Cohomology for infinitesimal unipotent algebraic and quantum groups

Abstract

In this paper we study the structure of cohomology spaces for the Frobenius kernels of unipotent and parabolic algebraic group schemes and of their quantum analogs. Given a simple algebraic group $G$, a parabolic subgroup $P_J$, and its unipotent radical $U_J$, we determine the ring structure of the cohomology ring $H^{\bullet }((U_J{)}_1,k)$. We also obtain new results on computing $H^{\bullet }((P_J{)}_1,L(\lambda ))$ as an $L_J$-module where $L(\lambda )$ is a simple $G$-module with high weight $\lambda$ in the closure of the bottom $p$-alcove. Finally, we provide generalizations of all our results to the quantum situation.

18 pages. Some proofs streamlined over previous version. Additional details added to some proofs in Section 5

References in corpus (3)

• Frobenius splitting of cotangent bundles of flag varieties and geometry of nilpotent cones
• Bernstein-Gelfand-Gelfand complexes and cohomology of nilpotent groups over ${\mathbb{Z}}_p$ for representations with p-small weights
• Representations and cohomology for Frobenius-Lusztig kernels