Wednesday, December 10, 2014 — 3:30 PM EST

**Keng Meng (Selwyn) Ng, Nanyang Technological University **

Tuesday, November 18, 2014 — 3:30 PM EST

**Sam Eisenstat, Department of Pure Mathematics, University of Waterloo**

Countable torsion-free abelian groups are very complicated objects in general. We focus on groups that are direct sums of subgroups of $\mathbb{Q}$ and investigate their computability-theoretic properties. We look at degree spectra, categoricity, complexity of presentations, and complexity of the index and isomorphism problems. $\Sigma_{7}$ shows up!

But first, we let Mohammad finish his lemma from last time.

MC 5046

Tuesday, November 11, 2014 — 3:30 PM EST

**Mohammad Mahmoud, Department of Pure Mathematics University of Waterloo **

We continue through the proof of Goncharov’s Theorem from Mcpherson’s research paper.

MC 5046

Tuesday, November 4, 2014 — 10:30 AM EST

**Ross Willard, Department of Pure Mathematics, University of Waterloo**

In this fourth of several lectures, I analyze singular pairs of variables, realizing their singu- larity in the congruence lattice of their associated constraint relation.

MC 5158B

Wednesday, October 29, 2014 — 3:30 PM EDT

**Denis Hirschfeldt, University of Chicago **

Tuesday, October 28, 2014 — 10:30 AM EDT

**Ross Willard, Department of Pure Mathematics, University of Waterloo **

In this third of several lectures, I begin the analysis of a template which has a Maltsev polymorphism and which survives the search for an inconsistency outlined in the first two lectures.

Wednesday, October 15, 2014 — 3:30 PM EDT

**Rahim Moosa, Department of Pure Mathematics, University of Waterloo **

“A model theory for meromorphic dynamics?”

Wednesday, October 1, 2014 — 3:40 PM EDT

**Alex Wires, Department of Pure Mathematics, University of Waterloo **