### QVEST, Winter 2010

#### Posted by Urs Schreiber

On somewhat short notice, for those in the vicinity of central Europe:

This Monday we have the first of a series of seminars:

**Quarterly Seminar on Topology and Geometry**December 20, 2010,

Univ. Utrecht, Netherlands

With the following talks:

Hessel Posthuma (Univ. Amsterdam)

*Integrable hierarchies and Frobenius manifolds*Abstract: I will explain the construction of an integrable hierarchy out of a Frobenius manifold, given in terms of a partition function of a cohomological field theory. In the homogeneous case, these hierarchies coincide with the ones constructed by Dubrovin and Zhang. Finally I will explain how one can use the action of the Givental group to deduce properties of these hierachies from those of the KdV equation when the underlying Frobenius manifold is semisimple. This is joint work with A. Buryak and S. Shadrin.

Julie Bergner (UC Riverside)

*Generalized classifying space constructions*Abstract: The process of constructing a classifying space for a group can be generalized so that we can find classifying spaces for categories. This construction is useful for many purposes, but also can be considered to lose much information if we use classical approaches in algebraic topology. In this talk, we give two approaches to strengthening the classifying space construction: one by changing how we think about spaces, and the other by changing the construction.

Christian Blohmann (MPI Bonn)

*Homotopy equivalence of correspondences and anafunctors of higher groupoids*Abstract: An anafunctor (also called span or zigzag) in the category of higher groupoids can be viewed as local trivialization of a principal bundle on a hypercover of a higher stack. Correspondences, on the other hand, are the higher generalization of groupoid bibundles. In the setting of ordinary categories the notions of anafunctors and bibundles are equivalent, both providing a localization of the category of groupoids at Morita equivalences. I will report on the generalization of this result to the setting of quasi-categories.

More details are on the seminar website. If you’d like to attend but need more info, please contact me.

Posted at December 16, 2010 8:51 PM UTC
## Re: QVEST, Winter 2010

Argh! Julie’s and Christian’s talks look so good. Please someone take notes! I’ll be in Wagga Wagga from Saturday, so apart from being on the other side of the world, I’ll be out in the sticks.