Tuesday, February 12
José Burillo, Universitat Politécnica de Catalunya
In this talk we will give a complete description of the abstract commensurator of Thompson's group F, and we will prove that it embeds in the quasi-isometry group of F, hence providing a large number of examples of quasi-isometries of F. As a corollary of this result, we classify all finite-index subgroups of F, proving that they are all virtually F, and identifying exactly those which are isomorphic to F itself. (Joint work with Sean Cleary and Claas Röver).
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