Integrable measure equivalence and the central extension of surface groups

  • Kajal Das

    École Normale Supérieure de Lyon, France
  • Romain Tessera

    Université Paris-Sud, Orsay, France

Abstract

Let Γg\Gamma_g be a surface group of genus g2g \geq 2. It is known that the canonical central extension \wtildeΓg\wtilde{\Gamma}_g and the direct product Γg×Z\Gamma_g\times \mathbb Z are quasi-isometric. It is also easy to see that they are measure equivalent. By contrast, in this paper, we prove that quasi-isometry and measure equivalence cannot be achieved "in a compatible way." More precisely, these two groups are not uniform (nor even integrable) measure equivalent. In particular, they cannot act continuously, properly and cocompactly by isometries on the same proper metric space, or equivalently they are not uniform lattices in a same locally compact group.

Cite this article

Kajal Das, Romain Tessera, Integrable measure equivalence and the central extension of surface groups. Groups Geom. Dyn. 10 (2016), no. 3, pp. 965–983

DOI 10.4171/GGD/373