(** ** Total correctness proof of [gcd] *)

Lemma gcd_total_proof:
forall x0 y0, (fun e => (VX e)=x0 /\ (VY e)=y0 /\ x0 > 0 /\ y0 > 0)
|= gcd  [= fun e => (Zis_gcd x0 y0 (VX e)) =].