proposition: Lemma serial_relT (X:Type) : forall x: X, exists y, relT x y.
proof: Proof. move => x. by exists x. Qed.
imports: mathcomp.ssreflect.ssreflect mathcomp(all_ssreflect) CompDecModal.libs(edone bcase fset base sltype) CompDecModal.CTL(CTL_def dags)