Section Set_of_tuple_of_positive.
Context {Ar : Arity}.
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.