Exact Borel subalgebras, idempotent quotients and idempotent subalgebras
Abstract
Abstract This article studies the compatibility of Koenig’s notion of an exact Borel subalgebra of a quasi-hereditary or, more generally, standardly stratified algebra with taking idempotent subalgebras or quotients. As an application, we provide bounds for the multiplicities of indecomposable projectives in the principal blocks of BGG category $$\mathcal {O}$$ O having basic regular exact Borel subalgebras.
Fields of Study & Subjects
Algebraic structures and combinatorial models
Homotopy and Cohomology in Algebraic Topology
Rings
Modules
and Algebras
Publication details
- Journal / source
- Mathematische Zeitschrift
- Volume
- 313
- Issue
- 1
- Publication date
- 9 April 2026
- Language
- EN