proposition: Lemma UM_default_proof : ~~ gen_dec fset0.
proof: Proof. pose M := FModel [rel x y : unit | false] (fun p => xpred0). apply: (@sat_cons M tt) => ?. by rewrite inE. Qed.
imports: mathcomp.ssreflect.ssreflect mathcomp(all_ssreflect) CompDecModal.libs(edone bcase fset base sltype) CompDecModal.K(K_def demo gentzen)