On Universally Stable Elements

Quart. J. Math. Oxford vol. 48 (1997) 493--498.  

Ian J. Leary, Bj\"orn Schuster, and Nobuaki Yagita

We show that certain subrings of the cohomology of a finite
p-group P may be realised as the images of restriction from 
suitable virtually free groups.  We deduce that the cohomology 
of P is a finite module for any such subring.  Examples include 
the ring of `universally stable elements' defined by Evens and 
Priddy, and rings of invariants such as the mod-2 Dickson 
algebras.