For more information about this meeting, contact Svetlana Katok, Anatole Katok.

Title: | generating sets of cofinitary groups. |

Seminar: | Center for Dynamics and Geometry Seminars |

Speaker: | Bart Kastermans, U. of Wisconsin |

Abstract: |

Cofinitary groups are subgroups of the symmetric group on the natural numbers where all elements other than the identity have only finitely many fixed points. It is unknown how concrete such groups can be --- that is what the possible complexity of maximal (w.r.t.
inclusion) cofinitary groups is. Some of the results on this question motivated Anatoly Vershik to ask a question about computably generated
groups: does there exist a group with a uniformly computable generating set whose isomorphism type is not computable.
I will explain the original question, and Vershiks question. Then I will explain parts of the proof; there are essentially three parts, the combinatorics, some observations on groups, and ideas from computability (no previous knowledge about computability will be presumed). |

### Room Reservation Information

Room Number: | MB106 |

Date: | 02 / 13 / 2008 |

Time: | 03:35pm - 04:35pm |