# Jerusalem Mathematics Colloquium

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Thursday, 6th December 2001, 4:00 pm

Mathematics Building, Lecture Hall 2

##

Alex Lubotzky

(Jerusalem)

"Counting congruence subgroups"

** Abstract: **

"Subgroup growth" deals with counting finite index subgroups
of a group. This theory led to counting congruence subgroups in
arithmetic groups. The latter counting is a kind of "non-commutative
analytic number theory" where "counting primes" on one hand and
delicate finite group theory, on the other hand, are combined.

We will present the main counting results, applications to group
theory and a connection with the congruence subgroup problem and
the structure of the fundamental groups of hyperbolic manifolds.

Coffee, Cookies at the faculty lounge at 3:30.

List of talks, 2001-02

List of talks, 2000-01

List of talks, 1998-99

List of talks, 1997-98