Published online by Cambridge University Press: 01 July 2009
The ‘hit problem’ of F. P. Peterson in algebraic topology asks for a minimal generating set for the polynomial algebra P(n) = 2[x1,. . ., xn] as a module over the Steenrod algebra 2. An equivalent problem is to find an 2-basis for the subring K(n) of elements f in the dual Hopf algebra D(n), a divided power algebra, such that Sqk(f)=0 for all k > 0. The Steenrod kernel K(n) is a 2GL(n,2)-module dual to the quotient Q(n) of P(n) by the hit elements +2P(n). A submodule S(n) of K(n) is obtained as the image of a family of maps from the permutation module Fl(n) of GL(n,2) on complete flags in an n-dimensional vector space V over 2. We use the Schubert cell decomposition of the flags to calculate S(n) in degrees , where λ1 > λ2 > ⋅⋅⋅ > λn ≥ 0. When λn = 0, we define a 2GL(n,2)-module map δ: Qd(n) → Q2d+n−1(n) analogous to the well-known isomorphism Qd(n) → Q2d+n(n) of M. Kameko. When λn−1 ≥ 2, we show that δ is surjective and δ*: S2d+n−1(n)→ Sd(n) is an isomorphism.