Past Seminars › Seminar Series

Topology Seminar (past)

Mon, 18/10/2010
15:45 		Jason Behrstock (CUNY) Topology Seminar Add to calendar L3
Curve complex projections and the mapping class group
Abstract: We will explain a certain natural way to project elements of the mapping class to simple closed curves on subsurfaces. Generalizing a coordinate system on hyperbolic space, we will use these projections to describe a way to characterize elements of the mapping class group in terms of these projections. This point of view is useful in several applications; time permitting we shall discuss how we have used this to prove the Rapid Decay property for the mapping class group. This talk will include joint work with Kleiner, Minksy, and Mosher.
Mon, 07/06/2010
15:45 		Christopher Douglas (Berkeley) Topology Seminar Add to calendar L3
NO SEMINAR - CANCELLED
Mon, 17/05/2010
15:45 		Wu Jie, Singapore (Singapore) Topology Seminar Add to calendar L3
Link Invariants Given by Homotopy Groups
In this talk, we introduce the (general) homotopy groups of spheres as link invariants for Brunnian-type links through the investigations on the intersection subgroup of the normal closures of the meridians of strongly nonsplittable links. The homotopy groups measure the difference between the intersection subgroup and symmetric commutator subgroup of the normal closures of the meridians and give the invariants of the links obtained in this way. Moreover all homotopy groups of any dimensional spheres can be obtained from the geometric Massey products on certain links.
Mon, 10/05/2010
15:45 		Anne Thomas (Oxford) Topology Seminar Add to calendar L3
Surface quotients of hyperbolic buildings
Bourdon's building is a negatively curved 2-complex built out of hyperbolic right-angled polygons. Its automorphism group is large (uncountable) and remarkably rich. We study, and mostly answer, the question of when there is a discrete subgroup of the automorphism group such that the quotient is a closed surface of genus g. This involves some fun elementary combinatorics, but quickly leads to open questions in group theory and number theory. This is joint work with David Futer.
Mon, 26/04/2010
15:45 		David Ayala (Copenhagen) Topology Seminar Add to calendar L3
Higher string topology
The talk will begin with a brief account of the construction of string topology operations. I will point out some mysteries with the formulation of these operations, such as the role of (moduli) of surfaces, and pose some questions. The remainder of the talk will address these issues. In particular, I will sketch some ideas for a higher-dimensional version of string topology. For instance, (1) I will describe an E_{d+1} algebra structure on the (shifted) homology of the free mapping space H_*(Map(S^d,M^n)) and (2) I will outline how to obtain operations H_*(Map(P,M)) -> H_*(Map(Q,M)) indexes by a moduli space of zero-surgery data on a smooth d-manifold P with resulting surgered manifold Q.
Mon, 08/03/2010
15:45 		Fred Cohen (Rochester) Topology Seminar Add to calendar L3
On spaces of homomorphisms and spaces of representations
The subject of this talk is the structure of the space of homomorphisms from a free abelian group to a Lie group G as well as quotients spaces given by the associated space of representations. These spaces of representations admit the structure of a simplicial space at the heart of the work here. Features of geometric realizations will be developed. What is the fundamental group or the first homology group of the associated space in case G is a finite, discrete group ? This deceptively elementary question as well as more global information given in this talk is based on joint work with A. Adem, E. Torres, and J. Gomez.
Mon, 01/03/2010
15:45 		Ralph Cohen (Stanford and Copenhagen) Topology Seminar Add to calendar L3
String Topology and Fukaya Categories
Mon, 22/02/2010
15:45 		Pierre-Emmanuel Caprace, Bruxelles (Bruxelles) Topology Seminar Add to calendar L3
On Coxeter groups which do not admit any Dehn twist
Mon, 15/02/2010
15:45 		Jeff Giansiracusa (Swansea and Oxford) Topology Seminar Add to calendar L3
Operads, formality, and diffeomorphisms of handlebodies
Mon, 08/02/2010
15:45 		Victor Schroeder (Zurich) Topology Seminar Add to calendar L3
A Moebius Characterization of the Heisenberg group
Mon, 25/01/2010
15:45 		Andrzej Zuk (Paris) Topology Seminar Add to calendar L3
L^2 Betti numbers of closed manifolds
TBA
Mon, 18/01/2010
15:45 		Professor Graem Segal (Oxford) Topology Seminar Add to calendar L3
Wick Rotation in Quantum Field Theory
Physical space-time is a manifold with a Lorentzianmetric, but the more mathematical treatments of the theory usually prefer toreplace the metric with a positive - i.e. Riemannian - one. The passage fromLorentzian to Riemannian metrics is called 'Wick rotation'. In my talk I shallgive a precise description of what is involved, and shall explain some of itsimplications for physics. 
Mon, 30/11/2009
15:45 		Fei Han (Singapore) Topology Seminar Add to calendar L3
Supersymmetric Field Theories and Bismut-Chern Character
Mon, 23/11/2009
15:45 		Oscar Randal-Williams (Oxford) Topology Seminar Add to calendar L3
Homological stability of spaces of surfaces
Mon, 16/11/2009
15:45 		Alex Suciu (Northeastern University) Topology Seminar Add to calendar L3
Cohomology jump loci, sigma-invariants, and fundamental groups of alge-
Mon, 02/11/2009
15:45 		Karen Vogtmann (Cornell and MPI Bonn) Topology Seminar Add to calendar L3
Embeddings of Out(Fn)

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

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