## Seminars and Colloquia by Series

Wednesday, October 24, 2012 - 14:00 , Location: none , none , none , Organizer: John Etnyre
Wednesday, September 12, 2012 - 14:00 , Location: Skiles 006 , Jamie Conway , Georgia Tech , Organizer: James Conway
We will investigate a method of "seeing" properties of four dimensional symplectic spaces by looking at two dimensional pictures.  We will see how to calculate the Euler characteristic, identify embedded surfaces, see intersection numbers, and how to see induced contact structures on the boundary of these manifolds.
Wednesday, September 5, 2012 - 14:00 , Location: Skiles 006 , Hyunshik Shin , School of Mathematics , Organizer:
The main goal is to characterize the dilatation of an outer automorphisms of free groups. It is known that for any automorphism, its dilatation is a weak Perron number. The converse was recently shown by Thurston; for every weak Perron number, there is an automorphism represented by a train track map. We will discuss Thurston's theorem and its proof.
Wednesday, August 29, 2012 - 14:00 , Location: Skiles 006 , Hyunshik Shin , School of Mathematics, Georgia Tech , Organizer:
We will discuss the basics of automorphisms of free groups and train track structure. We will define the growth rate which is a topological entropy of the train track map.
Wednesday, February 8, 2012 - 14:05 , Location: Skiles 169 , Jonathan Paprocki , Georgia Tech , Organizer:
We will prove a duality between locally compact Hausdorff spaces and the C*-algebra of continuous complex-valued functions on that space. Formally, this is the equivalence of the opposite category of commutative C*-algebras and the category of locally compact Hausdorff spaces.
Wednesday, January 25, 2012 - 14:00 , Location: Skiles 005 , Bulent Tosun , Georgia Tech , Organizer:
The aim of the talk is to give a complete proof of the fact that any closed oriented 3-manifold has a trivial tangent bundle.
Wednesday, November 9, 2011 - 14:05 , Location: Skiles 005 , Alan Diaz , Georgia Tech , Organizer:
TBA
Wednesday, November 2, 2011 - 14:05 , Location: Skiles 005 , Eric Choi , Emory University , Organizer:
Knowledge of rays and critical points of infinity in von Mangoldt planes can be applied to understanding the structure of open complete manifolds with lower radial curvature bounds. We will show how the set of souls is computed for every von Mangoldt plane of nonnegative curvature. We will also make some observations on the structure of the set of critical points of infinity for von Mangoldt planes with negative curvature.
Wednesday, October 26, 2011 - 14:00 , Location: Skiles 005 , Meredith Casey , Georgia Tech , Organizer:
The main purpose of this talk is to better understand how to use branched covers to construct 3-manifolds.  We will start with branched covers of 2-manifolds, carefully working through examples and learning the technology.  Using these methods in combination with open book decompositions we will show how to construct 3-manifolds by branching over link and knots in S^{3}.  Particular emphasis will be placed on using the map to get a "coloring" of the branched locus and how this combinatorial data is useful both for explicit constructions and for the general theory.
Wednesday, October 19, 2011 - 14:05 , Location: Skiles 005 , Amey Kaloti , Georgia Tech , Organizer:
In this talk we will outline proof due to Plameneveskaya and Van-Horn Morris that every virtually overtwisted contact structure on L(p,1) has a unique Stein filling. We will give a much simplified proof of this result. In addition, we will talk about classifying Stein fillings of ($L(p,q), \xi_{std})$ using only mapping class group basics.