Mon, December 4, 2023
Public Access

Category: All

December 2023
Mon Tue Wed Thu Fri Sat Sun
        1 2 3
4 5 6 7 8 9 10
11 12 13 14 15 16 17
18 19 20 21 22 23 24
25 26 27 28 29 30 31
11:00am [11:30am] Nitin Nitsure,  TIFR Mumbai (retd)

Mathematics Seminars and Colloquia

4 December 2023- 9 December 2023


Lecture series on algebraic stacks

Monday, 4th December, 11:30 am

Host: Sudarshan Gurjar

Venue: Ramanujan Hall

Speaker: Nitin Nitsure, TIFR (retd)

Title: Gerbes and their cohomology classes

Abstract: Locally trivial fiber bundles can be described by their transition functions, giving a class in the first Cech cohomology of the structure group. Gerbes can be regarded as a `higher' version of this twisting phenomenon. The local description of a gerbe gives rise to a class in the second Cech cohomology of the base with coefficients in the `band' (lien in French) of the gerbe. This description of the cohomology class of a gerbe is particularly simple when the band is abelian, which is the case we will describe in this talk. The cohomological Brauer class of Azumaya algebra (or of a projective bundle) is an example of such a cohomological class.

1:00pm [1:30pm] Yves Colin de Verdière, Fourier Institute, CNRS, University of Grenoble I

Analysis seminar
Monday 4 Dec, 2023, 1:30 pm - 2:30 pm


Venue: Meeting ID: 835 4823 3902, Passcode: 585182

Join Zoom Meeting

Host: Chandan Biswas

Speaker: Yves Colin de Verdière

Affiliation: Fourier Institute, CNRS, University of Grenoble I

Title: On the spectrum of the Poincaré operator in ellipsoids.

Abstract: The Poincaré equation describes the motion of an incompressible fluid in a domain submitted to a rotation. The associated wave operator is called the "Poincaré operator". If the domain is an ellipsoid, it was observed by several physicists that the spectrum is a pure point with polynomial eigenfields. I will give conceptual proof of this fact and an asymptotic result on the eigenvalues.