Dear colleagues:

We announce the following seminar at IPMU
(the Institute for the Physics and Mathematics of the Universe).

Regards,

Satoshi Kondo (IPMU)
http://ipmu.jp/

===========================================
Speaker: Robert Penner (Aarhus Univ/USC/Caltech)

Date: Mar. 2 (Tue) 2010, 13:15-14:45

Place:  Seminar Room A

Title: Finite type invariants and the Ptolemy groupoid

Abstract:
Recent joint work with Andersen, Bene, and Meilhan provides a new
link between 2d geometry and 3d quantum topology.  Specifically, we
introduce a finite type invariant of suitable 3-manifolds which is universal for
homology cylinders over a surface with boundary.  This new invariant
depends upon a choice of fatgraph spine for the surface, and representations
of its Ptolemy groupoid in the automorphism group of certain Jacobi diagrams
evolve from this dependence.  Applications include a TQFT-type
expression for the Le-Murakami-Ohtsuki invariant and a canonical cocycle,
which originated in joint work with Morita, representing the first
Johnson homomorphism.
The first 20-minute session will recall the Ptolemy groupoid and its utility
for explicating representations of subgroups of the mapping class groups
and then will formulate the basic problem of extending the LMO invariant
in this context.
============

You can check the location from
http://www.ipmu.jp/access/img/KashiwaCampusMap.png

The schedule of the seminar can be checked from
http://db.ipmu.jp/seminar/