Cohomology and generic cohomology of Specht modules for the symmetric group

Cohomology and generic cohomology of Specht modules for the symmetric group

Article history: Received 14 April 2008 Available online 3 July 2009 Communicated by Leonard L. Scott, Jr.

Low-Degree Cohomology of Integral Specht Modules

We introduce a way of describing cohomology of the symmetric groups Σn with coefficients in Specht modules. We study H (Σn, S λ R) for i ∈ {0, 1, 2} and R = Z, Fp. The focus lies on the isomorphism type of H(Σn, S λ Z ). Unfortunately, only in few cases can we determine this exactly. In many cases we obtain only some information about the prime divisors of |H(Σn, S λ Z )|. The most important to...

Realizing large gaps in cohomology for symmetric group modules

Symmetric Group Modules with Specht and Dual Specht Filtrations

The author and Nakano recently proved that multiplicities in a Specht filtration of a symmetric group module are well-defined precisely when the characteristic is at least five. This result suggested the possibility of a symmetric group theory analogous to that of good filtrations and tilting modules for GLn(k). This paper is an initial attempt at such a theory. We obtain two sufficient conditi...

The Complexity of Certain Specht Modules for the Symmetric Group

During the 2004-2005 academic year the VIGRE algebra research group at the University of Georgia computed the complexities of certain Specht modules S for the symmetric group Σd, using the computer algebra program Magma. The complexity of an indecomposable module does not exceed the p-rank of the defect group of its block. The Georgia group conjectured that, generically, the complexity of a Spe...