For more information about this meeting, contact Stephen Simpson, Jan Reimann.

Title: | A lightface analysis of the differentiability rank |

Seminar: | Logic Seminar |

Speaker: | Linda Brown Westrick, University of Califormia, Berkeley |

Abstract: |

We examine the computable part of the differentiability hierarchy defined by Kechris and Woodin. In that hierarchy, the rank of a differentiable function is an ordinal less than omega_1 which measures how complex it is to verify differentiability for that function. We show that for each recursive ordinal alpha > 0, the set of Turing indices of C[0,1] functions that are differentiable with rank at most alpha is Pi_{2 alpha + 1}-complete. This result is expressed in the notation of Ash and Knight. We also discuss connections with related hierarchies. |

### Room Reservation Information

Room Number: | MB315 |

Date: | 10 / 29 / 2013 |

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