Sheaves on polynomials and polynomial sheaves

Abstract

We show that several Dold-Kan type equivalences can be understood as a passage from constructible sheaves on symmetric products (i.e. spaces of polynomials) to polynomial sheaves in the sense of Goodwillie-Weiss calculus, by means of a natural analytic expansion functor. This geometric perspective provides access to standard tools from sheaf theory such as the six functor formalism and $t$-structures. For example, the equivalence between filtered objects and coherent chain complexes in a stable $\infty$-category receives a geometric incarnation as Verdier duality between $!$-sheaves and $*$-cosheaves on an $\infty$-dimensional simplex. As a main application, we obtain an intrinsic geometric explanation for the appearance of vanishing cycle data for perverse sheaves in a paracyclic variant of the Dold--Kan correspondence pioneered by Dwyer and Kan, at the same time lifting their equivalence to stable $\infty$-categories.