Uniformly Generated Submodules of Permutation Modules

Søren Riis
Meera Sitharam

September 1998

Abstract:

This paper is motivated by a link between algebraic proof complexity and the representation theory of the finite symmetric groups. Our perspective leads to a series of non-traditional problems in the representation theory of tex2html_wrap_inline23.

Most of our technical results concern the structure of ``uniformly'' generated submodules of permutation modules. We consider (for example) sequences tex2html_wrap_inline25 of submodules of the permutation modules tex2html_wrap_inline27 and prove that if the modules tex2html_wrap_inline25 are given in a uniform way - which we make precise - the dimension p(n) of tex2html_wrap_inline25 (as a vector space) is a single polynomial with rational coefficients, for all but finitely many ``singular'' values of n. Furthermore, we show that tex2html_wrap_inline37 for each singular value of tex2html_wrap_inline39. The results have a non-traditional flavor arising from the study of the irreducible structure of the submodules tex2html_wrap_inline25 beyond isomorphism types.

We sketch the link between our structure theorems and proof complexity questions, which can be viewed as special cases of the famous NP vs. co-NP problem in complexity theory. In particular, we focus on the efficiency of proof systems for showing membership in polynomial ideals, for example, based on Hilbert's Nullstellensatz.

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