(** * Coq codes *)
(** ** Dependencies *)
Require Export RegExp.Utility.
Require Export RegExp.Definitions.
Require Export RegExp.Boolean.
Require Export RegExp.Concat.
Require Export RegExp.Star.
(** ** Define [includes] *)
Definition includes (x y:RegExp) : Prop := (x || y) =R= y.
Notation "x <= y" := (includes x y) (at level 70).
Definition prop_eq (p q:Prop) : Prop := (p <-> q).

Lemma includes_antisymmetric : forall x y, x <= y -> y <= x -> x =R= y.