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arXiv · 1401.7256

Modular perverse sheaves on flag varieties II: Koszul duality and formality

Pramod N. Achar·Simon Riche
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Abstract

Building on the theory of parity sheaves due to Juteau-Mautner-Williamson, we develop a formalism of "mixed modular perverse sheaves" for varieties equipped with a stratification by affine spaces. We then give two applications: (1) a "Koszul-type" derived equivalence relating a given flag variety to the Langlands dual flag variety, and (2) a formality theorem for the modular derived category of a flag variety (extending a previous result of Riche-Soergel-Williamson).

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BibTeXRIS

Pramod N. Achar, Simon Riche. 2014-01-28. Modular perverse sheaves on flag varieties II: Koszul duality and formality. https://doi.org/10.1215/00127094-3165541

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