Degenerate Affine Flag Varieties and Quiver Grassmannians

Abstract

We study finite dimensional approximations to degenerate versions of affine flag varieties using quiver Grassmannians for cyclic quivers. We prove that they admit cellular decompositions parametrized by affine Dellac configurations, and that their irreducible components are normal Cohen-Macaulay varieties with rational singularities.

arXiv comment26 pages. Reference [3] and [11] added. Section 2.1, Proof of Theorem 3.13 and Section 5 revised