Algebra Seminar: Wang -- Stringy product on orbifold K-theory

Hello and welcome to a new year of Algebra Seminars, with a new seminar organiser, Anne
Thomas.  I’d like to thank the previous organiser James East for his great work running
the seminar and for his help getting me started.  

The series will officially resume in March, but next Wednesday 9 February we will have
an early talk given by Bryan Wang from ANU.  Title and abstract are below -- note the
unusual day and venue.  

After the seminar we will take Bryan to lunch at the Grandstand Bar.  So that I can give
the Grandstand accurate numbers, please email me by Monday 7 February if you plan to
attend the lunch.  

Finally, I am currently looking for speakers for March and April -- if you and/or any of
your visitors would like to give a talk, I would be very happy to hear from you.  

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Speaker: Bryan Wang (Australian National University) 

Date: Wednesday 9 February 

Time: 12 noon 

Venue: Carslaw Room 535 

Title: Stringy product on orbifold K-theory 

Abstract: Motivated by orbifold string theory models in physics, Chen and Ruan
discovered a new product called the stringy product on the cohomology for the inertia
orbifold of an almost complex orbifold.  This cohomology with the stringy product is now
called the Chen-Ruan cohomology, as a classical limit of orbifold quantum cohomology
theory.  Later, various versions of stringy product on orbifold K-theory of the inertia
orbifold were proposed.  In a recent joint work with Hu, we define a stringy product on
the orbifold K-theory for the orbifold itself and show that a modified de-localized
Chern character to the Chen-Ruan cohomology is an isomorphism over the complex
coefficient.  As an application, we find a new product on the equivariant K-theory of a
finite group with the conjugation product, which is different to the well-known
Pontryajin (or fusion) product.
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