Constrains, Stable, Invariant...more of the substitution axiom, but Union
does not work well with them
(* Title: HOL/RelPow.thy
ID: $Id$
Author: Tobias Nipkow
Copyright 1996 TU Muenchen
R^n = R O ... O R, the n-fold composition of R
*)
RelPow = Nat +
primrec
"R^0 = id"
"R^(Suc n) = R O (R^n)"
end