Definition rotate {A} (l : list A) n m := sublist (m - n) (Zlength l) l ++
  sublist 0 (m - n) l.

Lemma Forall_sublist_le : forall {A} {d : Inhabitant A} (P : A -> Prop) i j l (Hrangei : 0 <= i) (Hrangej : j <= Zlength l) (Hi : ~P (Znth i l)) (Hj : Forall P (sublist 0 j l)), j <= i.