red in |- *.
simpl in |- *.
split; auto.
Qed.
Definition seq_eq (A : Setoid) := StrEq (seq_eq_str A).

(* Specifications: *)
Lemma test2 :
forall (A : Setoid) (n m : nat) (v : seq n A) (w : seq m A),
seq_eq v w -> seq_eq w v.