on Rubik’s magic cube” are a collectors item, but it is still possible to buy a copy. I own a fifth edition (august 1980). These notes capture the Rubik craze of those years really well. Here’s a Conway story, from Siobhan Roberts’ excellent biography Genius at Play. The ICM in Helsinki in…

Grothendieck, at the theatre
A few days ago, the theatre production “Rêves et Motifs” (Dreams and Motives) was put on stage in Argenteuil by la Compagnie Les Rémouleurs. The stage director Anne Bitran only discovered Grothendieck’s life by reading the front pages of French newspapers, the day after Grothendieck passed away, in November 2014. « Rêves et Motifs »…