contradiction.
simpl in H;case_bool v (LiteraltoPropF a).
exists (LiteraltoPropF a);split;[in_solve|rewrite H0;trivial].
destruct (IHm H) as (?&?&?);exists x;split;[in_solve|assumption].
Qed.

(* Specifications: *)
Lemma Validated_valid : forall l, Validates (Countervaluation l) (map LiteraltoPropF l) -> Valid_Clause l.
intros l (A&H&K). apply in_map_iff in H as (p&?&H);subst;destruct p;unfold Countervaluation in K;simpl in K.