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GQT colloquium
The program of the GQT colloquium on Friday, September 26, 2008 at the University of Utrecht is as follows.
Location: room 503 of the Buys Ballot Laboratorium, Princetonplein 5.
For directions to the building click here
| 11:15-12:15 | |
| Speaker: | Bernardo Uribe (Universidad de Los Andes, Colombia, temporarily MPI) |
| Title: | Orbifold String Topology Revisited |
| 12:15 - 13:30 | Lunch |
| 13:30 - 14:30 | |
| Speaker: | Gil Cavalcanti (Mathematisch Instituut, Utrecht) |
| Title: | Type changing generalized complex manifolds |
| 14:30 - 14:40 | Announcements from the GQT board. |
| 14:40 - 15:00 | Coffee & Tea. |
| 15:00 - 16:00 | |
| Speaker: | Michael Polyak (Technion, Israel, temporarily MPI, Bonn) |
| Title: | Invariants of 3-manifolds via counting 3-valent graphs |
| 16:00 - | Drinks |
Abstracts of the talks
Bernardo Uribe: Orbifold String Topology Revisited.
Abstract: In 1999 Chas and Sullivan showed that the homology of the free loop space of a manifold can be endowed with the structure of a BV-algebra (this is what is know as "String Topology"). Ever since, many relations between the Hochschild cohomology of the cochain complex of the manifold and the string topology have been developed. For orbifolds not much about these relations is known.
In this talk I will propose a new model for the string topology on orbifolds that differs from the ones that are in the literature, with the advantage that it has very natural relations with Hochschild cohomology.I will review the main results on String Topology at the begining of the talk.
This is a joint work with E. Backelin and A. Angel.
Gil Cavalcanti: Type changing generalized complex manifolds.
Abstract: In 4-dimensions, the main difference between a generalized complex structure and a symplectic structure is that the former can be symplectic in an open and dense set, but turn complex along a a codimension 2 submanifold. This picture is specially clear in a subclass of generalized complex manifolds obtained from genus 1-Lefschetz fibrations of symplectic manifolds and bears similarities with Landau--Ginzburg models which arise from string theory. In this setting, one can also perform blow-ups and blow-downs and find several interesting examples of generalized complex manifolds. This study also raises the question of existence of Lefschetz fibrations for generalized complex manifolds.
Michael Polyak: Invariants of 3-manifolds via counting 3-valent graphs.
Abstract: We will discuss various constructions of 3-manifold invariants all of which involve- in different ways- trivalent graphs. One approach is geometric and involves configuration spaces and integration (or, more generally, homology intersections). Another approach is combinatorial and involves Gauss diagrams and their subdiagrams. Both are related to a variety of topics: Feynman diagrams, graph cohomology, Lie bialgebras, etc. We will explain these approaches and illustrate them on a fundamental example of the Casson-Walker invariant.