(** * Coq codes *)
(** ** Dependencies *)
Require Export RegExp.Utility.
Require Export RegExp.Definitions.
(** ** [Empty] *)
(** [Empty] corresponds to 0 in Kleene algebra. *)
(** ** [Eps] *)
(** [Eps] corresponds to 1 in Kleene algebra. *)
(** ** Boolean operations on [RegExp] are morphism. *)
(** [Or] corresponds to plus in Kleene algebra. *)
Add Parametric Morphism : Or with
signature re_eq ==> re_eq ==> re_eq as Or_morphism.
Add Parametric Morphism : And with
signature re_eq ==> re_eq ==> re_eq as And_morphism.
Add Parametric Morphism : Not with
signature re_eq ==> re_eq as Not_morphism.
(** [matches] is a homomorphism from [RegExp] to bool for [And], [Or], and [Not]. *)
(** ** Axioms for [Or] *)
(** Commutativity and associativity of [Or] and [And]. *)

Lemma Or_assoc_s : forall s r r' r'',
((r || r') || r'') ~= s = (r || (r' || r'')) ~= s.