intros;induction ll1;simpl.
reflexivity.
unfold CNFtoPropF in IHll1 at 1;rewrite IHll1.
apply andb_assoc.
Qed.

Lemma CNF_or_clause_valid : forall v l1 l2, TrueQ v (ClausetoPropF (l1++l2)) =
TrueQ v (ClausetoPropF l1) || TrueQ v (ClausetoPropF l2).