proposition: Lemma add_reduce5 : forall x y z a : Z, (x - a)%Z = (z - y)%Z -> x = (a + z - y)%Z.
proof: Proof. intros; omega. Qed.
imports: List DistributedReferenceCounting.machine2.invariant0 DistributedReferenceCounting.machine2.invariant1 DistributedReferenceCounting.machine2.invariant2