simpl in |- *.
red in |- *.
simpl in |- *.
intro i.
elim i.
intros.
apply Ap_comp; auto with algebra.
Qed.
Hint Resolve Seqtl_cons_inv: algebra.

Lemma Seqtl_to_seq :
forall (v : seq (S n) A) (i : Nat) (Hi : i < n) (HSi : S i < S n),
Seqtl v (Build_finiteT Hi) =' v (Build_finiteT HSi) in _.