Section Properties.
Implicit Types x y : TVar.
Implicit Types xs ys : list TVar.
(* ---------------------------------------------------------------------- *)
(** **** Abstract properties of ok *)
(* ---------------------------------------------------------------------- *)
(** **** Properties of binds *)
(* ---------------------------------------------------------------------- *)
(** **** Properties of all_binds *)

Theorem all_binds_single_single : forall A x y (v w : A),
x = y -> v = w ->
(x ∶ v) ⊏ (y ∶ w).