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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.