For more information about this meeting, contact Stephen Simpson.

Title: | Invariant measures, computability, and reverse mathematics |

Seminar: | Logic Seminar |

Speaker: | Stephen G. Simpson, Pennsylvania State University |

Abstract: |

Let S be the unit circle. We construct a computable homeomorphism f: S --> S such that no computable probability measure on S is invariant under f. This construction is due to Mathieu Hoyrup and Cristobal Rojas. We extend their method to prove the following result of reverse mathematics: WKL_0 is equivalent over RCA_0 to the statement that for every Z-action on a compact metric space there exists an invariant probability measure. |

### Room Reservation Information

Room Number: | MB315 |

Date: | 02 / 16 / 2010 |

Time: | 02:30pm - 03:45pm |