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SUMMARY:Richard Thomas
DTSTART:20210511T160000Z
DTEND:20210511T170000Z
DTSTAMP:20260423T021432Z
UID:eAKTS/20
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/eAKTS/20/">S
 quare root Euler classes and counting sheaves on Calabi-Yau 4-folds</a>\nb
 y Richard Thomas as part of electronic Algebraic K-theory Seminar\n\nLectu
 re held in 979 0634 7355.\n\nAbstract\nI will explain a nice characteristi
 c class of SO(2n\,C) bundles in both Chow cohomology and K-theory\, and ho
 w to localise it to the zeros of an isotropic section. This builds on work
  of Edidin-Graham\, Polishchuk-Vaintrob\, Anderson and others. This can be
  used to construct an algebraic virtual cycle (and virtual structure sheaf
 ) on moduli spaces of stable sheaves on Calabi-Yau 4-folds. It recovers th
 e real derived differential geometry virtual cycle of Borisov-Joyce but ha
 s nicer properties\, like a torus localisation formula. Joint work with Je
 ongseok Oh (KIAS).\n
LOCATION:https://researchseminars.org/talk/eAKTS/20/
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