Seminar

Friday, February 27, 2026 5:00 pm - 6:00 pm EST (GMT -05:00)

Pure math Grad colloquium

Open Mic

Come listen to or contribute a minitalk (no longer than 15 minutes). Anything (as long as it vaguely relates tomathematics and is reasonably accessible) goes!

MC 5479

(Refreshments will start at 16:30)

Tuesday, February 24, 2026 4:00 pm - 5:00 pm EST (GMT -05:00)

Model Theory Working Seminar

Rahim Moosa, University of Waterloo

Definable groups in CCM

I will survey what is known about the structure of definable groups in both the standard and nonstandard models of CCM.

MC 5479

Monday, February 23, 2026 1:00 pm - 2:30 pm EST (GMT -05:00)

Computability Learning Seminar

William Dan, University of Waterloo

A Characterization of Random, Left C.E. Reals

An immediate property of the halting probability of a prefix-free machine is that it is a left c.e. real. An easycorollary of the Kraft-Chaitin theorem is that the converse is true: any left c.e. real is the halting probability ofsome prefix-free machine. The most common example of a random real is Chaitin's omega, the haltingprobability of a universal prefix-free machine. In fact, it is a random left c.e. real. It is natural then to ask if theconverse holds in this case as well: that any random left c.e. real is the halting probability of some universalprefix-free machine. As it turns out, this is the case, and in this talk I will explain the concept used to solve thisquestion, Solovay reducibility, then prove the theorems demonstrating the converse. This talk follows sections9.1 and 9.2 of the Downey and Hirschfeldt book.

MC 5403

Thursday, October 4, 2018 3:30 pm - 3:30 pm EDT (GMT -04:00)

Model Theory Seminar

Rahim Moosa, Pure Mathematics, University of Waterloo

"Pseudo-finite sets and dimension, Part 2"

Having discussed the normalised counting measure on pseudo-finite sets and its application to Szemeredi Regularity, we now introduce the fine and coarse pseudo-finite dimensions for these sets, with an eye toward the Szemerdi-Trotter theorem.