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Jarod Alper will speak on  Existence of moduli spaces

Good moduli spaces are an intrinsic stack-theoretic categorization of GIT quotients by reductive groups.  After introducing the definition of a good moduli space and establishing some of its basic properties, we aim to provide necessary and sufficient conditions for an algebraic stack to admit a good moduli space which appeared in a recent paper joint with Halpern-Leistner and Heinloth.  The conditions are valuative criteria called Theta-reductivity and S-completeness, and we will spend a good amount of time motivating and explaining these criteria.