Hyperbolic and elliptic commensurations

Abstract: A group $G$ is said to commensurate a subgroup $H$, if for all $g$ in $G$, the intersection $H^g \cap H$ has finite index in both $H$ and $H^g$. (Here $H^g$ denotes the conjugate of $H$ by $g$.) The commensuration action of $G$ on $H$ can be studied dynamically. This gives rise to two extreme behaviours: hyperbolic and elliptic. We will discuss what these mean and survey a range of theorems and conjectures in this context, starting with work of Mostow and Margulis, and coming to the present day.

algebraic topologydifferential geometrydynamical systemsgroup theorygeometric topologysymplectic geometry

Audience: researchers in the topic

Geometry and topology online

Series comments: You can also find up-to-date information on the seminar homepage - warwick.ac.uk/fac/sci/maths/research/events/seminars/areas/geomtop/

The talks start at 13:30. Talks are typically fifty minutes long, with ten minutes for questions.