# Seminar of Algebra

### Limit roots of infinite Coxeter groups

Speaker:
Jean-Philippe Labbé (Hebrew University of Jerusalem)
Email:
labbe@math.huji.ac.il
Location:
Departamento de Álgebra
Date:
Fri, 22 jan 2016 13:00
Jean-Philippe Labbé is Postdoctoral fellow at HUJ. His research is at the intersection of group theory, discrete geometry and combinatorics. I use combinatorial, geometric, and computational approaches to study algebraic and topological structures: Coxeter groups, polytopes, triangulations, and simplicial complexes.

Coxeter groups form an abstraction of groups generated by reflections in a real vector space. To every Coxeter group corresponds a root system enclosing it geometric and algebraic structure. A root system is a set of vectors of the vector space which is stable under the action of the reflection group. When the group is infinite, so is the root system; giving rise to accumulation points in the projective space. These points are the limit roots of the Coxeter group. Limit roots give a lot of information and intuition on the structure of the group. Curiously, they often form fractals with certain unexplained properties. In this talk, we will present limit roots and related problems of this growing theory.