(* (c) Copyright 2006-2016 Microsoft Corporation and Inria.                  *)
(* Distributed under the terms of CeCILL-B.                                  *)
From mathcomp
From mathcomp
(*****************************************************************************)
(* This file clones the entire ssralg hierachy for finite types; this allows *)
(* type inference to function properly on expressions that mix combinatorial *)
(* and algebraic operators (e.g., [set x + y | x in A, y in A]).             *)
(*   finZmodType, finRingType, finComRingType, finUnitRingType,              *)
(*   finComUnitRingType, finIdomType, finFieldType finLmodType,              *)
(*   finLalgType finAlgType finUnitAlgType                                   *)
(*      == the finite counterparts of zmodType, etc.                         *)
(* Note that a finFieldType is canonically decidable. All these structures   *)
(* can be derived using [xxxType of T] forms, e.g., if R has both canonical  *)
(* finType and ringType structures, then                                     *)
(*     Canonical R_finRingType := Eval hnf in [finRingType of R].            *)
(* declares the derived finRingType structure for R. As the implementation   *)
(* of the derivation is somewhat involved, the Eval hnf normalization is     *)
(* strongly recommended.                                                     *)
(*   This file also provides direct tie-ins with finite group theory:        *)
(*  [baseFinGroupType of R for +%R] == the (canonical) additive group        *)
(*      [finGroupType of R for +%R]    structures for R                      *)
(*                         {unit R} == the type of units of R, which has a   *)
(*                                     canonical group structure.            *)
(*                FinRing.unit R Ux == the element of {unit R} corresponding *)
(*                                     to x, where Ux : x \in GRing.unit.    *)
(*                           'U%act == the action by right multiplication of *)
(*                                     {unit R} on R, via FinRing.unit_act.  *)
(*                                     (This is also a group action.)        *)
(*****************************************************************************)
Local Open Scope ring_scope.
Set Implicit Arguments.
Unset Strict Implicit.
Unset Printing Implicit Defensive.
Module FinRing.
Local Notation mixin_of T b := (Finite.mixin_of (EqType T b)).
Section Generic.
(* Implicits *)
Variables (type base_type : Type) (class_of base_of : Type -> Type).
Variable to_choice : forall T, base_of T -> Choice.class_of T.
Variable base_sort : base_type -> Type.
(* Explicits *)
Variable Pack : forall T, class_of T -> type.
Variable Class : forall T b, mixin_of T (to_choice b) -> class_of T.
Variable base_class : forall bT, base_of (base_sort bT).
Definition gen_pack T :=
fun bT b & phant_id (base_class bT) b =>
fun fT m & phant_id (Finite.class fT) (Finite.Class m) =>
Pack (@Class T b m).
End Generic.
Arguments gen_pack [type base_type class_of base_of to_choice base_sort].
Local Notation fin_ c := (@Finite.Class _ c c).
Local Notation do_pack pack T := (pack T _ _ id _ _ id).
Definition groupMixin V := FinGroup.Mixin (@addrA V) (@add0r V) (@addNr V).
Local Notation base_group T vT fT :=
(@FinGroup.PackBase T (groupMixin vT) (Finite.class fT)).
Local Notation fin_group B V := (@FinGroup.Pack B (@addNr V)).
Module Zmodule.
Section ClassDef.
Record class_of M :=
Class { base : GRing.Zmodule.class_of M; mixin : mixin_of M base }.
Local Coercion base : class_of >-> GRing.Zmodule.class_of.
Local Coercion mixin : class_of >-> mixin_of.
Structure type := Pack {sort; _ : class_of sort}.
Local Coercion sort : type >-> Sortclass.
Definition pack := gen_pack Pack Class GRing.Zmodule.class.
Variable cT : type.
Definition class := let: Pack _ c as cT' := cT return class_of cT' in c.
Let xT := let: Pack T _ := cT in T.
Notation xclass := (class : class_of xT).
Definition eqType := @Equality.Pack cT xclass.
Definition choiceType := @Choice.Pack cT xclass.
Definition countType := @Countable.Pack cT (fin_ xclass).
Definition finType := @Finite.Pack cT (fin_ xclass).
Definition zmodType := @GRing.Zmodule.Pack cT xclass.
Definition join_finType := @Finite.Pack zmodType (fin_ xclass).
Definition baseFinGroupType := base_group cT zmodType finType.
Definition finGroupType := fin_group baseFinGroupType zmodType.
Definition join_baseFinGroupType := base_group zmodType zmodType finType.
Definition join_finGroupType := fin_group join_baseFinGroupType zmodType.
End ClassDef.
Module Exports.
Coercion base : class_of >-> GRing.Zmodule.class_of.
Coercion mixin : class_of >-> mixin_of.
Coercion sort : type >-> Sortclass.
Bind Scope ring_scope with sort.
Coercion eqType : type >-> Equality.type.
Canonical eqType.
Coercion choiceType : type >-> Choice.type.
Canonical choiceType.
Coercion countType : type >-> Countable.type.
Canonical countType.
Coercion finType : type >-> Finite.type.
Canonical finType.
Coercion zmodType : type >-> GRing.Zmodule.type.
Canonical zmodType.
Canonical join_finType.
Notation finZmodType := type.
Notation "[ 'finZmodType' 'of' T ]" := (do_pack pack T)
(at level 0, format "[ 'finZmodType'  'of'  T ]") : form_scope.
Coercion baseFinGroupType : type >-> FinGroup.base_type.
Canonical baseFinGroupType.
Coercion finGroupType : type >-> FinGroup.type.
Canonical finGroupType.
Canonical join_baseFinGroupType.
Canonical join_finGroupType.
Notation "[ 'baseFinGroupType' 'of' R 'for' +%R ]" :=
(BaseFinGroupType R (groupMixin _))
(at level 0, format "[ 'baseFinGroupType'  'of'  R  'for'  +%R ]")
: form_scope.
Notation "[ 'finGroupType' 'of' R 'for' +%R ]" :=
(@FinGroup.clone R _ (finGroupType _) id _ id)
(at level 0, format "[ 'finGroupType'  'of'  R  'for'  +%R ]") : form_scope.
Canonical countZmodType (T : type) := [countZmodType of T].
End Exports.
End Zmodule.
Section AdditiveGroup.
Variable U : finZmodType.
Implicit Types x y : U.

Lemma intro_unit x y : y * x = 1 /\ x * y = 1 -> x \is a unit.