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L^p-compression and equivariant compression for Baumslag-Solitar groups


Speaker: Alain Valette, Unversity of Neuchatel, Switzerland
Location: 2112 MSB
Start time: Fri, Oct 14 2011, 3:10PM

Let BS(m,n) be a Baumslag-Solitar group. We show that the metric L^p-compression rate of BS(m,n) is 1, while the equivariant L^p-compression rate of BS(m,n) is 1/\min{p,2}, except in the virtually abelian case. The proof goes by embedding BS(m,n) equivariantly and in a bi-Lipschitz way into the product of a tree and a plane with constant nonpositive curvature. This is joint work with Y. Cornulier and D. Dreesen.