(** * Particular SF_seq *)

Definition SF_seq_f1 {T : Type} (f1 : R -> T) (P : seq R) : SF_seq :=
  mkSF_seq (head 0 P) (pairmap (fun x y => (y, f1 x)) (head 0 P) (behead P)).Definition SF_seq_f2 {T : Type} (f2 : R -> R -> T) (P : seq R) : SF_seq :=
  mkSF_seq (head 0 P) (pairmap (fun x y => (y, f2 x y)) (head 0 P) (behead P)).

Lemma ptd_f2 (f : R -> R -> R) s : sorted Rle s -> (forall x y, x <= y -> x <= f x y <= y) -> pointed_subdiv (SF_seq_f2 f s).