(** lists with same elements modulo [eqA] *)
Definition inclA l l' := forall x, InA x l -> InA x l'.
Definition equivlistA l l' := forall x, InA x l <-> InA x l'.

(* Specifications: *)
Lemma incl_nil l : inclA nil l.
Global Instance eqlistA_equiv : Equivalence eqlistA.