Resumen de Diagrammatic description for the categories of perverse sheaves on isotropic Grassmannians
Michael Ehrig, Catharina Stroppel
For each integer k≥4k≥4 , we describe diagrammatically a positively graded Koszul algebra DkDk such that the category of finite dimensional DkDk -modules is equivalent to the category of perverse sheaves on the isotropic Grassmannian of type DkDk or Bk−1Bk−1 , constructible with respect to the Schubert stratification. The algebra is obtained by a (non-trivial) “folding” procedure from a generalized Khovanov arc algebra. Properties such as graded cellularity and explicit closed formulas for graded decomposition numbers are established by elementary tools.
