Topological Lattice Models in Geometry and Physics

Björn Gohla
GFM, Universidade de Lisboa

Abstract: Lattice models arise in physics as discrete approximations of quantum field theories (QFT). Topological quantum field theories (TQFT) on the other hand by definition are QFTs, that can be defined on smooth or topological space-times, as opposed to the usual pseudo-Riemannian space-times required by QFTs. Interesting TQFTs can be defined as lattice models, giving exactly solvable models in 2 dimensions for example.

Compactification of Character Varieties

Sean Lawton
George Mason University - U.S.A.

Abstract: In this talk we will first discuss a general procedure for compactifying G-character varieties of discrete groups, where G is a semisimple algebraic group of adjoint type over an algebraically closed field. We will then discuss various properties of this compactification in special cases of the discrete group. This work is in collaboration with Dan Ramras and Indranil Biswas.

On the mean Euler characteristic of Gorenstein toric contact manifolds

Miguel Abreu
Dep. Matemática - Instituto Superior Técnico

Abstract: In this talk I will prove that the mean Euler characteristic of a Gorenstein toric contact manifold is equal to half the normalized volume of the corresponding toric diagram. I will also give some immediate applications of this result. This is joint work with Leonardo Macarini.

This seminar is supported by National Funding from FCT - Fundação para a Ciência e a Tecnologia, under the project: UID/MAT/04561/2013.