The reducibility of the Specht modules for the Iwahori–Hecke algebras in type A is still open in the case where the defining parameter q equals −1. We prove the reducibility of a large class of Specht modules for these algebras.

In this note, we explain how to model (ir)reducibility of rewriting on ground terms using (dis)equational constraints. We show in particular that innermost (ir)reducibility can be modeled with a particular narrowing relation and that (dis)equational constraints are issued from the most general unifiers of this narrowing relation.

The reducibility of the Specht modules for the Iwahori–Hecke algebras in type A is still open in the case where the defining parameter q equals −1. We prove the reducibility of a large class of Specht modules for these algebras.

The main purpose of this paper is to take apart the reducibility method in order to understand how its pieces fit together, and in particular, to recast the conditions on candidates of reducibility as sheaf conditions. There has been a feeling among experts on this subject that it should be possible to present the reducibility method using more semantic means, and that a deeper understanding wo...