induction ls; intuition; simpl in *; wftac.
Qed.

Theorem list_pred_listReplace :
forall n (A B : Set) P (lsa : list A)(lsb : list B),
list_pred P lsa lsb ->
forall a b defa defb,
P a b ->
P defa defb ->
list_pred P (listReplace lsa n a defa) (listReplace lsb n b defb).