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SUMMARY:Minimal models of symplectic quotient singularities - Ulrich Thiel
  (University of Kaiserslautern)
DTSTART:20200130T134500Z
DTEND:20200130T143500Z
UID:TALK138184@talks.cam.ac.uk
CONTACT:INI IT
DESCRIPTION:Namikawa associated to any conic symplectic singularity a hype
 rplane arrangement which is deeply intertwined with its geometry. For exam
 ple\, Bellamy proved that for a symplectic quotient singularity the cohomo
 logy of the complement of this arrangement encodes the number of minimal m
 odels of the singularity. For the symplectic singularity associated to a c
 omplex reflection group we were able to prove that the Namikawa arrangemen
 t coincides with the degenericity locus of the number of torus fixed point
 s of the corresponding Calogero-Moser deformation. This has a series of re
 markable consequences\, especially it proves a conjecture by Bonnaf&eacute
 \; and Rouquier. Using representation theory and sophisticated computer al
 gebraic methods\, we could compute this arrangement explicitly for several
  exceptional complex reflection groups. The arrangements seem to be of a n
 ew kind\, and many more are out there. This is joint work with Gwyn Bellam
 y (Glasgow) and Travis Schedler (London)\, and with C&eacute\;dric Bonnaf&
 eacute\; (Montpellier).
LOCATION:Seminar Room 1\, Newton Institute
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