Mixed perverse sheaves on flag varieties of Coxeter groups

Pramod N Achar (1) , Simon Riche (2, 3) , Cristian Vay (4)

1 LSU Mathematics - Department of Mathematics [Baton Rouge]
2 LMBP - Laboratoire de Mathématiques Blaise Pascal
3 UCA [2017-2020] - Université Clermont Auvergne [2017-2020]
4 CONICET - Consejo Nacional de Investigaciones Científicas y Técnicas [Buenos Aires]

In this paper we construct an abelian category of "mixed perverse sheaves" attached to any realization of a Coxeter group, in terms of the associated Elias-Williamson diagrammatic category. This construction extends previous work of the first two authors, where we worked with parity complexes instead of diagrams, and we extend most of the properties known in this case to the general setting. As an application we prove that the split Grothendieck group of the Elias-Williamson diagrammatic category is isomorphic to the corresponding Hecke algebra, for any choice of realization.

Domaines: Théorie des représentations [math.RT]

Pramod N Achar, Simon Riche, Cristian Vay. Mixed perverse sheaves on flag varieties of Coxeter groups. Canadian Journal of Mathematics, 2020, 72 (1), pp.1-55. ⟨hal-01719974⟩