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Carel Faber: On the cohomology of moduli spaces of stable pointed curves: genus 4 and small n, and the vanishing of H^7 and H^9

Tid: To 2021-09-16 kl 15.30 - 16.30

Plats: Institut Mittag-Leffler, Seminar Hall Kuskvillan (alt. Zoom, meeting ID: 921 756 1880)

Medverkande: Carel Faber (Universiteit Utrecht)

Abstract: Joint work with Jonas Bergström and Sam Payne.
For n at most 3, we determine the relevant terms of the point count of \(M_{4,n}\) over finite fields (\(S_n\)-equivariantly). Using several earlier results, we then determine the cohomology of \(\overline{M}_{4,n}\) and the full count for \(M_{4,n}\) and we deduce the mentioned vanishing for all g and n.