(** * Relating [x ?= y] to [=], [<=], [<], [>=] or [>] *)

Lemma Zcompare_eq_case :
forall (c1 c2 c3:Prop) (n m:Z),
c1 -> n = m -> match n ?= m with
| Eq => c1
| Lt => c2
| Gt => c3
end.