陈绿洲博士,Purdue University

Quasimorphisms are generalizations of homomorphisms to the real number. Groups with nice aciton on Gromov-hyperbolic spaces often have a large space of quasimorphisms, although such groups can have trivial abelianization. In this talk, I will give an introduction to quasimorphisms, including basic examples and constructions, their relation to bounded cohomology and group actions on certains spaces, and a duality theorem of Bavard that makes quasimorphisms a powerful tool to prove lower bounds of stable commutator length.