author | wenzelm |
Wed, 03 Nov 2010 21:53:56 +0100 | |
changeset 40335 | 3e4bb6e7c3ca |
parent 40091 | 1ca61fbd8a79 |
child 40498 | 5718fb91d2d8 |
permissions | -rw-r--r-- |
2640 | 1 |
(* Title: HOLCF/Pcpo.thy |
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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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class cpo = po + |
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assumes cpo: "chain S \<Longrightarrow> \<exists>x. range S <<| x" |
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begin |
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text {* in cpo's everthing equal to THE lub has lub properties for every chain *} |
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lemma cpo_lubI: "chain S \<Longrightarrow> range S <<| (\<Squnion>i. S i)" |
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by (fast dest: cpo elim: lubI) |
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|
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lemma thelubE: "\<lbrakk>chain S; (\<Squnion>i. S i) = l\<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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|
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lemma is_ub_thelub: "chain S \<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; 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_below_iff: "chain S \<Longrightarrow> (\<Squnion>i. S i) \<sqsubseteq> x \<longleftrightarrow> (\<forall>i. S i \<sqsubseteq> x)" |
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by (simp add: is_lub_below_iff [OF cpo_lubI] is_ub_def) |
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||
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lemma lub_range_mono: |
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"\<lbrakk>range X \<subseteq> range Y; chain Y; chain X\<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 \<Longrightarrow> (\<Squnion>i. Y (i + j)) = (\<Squnion>i. Y i)" |
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apply (rule below_antisym) |
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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 below_trans) |
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apply (erule chain_mono) |
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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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||
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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)" |
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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!: below_antisym) |
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apply (fast elim!: chain_mono) |
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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; chain Y; \<And>i. X i \<sqsubseteq> Y i\<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 below_trans) |
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apply (erule meta_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; 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: fun_eq_iff [symmetric]) |
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lemma lub_eq: |
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"(\<And>i. X i = Y i) \<Longrightarrow> (\<Squnion>i. X i) = (\<Squnion>i. Y i)" |
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by simp |
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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; 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; chain Y\<rbrakk> |
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\<Longrightarrow> (\<Squnion>i. X i) = (\<Squnion>i. Y i)" |
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by (blast intro: below_antisym lub_mono2 sym) |
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lemma lub_mono3: |
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"\<lbrakk>chain Y; 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 below_trans) |
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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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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 [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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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 below_antisym) |
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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 below_trans) |
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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 below_trans) |
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apply (rule chain_mono [OF 1 le_maxI1]) |
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apply (rule chain_mono [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 [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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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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end |
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subsection {* Pointed cpos *} |
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text {* The class pcpo of pointed cpos *} |
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class pcpo = cpo + |
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assumes least: "\<exists>x. \<forall>y. x \<sqsubseteq> y" |
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begin |
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|
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definition UU :: 'a where |
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"UU = (THE x. \<forall>y. x \<sqsubseteq> y)" |
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||
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notation (xsymbols) |
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UU ("\<bottom>") |
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text {* derive the old rule minimal *} |
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lemma UU_least: "\<forall>z. \<bottom> \<sqsubseteq> z" |
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apply (unfold UU_def) |
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apply (rule theI') |
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apply (rule ex_ex1I) |
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apply (rule least) |
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apply (blast intro: below_antisym) |
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done |
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lemma minimal [iff]: "\<bottom> \<sqsubseteq> x" |
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by (rule UU_least [THEN spec]) |
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end |
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text {* Simproc to rewrite @{term "\<bottom> = x"} to @{term "x = \<bottom>"}. *} |
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setup {* |
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Reorient_Proc.add |
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(fn Const(@{const_name UU}, _) => true | _ => false) |
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*} |
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simproc_setup reorient_bottom ("\<bottom> = x") = Reorient_Proc.proc |
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context pcpo |
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begin |
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||
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text {* useful lemmas about @{term \<bottom>} *} |
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lemma below_UU_iff [simp]: "(x \<sqsubseteq> \<bottom>) = (x = \<bottom>)" |
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by (simp add: po_eq_conv) |
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||
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lemma eq_UU_iff: "(x = \<bottom>) = (x \<sqsubseteq> \<bottom>)" |
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by simp |
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lemma UU_I: "x \<sqsubseteq> \<bottom> \<Longrightarrow> x = \<bottom>" |
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by (subst eq_UU_iff) |
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||
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lemma lub_eq_bottom_iff: "chain Y \<Longrightarrow> (\<Squnion>i. Y i) = \<bottom> \<longleftrightarrow> (\<forall>i. Y i = \<bottom>)" |
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by (simp only: eq_UU_iff lub_below_iff) |
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||
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lemma chain_UU_I: "\<lbrakk>chain Y; (\<Squnion>i. Y i) = \<bottom>\<rbrakk> \<Longrightarrow> \<forall>i. Y i = \<bottom>" |
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by (simp add: lub_eq_bottom_iff) |
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|
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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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by simp |
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|
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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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|
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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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|
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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_less) |
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||
244 |
end |
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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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|
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class chfin = po + |
251 |
assumes chfin: "chain Y \<Longrightarrow> \<exists>n. max_in_chain n Y" |
|
252 |
begin |
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25814 | 253 |
|
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subclass cpo |
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apply default |
|
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apply (frule chfin) |
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apply (blast intro: lub_finch1) |
|
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done |
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15563 | 259 |
|
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lemma chfin2finch: "chain Y \<Longrightarrow> finite_chain Y" |
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by (simp add: chfin finite_chain_def) |
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||
263 |
end |
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|
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class flat = pcpo + |
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assumes ax_flat: "x \<sqsubseteq> y \<Longrightarrow> x = \<bottom> \<or> x = y" |
|
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begin |
|
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268 |
|
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subclass chfin |
270 |
apply default |
|
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apply (unfold max_in_chain_def) |
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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_mono ax_flat) |
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done |
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lemma flat_below_iff: |
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shows "(x \<sqsubseteq> y) = (x = \<bottom> \<or> x = y)" |
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by (safe dest!: ax_flat) |
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|
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lemma flat_eq: "a \<noteq> \<bottom> \<Longrightarrow> a \<sqsubseteq> b = (a = b)" |
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by (safe dest!: ax_flat) |
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end |
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subsection {* Discrete cpos *} |
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|
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class discrete_cpo = below + |
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assumes discrete_cpo [simp]: "x \<sqsubseteq> y \<longleftrightarrow> x = y" |
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begin |
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|
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subclass po |
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proof qed simp_all |
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text {* In a discrete cpo, every chain is constant *} |
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||
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lemma discrete_chain_const: |
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assumes S: "chain S" |
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shows "\<exists>x. S = (\<lambda>i. x)" |
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proof (intro exI ext) |
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fix i :: nat |
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have "S 0 \<sqsubseteq> S i" using S le0 by (rule chain_mono) |
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hence "S 0 = S i" by simp |
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thus "S i = S 0" by (rule sym) |
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qed |
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||
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subclass chfin |
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proof |
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fix S :: "nat \<Rightarrow> 'a" |
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assume S: "chain S" |
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hence "\<exists>x. S = (\<lambda>i. x)" by (rule discrete_chain_const) |
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hence "max_in_chain 0 S" |
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unfolding max_in_chain_def by auto |
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thus "\<exists>i. max_in_chain i S" .. |
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qed |
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||
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end |
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322 |
|
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end |