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arXiv · 1708.07205

The semi-infinite intersection cohomology sheaf-II: the Ran space version

Dennis Gaitsgory
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Abstract

This paper is a sequel to [Ga1]. We study the semi-infinite category on the Ran version of the affine Grassmannian, and study a particular object in it that we call the semi-infinite intersection cohomology sheaf. Unlike the situation of [Ga1], this version of the semi-infinite intersection IC sheaf is defined as the middle of extension of the constant (more precisely, dualizing) sheaf on the basic stratum, in a certain t-structure. We give several explicit description and characterizations of our semi-infinite intersection IC sheaf: we describe its !- and *- stalks; we present it explicitly as a colimit; we relate it to the IC sheaf of Drinfeld's relative compactification; we describe it via the Drinfeld-Plucker formalism.

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Dennis Gaitsgory. 2017-08-23. The semi-infinite intersection cohomology sheaf-II: the Ran space version. https://arxiv.org/abs/1708.07205

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