intros.
apply split_hd_tl_equality; auto with algebra.
Qed.
Hint Resolve pointwise_cons: algebra.

Lemma pointwise_hd_tl :
forall (A B C : Setoid) (n : Nat) (v : seq (S n) A)
(w : seq (S n) B) (op : Map (cart A B) C),
pointwise op v w ='
op (couple (head v) (head w));; pointwise op (Seqtl v) (Seqtl w) in
seq _ _.