2019/09/24 by Eberhardt, Jens Niklas · 2 citations
#FOS: Mathematics #K-Theory and Homology (math.KT) #Representation Theory (math.RT)
paper · doi:10.48550/arxiv.1909.11151
We construct an ungraded version of Beilinson-Ginzburg-Soergel's Koszul duality for Langlands dual flag varieties, inspired by Beilinson's construction of rational motivic cohomology in terms of K-theory. For this, we introduce and study categories DKS(X) of S-constructible K-motivic sheaves on varieties X with an affine stratification S. We show that there is a natural and geometric functor, called Beilinson realisation, from S-constructible mixed sheaves DmixS(X) to DKS(X). We then show that Koszul duality intertwines the Betti realisation and Beilinson realisation functors and descends to an equivalence of constructible sheaves and constructible K-motivic sheaves on Langlands dual flag varieties.