2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/167015We prove that the center of a regular block of parabolic category O for the general linear Lie algebra is isomorphic to the cohomology algebra of a corresponding Springer fiber. This was conjectured by Khovanov. We also find presentations for the centers of singular blocks, which are cohomology algebras of Spaltenstein varieties.33 pagesRepresentation TheoryCombinatorics20C08text