Submodules of Specht modules for Weyl groups

Submodules of Specht Modules for Weyl Groups

The construction of all irreducible modules of the symmetric groups over an arbitrary field which reduce to Specht modules in the case of fields of characteristic zero is given by G.D.James. Halıcıoğlu and Morris describe a possible extension of James’ work for Weyl groups in general, where Young tableaux are interpreted in terms of root systems. In this paper we show how to construct submodule...

Weyl Submodules in Restrictions of Simple Modules

Let F be an algebraically closed field of characteristic p > 0. Suppose that SLn−1(F) is naturally embedded into SLn(F) (either in the top left corner or in the bottom right corner). We prove that certain Weyl modules over SLn−1(F) can be embedded into the restriction L(ω)↓SL n−1(F), where L(ω) is a simple SLn(F)-module. This allows us to construct new primitive vectors in L(ω)↓SL n−1(F) from a...

Row and Column Removal Theorems for Homomorphisms of Specht Modules and Weyl Modules

We prove a q-analogue of the row and column removal theorems for homomorphisms between Specht modules proved by Fayers and the first author [16]. These results can be considered as complements to James and Donkin’s row and column removal theorems for decomposition numbers of the symmetric and general linear groups. In this paper we consider homomorphisms between the Specht modules of the Hecke ...

Permutation resolutions for Specht modules

For every composition λ of a positive integer r , we construct a finite chain complex whose terms are direct sums of permutation modules M for the symmetric group Sr with Young subgroup stabilizers Sμ. The construction is combinatorial and can be carried out over every commutative base ring k. We conjecture that for every partition λ the chain complex has homology concentrated in one degree (at...

Submodules of Secondary Modules