proposition: Lemma the_CNF_p1: the_CNFB \0o = emptyset.
proof: Proof. move:(the_CNF_p0 OS0) => [[p1 p2 p3 p4] p5]. ex_middle nz. move /domain_set0_P: nz => nz. move: (cpred_pr p2 nz) => [mN mv]. rewrite /CNFBv mv in p4 p5. by case: (nesym (proj2 (CNFq_pg5 mN p4))). Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat)