Relativized computable categoricity

Java Darleen Villano (U of Connecticut)

Aug 06. 2025, 15:50 — 16:50

A computable structure A is computably categorical if for all computable copies B, there exists a computable isomorphism between A and B. We can relativize this notion to a specific Turing degree d in the following way: a computable structure A is computably categorical relative to d if for all d-computable copies B, there exists a d-computable isomorphism between A and B. In this talk, we will discuss notable behaviors of this notion in the Turing degrees, such as its nonmonotonicity below 0'. We will also discuss which classes of structures can have a computable witness to these behaviors. This talk is based on work from https://arxiv.org/abs/2401.06641 and https://arxiv.org/abs/2505.15706.

Further Information
Venue:
ESI Schrödinger and Boltzmann Lecture Hall
Recordings:
Recording
Associated Event:
Reverse Mathematics (Thematic Programme)
Organizer(s):
Juan Aguilera (TU Vienna)
Linda Brown Westrick (Penn State U)
Noam Greenberg (Victoria U of Wellington)
Denis Hirschfeldt (U of Chicago)