urbanc [Mon, 07 Nov 2005 14:35:25 +0100] rev 18104
added thms perm, distinct and fresh to the simplifier.
One would liket to add also inject, but this causes
problems with "congruences" like
Lam [a].t1 = Lam [b].t2
P (Lam [a].t1)
-----------------------
P (Lam [b].t2)
because the equation "Lam [a].t1 = Lam [b].t2" would simplify
to "[a].t1 = [b].t2" and then the goal is not true just by
simplification.