Postdoctoral Seminar

Matthew Harrison-Trainor, Department of Pure Mathematics, University of Waterloo

"How to know when you've proved the best possible characterization or classification"

Many theorems take the form of a classification -- a description of some type of object up to isomorphism -- or a classification -- a description of which objects satisfy some additional property. How do you know when such a theorem is as good as possible? One way is to use methods from computability theory. I'll talk about how to use index sets to show that a particular classification or characterization must be at least a certain complexity.

MC 5403