proposition: Lemma dmAll (xm : XM) X (P : X -> Prop) : (~ forall x, P x) -> exists x, ~ P x.
proof: Proof. move => H. apply: (dn xm) => C. apply H => x. apply: (dn xm) => nPx. firstorder. Qed.
imports: mathcomp.ssreflect.ssreflect mathcomp(all_ssreflect) CompDecModal.libs(edone bcase fset base modular_hilbert) CompDecModal.CTL(CTL_def hilbert)