Fixpoint make_conj (A : Type) (eval : A -> Prop) (l : list A) {struct l} : Prop :=
match l with
| nil => True
| cons e nil => (eval e)
| cons e l2 => ((eval e) /\ (make_conj eval l2))
end.

Lemma not_make_conj_cons : forall (A:Type) (t:A) a eval  (no_middle_eval : (eval t) \/ ~ (eval  t)),
~ make_conj  eval (t ::a) <-> ~  (eval t) \/ (~ make_conj  eval a).