Jon F. Carlson, Sunil K. Chebolu, Jan Minac: Finite generation of Tate cohomology,,

Submission: 2009, Oct 3

Let G be a finite group and let k be a field of characteristic p. Given a finitely generated indecomposable non-projective kG-module M, we conjecture that if the Tate cohomology of G with coefficients in M is finitely generated over the Tate cohomology ring, then the support variety V_G(M) of M is equal to the entire maximal ideal spectrum V_G(k). We prove various results which support this conjecture. The converse of this conjecture is established for modules in the connected component of k in the stable Auslander-Reiten quiver for kG, but it is shown to be false in general. It is also shown that all finitely generated kG-modules over a group G have finitely generated Tate cohomology if and only if G has periodic cohomology.

2000 Mathematics Subject Classification:

Keywords and Phrases: Tate cohomology, finite generation, periodic modules, support varieties, stable module category, almost split sequences.

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