Saturday, April 2, 20161:15 pmNERDS: New England Recursion & Definability SeminarLocklin Hall, Room 232, Springfield College

# Density and computability

## Eric Astor

### University of Connecticut

We develop and discuss some of the theory relating asymptotic density and computability, with attention to the inherent complexity of sets with density invariant under computable permutation. We will make a brief excursion into reverse mathematics on the way, pointing out that a key equivalence of Kjos-Hanssen, Merkle, and Stephan holds over **RCA _{0}**.

Eric Astor received his doctorate from the University of Chicago in 2015, under the supervision of Denis Hirschfeldt and Robert Soare. He now holds a postdoctoral position at the University of Connecticut.