Sam Eisenstat, Department of Pure Mathematics, University of Waterloo
“Computable Model Theory of Torsion-Free Abelian Groups”
Countable torsion-free abelian groups are very complicated objects in general. We focus on groups that are direct sums of subgroups of Q and investigate their computability-theoretic properties. We look at degree spectra, categoricity, complexity of presentations, and complexity of the index and isomorphism problems. Σ7 shows up!
But first, we let Mohammad finish his lemma from last time.