Abstract:

We define a localised Euler class for isotropic sections, and isotropic cones, in SO(N) bundles. We use this to give an algebraic definition of Borisov-Joyce sheaf counting invariants on Calabi-Yau 4-folds. When a torus acts, we prove a localisation result. This talk is based on the joint work with Richard. P. Thomas.

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https://us02web.zoom.us/j/89452171719?pwd=OWpRc084Z0toYlE3Ym54clF0dXk3UT09