Archive for the ‘blogging’ Category

Long pause

March 3, 2017

[Posted on march 3, 2017.]

Due to very little spare time on the horizon, this blog will not be updated for several months (until august, probably). All comments will be stuck in the moderation sandbox.

Hubble Chases a Small Stellar Galaxy in the Hunting Dog,

by NASA Goddard Space Flight Center



September 14, 2015

This blog goes into a long hibernation of several months.  It might come back to life in 2016.  Any comment will stay into the moderation queue in the meantime.

Château d’Amboise under snow and ice.

Alternative title : the snow triangle.

(February 2012, CC BY-NC-SA 2.0).

Cédric Villani’s book tour (cont’d), and a remarkable student

April 2, 2015

After his UK tour, Cédric Villani will apparently later this month tour the US  (incidentally, it is mathematics awareness month there).

I’ve noticed events occuring in New York City (15th), Seattle (16th), San Francisco (20th), Minneapolis (22nd), Cambridge MA (24th), and perhaps at other places.

While searching for these I came accross a remarkable interview (published today) of Thomas Mordant, a very young and talented french student (4 years ahead of normal age), who happens to have Osteogenesis Imperfecta, has met Villani, and plans to become a mathematician.

Bon courage à lui pour les prochaines épreuves de Normale Sup!

Edit (21 july 2015): the results are out, and well done to him! Ulm at 16 is not so common, an Auroux-esque feat!

The most expensive french integer is 1

March 15, 2015

The first ever domain name was recorded in 1985 (see this very nice infographics for a timeline from then to 2015).

Until recently, the historical TLDs (whether gTLDs like .com .org .net, or ccTLDs like .fr did not offer single character names : most single characters names of gTLDs were reserved in 1993 by IANA, and all 1 & 2 characters names of ccTLDs were too by their respective operators.

But in 2008 ICANN initiated a program to allow new TLDs, and 1930 applications met a 2011 deadline, which resulted in the approval of several hunded ones.

This meant that new money was about to pour in from investors vying for marketable names, especially short ones.  Perhaps as a result, in october 2009 single-characters names of .de  were made available, and snapped-up.

The period 2014-2015 sees many of the aforementioned new TLDs start selling domains in the usual three phases (sunrise, landrush, public), and some of them (a minority thought) are allowing single-characters names.

With the renewed interest in domain names, in 2014 the .fr operator afnic opened a similar procedure to sell 1 and 2 character names (with proceeds going to some public funds to reduce inequalities in France).  Afnic decided to price the 4 weeks of the landrush phase in a degressive manner : the first week each domain cost 15,000€ excluding VAT, the second they cost 10,000€, the third they were set at 5,000€, and the final week at 100€ (the next phae being at the public price, a few euros).  Of course, most people buy their domain name through a registrar, which means some extra costs.

I was obviously interested in buying a number like or name like and set my sight on the last week of landrush, which opened march, 9 at 12:00 Paris time.  The only number to have gone in a previous week was, for 5,000€, making it the most expensive french number.

When the moment arrived,  I was all set, and made my first order at 12:00:05. Already bought! Wow, tried several other numbers, all already gone!  Some controversy quickly erupted on twitter, with several users noticing that some registrars (specialized in the resale of domain names) had placed orders up to a full 30 minutes before the deadline.  Not fair indeed, and to the credit of Afnic these orders were swiftly canceled with the 311 corresponding names back for sale on the wednesday (and the culprits blacklisted)…only for other similar registars to buy them all within a few seconds after the start time. Lots of ordinary people interested in simply getting their initials or a number got disapointed.

So, except for, all domains from to will have their price set up on the secondary market, but I doubt they’ll top 🙂

Summer hiatus

July 6, 2014

Patrimonio, by Daniel Cremona on flickr


September 14, 2013

This blog will probably go extinct for the next 6 months ; in particular, all comments will have to go to the moderation queue.

In the meantime, here is barred spiral galaxy NGC 1300

(from NASA’s Goddard Space Flight Center on flickr)

Two summer polls

July 26, 2013

To test the Poll tool, here are a few semi-serious questions and answers.

Normally, things are set up to hide results and block repeat voters with both cookies and IP filtering. I’ll probably reveal the results in a month time when the polls close.

In both poll you should be able to pick several answers, if so inclined.

Here’s the first one:

And here’s the second one:

Update (august 27, 2013): I’ve now closed the polls, and it’s clear this corner of the web is not really visited at all, especially in august. Indeed, there’s been only 4 votes on each poll, and each one for a different answer. Thanks to those who voted, but no statistically significant result can be drawn from them, which ends this little experiment.

Revue de “Petite Initiation aux Mathématiques”, de Timothy Gowers

October 13, 2011

Il y a quelques jours, je déambulais chez un libraire, passant nonchalamment devant le présentoir des nouveautés du mois pour me diriger vers les romans. Mais, d’un coup d’œil furtif et accidentel audit présentoir, je remarque un titre tout à coup qui m’interpelle: Petite Initiation aux Mathématiques, publié tout récemment le 30 septembre.

Tiens, quelle drôle de couverture pour un livre de maths, me dis-je… Je regarde l’auteur: c’est le célèbre Tim Gowers, là, entre La médecine pour les nuls et L’officiel des prénoms!   Je me souviens alors d’un livre publié en 2002, la version anglaise originale, et que je n’avais pu me procurer à l’époque. Mais j’avais beaucoup apprécié le style de Gowers par ailleurs (ses fabuleuses undergraduate discussions, son texte plus philosophique sur “les deux cultures” — fort bienvenu de la part d’un mathématicien actif), il y avait donc tout lieux de penser que ce livre devait être agréable à lire également. Avec une traduction de Jean-Louis Basdevant, auteur de bons livres de physique, je suis convaincu, j’achète (et à 15€ c’est abordable).

Et bien, il tient toutes ses promesses!  Dans la préface, Gowers a semble-t-il en tête de s’adresser à des lecteurs, non-mathématiciens, qui sont curieux de découvrir d’une manière informelle comment on invente des maths nouvelles.  Je pense qu’effectivement le pari est gagné: en particulier, si vous êtes un(e) lycéen(e) de première S ou Terminale S, et que vous vous destinez à des études scientifiques, je vous le recommande chaudement. Le style est clair, les connaissances requises sont celles du lycée uniquement, et les thèmes abordés intéressants pour vos futures études, alors n’hésitez pas une seconde! (Et si 15€ c’est trop cher, allez voir les responsables de votre CDI pour leur suggérer de l’acheter, ou bien ceux de la bibliothèque/médiathèque de votre coin).  Le livre convient également tout à fait aux étudiants plus littéraires, notamment les philosophes (après s’être fait un petit rappel de juste quelques notions de base: nombres premiers, etc.).

La seule chose que je veux mentionner, c’est un ajout de taille à la liste de références historiques et philosophiques en fin d’ouvrage: pour ceux qui s’intéressent vraiment aux maths, il existe un ouvrage unique, également écrit par Gowers et deux co-auteurs, le Princeton Companion to Mathematics (voir aussi les listes d’errata si vous l’achetez: ici ,   et ), sorte d’encyclopédie moderne des maths pour l’étudiant(e) passionné(e), une splendeur.

Gowers est depuis quelques années un bloggeur régulier, et, sans surprise,  très intéressant. Il a notamment commencé récemment  une série d’articles (en anglais bien sûr) qui aborde les premières notions de mathématiques que l’on rencontre dans le supérieur (math sup ou L1: les connecteurs logiques, etc.), et que je recommande aux étudiants qui comprennent bien la langue anglaise (ou quitte à le traduire pour vous, mais sans faire de contresens!).

In six months time…

July 9, 2007

Stating the obvious: since many nice blogs by grad students and/or recent math PhDs have popped up recently and since there’s no reason for this trend to slow down (all the more since there seems to be nobody from places like Harvard, Orsay, Tokyo, Princeton, Oxford, etc. yet and surely they’ll join in), well my guess is that in, say, six months time, there will be way too much interesting stuff to read per day than is humanely possible.

And at that point this will mean people will have to choose carefully which blogs to read or not to, just to have a chance of catching up with what goes on there while still devoting most of a day on one’s own work. Put differently, we will need a kind of generic math blog server akin to the arxiv which would collect all known feeds and were new bloggers would submit theirs, rather than us blog readers having to manually search new feeds for our aggregators.

Am I right? If so there seems to be little chance that the arxiv could offer this since already for trackbacks things are quite experimental and require some manual control. So: where and who could set up this math blog referencing tool?

Other things that can be anticipated: enthusiastic grad students speaking too much about their unpublished projects and seeing a few weeks later somebody with a preprint exactly about that… What else? An environment which would help ideas to cross from one area to another faster and more easily than 30 years ago. But stronger trends/buzzwords effects too, probably.