Library mathcomp.ssreflect.ssrbool

From mathcomp Require Import ssreflect ssrfun.
From Coq Require Export ssrbool.

Local additions: [in A] == the applicative counterpart of a collective predicate A: [in A] x beta-expands to x \in A. This is similar to mem A, except that mem A x only simplfies to x \in A. --> These will become part of the core SSReflect library in later Coq versions. For the sake of backwards compatibility, this file also replicates v8.13-15 additions, including a generalization of the statments of `homoRL_in`, `homoLR_in`, `homo_mono_in`, `monoLR_in`, `monoRL_in`, and `can_mono_in`. v8.15 addtions

Section ReflectCombinators.

Variables (P Q : Prop) (p q : bool).

Hypothesis rP : reflect P p.
Hypothesis rQ : reflect Q q.

Lemma negPP : reflect (¬ P) (~~ p).

Lemma andPP : reflect (P Q) (p && q).

Lemma orPP : reflect (P Q) (p || q).

Lemma implyPP : reflect (P Q) (p ==> q).

End ReflectCombinators.
Arguments negPP {P p}.
Arguments andPP {P Q p q}.
Arguments orPP {P Q p q}.
Arguments implyPP {P Q p q}.

v8.16 additions pred_oapp T D := [pred x | oapp (mem D) false x]

Lemma mono1W_in (aT rT : predArgType) (f : aT rT) (aD : {pred aT})
    (aP : pred aT) (rP : pred rT) :
  {in aD, {mono f : x / aP x >-> rP x}}
  {in aD, {homo f : x / aP x >-> rP x}}.
Arguments mono1W_in [aT rT f aD aP rP].

Set Implicit Arguments.

v8.17 additions

Lemma all_sig2_cond {I T} (C : pred I) P Q :
    T ( x, C x {y : T | P x y & Q x y})
  {f : I T | x, C x P x (f x) & x, C x Q x (f x)}.

Lemma can_in_pcan [rT aT : Type] (A : {pred aT}) [f : aT rT] [g : rT aT] :
  {in A, cancel f g} {in A, pcancel f (fun y : rTSome (g y))}.

Lemma pcan_in_inj [rT aT : Type] [A : {pred aT}]
    [f : aT rT] [g : rT option aT] :
  {in A, pcancel f g} {in A &, injective f}.

Lemma in_inj_comp A B C (f : B A) (h : C B) (P : pred B) (Q : pred C) :
  {in P &, injective f} {in Q &, injective h} {homo h : x / Q x >-> P x}
  {in Q &, injective (f \o h)}.

Lemma can_in_comp [A B C : Type] (D : {pred B}) (D' : {pred C})
    [f : B A] [h : C B] [f' : A B] [h' : B C] :
  {homo h : x / x \in D' >-> x \in D}
  {in D, cancel f f'} {in D', cancel h h'}
  {in D', cancel (f \o h) (h' \o f')}.

Lemma pcan_in_comp [A B C : Type] (D : {pred B}) (D' : {pred C})
    [f : B A] [h : C B] [f' : A option B] [h' : B option C] :
  {homo h : x / x \in D' >-> x \in D}
  {in D, pcancel f f'} {in D', pcancel h h'}
  {in D', pcancel (f \o h) (obind h' \o f')}.

Definition pred_oapp T (D : {pred T}) : pred (option T) :=
  [pred x | oapp (mem D) false x].

Lemma ocan_in_comp [A B C : Type] (D : {pred B}) (D' : {pred C})
    [f : B option A] [h : C option B] [f' : A B] [h' : B C] :
  {homo h : x / x \in D' >-> x \in pred_oapp D}
  {in D, ocancel f f'} {in D', ocancel h h'}
  {in D', ocancel (obind f \o h) (h' \o f')}.

Lemma eqbLR (b1 b2 : bool) : b1 = b2 b1 b2.

Lemma eqbRL (b1 b2 : bool) : b1 = b2 b2 b1.

Lemma homo_mono1 [aT rT : Type] [f : aT rT] [g : rT aT]
    [aP : pred aT] [rP : pred rT] :
  cancel g f
  {homo f : x / aP x >-> rP x}
  {homo g : x / rP x >-> aP x} {mono g : x / rP x >-> aP x}.

Lemma if_and b1 b2 T (x y : T) :
  (if b1 && b2 then x else y) = (if b1 then if b2 then x else y else y).

Lemma if_or b1 b2 T (x y : T) :
  (if b1 || b2 then x else y) = (if b1 then x else if b2 then x else y).

Lemma if_implyb b1 b2 T (x y : T) :
  (if b1 ==> b2 then x else y) = (if b1 then if b2 then x else y else x).

Lemma if_implybC b1 b2 T (x y : T) :
  (if b1 ==> b2 then x else y) = (if b2 then x else if b1 then y else x).

Lemma if_add b1 b2 T (x y : T) :
  (if b1 (+) b2 then x else y) = (if b1 then if b2 then y else x else if b2 then x else y).

Future additions

Notation "[ 'in' A ]" := (in_mem^~ (mem A))
  (at level 0, format "[ 'in' A ]") : function_scope.

Lemma relpre_trans {T' T : Type} {leT : rel T} {f : T' T} :
  transitive leT transitive (relpre f leT).

The notations below are already defined in Coq.ssr.ssrbool, but we redefine them in different notation scopes (mostly fun_scope -> function_scope, in order to replace the former with the latter).

Notation "[ 'pred' : T | E ]" := (SimplPred (fun _ : TE%B)) :
  function_scope.
Notation "[ 'pred' x | E ]" := (SimplPred (fun xE%B)) : function_scope.
Notation "[ 'pred' x | E1 & E2 ]" := [pred x | E1 && E2 ] : function_scope.
Notation "[ 'pred' x : T | E ]" :=
  (SimplPred (fun x : TE%B)) (only parsing) : function_scope.
Notation "[ 'pred' x : T | E1 & E2 ]" :=
  [pred x : T | E1 && E2 ] (only parsing) : function_scope.

Notation "[ 'rel' x y | E ]" := (SimplRel (fun x yE%B))
  (only parsing) : function_scope.
Notation "[ 'rel' x y : T | E ]" :=
  (SimplRel (fun x y : TE%B)) (only parsing) : function_scope.

Notation "[ 'mem' A ]" :=
  (pred_of_simpl (simpl_of_mem (mem A))) (only parsing) : function_scope.

Notation "[ 'pred' x 'in' A ]" := [pred x | x \in A] : function_scope.
Notation "[ 'pred' x 'in' A | E ]" := [pred x | x \in A & E] : function_scope.
Notation "[ 'pred' x 'in' A | E1 & E2 ]" :=
  [pred x | x \in A & E1 && E2 ] : function_scope.

Notation "[ 'rel' x y 'in' A & B | E ]" :=
  [rel x y | (x \in A) && (y \in B) && E] : function_scope.
Notation "[ 'rel' x y 'in' A & B ]" :=
  [rel x y | (x \in A) && (y \in B)] : function_scope.
Notation "[ 'rel' x y 'in' A | E ]" := [rel x y in A & A | E] : function_scope.
Notation "[ 'rel' x y 'in' A ]" := [rel x y in A & A] : function_scope.

Both bodies and the scope have been changed for the following notations.
Notation "[ 'predI' A & B ]" := (predI [in A] [in B]) : function_scope.
Notation "[ 'predU' A & B ]" := (predU [in A] [in B]) : function_scope.
Notation "[ 'predD' A & B ]" := (predD [in A] [in B]) : function_scope.
Notation "[ 'predC' A ]" := (predC [in A]) : function_scope.
Notation "[ 'preim' f 'of' A ]" := (preim f [in A]) : function_scope.