Nilpotence for modules over the mod 2 Steenrod algebra I.
John H. Palmieri.

Abstract. Let B be a sub-Hopf algebra of the mod 2 Steenrod algebra, and let
M be a finite dimensional B-module. We prove that one can detect nilpotence
of elements in Ext_B(M;M) by restricting to elementary sub-Hopf algebras,
and we prove a similar result at odd primes.