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Category Archives: Mathematics

Bourbaki seminar online

Whenever I can, I like to attend the Bourbaki Seminar in Paris, but that’s not always feasible. Of course, even without being present, the written text of the seminar is always available later to learn what the talks were about. But, especially when the subject is not close to something I know, it’s often much […]

Leo’s first theorem

I learnt the following from my son Léo: the teacher asks to compute ; that’s easy But no! The actual question is to compute times ! We must correct this! But it’s just as easy without starting from scratch: we turn the “plus” cross a quarter turn on the left-hand side: and then switch the […]

Chicheley Hall meeting

Just after the end of the semester last week, I went to a short meeting organized by J. Keating, Z. Rudnick and T. Wooley, in the stately English house of Chicheley Hall, where the Royal Society has a conference center. This was quite a fun occasion, and not only because the curtains had one the […]

Is the Kierkegaardian idea true? and other queries

In February, I was invited to give talks in Bristol and Oxford, and I spent the night after the second talk in a guest room of Worcester College. While looking at the brochure explaining the history of this college, I noticed that a previous guest had left a cryptic inscription, which I took a photograph […]

The discrete spectrum is discrete

No, this post is not an exercise in tautological reasoning: the point is that the word “discrete” is relatively overloaded. In the theory of automorphic forms, “discrete spectrum” (or “spectre discret”) is the same as “cuspidal spectrum”, and refers to those automorphic representations (of a given group over a given global field ) which are […]