Events - June 2019

Luke MacLean, Department of Pure Mathematics, University of Waterloo

"Different extensions of first-order logic"

How does one capture the properties that aren’t definable by first-order sentences or even theories? One way is to allow infinitary conjunctions of first-order sentences. Another is to expand the language that is being used. In this talk I will discuss the cases when these two extensions coincide, and sketch a proof by W. Craig and R.L. Vaught that a computably axiomatizable theory can be finitely axiomatized using additional predicates.

Roger Smith, Texas A&M University

"A Galois correspondence for crossed products"

We consider a discrete group G acting by outer automorphisms on a simple unital C*-algebra A. We address the problem of characterising the C*-algebras lying between A and its crossed product by G. The main result is that these are parameterised by the subgroups of G. This is joint work with Jan Cameron.

MC 5417

Mohammad Mahmoud, Department of Pure Mathematics, University of Waterloo

"The Isomorphism Problem of the Class of Computable Trees of Finite Rank"

Jeff Samuelson, Department of Pure Mathematics, University of Waterloo

"A variety of schemes, part II"

We give the general definition of schemes and discuss several examples. 

MC 5479

Valentina Harizanov, George Washington University

"Arithmetically categorical structures"

Nickolas Rollick, Department of Pure Mathematics, University of Waterloo

"Approximation Constants for Closed Subschemes of Projective Varieties"

Christopher Lang, Department of Pure Mathematics, University of Waterloo

"The ADHM-Nahm Procedure"

In my last talk, we examined how group actions simplify the Nahm equations.  In this talk, we outline the procedure that generates monopoles from solutions of these equations, the ADHM-Nahm procedure.  Then, using Maple,, we follow this procedure to generate explicit examples of monopoles.

Spencer Whitehead, Department of Pure Mathematics, University of Waterloo

'Decorated Coxeter Diagrams'

Anton Mosunov, Department of Pure Mathematics, University of Waterloo

"Absolute Bounds on the Number of Solutions of Certain Equations of Thue and Thue-Mahler Type"

Let $F(X, Y)$ be an irreducible polynomial with integer coefficients of degree at least three. In 1909 it was proved by Thue that the Diophantine equation

$$F(x, y) = m,$$