Tilting Modules for Cyclotomic Schur Algebras

This paper investigates the tilting modules of the cyclotomic q–Schur algebras, the Young modules of the Ariki–Koike algebras, and the interconnections between them. The main tools used to understand the tilting modules are contragredient duality, and the Specht filtrations and dual Specht filtrations of certain permutation modules. Surprisingly, Weyl filtrations — which are in general more powerful than Specht filtrations — play only a secondary role.