Martin Bridson

Subgroups of direct products of free, surface and limit groups

The subgroups of direct products of free and surface groups are
remarkably diverse in nature. Interest in understanding them is
heightened by a theorem of Delzant and Gromov that shows such
subgroups play an important role in the understanding of Kahler
groups. In a different direction, it is natural to explore the extent
to which results about subdirect products of free and surface groups
can be explained (and extended) in the context of subdirect products
of limit groups (in the sense of Sela).

I shall begin this talk with a brief survey of what is known in this
area, outlining a programme to understand all such subdirect
products. I shall then concentrate on a recent construction of myself,
Howie, Miller and Short that provides a novel class of examples that
are in a certain sense "typical" (but quite different from what was
known previously).