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1 module logic where
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2
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3 open import Level
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4 open import Relation.Nullary
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5 open import Relation.Binary hiding (_⇔_ )
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6 open import Data.Empty
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7
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8 data Bool : Set where
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9 true : Bool
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10 false : Bool
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11
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12 data Two : Set where
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13 i0 : Two
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14 i1 : Two
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15
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16 record _∧_ {n m : Level} (A : Set n) ( B : Set m ) : Set (n ⊔ m) where
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17 constructor ⟪_,_⟫
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18 field
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19 proj1 : A
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20 proj2 : B
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21
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22 data _∨_ {n m : Level} (A : Set n) ( B : Set m ) : Set (n ⊔ m) where
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23 case1 : A → A ∨ B
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24 case2 : B → A ∨ B
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25
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26 _⇔_ : {n m : Level } → ( A : Set n ) ( B : Set m ) → Set (n ⊔ m)
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27 _⇔_ A B = ( A → B ) ∧ ( B → A )
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28
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29 ∧-exch : {n m : Level} {A : Set n} { B : Set m } → A ∧ B → B ∧ A
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30 ∧-exch p = ⟪ _∧_.proj2 p , _∧_.proj1 p ⟫
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31
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32 ∨-exch : {n m : Level} {A : Set n} { B : Set m } → A ∨ B → B ∨ A
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33 ∨-exch (case1 x) = case2 x
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34 ∨-exch (case2 x) = case1 x
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35
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36 contra-position : {n m : Level } {A : Set n} {B : Set m} → (A → B) → ¬ B → ¬ A
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37 contra-position {n} {m} {A} {B} f ¬b a = ¬b ( f a )
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38
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39 double-neg : {n : Level } {A : Set n} → A → ¬ ¬ A
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40 double-neg A notnot = notnot A
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41
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42 double-neg2 : {n : Level } {A : Set n} → ¬ ¬ ¬ A → ¬ A
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43 double-neg2 notnot A = notnot ( double-neg A )
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44
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45 de-morgan : {n : Level } {A B : Set n} → A ∧ B → ¬ ( (¬ A ) ∨ (¬ B ) )
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46 de-morgan {n} {A} {B} and (case1 ¬A) = ⊥-elim ( ¬A ( _∧_.proj1 and ))
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47 de-morgan {n} {A} {B} and (case2 ¬B) = ⊥-elim ( ¬B ( _∧_.proj2 and ))
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48
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49 de-morgan∨ : {n : Level } {A B : Set n} → A ∨ B → ¬ ( (¬ A ) ∧ (¬ B ) )
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50 de-morgan∨ {n} {A} {B} (case1 a) and = ⊥-elim ( _∧_.proj1 and a )
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51 de-morgan∨ {n} {A} {B} (case2 b) and = ⊥-elim ( _∧_.proj2 and b )
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52
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53 dont-or : {n m : Level} {A : Set n} { B : Set m } → A ∨ B → ¬ A → B
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54 dont-or {A} {B} (case1 a) ¬A = ⊥-elim ( ¬A a )
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55 dont-or {A} {B} (case2 b) ¬A = b
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56
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57 dont-orb : {n m : Level} {A : Set n} { B : Set m } → A ∨ B → ¬ B → A
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58 dont-orb {A} {B} (case2 b) ¬B = ⊥-elim ( ¬B b )
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59 dont-orb {A} {B} (case1 a) ¬B = a
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60
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61 infixr 130 _∧_
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62 infixr 140 _∨_
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63 infixr 150 _⇔_
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64
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65 _/\_ : Bool → Bool → Bool
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66 true /\ true = true
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67 _ /\ _ = false
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68
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69 _\/_ : Bool → Bool → Bool
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70 false \/ false = false
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71 _ \/ _ = true
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72
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73 not : Bool → Bool
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74 not true = false
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75 not false = true
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76
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77 _<=>_ : Bool → Bool → Bool
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78 true <=> true = true
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79 false <=> false = true
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80 _ <=> _ = false
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81
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82 open import Relation.Binary.PropositionalEquality
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83
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84 not-not-bool : { b : Bool } → not (not b) ≡ b
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85 not-not-bool {true} = refl
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86 not-not-bool {false} = refl
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87
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88 record Bijection {n m : Level} (R : Set n) (S : Set m) : Set (n Level.⊔ m) where
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89 field
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90 fun← : S → R
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91 fun→ : R → S
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92 fiso← : (x : R) → fun← ( fun→ x ) ≡ x
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93 fiso→ : (x : S ) → fun→ ( fun← x ) ≡ x
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94
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95 injection : {n m : Level} (R : Set n) (S : Set m) (f : R → S ) → Set (n Level.⊔ m)
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96 injection R S f = (x y : R) → f x ≡ f y → x ≡ y
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97
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98
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99 ¬t=f : (t : Bool ) → ¬ ( not t ≡ t)
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100 ¬t=f true ()
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101 ¬t=f false ()
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102
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103 infixr 130 _\/_
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104 infixr 140 _/\_
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105
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106 ≡-Bool-func : {A B : Bool } → ( A ≡ true → B ≡ true ) → ( B ≡ true → A ≡ true ) → A ≡ B
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107 ≡-Bool-func {true} {true} a→b b→a = refl
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108 ≡-Bool-func {false} {true} a→b b→a with b→a refl
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109 ... | ()
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110 ≡-Bool-func {true} {false} a→b b→a with a→b refl
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111 ... | ()
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112 ≡-Bool-func {false} {false} a→b b→a = refl
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113
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114 bool-≡-? : (a b : Bool) → Dec ( a ≡ b )
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115 bool-≡-? true true = yes refl
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116 bool-≡-? true false = no (λ ())
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117 bool-≡-? false true = no (λ ())
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118 bool-≡-? false false = yes refl
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119
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120 ¬-bool-t : {a : Bool} → ¬ ( a ≡ true ) → a ≡ false
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121 ¬-bool-t {true} ne = ⊥-elim ( ne refl )
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122 ¬-bool-t {false} ne = refl
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123
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124 ¬-bool-f : {a : Bool} → ¬ ( a ≡ false ) → a ≡ true
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125 ¬-bool-f {true} ne = refl
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126 ¬-bool-f {false} ne = ⊥-elim ( ne refl )
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127
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128 ¬-bool : {a : Bool} → a ≡ false → a ≡ true → ⊥
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129 ¬-bool refl ()
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130
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131 lemma-∧-0 : {a b : Bool} → a /\ b ≡ true → a ≡ false → ⊥
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132 lemma-∧-0 {true} {true} refl ()
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133 lemma-∧-0 {true} {false} ()
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134 lemma-∧-0 {false} {true} ()
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135 lemma-∧-0 {false} {false} ()
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136
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137 lemma-∧-1 : {a b : Bool} → a /\ b ≡ true → b ≡ false → ⊥
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138 lemma-∧-1 {true} {true} refl ()
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139 lemma-∧-1 {true} {false} ()
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140 lemma-∧-1 {false} {true} ()
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141 lemma-∧-1 {false} {false} ()
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142
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143 bool-and-tt : {a b : Bool} → a ≡ true → b ≡ true → ( a /\ b ) ≡ true
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144 bool-and-tt refl refl = refl
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145
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146 bool-∧→tt-0 : {a b : Bool} → ( a /\ b ) ≡ true → a ≡ true
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147 bool-∧→tt-0 {true} {true} refl = refl
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148 bool-∧→tt-0 {false} {_} ()
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149
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150 bool-∧→tt-1 : {a b : Bool} → ( a /\ b ) ≡ true → b ≡ true
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151 bool-∧→tt-1 {true} {true} refl = refl
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152 bool-∧→tt-1 {true} {false} ()
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153 bool-∧→tt-1 {false} {false} ()
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154
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155 bool-or-1 : {a b : Bool} → a ≡ false → ( a \/ b ) ≡ b
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156 bool-or-1 {false} {true} refl = refl
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157 bool-or-1 {false} {false} refl = refl
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158 bool-or-2 : {a b : Bool} → b ≡ false → (a \/ b ) ≡ a
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159 bool-or-2 {true} {false} refl = refl
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160 bool-or-2 {false} {false} refl = refl
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161
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162 bool-or-3 : {a : Bool} → ( a \/ true ) ≡ true
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163 bool-or-3 {true} = refl
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164 bool-or-3 {false} = refl
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165
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166 bool-or-31 : {a b : Bool} → b ≡ true → ( a \/ b ) ≡ true
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167 bool-or-31 {true} {true} refl = refl
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168 bool-or-31 {false} {true} refl = refl
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169
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170 bool-or-4 : {a : Bool} → ( true \/ a ) ≡ true
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171 bool-or-4 {true} = refl
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172 bool-or-4 {false} = refl
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173
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174 bool-or-41 : {a b : Bool} → a ≡ true → ( a \/ b ) ≡ true
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175 bool-or-41 {true} {b} refl = refl
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176
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177 bool-and-1 : {a b : Bool} → a ≡ false → (a /\ b ) ≡ false
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178 bool-and-1 {false} {b} refl = refl
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179 bool-and-2 : {a b : Bool} → b ≡ false → (a /\ b ) ≡ false
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180 bool-and-2 {true} {false} refl = refl
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181 bool-and-2 {false} {false} refl = refl
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182
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183
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184 open import Data.Nat
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185 open import Data.Nat.Properties
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186
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187 _≥b_ : ( x y : ℕ) → Bool
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188 x ≥b y with <-cmp x y
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189 ... | tri< a ¬b ¬c = false
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190 ... | tri≈ ¬a b ¬c = true
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191 ... | tri> ¬a ¬b c = true
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192
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193 _>b_ : ( x y : ℕ) → Bool
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194 x >b y with <-cmp x y
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195 ... | tri< a ¬b ¬c = false
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196 ... | tri≈ ¬a b ¬c = false
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197 ... | tri> ¬a ¬b c = true
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198
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199 _≤b_ : ( x y : ℕ) → Bool
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200 x ≤b y = y ≥b x
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201
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202 _<b_ : ( x y : ℕ) → Bool
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203 x <b y = y >b x
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204
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205 open import Relation.Binary.PropositionalEquality
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206
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207 ¬i0≡i1 : ¬ ( i0 ≡ i1 )
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208 ¬i0≡i1 ()
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209
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210 ¬i0→i1 : {x : Two} → ¬ (x ≡ i0 ) → x ≡ i1
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211 ¬i0→i1 {i0} ne = ⊥-elim ( ne refl )
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212 ¬i0→i1 {i1} ne = refl
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213
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214 ¬i1→i0 : {x : Two} → ¬ (x ≡ i1 ) → x ≡ i0
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215 ¬i1→i0 {i0} ne = refl
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216 ¬i1→i0 {i1} ne = ⊥-elim ( ne refl )
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217
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