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Stratified hyperkähler spaces

Maxence Mayrand (University of Oxford)
Wednesday, 6 February, 2019, at 13:00-14:00, in Aud. D1 (1531-113)
Symplectic reduction is the natural quotient construction in symplectic geometry. Given a free and Hamiltonian action of a compact Lie group G on a symplectic manifold M, this produces a new symplectic manifold of dimension dim(M) - 2 dim(G). If we drop the freeness assumption, the reduced space is usually fairly singular, but Sjamaar-Lerman showed that we can still decompose it into smooth symplectic manifolds which “fit together nicely” in a precise sense. In this talk, I will explain how to get an analogue of Sjamaar-Lerman’s result in hyperkähler geometry and give interesting examples coming from the so-called Nahm equations.
Organised by: QGM
Contact person: William E. Petersen