Beyond twisted maps:~applications to motivic integration

Matthew Satriano, Jeremy Usatine
Mathematics, Algebraic Geometry, Algebraic Geometry (math.AG)
2023-09-19 16:00:00
Twisted maps are of great importance in the study of Deligne--Mumford stacks. We introduce a natural generalization of twisted maps, called \emph{warped maps}, that are better suited for studying Artin stacks. Heuristically, warped maps see the hidden proper-like behavior satisfied by good moduli space maps. Specifically, we show that every arc of a good moduli space admits a \emph{canonical} lift, in a warped sense, thereby proving a valuative criterion for good moduli spaces. Furthermore, we prove that warped maps to an Artin stack $\mathcal{X}$ are given by usual maps to an auxiliary Artin stack $\mathscr{W}(\mathcal{X})$, immediately obtaining a versatile framework for bootstrapping results about usual maps to the setting of warped maps. As an application we obtain a motivic change of variables formula that, given a stacky resolution of singularities $\mathcal{X} \to Y$, canonically expresses any given motivic integral over arcs of $Y$ as a certain motivic integral over warped arcs of $\mathcal{X}$.
PDF: Beyond twisted maps:~applications to motivic integration.pdf
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