The signature and cusp geometry of hyperbolic knots
Davies, A Juhász, A Lackenby, M Tomasev, N (30 Nov 2021)
LATENCY AND LIQUIDITY RISK
Cartea, A Jaimungal, S Sanchez-Betancourt, L INTERNATIONAL JOURNAL OF THEORETICAL AND APPLIED FINANCE volume 24 issue 6-7 2150035 (11 Nov 2021)
Mon, 28 Feb 2022
14:15
L5

Chow quotients and geometric invariant theoretic quotients for group actions on complex projective varieties

Frances Kirwan
(University of Oxford)
Further Information

The talk will be both online (Teams) and in person (L5)

Abstract

When a reductive group G acts on a complex projective variety
X, there exist different methods for finding an open G-invariant subset
of X with a geometric quotient (the 'stable locus'), which is a
quasi-projective variety and has a projective completion X//G. Mumford's
geometric invariant theory (GIT) developed in the 1960s provides one way
to do this, given a lift of the action to an ample line bundle on X,
though with no guarantee that the stable locus is not empty. An
alternative approach due to Kapranov and others in the 1990s is to use
Chow varieties to define a 'Chow quotient' X//G. The aim of this talk is
to review the relationship between these constructions for reductive
groups, and to discuss the situation when G is not reductive.

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