58 research outputs found
Andersen Filtration and Hard Lefschetz
On the space of homomorphisms from a Verma module to an indecomposable
tilting module of the BGG-category O we define a natural filtration following
Andersen and establish a formula expressing the dimensions of the filtration
steps in terms of coefficients of Kazhdan-Lusztig polynomials.Comment: English version of math.RT/0604589, v3 revised translatio
Modular Koszul duality
We prove an analogue of Koszul duality for category of a
reductive group in positive characteristic larger than 1 plus the
number of roots of . However there are no Koszul rings, and we do not prove
an analogue of the Kazhdan--Lusztig conjectures in this context. The main
technical result is the formality of the dg-algebra of extensions of parity
sheaves on the flag variety if the characteristic of the coefficients is at
least the number of roots of plus 2.Comment: 62 pages; image displays best in pd
The Hochschild cohomology ring of regular maximal primitive quotients of enveloping algebras of semisimple Lie algebras
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