Equivalence of $v$-decomposition matrices for blocks of Ariki-Koike algebras

Abstract

We consider the representation theory of the Ariki-Koike algebra, a $q$-deformation of the group algebra of the complex reflection group $C_r\wr {\mathfrak{S}}_n$. We examine blocks of the Ariki-Koike algebra. In particular, we prove a sufficient condition such that restriction of modules leads to a natural correspondence between the multipartitions of $n$ whose Specht modules belong to a block $B$ and those of $n-{\delta }_i(B)$ whose Specht modules belong to the block $B^{\prime }$, obtained from $B$ applying a Scopes' equivalence. This bijection gives us an equivalence for the $v$-decomposition numbers of the Ariki-Koike algebras.

arXiv comment20 pages; we generalise the equivalence of decomposition matrices to graded decomposition matrices. To appear in Journal of Pure and Applied Algebra