intros;induction ll1;simpl.
reflexivity.
rewrite CNF_and_valid;rewrite IHll1;rewrite CNF_add_clause_valid.
rewrite orb_andb_distrib_l;reflexivity.
Qed.

Theorem CNF_equiv_valid : forall v A, TrueQ v (CNFtoPropF (MakeCNF A)) = TrueQ v (NNFtoPropF A).
intros;induction A;simpl;try reflexivity;try (destruct (v p);simpl;reflexivity;fail);
[rewrite CNF_and_valid|rewrite CNF_or_valid];rewrite IHA1;rewrite IHA2;reflexivity.