src/HOL/Complete_Partial_Order.thy
changeset 53361 1cb7d3c0cf31
parent 46041 1e3ff542e83e
child 54630 9061af4d5ebc
equal deleted inserted replaced
53358:b46e6cd75dc6 53361:1cb7d3c0cf31
   153     fix x assume "x \<le> z" with f have "f x \<le> f z" by (rule monotoneD)
   153     fix x assume "x \<le> z" with f have "f x \<le> f z" by (rule monotoneD)
   154     also note z finally show "f x \<le> z" .
   154     also note z finally show "f x \<le> z" .
   155   qed (auto intro: ccpo_Sup_least)
   155   qed (auto intro: ccpo_Sup_least)
   156 qed
   156 qed
   157 
   157 
       
   158 end
   158 
   159 
   159 subsection {* Fixpoint induction *}
   160 subsection {* Fixpoint induction *}
   160 
   161 
   161 definition
   162 setup {* Sign.map_naming (Name_Space.mandatory_path "ccpo") *}
   162   admissible :: "('a \<Rightarrow> bool) \<Rightarrow> bool"
   163 
   163 where
   164 definition admissible :: "('a set \<Rightarrow> 'a) \<Rightarrow> ('a \<Rightarrow> 'a \<Rightarrow> bool) \<Rightarrow> ('a \<Rightarrow> bool) \<Rightarrow> bool"
   164   "admissible P = (\<forall>A. chain (op \<le>) A \<longrightarrow> (\<forall>x\<in>A. P x) \<longrightarrow> P (Sup A))"
   165 where "admissible lub ord P = (\<forall>A. chain ord A \<longrightarrow> (\<forall>x\<in>A. P x) \<longrightarrow> P (lub A))"
   165 
   166 
   166 lemma admissibleI:
   167 lemma admissibleI:
   167   assumes "\<And>A. chain (op \<le>) A \<Longrightarrow> \<forall>x\<in>A. P x \<Longrightarrow> P (Sup A)"
   168   assumes "\<And>A. chain ord A \<Longrightarrow> \<forall>x\<in>A. P x \<Longrightarrow> P (lub A)"
   168   shows "admissible P"
   169   shows "ccpo.admissible lub ord P"
   169 using assms unfolding admissible_def by fast
   170 using assms unfolding ccpo.admissible_def by fast
   170 
   171 
   171 lemma admissibleD:
   172 lemma admissibleD:
   172   assumes "admissible P"
   173   assumes "ccpo.admissible lub ord P"
   173   assumes "chain (op \<le>) A"
   174   assumes "chain ord A"
   174   assumes "\<And>x. x \<in> A \<Longrightarrow> P x"
   175   assumes "\<And>x. x \<in> A \<Longrightarrow> P x"
   175   shows "P (Sup A)"
   176   shows "P (lub A)"
   176 using assms by (auto simp: admissible_def)
   177 using assms by (auto simp: ccpo.admissible_def)
   177 
   178 
   178 lemma fixp_induct:
   179 setup {* Sign.map_naming Name_Space.parent_path *}
   179   assumes adm: "admissible P"
   180 
       
   181 lemma (in ccpo) fixp_induct:
       
   182   assumes adm: "ccpo.admissible Sup (op \<le>) P"
   180   assumes mono: "monotone (op \<le>) (op \<le>) f"
   183   assumes mono: "monotone (op \<le>) (op \<le>) f"
   181   assumes step: "\<And>x. P x \<Longrightarrow> P (f x)"
   184   assumes step: "\<And>x. P x \<Longrightarrow> P (f x)"
   182   shows "P (fixp f)"
   185   shows "P (fixp f)"
   183 unfolding fixp_def using adm chain_iterates[OF mono]
   186 unfolding fixp_def using adm chain_iterates[OF mono]
   184 proof (rule admissibleD)
   187 proof (rule ccpo.admissibleD)
   185   fix x assume "x \<in> iterates f"
   188   fix x assume "x \<in> iterates f"
   186   thus "P x"
   189   thus "P x"
   187     by (induct rule: iterates.induct)
   190     by (induct rule: iterates.induct)
   188       (auto intro: step admissibleD adm)
   191       (auto intro: step ccpo.admissibleD adm)
   189 qed
   192 qed
   190 
   193 
   191 lemma admissible_True: "admissible (\<lambda>x. True)"
   194 lemma admissible_True: "ccpo.admissible lub ord (\<lambda>x. True)"
   192 unfolding admissible_def by simp
   195 unfolding ccpo.admissible_def by simp
   193 
   196 
   194 lemma admissible_False: "\<not> admissible (\<lambda>x. False)"
   197 lemma admissible_False: "\<not> ccpo.admissible lub ord (\<lambda>x. False)"
   195 unfolding admissible_def chain_def by simp
   198 unfolding ccpo.admissible_def chain_def by simp
   196 
   199 
   197 lemma admissible_const: "admissible (\<lambda>x. t) = t"
   200 lemma admissible_const: "ccpo.admissible lub ord (\<lambda>x. t) = t"
   198 by (cases t, simp_all add: admissible_True admissible_False)
   201 by (cases t, simp_all add: admissible_True admissible_False)
   199 
   202 
   200 lemma admissible_conj:
   203 lemma admissible_conj:
   201   assumes "admissible (\<lambda>x. P x)"
   204   assumes "ccpo.admissible lub ord (\<lambda>x. P x)"
   202   assumes "admissible (\<lambda>x. Q x)"
   205   assumes "ccpo.admissible lub ord (\<lambda>x. Q x)"
   203   shows "admissible (\<lambda>x. P x \<and> Q x)"
   206   shows "ccpo.admissible lub ord (\<lambda>x. P x \<and> Q x)"
   204 using assms unfolding admissible_def by simp
   207 using assms unfolding ccpo.admissible_def by simp
   205 
   208 
   206 lemma admissible_all:
   209 lemma admissible_all:
   207   assumes "\<And>y. admissible (\<lambda>x. P x y)"
   210   assumes "\<And>y. ccpo.admissible lub ord (\<lambda>x. P x y)"
   208   shows "admissible (\<lambda>x. \<forall>y. P x y)"
   211   shows "ccpo.admissible lub ord (\<lambda>x. \<forall>y. P x y)"
   209 using assms unfolding admissible_def by fast
   212 using assms unfolding ccpo.admissible_def by fast
   210 
   213 
   211 lemma admissible_ball:
   214 lemma admissible_ball:
   212   assumes "\<And>y. y \<in> A \<Longrightarrow> admissible (\<lambda>x. P x y)"
   215   assumes "\<And>y. y \<in> A \<Longrightarrow> ccpo.admissible lub ord (\<lambda>x. P x y)"
   213   shows "admissible (\<lambda>x. \<forall>y\<in>A. P x y)"
   216   shows "ccpo.admissible lub ord (\<lambda>x. \<forall>y\<in>A. P x y)"
   214 using assms unfolding admissible_def by fast
   217 using assms unfolding ccpo.admissible_def by fast
   215 
   218 
   216 lemma chain_compr: "chain (op \<le>) A \<Longrightarrow> chain (op \<le>) {x \<in> A. P x}"
   219 lemma chain_compr: "chain ord A \<Longrightarrow> chain ord {x \<in> A. P x}"
   217 unfolding chain_def by fast
   220 unfolding chain_def by fast
       
   221 
       
   222 context ccpo begin
   218 
   223 
   219 lemma admissible_disj_lemma:
   224 lemma admissible_disj_lemma:
   220   assumes A: "chain (op \<le>)A"
   225   assumes A: "chain (op \<le>)A"
   221   assumes P: "\<forall>x\<in>A. \<exists>y\<in>A. x \<le> y \<and> P y"
   226   assumes P: "\<forall>x\<in>A. \<exists>y\<in>A. x \<le> y \<and> P y"
   222   shows "Sup A = Sup {x \<in> A. P x}"
   227   shows "Sup A = Sup {x \<in> A. P x}"
   236     done
   241     done
   237 qed
   242 qed
   238 
   243 
   239 lemma admissible_disj:
   244 lemma admissible_disj:
   240   fixes P Q :: "'a \<Rightarrow> bool"
   245   fixes P Q :: "'a \<Rightarrow> bool"
   241   assumes P: "admissible (\<lambda>x. P x)"
   246   assumes P: "ccpo.admissible Sup (op \<le>) (\<lambda>x. P x)"
   242   assumes Q: "admissible (\<lambda>x. Q x)"
   247   assumes Q: "ccpo.admissible Sup (op \<le>) (\<lambda>x. Q x)"
   243   shows "admissible (\<lambda>x. P x \<or> Q x)"
   248   shows "ccpo.admissible Sup (op \<le>) (\<lambda>x. P x \<or> Q x)"
   244 proof (rule admissibleI)
   249 proof (rule ccpo.admissibleI)
   245   fix A :: "'a set" assume A: "chain (op \<le>) A"
   250   fix A :: "'a set" assume A: "chain (op \<le>) A"
   246   assume "\<forall>x\<in>A. P x \<or> Q x"
   251   assume "\<forall>x\<in>A. P x \<or> Q x"
   247   hence "(\<forall>x\<in>A. \<exists>y\<in>A. x \<le> y \<and> P y) \<or> (\<forall>x\<in>A. \<exists>y\<in>A. x \<le> y \<and> Q y)"
   252   hence "(\<forall>x\<in>A. \<exists>y\<in>A. x \<le> y \<and> P y) \<or> (\<forall>x\<in>A. \<exists>y\<in>A. x \<le> y \<and> Q y)"
   248     using chainD[OF A] by blast
   253     using chainD[OF A] by blast
   249   hence "Sup A = Sup {x \<in> A. P x} \<or> Sup A = Sup {x \<in> A. Q x}"
   254   hence "Sup A = Sup {x \<in> A. P x} \<or> Sup A = Sup {x \<in> A. Q x}"
   250     using admissible_disj_lemma [OF A] by fast
   255     using admissible_disj_lemma [OF A] by fast
   251   thus "P (Sup A) \<or> Q (Sup A)"
   256   thus "P (Sup A) \<or> Q (Sup A)"
   252     apply (rule disjE, simp_all)
   257     apply (rule disjE, simp_all)
   253     apply (rule disjI1, rule admissibleD [OF P chain_compr [OF A]], simp)
   258     apply (rule disjI1, rule ccpo.admissibleD [OF P chain_compr [OF A]], simp)
   254     apply (rule disjI2, rule admissibleD [OF Q chain_compr [OF A]], simp)
   259     apply (rule disjI2, rule ccpo.admissibleD [OF Q chain_compr [OF A]], simp)
   255     done
   260     done
   256 qed
   261 qed
   257 
   262 
   258 end
   263 end
   259 
   264 
   269     by (rule lfp_lowerbound, subst fixp_unfold [OF f'], rule order_refl)
   274     by (rule lfp_lowerbound, subst fixp_unfold [OF f'], rule order_refl)
   270   show "fixp f \<le> lfp f"
   275   show "fixp f \<le> lfp f"
   271     by (rule fixp_lowerbound [OF f'], subst lfp_unfold [OF f], rule order_refl)
   276     by (rule fixp_lowerbound [OF f'], subst lfp_unfold [OF f], rule order_refl)
   272 qed
   277 qed
   273 
   278 
   274 hide_const (open) iterates fixp admissible
   279 hide_const (open) iterates fixp
   275 
   280 
   276 end
   281 end