Forthcoming Seminars › Seminar Series

Topology Seminar

Mon, 13/10/2008
15:45 		Professor Martin Bridson (Oxford) Topology Seminar Add to calendar L3
The Andrew Curtis Conjecture
Mon, 20/10/2008
14:15 		Stefan Friedl (Warwick) Topology Seminar Add to calendar L3
"Fibered 3-manifolds and twisted Alexander polynomials"
It is a classical result that the Alexander polynomial of a fibered knot has to be monic. But in general the converse does not hold, i.e. the Alexander polynomial does not detect fibered knots. We will show that the collection of all twisted Alexander polynomials (which are a natural generalization of the ordinary Alexander polynomial) detect fibered 3-manifolds. As a corollary it follows that given a 3-manifold N the product S1 x N is symplectic if and only if N is fibered.
Mon, 20/10/2008
15:30 		Anne Thomas (Cornell) Topology Seminar Add to calendar L3
"Lattices acting on Platonic polygonal complexes and Fuchsian buildings"
A polygonal complex $ X $ is Platonic if its automorphism group $ G $ acts transitively on the flags (vertex, edge, face) in $ X $. Compact examples include the boundaries of Platonic solids.  Noncompact examples $ X $ with nonpositive curvature (in an appropriate sense) and three polygons meeting at each edge were classified by \'Swi\c{a}tkowski, who also determined when the group $ G=Aut(X) $, equipped with the compact-open topology, is nondiscrete.  For example, there is a unique $ X $ with the link of each vertex the Petersen graph, and in this case $ G $ is nondiscrete.  A Fuchsian building is a two-dimensional also determined when the group $ G=Aut(X) $, equipped with the compact-open topology, is nondiscrete.  For example, there is a unique $ X $ with the link of each vertex the Petersen graph, and in this case $ G $ is nondiscrete.  A Fuchsian building is a two-dimensional hyperbolic building.  We study lattices in automorphism groups of Platonic complexes and Fuchsian buildings.  Using similar methods for both cases, we construct uniform and nonuniform lattices in $ G=Aut(X) $.  We also show that for some $ X $ the set of covolumes of lattices in $ G $ is nondiscrete, and that $ G $ admits lattices which are not finitely generated.  In fact our results apply to the larger class of Davis complexes, which includes examples in dimension > 2.
Mon, 20/10/2008
16:45 		Ian Leary (Ohio State; visitin Bristol) Topology Seminar Add to calendar L3
"Simple platonic polygonal complexes."
We classify 2-dimensional polygonal complexes that are simply connected, platonic (in the sense that they admit a flag-transitive group of symmetries) and simple (in the sense that each vertex link is a complete graph).  These are a natural generalization of the 2-skeleta of simple polytopes. Our classification is complete except for some existence questions for complexes made from squares and pentagons. (Joint with Tadeusz Januszkiewicz, Raciel Valle and Roger Vogeler.)
Mon, 03/11/2008
15:45 		Jonathan Hillman (Sydney and Durham) Topology Seminar Add to calendar L3
Indecomposable PD_3-complexes
$ PD $-complexes model the homotopy theory of manifolds. In dimension 3, the unique factorization theorem holds to the extent that a $ PD_3 $-complex is a connected sum if and only if its fundamental group is a free product, and the indecomposables are aspherical or have virtually free fundamental group [Tura'ev,Crisp]. However in contrast to the 3-manifold case the group of an indecomposable may have infinitely many ends (i.e., not be virtually cyclic). We shall sketch the construction of one such example, and outline some recent work using only group theory that imposes strong restrictions on any other such examples.
Mon, 10/11/2008
15:45 		Siegfried Echterhoff (Goettingen) K-Theory Day Add to calendar
Topology Seminar Add to calendar 		L3
Fibrations with non-commutative fibres
We study non-commutative analogues of Serre-ï¬~Abrations in topology. We shall present several examples of such ï¬~Abrations and give applications for the computation of the K-theory of certain C*-algebras. (Joint work with Ryszard Nest and Herve Oyono-Oyono.)
Mon, 10/11/2008
17:00 		Richard Szabo (Heriot Watt University) Topology Seminar Add to calendar L3
D-branes, duality and non-commutative correspondences
Mon, 17/11/2008
15:45 		Gilbert Levitt Topology Seminar Add to calendar L3
Around Baumslag-Solitar groups
Baumslag-Solitar groups are very simple groups which are not Hopfian (they are isomorphic to proper quotients). I will discuss these groups, as well as their obvious generalizations, with emphasis on their automorphisms and their generating sets
Mon, 24/11/2008
15:45 		Paolo Salvatore (Rome) Topology Seminar Add to calendar L3
The topological cyclic Deligne conjecture
Wed, 26/11/2008
12:00 		Kiyoshi Igusa (Brandeis) Topology Seminar Add to calendar L3
Graph cohomology I: Introduction
Thu, 27/11/2008
10:00 		Kiyoshi Igusa (Brandeis) Topology Seminar Add to calendar L3
Graph cohomology II: Kozul duality of operads
Fri, 28/11/2008
10:00 		Kiyoshi Igusa (Brandeis) Topology Seminar Add to calendar L3
Graph cohomology III: A_infinity algebras
Mon, 01/12/2008
15:45 		Loretta Bartolini (Oklahoma State University) Topology Seminar Add to calendar L3
"One-sided Heegaard splittings of 3-manifolds"

For any corrections/updates to these listings, please contact seminars [-at-] maths [dot] ox [dot] ac [dot] uk.

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