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Details of talk

TitleExtending Margulis' Normal Subgroup Theorem to Commensurated Subgroups
PresenterGeorge Willis (The University of Newcastle)
Author(s)Prof George Willis
Time14:30:00 2016-12-08

Margulisí Normal Subgroup Theorem asserts that higher-rank arithmetic groups
have few normal subgroups, for example, every normal subgroup of
$SL(N,\mathbb{Z})$ is either finite or have finite index. Joint work with Yehuda
Shalom extends this theorem to commensurates subgroups, that is, subgroups $N$
of $\Gamma$ such that $gNg^{-1}$ has finite index in both $N$ and $gNg^{-1}$ for
every $g$ in $G$. The proof reduces to problem to Margulisí Theorem and the talk
will explain the main ideas in the reduction.