London Algebra Colloquium abstract
Subgroups of finite index and the just infinite property
Colin D. Reid (Queen Mary), 8th October 2009
Abstract
An infinite residually finite (profinite) group G is just infinite
if every non-trivial (closed) normal subgroup is of finite index,
and hereditarily just infinite if every subgroup of finite index is
just infinite. But which subgroups of finite index need to be just infinite to
ensure that all of them are? I will present a partial answer to this
question, after a brief overview of the basic types of just infinite groups
and why they are of interest.