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

Theorem binds_single_inv : forall A x y (v w: A),
x ∹ v ⋲ (y ∶ w) ->
x = y ∧ v = w.