Quasimorphisms from bi-invariant partial orders

Tobias Hartnick (Zürich), 12 May 2009, 11h15, CM113

Title: Quasimorphisms from bi-invariant partial orders

Abstract: We will visit the zoo of quasimorphisms and have a look at some interesting representatives from Lie theory, dynamics and symplectic/contact geometry. Then we present a uniform construction for all these (in fact, all) quasimorphisms: They arise as relative growth functions of special bi-invariant partial orders. In this correspondence, additional properties of the quasimorphism sould be reflected by special properties of the corresponding orders. We discuss this for continuous orders and continuous quasimorphisms on Lie groups. (This is joint work with Gabi Ben Simon, ENS Lyon.)