author | huffman |
Tue, 18 Dec 2007 22:18:31 +0100 | |
changeset 25701 | 73fbe868b4e7 |
parent 25131 | 2c8caac48ade |
child 25723 | 80c06e4d4db6 |
permissions | -rw-r--r-- |
2640 | 1 |
(* Title: HOLCF/Pcpo.thy |
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ID: $Id$ |
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Author: Franz Regensburger |
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*) |
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header {* Classes cpo and pcpo *} |
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theory Pcpo |
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imports Porder |
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begin |
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Franz Regensburger's Higher-Order Logic of Computable Functions embedding LCF
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subsection {* Complete partial orders *} |
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text {* The class cpo of chain complete partial orders *} |
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axclass cpo < po |
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-- {* class axiom: *} |
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cpo: "chain S \<Longrightarrow> \<exists>x. range S <<| x" |
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text {* in cpo's everthing equal to THE lub has lub properties for every chain *} |
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lemma thelubE: "\<lbrakk>chain S; (\<Squnion>i. S i) = (l::'a::cpo)\<rbrakk> \<Longrightarrow> range S <<| l" |
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by (blast dest: cpo intro: lubI) |
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text {* Properties of the lub *} |
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lemma is_ub_thelub: "chain (S::nat \<Rightarrow> 'a::cpo) \<Longrightarrow> S x \<sqsubseteq> (\<Squnion>i. S i)" |
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by (blast dest: cpo intro: lubI [THEN is_ub_lub]) |
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lemma is_lub_thelub: |
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"\<lbrakk>chain (S::nat \<Rightarrow> 'a::cpo); range S <| x\<rbrakk> \<Longrightarrow> (\<Squnion>i. S i) \<sqsubseteq> x" |
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by (blast dest: cpo intro: lubI [THEN is_lub_lub]) |
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lemma lub_range_mono: |
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"\<lbrakk>range X \<subseteq> range Y; chain Y; chain (X::nat \<Rightarrow> 'a::cpo)\<rbrakk> |
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\<Longrightarrow> (\<Squnion>i. X i) \<sqsubseteq> (\<Squnion>i. Y i)" |
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apply (erule is_lub_thelub) |
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apply (rule ub_rangeI) |
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apply (subgoal_tac "\<exists>j. X i = Y j") |
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apply clarsimp |
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apply (erule is_ub_thelub) |
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apply auto |
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done |
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lemma lub_range_shift: |
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"chain (Y::nat \<Rightarrow> 'a::cpo) \<Longrightarrow> (\<Squnion>i. Y (i + j)) = (\<Squnion>i. Y i)" |
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apply (rule antisym_less) |
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apply (rule lub_range_mono) |
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apply fast |
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apply assumption |
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apply (erule chain_shift) |
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apply (rule is_lub_thelub) |
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apply assumption |
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apply (rule ub_rangeI) |
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apply (rule_tac y="Y (i + j)" in trans_less) |
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apply (erule chain_mono3) |
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apply (rule le_add1) |
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apply (rule is_ub_thelub) |
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apply (erule chain_shift) |
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done |
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lemma maxinch_is_thelub: |
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"chain Y \<Longrightarrow> max_in_chain i Y = ((\<Squnion>i. Y i) = ((Y i)::'a::cpo))" |
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apply (rule iffI) |
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apply (fast intro!: thelubI lub_finch1) |
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apply (unfold max_in_chain_def) |
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apply (safe intro!: antisym_less) |
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apply (fast elim!: chain_mono3) |
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apply (drule sym) |
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apply (force elim!: is_ub_thelub) |
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done |
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text {* the @{text "\<sqsubseteq>"} relation between two chains is preserved by their lubs *} |
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lemma lub_mono: |
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"\<lbrakk>chain (X::nat \<Rightarrow> 'a::cpo); chain Y; \<forall>k. X k \<sqsubseteq> Y k\<rbrakk> |
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\<Longrightarrow> (\<Squnion>i. X i) \<sqsubseteq> (\<Squnion>i. Y i)" |
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apply (erule is_lub_thelub) |
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apply (rule ub_rangeI) |
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apply (rule trans_less) |
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apply (erule spec) |
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apply (erule is_ub_thelub) |
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done |
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text {* the = relation between two chains is preserved by their lubs *} |
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lemma lub_equal: |
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"\<lbrakk>chain (X::nat \<Rightarrow> 'a::cpo); chain Y; \<forall>k. X k = Y k\<rbrakk> |
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\<Longrightarrow> (\<Squnion>i. X i) = (\<Squnion>i. Y i)" |
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by (simp only: expand_fun_eq [symmetric]) |
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text {* more results about mono and = of lubs of chains *} |
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lemma lub_mono2: |
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"\<lbrakk>\<exists>j. \<forall>i>j. X i = Y i; chain (X::nat \<Rightarrow> 'a::cpo); chain Y\<rbrakk> |
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\<Longrightarrow> (\<Squnion>i. X i) \<sqsubseteq> (\<Squnion>i. Y i)" |
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apply (erule exE) |
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apply (subgoal_tac "(\<Squnion>i. X (i + Suc j)) \<sqsubseteq> (\<Squnion>i. Y (i + Suc j))") |
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apply (thin_tac "\<forall>i>j. X i = Y i") |
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apply (simp only: lub_range_shift) |
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apply simp |
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done |
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lemma lub_equal2: |
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"\<lbrakk>\<exists>j. \<forall>i>j. X i = Y i; chain (X::nat \<Rightarrow> 'a::cpo); chain Y\<rbrakk> |
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\<Longrightarrow> (\<Squnion>i. X i) = (\<Squnion>i. Y i)" |
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by (blast intro: antisym_less lub_mono2 sym) |
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lemma lub_mono3: |
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"\<lbrakk>chain (Y::nat \<Rightarrow> 'a::cpo); chain X; \<forall>i. \<exists>j. Y i \<sqsubseteq> X j\<rbrakk> |
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\<Longrightarrow> (\<Squnion>i. Y i) \<sqsubseteq> (\<Squnion>i. X i)" |
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apply (erule is_lub_thelub) |
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apply (rule ub_rangeI) |
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apply (erule allE) |
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apply (erule exE) |
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apply (erule trans_less) |
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apply (erule is_ub_thelub) |
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done |
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lemma ch2ch_lub: |
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fixes Y :: "nat \<Rightarrow> nat \<Rightarrow> 'a::cpo" |
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assumes 1: "\<And>j. chain (\<lambda>i. Y i j)" |
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assumes 2: "\<And>i. chain (\<lambda>j. Y i j)" |
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shows "chain (\<lambda>i. \<Squnion>j. Y i j)" |
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apply (rule chainI) |
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apply (rule lub_mono [rule_format, OF 2 2]) |
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apply (rule chainE [OF 1]) |
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done |
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lemma diag_lub: |
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fixes Y :: "nat \<Rightarrow> nat \<Rightarrow> 'a::cpo" |
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assumes 1: "\<And>j. chain (\<lambda>i. Y i j)" |
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assumes 2: "\<And>i. chain (\<lambda>j. Y i j)" |
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shows "(\<Squnion>i. \<Squnion>j. Y i j) = (\<Squnion>i. Y i i)" |
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proof (rule antisym_less) |
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have 3: "chain (\<lambda>i. Y i i)" |
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apply (rule chainI) |
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apply (rule trans_less) |
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apply (rule chainE [OF 1]) |
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apply (rule chainE [OF 2]) |
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done |
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have 4: "chain (\<lambda>i. \<Squnion>j. Y i j)" |
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by (rule ch2ch_lub [OF 1 2]) |
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show "(\<Squnion>i. \<Squnion>j. Y i j) \<sqsubseteq> (\<Squnion>i. Y i i)" |
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apply (rule is_lub_thelub [OF 4]) |
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apply (rule ub_rangeI) |
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apply (rule lub_mono3 [rule_format, OF 2 3]) |
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apply (rule exI) |
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apply (rule trans_less) |
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apply (rule chain_mono3 [OF 1 le_maxI1]) |
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apply (rule chain_mono3 [OF 2 le_maxI2]) |
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done |
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show "(\<Squnion>i. Y i i) \<sqsubseteq> (\<Squnion>i. \<Squnion>j. Y i j)" |
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apply (rule lub_mono [rule_format, OF 3 4]) |
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apply (rule is_ub_thelub [OF 2]) |
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done |
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qed |
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lemma ex_lub: |
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fixes Y :: "nat \<Rightarrow> nat \<Rightarrow> 'a::cpo" |
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assumes 1: "\<And>j. chain (\<lambda>i. Y i j)" |
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assumes 2: "\<And>i. chain (\<lambda>j. Y i j)" |
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shows "(\<Squnion>i. \<Squnion>j. Y i j) = (\<Squnion>j. \<Squnion>i. Y i j)" |
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by (simp add: diag_lub 1 2) |
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subsection {* Pointed cpos *} |
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text {* The class pcpo of pointed cpos *} |
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axclass pcpo < cpo, ppo |
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lemma chain_UU_I: "\<lbrakk>chain Y; (\<Squnion>i. Y i) = \<bottom>\<rbrakk> \<Longrightarrow> \<forall>i. Y i = (\<bottom>::'a::pcpo)" |
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apply (rule allI) |
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apply (rule UU_I) |
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apply (erule subst) |
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apply (erule is_ub_thelub) |
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done |
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lemma chain_UU_I_inverse: "\<forall>i::nat. Y i = \<bottom> \<Longrightarrow> (\<Squnion>i. Y i) = \<bottom>" |
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apply (rule lub_chain_maxelem) |
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apply (erule spec) |
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apply simp |
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done |
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lemma chain_UU_I_inverse2: "(\<Squnion>i. Y i) \<noteq> \<bottom> \<Longrightarrow> \<exists>i::nat. Y i \<noteq> \<bottom>" |
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by (blast intro: chain_UU_I_inverse) |
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lemma notUU_I: "\<lbrakk>x \<sqsubseteq> y; x \<noteq> \<bottom>\<rbrakk> \<Longrightarrow> y \<noteq> \<bottom>" |
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by (blast intro: UU_I) |
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lemma chain_mono2: "\<lbrakk>\<exists>j. Y j \<noteq> \<bottom>; chain Y\<rbrakk> \<Longrightarrow> \<exists>j. \<forall>i>j. Y i \<noteq> \<bottom>" |
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by (blast dest: notUU_I chain_mono) |
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subsection {* Chain-finite and flat cpos *} |
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text {* further useful classes for HOLCF domains *} |
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axclass chfin < po |
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chfin: "\<forall>Y. chain Y \<longrightarrow> (\<exists>n. max_in_chain n Y)" |
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axclass flat < ppo |
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ax_flat: "\<forall>x y. x \<sqsubseteq> y \<longrightarrow> (x = \<bottom>) \<or> (x = y)" |
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text {* some properties for chfin and flat *} |
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text {* chfin types are cpo *} |
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lemma chfin_imp_cpo: |
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"chain (S::nat \<Rightarrow> 'a::chfin) \<Longrightarrow> \<exists>x. range S <<| x" |
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apply (frule chfin [rule_format]) |
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apply (blast intro: lub_finch1) |
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done |
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instance chfin < cpo |
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by intro_classes (rule chfin_imp_cpo) |
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text {* flat types are chfin *} |
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lemma flat_imp_chfin: |
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"\<forall>Y::nat \<Rightarrow> 'a::flat. chain Y \<longrightarrow> (\<exists>n. max_in_chain n Y)" |
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apply (unfold max_in_chain_def) |
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apply clarify |
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apply (case_tac "\<forall>i. Y i = \<bottom>") |
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apply simp |
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apply simp |
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apply (erule exE) |
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apply (rule_tac x="i" in exI) |
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apply clarify |
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apply (blast dest: chain_mono3 ax_flat [rule_format]) |
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done |
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instance flat < chfin |
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by intro_classes (rule flat_imp_chfin) |
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instance flat < pcpo .. |
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text {* flat subclass of chfin; @{text adm_flat} not needed *} |
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lemma flat_eq: "(a::'a::flat) \<noteq> \<bottom> \<Longrightarrow> a \<sqsubseteq> b = (a = b)" |
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by (safe dest!: ax_flat [rule_format]) |
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lemma chfin2finch: "chain (Y::nat \<Rightarrow> 'a::chfin) \<Longrightarrow> finite_chain Y" |
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by (simp add: chfin finite_chain_def) |
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text {* lemmata for improved admissibility introdution rule *} |
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|
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lemma infinite_chain_adm_lemma: |
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"\<lbrakk>chain Y; \<forall>i. P (Y i); |
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\<And>Y. \<lbrakk>chain Y; \<forall>i. P (Y i); \<not> finite_chain Y\<rbrakk> \<Longrightarrow> P (\<Squnion>i. Y i)\<rbrakk> |
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\<Longrightarrow> P (\<Squnion>i. Y i)" |
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apply (case_tac "finite_chain Y") |
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prefer 2 apply fast |
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apply (unfold finite_chain_def) |
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apply safe |
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apply (erule lub_finch1 [THEN thelubI, THEN ssubst]) |
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apply assumption |
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apply (erule spec) |
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done |
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lemma increasing_chain_adm_lemma: |
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"\<lbrakk>chain Y; \<forall>i. P (Y i); \<And>Y. \<lbrakk>chain Y; \<forall>i. P (Y i); |
263 |
\<forall>i. \<exists>j>i. Y i \<noteq> Y j \<and> Y i \<sqsubseteq> Y j\<rbrakk> \<Longrightarrow> P (\<Squnion>i. Y i)\<rbrakk> |
|
264 |
\<Longrightarrow> P (\<Squnion>i. Y i)" |
|
15563 | 265 |
apply (erule infinite_chain_adm_lemma) |
266 |
apply assumption |
|
267 |
apply (erule thin_rl) |
|
268 |
apply (unfold finite_chain_def) |
|
269 |
apply (unfold max_in_chain_def) |
|
270 |
apply (fast dest: le_imp_less_or_eq elim: chain_mono) |
|
271 |
done |
|
15576
efb95d0d01f7
converted to new-style theories, and combined numbered files
huffman
parents:
15563
diff
changeset
|
272 |
|
16626 | 273 |
end |