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Seminários do IMPA

Geometria Diferencial

Título
Entropy and quasimorphisms
Expositor
Michael Brandenbursky

Ben-Gurion University
Data
Terça-feira, 12 de setembro de 2017, 15:30
Local
Sala 236
Resumo

Let S be a compact oriented surface. In this talk we prove that there are infinitely many linearly independent homogeneous quasimorphisms on on Diff(S, area), on Diff_0(S, area) and on Ham(S) whose absolute values bound from below the topological entropy. In addition, we define a bi-invariant metric on these groups, called the entropy metric, and show that it is unbounded. In particular, we reprove the fact that the autonomous metric on Ham(S) is unbounded. Based on a joint work with M. Marcinkowski.