RoCK blocks for affine categorical representations

Abstract

Given a categorical action of a Lie algebra, a celebrated theorem of Chuang and Rouquier proves that the blocks corresponding to weight spaces in the same orbit of the Weyl group are derived equivalent, proving an even more celebrated conjecture of Broué for the case of the symmetric group. In many cases, these derived equivalences are $t$-exact and thus induce equivalences of abelian categories between different blocks. We call two such blocks “Scopes equivalent.” In this paper, we describe how Scopes equivalence classes for any affine categorification can be classified by the chambers of a finite hyperplane arrangement, which can be found through simple Lie theoretic calculations. We pay special attention to the largest equivalence classes, which we call RoCK, and show how this matches with recent work of Lyle on Rouquier blocks for Ariki–Koike algebras. We also provide Sage code that tests whether blocks are RoCK and finds RoCK blocks for Ariki–Koike algebras.