Topology Seminars

Spring 2018

Speaker: Ben Wormleighton, UC Berkeley
Date and time: Tuesday, May 8, 5:30--6:30pm
Place: Phillips Hall 730
Title: The geometry of quivers

Abstract: A quiver is simply a directed graph, yet there are many rich and intriguing spaces that can be associated to a given quiver, widely called quiver varieties.  Just as directed graphs are widespread in mathematics, so are quiver varieties appearing in algebraic and symplectic geometry, representation theory, physics, combinatorics, ... I will summarise the general theory of quiver varieties from two points of view (algebraic and symplectic), describe some of the big victories of the theory, and discuss some new variations on this theme, especially the theory of multiplicative quiver varieties and group-valued moment maps.

Joint Topology-Logic Seminar
Speaker: Stepan Orevkov, the University of Toulouse, France
Date and time: Thursday, May 3, 4--5pm
Place: Phillips Hall 730
Title: Braids: Garside theory and its application for the recognition ofquasipositive braids.

Abstract: Garide theory is a tool for solving classical algorithmic problems (word problem and conjugacy problem) for the braid group and its generalizations. I am going to give a rather exhaustive introduction to this theory and to present my recent results on algorithmic recognition of quasipositive braids in in some particular cases.
Recall that a braid is called quasipositive if it is a product of conjugates of standard generators. The problem of decision whether a given braid is quasipositive or not, naturally appears in the study of plane real or complex algebraic curves.

Speaker:  Norbert A'Campo (University of Basel)

Title: Planar Hyperbolic Geometry.

Date and Time: April 5 (Thursday) 5:30-6:30 pm

Place. Seminar Room (Phillips 730)

Abstract: Hyperbolic Geometry is the geometry of solving second order equations x^2+bx+c=0. {C}

{C} {C} {C}