Fixpoint eqList (l1 l2 : list positive) :=
    match l1, l2 with
      | nil, nil => True
      | (hd1 :: tl1), (hd2 :: tl2) => (Pos.eq hd1 hd2) /\ (eqList tl1 tl2)
      | _, _ => False
    end.

Lemma eqListSym : forall l l', eqList l l' -> eqList l' l.