Lie Groups and Representation Theory Seminar
[ Seminar 2019  Past Seminars  Related conferences etc. ]
Upcoming talks
 
 集中講義 intensive lectures (数理科学特論VIII) 
Date: 
Oct 3, 10, 17, 24, 31, Nov 7, 14, 21, 28, 2019, 13:0014:45 
Place: 
Room 128, Graduate School of Mathematical Sciences, the University of Tokyo 
Speaker: 
Yves Benoist (CNRS, Université ParisSud) 
Title: 
Kleinian groups 
Abstract:

Kleinian groups are discrete groups of isometries of the hyperbolic
space.
We will study both subgroups of finite and infinite covolume.
Here are a few aspects that we will discuss:
 The hyperbolic space, its boundary and its isometries.
 Construction of discrete subgroups and lattices.
 Limit set, convex cocompact subgroups and autosimilar fractal sets.
 Hausdorff dimension, critical exponent and spectrum of the Laplacian.

 
 談話会 Colloquium 
Date: 
Oct 25, 2019, 15:3016:30 
Place: 
Room 123, Graduate School of Mathematical Sciences, the University of Tokyo 
Speaker: 
Yves Benoist (CNRS, Université ParisSud) 
Title: 
Arithmeticity of discrete subgroups 
Abstract:

By a theorem of Borel and HarishChandra,
an arithmetic group in a semisimple Lie group is a lattice.
Conversely, by a celebrated theorem of Margulis,
in a higher rank semisimple Lie group G
any irreducible lattice is an arithmetic group.
The aim of this lecture is to survey an
arithmeticity criterium for discrete subgroups
which are not assumed to be lattices.
This criterium, obtained with Miquel,
generalizes works of Selberg and Hee Oh
and solves a conjecture of Margulis. It says:
a discrete irreducible Zariskidense subgroup
of G that intersects cocompactly at least one
horospherical subgroup of G is an arithmetic group.

Past seminars
© Toshiyuki Kobayashi