Seminar series
Date
Mon, 16 Feb 2015
15:45
15:45
Location
L6
Speaker
John M. Mackay
Organisation
Bristol
Building a suitable family of walls in the Cayley complex of a finitely
presented group G leads to a nontrivial action of G on a CAT(0) cube
complex, which shows that G does not have Kazhdan's property (T). I
will discuss how this can be done for certain random groups in Gromov's
density model. Ollivier and Wise (building on earlier work of Wise on
small-cancellation groups) have built suitable walls at densities <1/5,
but their method fails at higher densities. In recent joint work with
Piotr Przytycki we give a new construction which finds walls at densites
<5/24.