Past Seminars › Seminar Series

Topology Seminar (past)

Mon, 09/03/2009
15:45 		Marc Lackenby (Oxford) Topology Seminar Add to calendar L3
The maximal number of exceptional Dehn surgeries
I will outline the proof of two old conjectures of Cameron Gordon. The first states that the maximal number of exceptional Dehn surgeries on a 1-cusped hyperbolic 3-manifold is 10. The second states the maximal distance between exceptional Dehn surgeries on a 1-cusped hyperbolic 3-manifold is 8. The proof uses a combination of new geometric techniques and rigorous computer-assisted calculations. This is joint work with Rob Meyerhoff.
Mon, 02/03/2009
15:45 		Jacob Rasmussen (Cambridge) Topology Seminar Add to calendar L3
The Alexander polynomial of sutured manifolds
The notion of a sutured 3-manifold was introduced by Gabai. It is a powerful tool in 3-dimensional topology. A few years ago, Andras Juhasz defined an invariant of sutured manifolds called sutured Floer homology. I'll discuss a simpler invariant obtained by taking the Euler characteristic of this theory. This invariant turns out to have many properties in common with the Alexander polynomial. Joint work with Stefan Friedl and Andras Juhasz.
Mon, 23/02/2009
15:45 		Neil Strickland (Sheffield) Topology Seminar Add to calendar L3
Chromatic phenomena in equivariant stable homotopy
There is a well-known relationship between the theory of formal group schemes and stable homotopy theory, with Ravenel's chromatic filtration and the nilpotence theorem of Hopkins, Devinatz and Smith playing a central role. It is also familiar that one can sometimes get a more geometric understanding of homotopical phenomena by examining how they interact with group actions. In this talk we will explore this interaction from the chromatic point of view.
Mon, 16/02/2009
15:45 		Alain Valette (Universite de Neuchatel) Topology Seminar Add to calendar L3
Permanence properties of a-T-menability
Mon, 09/02/2009
15:45 		TBA Topology Seminar Add to calendar L3
BOS Day in Bristol
Mon, 02/02/2009
15:45 		Panos Papozoglou (Oxford) Topology Seminar Add to calendar L3
Isoperimetric profiles of surfaces and filling functions
Mon, 26/01/2009
15:45 		Karen Vogtmann (Cornell) Topology Seminar Add to calendar L3
Automorphisms of right-angled Artin groups
Mon, 19/01/2009
15:45 		Yoshikata Kida (Tohoku) Topology Seminar Add to calendar L3
Measure-theoretic rigidity for mapping class groups
Mon, 01/12/2008
15:45 		Loretta Bartolini (Oklahoma State University) Topology Seminar Add to calendar L3
"One-sided Heegaard splittings of 3-manifolds"
Fri, 28/11/2008
10:00 		Kiyoshi Igusa (Brandeis) Topology Seminar Add to calendar L3
Graph cohomology III: A_infinity algebras
Thu, 27/11/2008
10:00 		Kiyoshi Igusa (Brandeis) Topology Seminar Add to calendar L3
Graph cohomology II: Kozul duality of operads
Wed, 26/11/2008
12:00 		Kiyoshi Igusa (Brandeis) Topology Seminar Add to calendar L3
Graph cohomology I: Introduction
Mon, 24/11/2008
15:45 		Paolo Salvatore (Rome) Topology Seminar Add to calendar L3
The topological cyclic Deligne conjecture
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, 10/11/2008
17:00 		Richard Szabo (Heriot Watt University) Topology Seminar Add to calendar L3
D-branes, duality and non-commutative correspondences
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, 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, 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, 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.

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

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