University of Birmingham > Talks@bham > Geometry and Mathematical Physics seminar > Witten conjecture for Mumford's kappa classes

## Witten conjecture for Mumford's kappa classesAdd to your list(s) Download to your calendar using vCal - Renzo Cavalieri (Colorado State)
- Wednesday 29 May 2019, 13:30-14:30
- Watson Building (Mathematics, R15 on map) Lecture Room C.
If you have a question about this talk, please contact Tyler Kelly. Kappa classes were introduced by Mumford, as a tool to explore the intersection theory of the moduli space of curves. Iterated use of the projection formula shows there is a close connection between the intersection theory of kappa classes on the moduli space of unpointed curves, and the intersection theory of psi classes on all moduli spaces. In terms of generating functions, we show that the potential for kappa classes is related to the Gromov-Witten potential of a point via a change of variables essentially given by complete symmetric polynomials, rediscovering a theorem of Manin and Zokgraf from ‘99. Surprisingly, the starting point of our story is a combinatorial formula that relates intersections of kappa classes and psi classes via a graph theoretic algorithm (the relevant graphs being dual graphs to stable curves). Further, this story is part of a large wall-crossing picture for the intersection theory of Hassett spaces, a family of birational models of the moduli space of curves. This is joint work with Vance Blankers (arXiv:1810.11443) . This talk is part of the Geometry and Mathematical Physics seminar series. ## This talk is included in these lists:- Bham Talks
- Geometry and Mathematical Physics seminar
- School of Mathematics Events
- Watson Building (Mathematics, R15 on map) Lecture Room C
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