1 | include "basics/types.ma". |
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2 | include "utilities/binary/positive.ma". |
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3 | include "ASM/Util.ma". (* bool_to_Prop *) |
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4 | |
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5 | inductive positive_map (A:Type[0]) : Type[0] ≝ |
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6 | | pm_leaf : positive_map A |
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7 | | pm_node : option A → positive_map A → positive_map A → positive_map A. |
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8 | |
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9 | let rec lookup_opt (A:Type[0]) (b:Pos) (t:positive_map A) on t : option A ≝ |
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10 | match t with |
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11 | [ pm_leaf ⇒ None ? |
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12 | | pm_node a l r ⇒ |
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13 | match b with |
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14 | [ one ⇒ a |
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15 | | p0 tl ⇒ lookup_opt A tl l |
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16 | | p1 tl ⇒ lookup_opt A tl r |
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17 | ] |
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18 | ]. |
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19 | |
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20 | definition lookup: ∀A:Type[0].Pos → positive_map A → A → A ≝ |
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21 | λA.λb.λt.λx. |
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22 | match lookup_opt A b t with |
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23 | [ None ⇒ x |
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24 | | Some r ⇒ r |
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25 | ]. |
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26 | |
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27 | let rec insert (A:Type[0]) (b:Pos) (a:A) (t:positive_map A) on b : positive_map A ≝ |
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28 | match b with |
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29 | [ one ⇒ |
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30 | match t with |
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31 | [ pm_leaf ⇒ pm_node A (Some ? a) (pm_leaf A) (pm_leaf A) |
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32 | | pm_node _ l r ⇒ pm_node A (Some ? a) l r |
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33 | ] |
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34 | | p0 tl ⇒ |
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35 | match t with |
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36 | [ pm_leaf ⇒ pm_node A (None ?) (insert A tl a (pm_leaf A)) (pm_leaf A) |
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37 | | pm_node x l r ⇒ pm_node A x (insert A tl a l) r |
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38 | ] |
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39 | | p1 tl ⇒ |
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40 | match t with |
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41 | [ pm_leaf ⇒ pm_node A (None ?) (pm_leaf A) (insert A tl a (pm_leaf A)) |
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42 | | pm_node x l r ⇒ pm_node A x l (insert A tl a r) |
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43 | ] |
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44 | ]. |
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45 | |
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46 | let rec update (A:Type[0]) (b:Pos) (a:A) (t:positive_map A) on b : option (positive_map A) ≝ |
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47 | match b with |
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48 | [ one ⇒ |
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49 | match t with |
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50 | [ pm_leaf ⇒ None ? |
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51 | | pm_node x l r ⇒ option_map ?? (λ_. pm_node A (Some ? a) l r) x |
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52 | ] |
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53 | | p0 tl ⇒ |
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54 | match t with |
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55 | [ pm_leaf ⇒ None ? |
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56 | | pm_node x l r ⇒ option_map ?? (λl. pm_node A x l r) (update A tl a l) |
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57 | ] |
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58 | | p1 tl ⇒ |
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59 | match t with |
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60 | [ pm_leaf ⇒ None ? |
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61 | | pm_node x l r ⇒ option_map ?? (λr. pm_node A x l r) (update A tl a r) |
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62 | ] |
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63 | ]. |
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64 | |
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65 | lemma lookup_opt_insert_hit : |
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66 | ∀A:Type[0].∀v:A.∀b:Pos.∀t:positive_map A. |
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67 | lookup_opt … b (insert … b v t) = Some A v. |
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68 | #A #v #b elim b |
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69 | [ * // |
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70 | | #tl #IH * |
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71 | [ whd in ⊢ (??%%); @IH |
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72 | | #x #l #r @IH |
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73 | ] |
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74 | | #tl #IH * |
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75 | [ whd in ⊢ (??%%); @IH |
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76 | | #x #l #r @IH |
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77 | ] |
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78 | ] qed. |
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79 | |
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80 | lemma lookup_insert_hit: |
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81 | ∀a: Type[0]. |
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82 | ∀v: a. |
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83 | ∀b: Pos. |
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84 | ∀t: positive_map a. |
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85 | ∀d: a. |
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86 | lookup … b (insert … b v t) d = v. |
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87 | #A #v #b #t #d whd in ⊢ (??%?); >lookup_opt_insert_hit % |
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88 | qed. |
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89 | |
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90 | lemma lookup_opt_insert_miss: |
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91 | ∀A:Type[0].∀v:A.∀b,c:Pos.∀t:positive_map A. |
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92 | b ≠ c → lookup_opt … b (insert … c v t) = lookup_opt … b t. |
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93 | #A #v #b elim b |
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94 | [ * [ #t * #H elim (H (refl …)) |
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95 | | *: #c' #t #NE cases t // |
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96 | ] |
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97 | | #b' #IH * |
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98 | [ * [ #NE @refl | #x #l #r #NE @refl ] |
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99 | | #c' * [ #NE whd in ⊢ (??%%); @IH /2/ |
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100 | | #x #l #r #NE whd in ⊢ (??%%); @IH /2/ |
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101 | ] |
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102 | | #c' * // |
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103 | ] |
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104 | | #b' #IH * |
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105 | [ * [ #NE @refl | #x #l #r #NE @refl ] |
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106 | | #c' * // |
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107 | | #c' * [ #NE whd in ⊢ (??%%); @IH /2/ |
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108 | | #x #l #r #NE whd in ⊢ (??%%); @IH /2/ |
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109 | ] |
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110 | ] |
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111 | ] qed. |
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112 | |
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113 | let rec fold (A, B: Type[0]) (f: Pos → A → B → B) |
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114 | (t: positive_map A) (b: B) on t: B ≝ |
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115 | match t with |
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116 | [ pm_leaf ⇒ b |
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117 | | pm_node a l r ⇒ |
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118 | let b ≝ match a with [ None ⇒ b | Some a ⇒ f one a b ] in |
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119 | let b ≝ fold A B (λx.f (p0 x)) l b in |
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120 | fold A B (λx.f (p1 x)) r b |
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121 | ]. |
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122 | |
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123 | lemma update_fail : ∀A,b,a,t. |
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124 | update A b a t = None ? → |
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125 | lookup_opt A b t = None ?. |
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126 | #A #b #a elim b |
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127 | [ * [ // | * // #x #l #r normalize #E destruct ] |
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128 | | #b' #IH * [ // | #x #l #r #U @IH whd in U:(??%?); |
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129 | cases (update A b' a r) in U ⊢ %; |
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130 | [ // | normalize #t #E destruct ] |
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131 | ] |
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132 | | #b' #IH * [ // | #x #l #r #U @IH whd in U:(??%?); |
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133 | cases (update A b' a l) in U ⊢ %; |
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134 | [ // | normalize #t #E destruct ] |
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135 | ] |
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136 | ] qed. |
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137 | |
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138 | lemma update_lookup_opt_same : ∀A,b,a,t,t'. |
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139 | update A b a t = Some ? t' → |
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140 | lookup_opt A b t' = Some ? a. |
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141 | #A #b #a elim b |
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142 | [ * [ #t' normalize #E destruct |
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143 | | * [ 2: #x ] #l #r #t' whd in ⊢ (??%? → ??%?); |
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144 | #E destruct // |
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145 | ] |
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146 | | #b' #IH * |
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147 | [ #t' normalize #E destruct |
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148 | | #x #l #r #t' whd in ⊢ (??%? → ??%?); |
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149 | lapply (IH r) |
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150 | cases (update A b' a r) |
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151 | [ #_ normalize #E destruct |
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152 | | #r' #H normalize #E destruct @H @refl |
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153 | ] |
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154 | ] |
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155 | | #b' #IH * |
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156 | [ #t' normalize #E destruct |
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157 | | #x #l #r #t' whd in ⊢ (??%? → ??%?); |
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158 | lapply (IH l) |
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159 | cases (update A b' a l) |
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160 | [ #_ normalize #E destruct |
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161 | | #r' #H normalize #E destruct @H @refl |
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162 | ] |
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163 | ] |
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164 | ] qed. |
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165 | |
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166 | lemma update_lookup_opt_other : ∀A,b,a,t,t'. |
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167 | update A b a t = Some ? t' → |
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168 | ∀b'. b ≠ b' → |
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169 | lookup_opt A b' t = lookup_opt A b' t'. |
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170 | #A #b #a elim b |
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171 | [ * [ #t' normalize #E destruct |
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172 | | * [2: #x] #l #r #t' normalize #E destruct |
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173 | * [ * #H elim (H (refl …)) ] |
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174 | #tl #NE normalize // |
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175 | ] |
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176 | | #b' #IH * |
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177 | [ #t' normalize #E destruct |
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178 | | #x #l #r #t' normalize |
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179 | lapply (IH r) |
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180 | cases (update A b' a r) |
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181 | [ #_ normalize #E destruct |
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182 | | #t'' #H normalize #E destruct * // #b'' #NE @H /2/ |
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183 | ] |
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184 | ] |
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185 | | #b' #IH * |
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186 | [ #t' normalize #E destruct |
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187 | | #x #l #r #t' normalize |
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188 | lapply (IH l) |
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189 | cases (update A b' a l) |
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190 | [ #_ normalize #E destruct |
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191 | | #t'' #H normalize #E destruct * // #b'' #NE @H /2/ |
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192 | ] |
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193 | ] |
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194 | ] qed. |
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195 | |
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196 | include "utilities/option.ma". |
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197 | |
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198 | let rec map_opt A B (f : A → option B) (b : positive_map A) on b : positive_map B ≝ |
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199 | match b with |
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200 | [ pm_leaf ⇒ pm_leaf ? |
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201 | | pm_node a l r ⇒ pm_node ? (a »= f) |
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202 | (map_opt ?? f l) |
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203 | (map_opt ?? f r) |
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204 | ]. |
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205 | |
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206 | definition map ≝ λA,B,f.map_opt A B (λx. Some ? (f x)). |
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207 | |
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208 | lemma lookup_opt_map : ∀A,B,f,b,p. |
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209 | lookup_opt … p (map_opt A B f b) = ! x ← lookup_opt … p b ; f x. |
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210 | #A#B#f#b elim b [//] |
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211 | #a #l #r #Hil #Hir * [//] |
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212 | #p |
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213 | whd in ⊢ (??(???%)(????%?)); |
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214 | whd in ⊢ (??%?); // |
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215 | qed. |
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216 | |
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217 | lemma map_opt_id_eq_ext : ∀A,m,f.(∀x.f x = Some ? x) → map_opt A A f m = m. |
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218 | #A #m #f #Hf elim m [//] |
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219 | * [2:#x] #l #r #Hil #Hir normalize [>Hf] // |
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220 | qed. |
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221 | |
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222 | lemma map_opt_id : ∀A,m.map_opt A A (λx. Some ? x) m = m. |
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223 | #A #m @map_opt_id_eq_ext // |
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224 | qed. |
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225 | |
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226 | let rec merge A B C (choice : option A → option B → option C) |
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227 | (a : positive_map A) (b : positive_map B) on a : positive_map C ≝ |
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228 | match a with |
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229 | [ pm_leaf ⇒ map_opt ?? (λx.choice (None ?) (Some ? x)) b |
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230 | | pm_node o l r ⇒ |
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231 | match b with |
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232 | [ pm_leaf ⇒ map_opt ?? (λx.choice (Some ? x) (None ?)) a |
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233 | | pm_node o' l' r' ⇒ |
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234 | pm_node ? (choice o o') |
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235 | (merge … choice l l') |
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236 | (merge … choice r r') |
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237 | ] |
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238 | ]. |
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239 | |
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240 | lemma lookup_opt_merge : ∀A,B,C,choice,a,b,p. |
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241 | choice (None ?) (None ?) = None ? → |
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242 | lookup_opt … p (merge A B C choice a b) = |
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243 | choice (lookup_opt … p a) (lookup_opt … p b). |
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244 | #A#B#C#choice#a elim a |
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245 | [ normalize #b |
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246 | | #o#l#r#Hil#Hir * [2: #o'#l'#r' * normalize /2 by /] |
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247 | ] |
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248 | #p#choice_good >lookup_opt_map |
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249 | elim (lookup_opt ???) |
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250 | normalize // |
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251 | qed. |
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252 | |
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253 | let rec domain_size (A : Type[0]) (b : positive_map A) on b : ℕ ≝ |
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254 | match b with |
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255 | [ pm_leaf ⇒ 0 |
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256 | | pm_node a l r ⇒ |
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257 | (match a with |
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258 | [ Some _ ⇒ 1 |
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259 | | None ⇒ 0 |
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260 | ]) + domain_size A l + domain_size A r |
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261 | ]. |
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262 | |
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263 | (* just to load notation for 'norm (list.ma's notation overrides core's 'card)*) |
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264 | include "basics/lists/list.ma". |
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265 | interpretation "positive map size" 'norm p = (domain_size ? p). |
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266 | |
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267 | lemma map_opt_size : ∀A,B,f,b.|map_opt A B f b| ≤ |b|. |
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268 | #A#B#f#b elim b [//] |
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269 | *[2:#x]#l#r#Hil#Hir normalize |
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270 | [elim (f ?) normalize [@(transitive_le ? ? ? ? (le_n_Sn ?)) | #y @le_S_S ] ] |
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271 | @le_plus assumption |
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272 | qed. |
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273 | |
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274 | lemma map_size : ∀A,B,f,b.|map A B f b| = |b|. |
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275 | #A#B#f#b elim b [//] |
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276 | *[2:#x]#l#r#Hil#Hir normalize |
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277 | >Hil >Hir @refl |
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278 | qed. |
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279 | |
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280 | lemma lookup_opt_O_lt_size : ∀A,m,p. lookup_opt A p m ≠ None ? → 0 < |m|. |
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281 | #A#m elim m |
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282 | [#p normalize #F elim (absurd ? (refl ??) F) |
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283 | |* [2: #x] #l #r #Hil #Hir * normalize |
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284 | [1,2,3: // |
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285 | |4: #F elim (absurd ? (refl ??) F)] |
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286 | #p #H [@(transitive_le … (Hir ? H)) | @(transitive_le … (Hil ? H))] // |
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287 | qed. |
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288 | |
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289 | lemma insert_size : ∀A,p,a,m. |insert A p a m| = |
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290 | (match lookup_opt … p m with [Some _ ⇒ 0 | None ⇒ 1]) + |m|. |
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291 | #A#p elim p |
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292 | [ #a * [2: * [2: #x] #l #r] normalize // |
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293 | |*: #p #Hi #a * [2,4: * [2,4: #x] #l #r] normalize >Hi // |
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294 | ] qed. |
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295 | |
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296 | (* Testing all of the entries with a boolean predicate, where the predicate |
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297 | is given a proof that the entry is in the map. *) |
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298 | |
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299 | let rec pm_all_aux (A:Type[0]) (m,t:positive_map A) (pre:Pos → Pos) on t : (∀p. lookup_opt A (pre p) m = lookup_opt A p t) → (∀p,a.lookup_opt A p m = Some A a → bool) → bool ≝ |
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300 | match t return λt. (∀p. lookup_opt A (pre p) m = lookup_opt A p t) → (∀p,a.lookup_opt A p m = Some A a → bool) → bool with |
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301 | [ pm_leaf ⇒ λ_.λ_. true |
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302 | | pm_node a l r ⇒ λH,f. |
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303 | pm_all_aux A m l (λx. pre (p0 x)) ? f ∧ |
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304 | ((match a return λa. (∀p. ? = lookup_opt A p (pm_node ? a ??)) → ? with [ None ⇒ λ_. true | Some a' ⇒ λH. f (pre one) a' ? ]) H) ∧ |
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305 | pm_all_aux A m r (λx. pre (p1 x)) ? f |
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306 | ]. |
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307 | [ >H % |
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308 | | #p >H % |
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309 | | #p >H % |
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310 | ] qed. |
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311 | |
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312 | definition pm_all : ∀A. ∀m:positive_map A. (∀p,a. lookup_opt A p m = Some A a → bool) → bool ≝ |
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313 | λA,m,f. pm_all_aux A m m (λx.x) (λp. refl ??) f. |
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314 | |
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315 | (* Proof irrelevance doesn't seem to apply to arbitrary variables, but we can |
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316 | use the function graph to show that it's fine. *) |
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317 | |
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318 | inductive pm_all_pred_graph : ∀A,m,p,a,L. ∀f:∀p:Pos.∀a:A.lookup_opt A p m=Some A a→bool. bool → Prop ≝ |
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319 | | pmallpg : ∀A,m,p,a,L. ∀f:∀p:Pos.∀a:A.lookup_opt A p m=Some A a→bool. pm_all_pred_graph A m p a L f (f p a L). |
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320 | |
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321 | lemma pm_all_pred_irr : ∀A,m,p,a,L,L'. |
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322 | ∀f:∀p:Pos.∀a:A.lookup_opt A p m=Some A a→bool. |
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323 | f p a L = f p a L'. |
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324 | #A #m #p #a #L #L' #f |
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325 | cut (pm_all_pred_graph A m p a L f (f p a L)) [ % ] |
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326 | cases (f p a L) #H cut (pm_all_pred_graph A m p a L' f ?) [2,5: @H | 1,4: skip] |
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327 | * // |
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328 | qed. |
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329 | |
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330 | lemma pm_all_aux_ok_aux : ∀A,m,t,pre,H,f,a,L. |
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331 | pm_all_aux A m t pre H f → |
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332 | lookup_opt A one t = Some A a → |
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333 | f (pre one) a L. |
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334 | #A #m * |
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335 | [ #pre #H #f #a #L #H #L' normalize in L'; destruct |
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336 | | * [ #l #r #pre #H #f #a #L #H' #L' normalize in L'; destruct |
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337 | | #a' #l #r #pre #H #f #a #L #AUX #L' normalize in L'; destruct |
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338 | cases (andb_Prop_true … AUX) #AUX' cases (andb_Prop_true … AUX') |
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339 | #_ #HERE #_ whd in HERE:(?%); @eq_true_to_b <HERE @pm_all_pred_irr |
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340 | ] |
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341 | ] qed. |
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342 | |
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343 | lemma pm_all_aux_ok : ∀A,m,t,pre,H,f. |
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344 | bool_to_Prop (pm_all_aux A m t pre H f) ↔ (∀p,a,H. f (pre p) a H). |
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345 | #A #m #t #pre #H #f % |
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346 | [ #H' #p generalize in match pre in H H' ⊢ %; -pre generalize in match t; elim p |
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347 | [ #t #pre #H #H' #a #L lapply (refl ? (Some A a)) <L in ⊢ (??%? → ?); >H @pm_all_aux_ok_aux // |
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348 | | #q #IH * [ #pre #H #H' #a #L @⊥ >H in L; normalize #E destruct |
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349 | | #x #l #r #pre #H #H' #a #L @(IH r) |
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350 | [ #x >H % | cases (andb_Prop_true … H') #_ // ] |
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351 | ] |
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352 | | #q #IH * [ #pre #H #H' #a #L @⊥ >H in L; normalize #E destruct |
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353 | | #x #l #r #pre #H #H' #a #L @(IH l) |
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354 | [ #x >H % | cases (andb_Prop_true … H') #H'' cases (andb_Prop_true … H'') // ] |
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355 | ] |
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356 | ] |
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357 | | #H' generalize in match pre in H H' ⊢ %; -pre elim t |
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358 | [ // |
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359 | | * [2:#x] #l #r #IHl #IHr #pre #H #H' @andb_Prop |
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360 | [ 1,3: @andb_Prop |
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361 | [ 1,3: @IHl // |
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362 | | @(H' one x) |
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363 | | % |
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364 | ] |
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365 | | 2,4: @IHr // |
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366 | ] |
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367 | ] |
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368 | ] qed. |
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369 | |
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370 | lemma pm_all_ok : ∀A,m,f. |
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371 | bool_to_Prop (pm_all A m f) ↔ (∀p,a,H. f p a H). |
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372 | #A #m #f @pm_all_aux_ok |
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373 | qed. |
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374 | |
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375 | |
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376 | (* Attempt to choose an entry in the map, and if successful return the entry |
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377 | and the map without it. *) |
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378 | |
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379 | let rec pm_choose (A:Type[0]) (t:positive_map A) on t : option (Pos × A × (positive_map A)) ≝ |
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380 | match t with |
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381 | [ pm_leaf ⇒ None ? |
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382 | | pm_node a l r ⇒ |
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383 | match pm_choose A l with |
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384 | [ None ⇒ |
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385 | match pm_choose A r with |
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386 | [ None ⇒ |
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387 | match a with |
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388 | [ None ⇒ None ? |
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389 | | Some a ⇒ Some ? 〈〈one, a〉, pm_leaf A〉 |
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390 | ] |
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391 | | Some x ⇒ Some ? 〈〈p1 (\fst (\fst x)), \snd (\fst x)〉, pm_node A a l (\snd x)〉 |
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392 | ] |
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393 | | Some x ⇒ Some ? 〈〈p0 (\fst (\fst x)), \snd (\fst x)〉, pm_node A a (\snd x) r〉 |
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394 | ] |
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395 | ]. |
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396 | |
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397 | lemma pm_choose_empty : ∀A,t. |
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398 | pm_choose A t = None ? ↔ ∀p. lookup_opt A p t = None A. |
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399 | #A #t elim t |
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400 | [ % // |
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401 | | * |
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402 | [ #l #r * #IHl #IHl' * #IHr #IHr' % |
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403 | [ #C * |
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404 | [ % |
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405 | | #p whd in C:(??%?) ⊢ (??%?); |
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406 | @IHr cases (pm_choose A r) in C ⊢ %; |
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407 | [ // |
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408 | | #x normalize cases (pm_choose A l) [2: #y] normalize #E destruct |
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409 | ] |
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410 | | #p whd in C:(??%?) ⊢ (??%?); |
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411 | @IHl cases (pm_choose A l) in C ⊢ %; |
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412 | [ // |
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413 | | #x normalize #E destruct |
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414 | ] |
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415 | ] |
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416 | | #L whd in ⊢ (??%?); >IHl' [ normalize >IHr' [ % | #p @(L (p1 p)) ] | #p @(L (p0 p)) ] |
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417 | ] |
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418 | | #a #l #r #IHl #IHr % |
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419 | [ normalize cases (pm_choose A l) [2: normalize #x #E destruct ] |
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420 | normalize cases (pm_choose A r) [2: #x] normalize #E destruct |
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421 | | #L lapply (L one) normalize #E destruct |
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422 | ] |
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423 | ] |
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424 | ] qed. |
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425 | |
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426 | lemma pm_choose_empty_card : ∀A,t. |
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427 | pm_choose A t = None ? ↔ |t| = 0. |
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428 | #A #t elim t |
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429 | [ /2/ |
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430 | | * [ #l #r * #IHl #IHl' * #IHr #IHr' % |
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431 | [ normalize lapply IHl cases (pm_choose A l) [2: #x #_ #E normalize in E; destruct ] |
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432 | normalize lapply IHr cases (pm_choose A r) [2: #x #_ #_ #E normalize in E; destruct ] |
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433 | #H1 #H2 #_ >(H1 (refl ??)) >(H2 (refl ??)) % |
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434 | | normalize #CARD >IHl' [ >IHr' ] /2 by refl, le_n_O_to_eq/ |
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435 | ] |
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436 | | #a #l #r #_ #_ % normalize |
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437 | [ cases (pm_choose A l) [ cases (pm_choose A r) [ | #x ] | #x ] |
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438 | #E normalize in E; destruct |
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439 | | #E destruct |
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440 | ] |
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441 | ] |
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442 | ] qed. |
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443 | |
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444 | lemma pm_choose_some : ∀A,t,p,a,t'. |
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445 | pm_choose A t = Some ? 〈〈p,a〉,t'〉 → |
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446 | lookup_opt A p t = Some A a ∧ |
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447 | lookup_opt A p t' = None A ∧ |
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448 | (∀q. p = q ∨ lookup_opt A q t = lookup_opt A q t') ∧ |
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449 | |t| = S (|t'|). |
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450 | #A #t elim t |
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451 | [ #p #a #t' normalize #E destruct |
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452 | | #ao #l #r #IHl #IHr * |
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453 | [ #a #t' normalize |
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454 | lapply (pm_choose_empty_card A l) |
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455 | lapply (pm_choose_empty A l) |
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456 | cases (pm_choose A l) normalize [2: #x #_ #_ #E destruct ] * #EMPl #EMPl' * #CARDl #CARDl' |
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457 | lapply (pm_choose_empty_card A r) |
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458 | lapply (pm_choose_empty A r) |
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459 | cases (pm_choose A r) normalize [2: #x #_ #_ #E destruct ] * #EMPr #EMPr' * #CARDr #CARDr' |
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460 | cases ao normalize [2:#x] #E destruct |
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461 | % [ % /2/ * /2/ #q %2 whd in ⊢ (??%%); /2/ | >CARDl >CARDr // ] |
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462 | | #p #a #t' normalize |
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463 | lapply (pm_choose_empty_card A l) |
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464 | lapply (pm_choose_empty A l) |
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465 | cases (pm_choose A l) normalize [2: #x #_ #_ #E destruct ] * #EMPl #EMPl' * #CARDl #CARDl' |
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466 | lapply (IHr p) |
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467 | cases (pm_choose A r) normalize [ #_ cases ao [2:#a'] normalize #E destruct ] |
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468 | * * #p' #a' #t'' #IH #E destruct |
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469 | cases (IH ?? (refl ??)) * * #L1 #L2 #L3 #CARD |
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470 | % [ % [ % [ // | @L2 ]| * /2/ #q cases (L3 q) /2/ #L4 %2 @L4 ] | cases ao normalize >CARD // ] |
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471 | | #p #a #t' normalize |
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472 | lapply (IHl p) |
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473 | cases (pm_choose A l) normalize |
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474 | [ #_ cases (pm_choose A r) normalize [ cases ao [2:#a'] normalize #E destruct |
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475 | | #x #E destruct ] |
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476 | | * * #p' #a' #t'' #IH #E destruct |
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477 | cases (IH ?? (refl ??)) * * #L1 #L2 #L3 #CARD |
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478 | % [ % [ % [ // | @L2 ]| * /2/ #q cases (L3 q) /2/ #L4 %2 @L4 ] | cases ao normalize >CARD // ] |
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479 | ] |
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480 | ] |
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481 | ] qed. |
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482 | |
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483 | (* Try to remove an element, return updated map if successful *) |
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484 | |
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485 | let rec pm_try_remove (A:Type[0]) (b:Pos) (t:positive_map A) on b : option (A × (positive_map A)) ≝ |
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486 | match b with |
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487 | [ one ⇒ |
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488 | match t with |
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489 | [ pm_leaf ⇒ None ? |
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490 | | pm_node x l r ⇒ option_map ?? (λx. 〈x, pm_node A (None ?) l r〉) x |
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491 | ] |
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492 | | p0 tl ⇒ |
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493 | match t with |
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494 | [ pm_leaf ⇒ None ? |
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495 | | pm_node x l r ⇒ option_map ?? (λxl. 〈\fst xl, pm_node A x (\snd xl) r〉) (pm_try_remove A tl l) |
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496 | ] |
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497 | | p1 tl ⇒ |
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498 | match t with |
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499 | [ pm_leaf ⇒ None ? |
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500 | | pm_node x l r ⇒ option_map ?? (λxr. 〈\fst xr, pm_node A x l (\snd xr)〉) (pm_try_remove A tl r) |
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501 | ] |
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502 | ]. |
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503 | |
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504 | lemma pm_try_remove_none : ∀A,b,t. |
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505 | pm_try_remove A b t = None ? ↔ lookup_opt A b t = None ?. |
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506 | #A #b elim b |
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507 | [ * [ /2/ | * [ /2/ | #a #l #r % normalize #E destruct ] ] |
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508 | | #p #IH * [ /2/ | #x #l #r % normalize cases (IH r) cases (pm_try_remove A p r) |
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509 | [ normalize #H #X @H | * #a #t' #_ normalize #_ #X destruct |
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510 | | normalize // | * #a #t' normalize #A #B #C lapply (B C) #E destruct |
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511 | ] ] |
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512 | | #p #IH * [ /2/ | #x #l #r % normalize cases (IH l) cases (pm_try_remove A p l) |
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513 | [ normalize #H #X @H | * #a #t' #_ normalize #_ #X destruct |
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514 | | normalize // | * #a #t' normalize #A #B #C lapply (B C) #E destruct |
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515 | ] ] |
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516 | ] qed. |
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517 | |
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518 | lemma pm_try_remove_some : ∀A,p,t,a,t'. |
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519 | pm_try_remove A p t = Some ? 〈a,t'〉 → |
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520 | lookup_opt A p t = Some A a ∧ |
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521 | lookup_opt A p t' = None A ∧ |
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522 | (∀q. p = q ∨ lookup_opt A q t = lookup_opt A q t') ∧ |
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523 | |t| = S (|t'|). |
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524 | #A #p elim p |
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525 | [ * [ #a #t' #E normalize in E; destruct |
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526 | | * [ #l #r #a #t' #E normalize in E; destruct |
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527 | | #a' #l #r #a #t' #E normalize in E; destruct % [ % [ % // | * /2/ ]| // ] |
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528 | ] |
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529 | ] |
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530 | | #p' #IH * |
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531 | [ #a #t' #E normalize in E; destruct |
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532 | | #x #l #r #a #t' whd in ⊢ (??%? → ?); |
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533 | lapply (IH r) cases (pm_try_remove A p' r) [ #_ #E normalize in E; destruct ] |
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534 | * #a' #r' #H #E whd in E:(??%?); destruct |
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535 | cases (H a r' (refl ??)) * * #L1 #L2 #L3 #CARD |
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536 | @conj try @conj try @conj |
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537 | [ @L1 | @L2 | * /2/ #q cases (L3 q) [ /2/ | #E %2 @E ] | cases x normalize >CARD // ] |
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538 | ] |
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539 | | #p' #IH * |
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540 | [ #a #t' #E normalize in E; destruct |
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541 | | #x #l #r #a #t' whd in ⊢ (??%? → ?); |
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542 | lapply (IH l) cases (pm_try_remove A p' l) [ #_ #E normalize in E; destruct ] |
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543 | * #a' #l' #H #E whd in E:(??%?); destruct |
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544 | cases (H a l' (refl ??)) * * #L1 #L2 #L3 #CARD |
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545 | @conj try @conj try @conj |
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546 | [ @L1 | @L2 | * /2/ #q cases (L3 q) [ /2/ | #E %2 @E ] | cases x normalize >CARD // ] |
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547 | ] |
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548 | ] qed. |
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549 | |
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550 | |
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551 | |
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