Boston College Colloquium Series

Fall 2011

Time: Thursday October 13, 2.30-3.30, Carney 309
Speaker: Izzet Coskun (University of Illinois, Chicago)
Title: Pictures and homogeneous spaces


Many important problems in representation theory have analogues in geometry. For example, decomposing tensor products of representations of GL(n) into irreducible representations is very closely tied to the geometry of the Grassmannian. Similarly, studying the restriction of a representation of GL(n) to subgroups such as SO(n) or SP(n) has geometric analogues in terms of the geometry of flag varieties. In this talk, I will show you how drawing a few  pictures can make studying such lofty problems a lot of fun. I will specifically concentrate on Littlewood-Richardson rules and geometric branching rules. I intend to make the talk accessible to anyone who is willing to be seduced by pictures.

Time: Thursday October 27, 4.00-5.00, Fulton Hall 230
Speaker: Richard Askey (University of Wisconsin)
Title: The binomial theorem, beta and gamma functions, and some extensions of each.

It is well known that the number of permutations of the set 1,2,...,n is n!. An extension of this where one counts inversions was posed as a problem by M. Stern in 1839. These will be the starting place to build up the binomial theorem, the extension of n! which we now write as the gamma function, the beta integral of John Wallis, Euler's integral representation of the gamma function as an integral, and the connection between these three things. This connection will be looked at in two different settings, the classical one which most of you know reasonable well, and what will be called q-extensions of these classical results into a world which has finally started to come into its own.

Time: Wednesday, November 9, from 4-5pm, Carney 309
Speaker: András Stipsicz (Rényi Institute of Mathematics)
Title:  3-dimensional contact topology

After reviewing results about the existence of tight contact structures on closed 3-manifolds, we show how to use Heegaard Floer theory (in particular, the contact Ozsvath-Szabo invariant) to verify tightness of certain contact structures on 3-maniolds given by surgery along specific knots in S^3.

Time: Thursday November 17, 2.30-3.30, Carney 309
Speaker: Joseph Harris (Harvard University)
Title:  The Interpoloation Problem


Time: Wednesday December 7, 4.15-5.15, Carney 309
Speaker: Ian Agol (University of California, Berkeley)
Title: Virtual properties of 3-manifolds

Abstract: In his article "3-Dimensional manifolds, Kleinian groups, and hyperbolic geometry", William Thurston posed 24 problems related to the topology and geometry of Kleinian groups and hyperbolic 3-manifolds. We'll discuss four of the remaining open problems from this list, 15-18, having to do principally with finite-sheeted covers of hyperbolic 3-manifolds. We'll discuss how recent work of Kahn-Markovic and Wise implies that these problems are essentially equivalent, and the prospects for answering these questions combining their results.