Coarse rigidity for Teichm\"uller space

15 June 2015
Brian Bowditch
We describe some results regarding the quasi-isometric rigidity of
Teichm\"uller space in either the Teichm\"uller metric or the Weil-Petersson
metric; as well as some other spaces canonically associated to a surface.
A key feature which these spaces have in common is that they admit
a ternary operation, which in an appropriate sense, satisfies the
axioms of a median algebra, up to bounded distance.  This allows
us to set many of the arguments in a general context.
We note that quasi-isometric rigidity of the Teichm\"uller metric has recently
been obtained independently by Eskin, Masur and Rafi by different methods.