Séminaires : Séminaire de géométrie algébrique

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Le jeudi à 14h.
septembre-décembre Sophie-Germain, janvier-mars ENS, avril-juin Jussieu

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Orateur(s) Johannes Schmitt - ,
Titre Zero cycles on moduli spaces of curves
Horaire14:00 à 15:30

Tautological zero cycles form a one-dimensional subspace of the set of all algebraic zero-cycles on the moduli space of stable curves. The full group of zero cycles can in general be infinite-dimensional, so not all points of the moduli space will represent a tautological class. In the talk, I will present geometric conditions ensuring that a pointed curve does define a tautological point. On the other hand, given any point Q in the moduli space we can find other points P_1, ..., P_m such that Q+P_1+ ... + P_m is tautological. The necessary number m is uniformly bounded in terms of g,n, but the question of its minimal value is open. This is joint work with Rahul Pandharipande.