A Freeness Theorem for RO(Z/2)-graded Cohomology.

link: http://arxiv.org/abs/0908.3825
Abstract

In this paper it is shown that the RO(Z/2)-graded cohomology of a certain
class of Rep(Z/2)-complexes, which includes projective spaces and Grassmann
manifolds, is always free as a module over the cohomology of a point when the
coefficient Mackey functor is \underline{Z/2}.