src/HOL/HOLCF/Universal.thy
author wenzelm
Wed Dec 29 17:34:41 2010 +0100 (2010-12-29)
changeset 41413 64cd30d6b0b8
parent 41394 51c866d1b53b
child 41430 1aa23e9f2c87
permissions -rw-r--r--
explicit file specifications -- avoid secondary load path;
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(*  Title:      HOLCF/Universal.thy
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    Author:     Brian Huffman
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*)
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header {* A universal bifinite domain *}
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theory Universal
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imports Bifinite Completion "~~/src/HOL/Library/Nat_Bijection"
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begin
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subsection {* Basis for universal domain *}
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subsubsection {* Basis datatype *}
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type_synonym ubasis = nat
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definition
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  node :: "nat \<Rightarrow> ubasis \<Rightarrow> ubasis set \<Rightarrow> ubasis"
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where
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  "node i a S = Suc (prod_encode (i, prod_encode (a, set_encode S)))"
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lemma node_not_0 [simp]: "node i a S \<noteq> 0"
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unfolding node_def by simp
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lemma node_gt_0 [simp]: "0 < node i a S"
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unfolding node_def by simp
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lemma node_inject [simp]:
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  "\<lbrakk>finite S; finite T\<rbrakk>
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    \<Longrightarrow> node i a S = node j b T \<longleftrightarrow> i = j \<and> a = b \<and> S = T"
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unfolding node_def by (simp add: prod_encode_eq set_encode_eq)
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lemma node_gt0: "i < node i a S"
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unfolding node_def less_Suc_eq_le
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by (rule le_prod_encode_1)
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lemma node_gt1: "a < node i a S"
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unfolding node_def less_Suc_eq_le
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by (rule order_trans [OF le_prod_encode_1 le_prod_encode_2])
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lemma nat_less_power2: "n < 2^n"
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by (induct n) simp_all
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lemma node_gt2: "\<lbrakk>finite S; b \<in> S\<rbrakk> \<Longrightarrow> b < node i a S"
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unfolding node_def less_Suc_eq_le set_encode_def
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apply (rule order_trans [OF _ le_prod_encode_2])
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apply (rule order_trans [OF _ le_prod_encode_2])
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apply (rule order_trans [where y="setsum (op ^ 2) {b}"])
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apply (simp add: nat_less_power2 [THEN order_less_imp_le])
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apply (erule setsum_mono2, simp, simp)
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done
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lemma eq_prod_encode_pairI:
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  "\<lbrakk>fst (prod_decode x) = a; snd (prod_decode x) = b\<rbrakk> \<Longrightarrow> x = prod_encode (a, b)"
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by (erule subst, erule subst, simp)
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lemma node_cases:
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  assumes 1: "x = 0 \<Longrightarrow> P"
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  assumes 2: "\<And>i a S. \<lbrakk>finite S; x = node i a S\<rbrakk> \<Longrightarrow> P"
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  shows "P"
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 apply (cases x)
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  apply (erule 1)
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 apply (rule 2)
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  apply (rule finite_set_decode)
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 apply (simp add: node_def)
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 apply (rule eq_prod_encode_pairI [OF refl])
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 apply (rule eq_prod_encode_pairI [OF refl refl])
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done
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lemma node_induct:
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  assumes 1: "P 0"
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  assumes 2: "\<And>i a S. \<lbrakk>P a; finite S; \<forall>b\<in>S. P b\<rbrakk> \<Longrightarrow> P (node i a S)"
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  shows "P x"
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 apply (induct x rule: nat_less_induct)
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 apply (case_tac n rule: node_cases)
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  apply (simp add: 1)
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 apply (simp add: 2 node_gt1 node_gt2)
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done
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subsubsection {* Basis ordering *}
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inductive
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  ubasis_le :: "nat \<Rightarrow> nat \<Rightarrow> bool"
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where
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  ubasis_le_refl: "ubasis_le a a"
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| ubasis_le_trans:
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    "\<lbrakk>ubasis_le a b; ubasis_le b c\<rbrakk> \<Longrightarrow> ubasis_le a c"
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| ubasis_le_lower:
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    "finite S \<Longrightarrow> ubasis_le a (node i a S)"
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| ubasis_le_upper:
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    "\<lbrakk>finite S; b \<in> S; ubasis_le a b\<rbrakk> \<Longrightarrow> ubasis_le (node i a S) b"
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lemma ubasis_le_minimal: "ubasis_le 0 x"
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apply (induct x rule: node_induct)
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apply (rule ubasis_le_refl)
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apply (erule ubasis_le_trans)
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apply (erule ubasis_le_lower)
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done
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interpretation udom: preorder ubasis_le
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apply default
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apply (rule ubasis_le_refl)
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apply (erule (1) ubasis_le_trans)
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done
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subsubsection {* Generic take function *}
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function
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  ubasis_until :: "(ubasis \<Rightarrow> bool) \<Rightarrow> ubasis \<Rightarrow> ubasis"
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where
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  "ubasis_until P 0 = 0"
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| "finite S \<Longrightarrow> ubasis_until P (node i a S) =
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    (if P (node i a S) then node i a S else ubasis_until P a)"
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    apply clarify
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    apply (rule_tac x=b in node_cases)
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     apply simp
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    apply simp
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    apply fast
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   apply simp
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  apply simp
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 apply simp
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done
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termination ubasis_until
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apply (relation "measure snd")
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apply (rule wf_measure)
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apply (simp add: node_gt1)
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done
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lemma ubasis_until: "P 0 \<Longrightarrow> P (ubasis_until P x)"
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by (induct x rule: node_induct) simp_all
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lemma ubasis_until': "0 < ubasis_until P x \<Longrightarrow> P (ubasis_until P x)"
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by (induct x rule: node_induct) auto
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lemma ubasis_until_same: "P x \<Longrightarrow> ubasis_until P x = x"
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by (induct x rule: node_induct) simp_all
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lemma ubasis_until_idem:
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  "P 0 \<Longrightarrow> ubasis_until P (ubasis_until P x) = ubasis_until P x"
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by (rule ubasis_until_same [OF ubasis_until])
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lemma ubasis_until_0:
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  "\<forall>x. x \<noteq> 0 \<longrightarrow> \<not> P x \<Longrightarrow> ubasis_until P x = 0"
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by (induct x rule: node_induct) simp_all
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lemma ubasis_until_less: "ubasis_le (ubasis_until P x) x"
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apply (induct x rule: node_induct)
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apply (simp add: ubasis_le_refl)
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apply (simp add: ubasis_le_refl)
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apply (rule impI)
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apply (erule ubasis_le_trans)
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apply (erule ubasis_le_lower)
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done
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lemma ubasis_until_chain:
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  assumes PQ: "\<And>x. P x \<Longrightarrow> Q x"
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  shows "ubasis_le (ubasis_until P x) (ubasis_until Q x)"
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apply (induct x rule: node_induct)
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apply (simp add: ubasis_le_refl)
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apply (simp add: ubasis_le_refl)
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apply (simp add: PQ)
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apply clarify
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apply (rule ubasis_le_trans)
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apply (rule ubasis_until_less)
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apply (erule ubasis_le_lower)
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done
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lemma ubasis_until_mono:
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  assumes "\<And>i a S b. \<lbrakk>finite S; P (node i a S); b \<in> S; ubasis_le a b\<rbrakk> \<Longrightarrow> P b"
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  shows "ubasis_le a b \<Longrightarrow> ubasis_le (ubasis_until P a) (ubasis_until P b)"
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proof (induct set: ubasis_le)
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  case (ubasis_le_refl a) show ?case by (rule ubasis_le.ubasis_le_refl)
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next
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  case (ubasis_le_trans a b c) thus ?case by - (rule ubasis_le.ubasis_le_trans)
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next
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  case (ubasis_le_lower S a i) thus ?case
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    apply (clarsimp simp add: ubasis_le_refl)
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    apply (rule ubasis_le_trans [OF ubasis_until_less])
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    apply (erule ubasis_le.ubasis_le_lower)
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    done
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next
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  case (ubasis_le_upper S b a i) thus ?case
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    apply clarsimp
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    apply (subst ubasis_until_same)
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     apply (erule (3) prems)
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    apply (erule (2) ubasis_le.ubasis_le_upper)
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    done
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qed
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lemma finite_range_ubasis_until:
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  "finite {x. P x} \<Longrightarrow> finite (range (ubasis_until P))"
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apply (rule finite_subset [where B="insert 0 {x. P x}"])
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apply (clarsimp simp add: ubasis_until')
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apply simp
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done
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subsection {* Defining the universal domain by ideal completion *}
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typedef (open) udom = "{S. udom.ideal S}"
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by (rule udom.ex_ideal)
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instantiation udom :: below
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begin
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definition
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  "x \<sqsubseteq> y \<longleftrightarrow> Rep_udom x \<subseteq> Rep_udom y"
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instance ..
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end
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instance udom :: po
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using type_definition_udom below_udom_def
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by (rule udom.typedef_ideal_po)
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instance udom :: cpo
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using type_definition_udom below_udom_def
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by (rule udom.typedef_ideal_cpo)
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definition
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  udom_principal :: "nat \<Rightarrow> udom" where
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  "udom_principal t = Abs_udom {u. ubasis_le u t}"
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lemma ubasis_countable: "\<exists>f::ubasis \<Rightarrow> nat. inj f"
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by (rule exI, rule inj_on_id)
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interpretation udom:
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  ideal_completion ubasis_le udom_principal Rep_udom
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using type_definition_udom below_udom_def
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using udom_principal_def ubasis_countable
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by (rule udom.typedef_ideal_completion)
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text {* Universal domain is pointed *}
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lemma udom_minimal: "udom_principal 0 \<sqsubseteq> x"
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apply (induct x rule: udom.principal_induct)
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apply (simp, simp add: ubasis_le_minimal)
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done
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instance udom :: pcpo
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by intro_classes (fast intro: udom_minimal)
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lemma inst_udom_pcpo: "\<bottom> = udom_principal 0"
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by (rule udom_minimal [THEN UU_I, symmetric])
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subsection {* Compact bases of domains *}
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typedef (open) 'a compact_basis = "{x::'a::pcpo. compact x}"
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by auto
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lemma Rep_compact_basis' [simp]: "compact (Rep_compact_basis a)"
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by (rule Rep_compact_basis [unfolded mem_Collect_eq])
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lemma Abs_compact_basis_inverse' [simp]:
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   "compact x \<Longrightarrow> Rep_compact_basis (Abs_compact_basis x) = x"
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by (rule Abs_compact_basis_inverse [unfolded mem_Collect_eq])
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instantiation compact_basis :: (pcpo) below
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begin
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definition
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  compact_le_def:
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    "(op \<sqsubseteq>) \<equiv> (\<lambda>x y. Rep_compact_basis x \<sqsubseteq> Rep_compact_basis y)"
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instance ..
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end
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instance compact_basis :: (pcpo) po
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using type_definition_compact_basis compact_le_def
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by (rule typedef_po)
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definition
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  approximants :: "'a \<Rightarrow> 'a compact_basis set" where
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  "approximants = (\<lambda>x. {a. Rep_compact_basis a \<sqsubseteq> x})"
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definition
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  compact_bot :: "'a::pcpo compact_basis" where
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  "compact_bot = Abs_compact_basis \<bottom>"
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lemma Rep_compact_bot [simp]: "Rep_compact_basis compact_bot = \<bottom>"
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unfolding compact_bot_def by simp
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lemma compact_bot_minimal [simp]: "compact_bot \<sqsubseteq> a"
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unfolding compact_le_def Rep_compact_bot by simp
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subsection {* Universality of \emph{udom} *}
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text {* We use a locale to parameterize the construction over a chain
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of approx functions on the type to be embedded. *}
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locale bifinite_approx_chain = approx_chain +
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  constrains approx :: "nat \<Rightarrow> 'a::bifinite \<rightarrow> 'a"
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begin
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subsubsection {* Choosing a maximal element from a finite set *}
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lemma finite_has_maximal:
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  fixes A :: "'a compact_basis set"
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  shows "\<lbrakk>finite A; A \<noteq> {}\<rbrakk> \<Longrightarrow> \<exists>x\<in>A. \<forall>y\<in>A. x \<sqsubseteq> y \<longrightarrow> x = y"
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proof (induct rule: finite_ne_induct)
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  case (singleton x)
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    show ?case by simp
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next
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  case (insert a A)
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  from `\<exists>x\<in>A. \<forall>y\<in>A. x \<sqsubseteq> y \<longrightarrow> x = y`
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  obtain x where x: "x \<in> A"
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           and x_eq: "\<And>y. \<lbrakk>y \<in> A; x \<sqsubseteq> y\<rbrakk> \<Longrightarrow> x = y" by fast
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  show ?case
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  proof (intro bexI ballI impI)
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    fix y
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    assume "y \<in> insert a A" and "(if x \<sqsubseteq> a then a else x) \<sqsubseteq> y"
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    thus "(if x \<sqsubseteq> a then a else x) = y"
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      apply auto
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      apply (frule (1) below_trans)
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      apply (frule (1) x_eq)
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      apply (rule below_antisym, assumption)
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      apply simp
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      apply (erule (1) x_eq)
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      done
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  next
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    show "(if x \<sqsubseteq> a then a else x) \<in> insert a A"
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      by (simp add: x)
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  qed
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qed
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definition
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  choose :: "'a compact_basis set \<Rightarrow> 'a compact_basis"
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where
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  "choose A = (SOME x. x \<in> {x\<in>A. \<forall>y\<in>A. x \<sqsubseteq> y \<longrightarrow> x = y})"
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lemma choose_lemma:
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  "\<lbrakk>finite A; A \<noteq> {}\<rbrakk> \<Longrightarrow> choose A \<in> {x\<in>A. \<forall>y\<in>A. x \<sqsubseteq> y \<longrightarrow> x = y}"
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unfolding choose_def
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   337
apply (rule someI_ex)
huffman@27411
   338
apply (frule (1) finite_has_maximal, fast)
huffman@27411
   339
done
huffman@27411
   340
huffman@27411
   341
lemma maximal_choose:
huffman@27411
   342
  "\<lbrakk>finite A; y \<in> A; choose A \<sqsubseteq> y\<rbrakk> \<Longrightarrow> choose A = y"
huffman@27411
   343
apply (cases "A = {}", simp)
huffman@27411
   344
apply (frule (1) choose_lemma, simp)
huffman@27411
   345
done
huffman@27411
   346
huffman@27411
   347
lemma choose_in: "\<lbrakk>finite A; A \<noteq> {}\<rbrakk> \<Longrightarrow> choose A \<in> A"
huffman@27411
   348
by (frule (1) choose_lemma, simp)
huffman@27411
   349
huffman@27411
   350
function
huffman@27411
   351
  choose_pos :: "'a compact_basis set \<Rightarrow> 'a compact_basis \<Rightarrow> nat"
huffman@27411
   352
where
huffman@27411
   353
  "choose_pos A x =
huffman@27411
   354
    (if finite A \<and> x \<in> A \<and> x \<noteq> choose A
huffman@27411
   355
      then Suc (choose_pos (A - {choose A}) x) else 0)"
huffman@27411
   356
by auto
huffman@27411
   357
huffman@27411
   358
termination choose_pos
huffman@27411
   359
apply (relation "measure (card \<circ> fst)", simp)
huffman@27411
   360
apply clarsimp
huffman@27411
   361
apply (rule card_Diff1_less)
huffman@27411
   362
apply assumption
huffman@27411
   363
apply (erule choose_in)
huffman@27411
   364
apply clarsimp
huffman@27411
   365
done
huffman@27411
   366
huffman@27411
   367
declare choose_pos.simps [simp del]
huffman@27411
   368
huffman@27411
   369
lemma choose_pos_choose: "finite A \<Longrightarrow> choose_pos A (choose A) = 0"
huffman@27411
   370
by (simp add: choose_pos.simps)
huffman@27411
   371
huffman@27411
   372
lemma inj_on_choose_pos [OF refl]:
huffman@27411
   373
  "\<lbrakk>card A = n; finite A\<rbrakk> \<Longrightarrow> inj_on (choose_pos A) A"
huffman@27411
   374
 apply (induct n arbitrary: A)
huffman@27411
   375
  apply simp
huffman@27411
   376
 apply (case_tac "A = {}", simp)
huffman@27411
   377
 apply (frule (1) choose_in)
huffman@27411
   378
 apply (rule inj_onI)
huffman@27411
   379
 apply (drule_tac x="A - {choose A}" in meta_spec, simp)
huffman@27411
   380
 apply (simp add: choose_pos.simps)
huffman@27411
   381
 apply (simp split: split_if_asm)
huffman@27411
   382
 apply (erule (1) inj_onD, simp, simp)
huffman@27411
   383
done
huffman@27411
   384
huffman@27411
   385
lemma choose_pos_bounded [OF refl]:
huffman@27411
   386
  "\<lbrakk>card A = n; finite A; x \<in> A\<rbrakk> \<Longrightarrow> choose_pos A x < n"
huffman@27411
   387
apply (induct n arbitrary: A)
huffman@27411
   388
apply simp
huffman@27411
   389
 apply (case_tac "A = {}", simp)
huffman@27411
   390
 apply (frule (1) choose_in)
huffman@27411
   391
apply (subst choose_pos.simps)
huffman@27411
   392
apply simp
huffman@27411
   393
done
huffman@27411
   394
huffman@27411
   395
lemma choose_pos_lessD:
huffman@41182
   396
  "\<lbrakk>choose_pos A x < choose_pos A y; finite A; x \<in> A; y \<in> A\<rbrakk> \<Longrightarrow> x \<notsqsubseteq> y"
huffman@27411
   397
 apply (induct A x arbitrary: y rule: choose_pos.induct)
huffman@27411
   398
 apply simp
huffman@27411
   399
 apply (case_tac "x = choose A")
huffman@27411
   400
  apply simp
huffman@27411
   401
  apply (rule notI)
huffman@27411
   402
  apply (frule (2) maximal_choose)
huffman@27411
   403
  apply simp
huffman@27411
   404
 apply (case_tac "y = choose A")
huffman@27411
   405
  apply (simp add: choose_pos_choose)
huffman@27411
   406
 apply (drule_tac x=y in meta_spec)
huffman@27411
   407
 apply simp
huffman@27411
   408
 apply (erule meta_mp)
huffman@27411
   409
 apply (simp add: choose_pos.simps)
huffman@27411
   410
done
huffman@27411
   411
huffman@39974
   412
subsubsection {* Compact basis take function *}
huffman@27411
   413
huffman@27411
   414
primrec
huffman@39974
   415
  cb_take :: "nat \<Rightarrow> 'a compact_basis \<Rightarrow> 'a compact_basis" where
huffman@27411
   416
  "cb_take 0 = (\<lambda>x. compact_bot)"
huffman@39974
   417
| "cb_take (Suc n) = (\<lambda>a. Abs_compact_basis (approx n\<cdot>(Rep_compact_basis a)))"
huffman@39974
   418
huffman@39974
   419
declare cb_take.simps [simp del]
huffman@39974
   420
huffman@39974
   421
lemma cb_take_zero [simp]: "cb_take 0 a = compact_bot"
huffman@39974
   422
by (simp only: cb_take.simps)
huffman@39974
   423
huffman@39974
   424
lemma Rep_cb_take:
huffman@39974
   425
  "Rep_compact_basis (cb_take (Suc n) a) = approx n\<cdot>(Rep_compact_basis a)"
huffman@41370
   426
by (simp add: cb_take.simps(2))
huffman@39974
   427
huffman@39974
   428
lemmas approx_Rep_compact_basis = Rep_cb_take [symmetric]
huffman@27411
   429
huffman@27411
   430
lemma cb_take_covers: "\<exists>n. cb_take n x = x"
huffman@39974
   431
apply (subgoal_tac "\<exists>n. cb_take (Suc n) x = x", fast)
huffman@39974
   432
apply (simp add: Rep_compact_basis_inject [symmetric])
huffman@39974
   433
apply (simp add: Rep_cb_take)
huffman@39974
   434
apply (rule compact_eq_approx)
huffman@41370
   435
apply (rule Rep_compact_basis')
huffman@27411
   436
done
huffman@27411
   437
huffman@27411
   438
lemma cb_take_less: "cb_take n x \<sqsubseteq> x"
huffman@39974
   439
unfolding compact_le_def
huffman@39974
   440
by (cases n, simp, simp add: Rep_cb_take approx_below)
huffman@27411
   441
huffman@27411
   442
lemma cb_take_idem: "cb_take n (cb_take n x) = cb_take n x"
huffman@39974
   443
unfolding Rep_compact_basis_inject [symmetric]
huffman@39974
   444
by (cases n, simp, simp add: Rep_cb_take approx_idem)
huffman@27411
   445
huffman@27411
   446
lemma cb_take_mono: "x \<sqsubseteq> y \<Longrightarrow> cb_take n x \<sqsubseteq> cb_take n y"
huffman@39974
   447
unfolding compact_le_def
huffman@39974
   448
by (cases n, simp, simp add: Rep_cb_take monofun_cfun_arg)
huffman@27411
   449
huffman@27411
   450
lemma cb_take_chain_le: "m \<le> n \<Longrightarrow> cb_take m x \<sqsubseteq> cb_take n x"
huffman@39974
   451
unfolding compact_le_def
huffman@39974
   452
apply (cases m, simp, cases n, simp)
huffman@39974
   453
apply (simp add: Rep_cb_take, rule chain_mono, simp, simp)
huffman@27411
   454
done
huffman@27411
   455
huffman@27411
   456
lemma finite_range_cb_take: "finite (range (cb_take n))"
huffman@27411
   457
apply (cases n)
huffman@39974
   458
apply (subgoal_tac "range (cb_take 0) = {compact_bot}", simp, force)
huffman@39974
   459
apply (rule finite_imageD [where f="Rep_compact_basis"])
huffman@39974
   460
apply (rule finite_subset [where B="range (\<lambda>x. approx (n - 1)\<cdot>x)"])
huffman@39974
   461
apply (clarsimp simp add: Rep_cb_take)
huffman@39974
   462
apply (rule finite_range_approx)
huffman@39974
   463
apply (rule inj_onI, simp add: Rep_compact_basis_inject)
huffman@27411
   464
done
huffman@27411
   465
huffman@39974
   466
subsubsection {* Rank of basis elements *}
huffman@39974
   467
huffman@27411
   468
definition
huffman@27411
   469
  rank :: "'a compact_basis \<Rightarrow> nat"
huffman@27411
   470
where
huffman@27411
   471
  "rank x = (LEAST n. cb_take n x = x)"
huffman@27411
   472
huffman@27411
   473
lemma compact_approx_rank: "cb_take (rank x) x = x"
huffman@27411
   474
unfolding rank_def
huffman@27411
   475
apply (rule LeastI_ex)
huffman@27411
   476
apply (rule cb_take_covers)
huffman@27411
   477
done
huffman@27411
   478
huffman@27411
   479
lemma rank_leD: "rank x \<le> n \<Longrightarrow> cb_take n x = x"
huffman@31076
   480
apply (rule below_antisym [OF cb_take_less])
huffman@27411
   481
apply (subst compact_approx_rank [symmetric])
huffman@27411
   482
apply (erule cb_take_chain_le)
huffman@27411
   483
done
huffman@27411
   484
huffman@27411
   485
lemma rank_leI: "cb_take n x = x \<Longrightarrow> rank x \<le> n"
huffman@27411
   486
unfolding rank_def by (rule Least_le)
huffman@27411
   487
huffman@27411
   488
lemma rank_le_iff: "rank x \<le> n \<longleftrightarrow> cb_take n x = x"
huffman@27411
   489
by (rule iffI [OF rank_leD rank_leI])
huffman@27411
   490
huffman@30505
   491
lemma rank_compact_bot [simp]: "rank compact_bot = 0"
huffman@30505
   492
using rank_leI [of 0 compact_bot] by simp
huffman@30505
   493
huffman@30505
   494
lemma rank_eq_0_iff [simp]: "rank x = 0 \<longleftrightarrow> x = compact_bot"
huffman@30505
   495
using rank_le_iff [of x 0] by auto
huffman@30505
   496
huffman@27411
   497
definition
huffman@27411
   498
  rank_le :: "'a compact_basis \<Rightarrow> 'a compact_basis set"
huffman@27411
   499
where
huffman@27411
   500
  "rank_le x = {y. rank y \<le> rank x}"
huffman@27411
   501
huffman@27411
   502
definition
huffman@27411
   503
  rank_lt :: "'a compact_basis \<Rightarrow> 'a compact_basis set"
huffman@27411
   504
where
huffman@27411
   505
  "rank_lt x = {y. rank y < rank x}"
huffman@27411
   506
huffman@27411
   507
definition
huffman@27411
   508
  rank_eq :: "'a compact_basis \<Rightarrow> 'a compact_basis set"
huffman@27411
   509
where
huffman@27411
   510
  "rank_eq x = {y. rank y = rank x}"
huffman@27411
   511
huffman@27411
   512
lemma rank_eq_cong: "rank x = rank y \<Longrightarrow> rank_eq x = rank_eq y"
huffman@27411
   513
unfolding rank_eq_def by simp
huffman@27411
   514
huffman@27411
   515
lemma rank_lt_cong: "rank x = rank y \<Longrightarrow> rank_lt x = rank_lt y"
huffman@27411
   516
unfolding rank_lt_def by simp
huffman@27411
   517
huffman@27411
   518
lemma rank_eq_subset: "rank_eq x \<subseteq> rank_le x"
huffman@27411
   519
unfolding rank_eq_def rank_le_def by auto
huffman@27411
   520
huffman@27411
   521
lemma rank_lt_subset: "rank_lt x \<subseteq> rank_le x"
huffman@27411
   522
unfolding rank_lt_def rank_le_def by auto
huffman@27411
   523
huffman@27411
   524
lemma finite_rank_le: "finite (rank_le x)"
huffman@27411
   525
unfolding rank_le_def
huffman@27411
   526
apply (rule finite_subset [where B="range (cb_take (rank x))"])
huffman@27411
   527
apply clarify
huffman@27411
   528
apply (rule range_eqI)
huffman@27411
   529
apply (erule rank_leD [symmetric])
huffman@27411
   530
apply (rule finite_range_cb_take)
huffman@27411
   531
done
huffman@27411
   532
huffman@27411
   533
lemma finite_rank_eq: "finite (rank_eq x)"
huffman@27411
   534
by (rule finite_subset [OF rank_eq_subset finite_rank_le])
huffman@27411
   535
huffman@27411
   536
lemma finite_rank_lt: "finite (rank_lt x)"
huffman@27411
   537
by (rule finite_subset [OF rank_lt_subset finite_rank_le])
huffman@27411
   538
huffman@27411
   539
lemma rank_lt_Int_rank_eq: "rank_lt x \<inter> rank_eq x = {}"
huffman@27411
   540
unfolding rank_lt_def rank_eq_def rank_le_def by auto
huffman@27411
   541
huffman@27411
   542
lemma rank_lt_Un_rank_eq: "rank_lt x \<union> rank_eq x = rank_le x"
huffman@27411
   543
unfolding rank_lt_def rank_eq_def rank_le_def by auto
huffman@27411
   544
huffman@30505
   545
subsubsection {* Sequencing basis elements *}
huffman@27411
   546
huffman@27411
   547
definition
huffman@30505
   548
  place :: "'a compact_basis \<Rightarrow> nat"
huffman@27411
   549
where
huffman@30505
   550
  "place x = card (rank_lt x) + choose_pos (rank_eq x) x"
huffman@27411
   551
huffman@30505
   552
lemma place_bounded: "place x < card (rank_le x)"
huffman@30505
   553
unfolding place_def
huffman@27411
   554
 apply (rule ord_less_eq_trans)
huffman@27411
   555
  apply (rule add_strict_left_mono)
huffman@27411
   556
  apply (rule choose_pos_bounded)
huffman@27411
   557
   apply (rule finite_rank_eq)
huffman@27411
   558
  apply (simp add: rank_eq_def)
huffman@27411
   559
 apply (subst card_Un_disjoint [symmetric])
huffman@27411
   560
    apply (rule finite_rank_lt)
huffman@27411
   561
   apply (rule finite_rank_eq)
huffman@27411
   562
  apply (rule rank_lt_Int_rank_eq)
huffman@27411
   563
 apply (simp add: rank_lt_Un_rank_eq)
huffman@27411
   564
done
huffman@27411
   565
huffman@30505
   566
lemma place_ge: "card (rank_lt x) \<le> place x"
huffman@30505
   567
unfolding place_def by simp
huffman@27411
   568
huffman@30505
   569
lemma place_rank_mono:
huffman@27411
   570
  fixes x y :: "'a compact_basis"
huffman@30505
   571
  shows "rank x < rank y \<Longrightarrow> place x < place y"
huffman@30505
   572
apply (rule less_le_trans [OF place_bounded])
huffman@30505
   573
apply (rule order_trans [OF _ place_ge])
huffman@27411
   574
apply (rule card_mono)
huffman@27411
   575
apply (rule finite_rank_lt)
huffman@27411
   576
apply (simp add: rank_le_def rank_lt_def subset_eq)
huffman@27411
   577
done
huffman@27411
   578
huffman@30505
   579
lemma place_eqD: "place x = place y \<Longrightarrow> x = y"
huffman@27411
   580
 apply (rule linorder_cases [where x="rank x" and y="rank y"])
huffman@30505
   581
   apply (drule place_rank_mono, simp)
huffman@30505
   582
  apply (simp add: place_def)
huffman@27411
   583
  apply (rule inj_on_choose_pos [where A="rank_eq x", THEN inj_onD])
huffman@27411
   584
     apply (rule finite_rank_eq)
huffman@27411
   585
    apply (simp cong: rank_lt_cong rank_eq_cong)
huffman@27411
   586
   apply (simp add: rank_eq_def)
huffman@27411
   587
  apply (simp add: rank_eq_def)
huffman@30505
   588
 apply (drule place_rank_mono, simp)
huffman@27411
   589
done
huffman@27411
   590
huffman@30505
   591
lemma inj_place: "inj place"
huffman@30505
   592
by (rule inj_onI, erule place_eqD)
huffman@27411
   593
huffman@27411
   594
subsubsection {* Embedding and projection on basis elements *}
huffman@27411
   595
huffman@30505
   596
definition
huffman@30505
   597
  sub :: "'a compact_basis \<Rightarrow> 'a compact_basis"
huffman@30505
   598
where
huffman@30505
   599
  "sub x = (case rank x of 0 \<Rightarrow> compact_bot | Suc k \<Rightarrow> cb_take k x)"
huffman@30505
   600
huffman@30505
   601
lemma rank_sub_less: "x \<noteq> compact_bot \<Longrightarrow> rank (sub x) < rank x"
huffman@30505
   602
unfolding sub_def
huffman@30505
   603
apply (cases "rank x", simp)
huffman@30505
   604
apply (simp add: less_Suc_eq_le)
huffman@30505
   605
apply (rule rank_leI)
huffman@30505
   606
apply (rule cb_take_idem)
huffman@30505
   607
done
huffman@30505
   608
huffman@30505
   609
lemma place_sub_less: "x \<noteq> compact_bot \<Longrightarrow> place (sub x) < place x"
huffman@30505
   610
apply (rule place_rank_mono)
huffman@30505
   611
apply (erule rank_sub_less)
huffman@30505
   612
done
huffman@30505
   613
huffman@30505
   614
lemma sub_below: "sub x \<sqsubseteq> x"
huffman@30505
   615
unfolding sub_def by (cases "rank x", simp_all add: cb_take_less)
huffman@30505
   616
huffman@30505
   617
lemma rank_less_imp_below_sub: "\<lbrakk>x \<sqsubseteq> y; rank x < rank y\<rbrakk> \<Longrightarrow> x \<sqsubseteq> sub y"
huffman@30505
   618
unfolding sub_def
huffman@30505
   619
apply (cases "rank y", simp)
huffman@30505
   620
apply (simp add: less_Suc_eq_le)
huffman@30505
   621
apply (subgoal_tac "cb_take nat x \<sqsubseteq> cb_take nat y")
huffman@30505
   622
apply (simp add: rank_leD)
huffman@30505
   623
apply (erule cb_take_mono)
huffman@30505
   624
done
huffman@30505
   625
huffman@27411
   626
function
huffman@27411
   627
  basis_emb :: "'a compact_basis \<Rightarrow> ubasis"
huffman@27411
   628
where
huffman@27411
   629
  "basis_emb x = (if x = compact_bot then 0 else
huffman@30505
   630
    node (place x) (basis_emb (sub x))
huffman@30505
   631
      (basis_emb ` {y. place y < place x \<and> x \<sqsubseteq> y}))"
huffman@27411
   632
by auto
huffman@27411
   633
huffman@27411
   634
termination basis_emb
huffman@30505
   635
apply (relation "measure place", simp)
huffman@30505
   636
apply (simp add: place_sub_less)
huffman@27411
   637
apply simp
huffman@27411
   638
done
huffman@27411
   639
huffman@27411
   640
declare basis_emb.simps [simp del]
huffman@27411
   641
huffman@27411
   642
lemma basis_emb_compact_bot [simp]: "basis_emb compact_bot = 0"
huffman@27411
   643
by (simp add: basis_emb.simps)
huffman@27411
   644
huffman@30505
   645
lemma fin1: "finite {y. place y < place x \<and> x \<sqsubseteq> y}"
huffman@27411
   646
apply (subst Collect_conj_eq)
huffman@27411
   647
apply (rule finite_Int)
huffman@27411
   648
apply (rule disjI1)
huffman@30505
   649
apply (subgoal_tac "finite (place -` {n. n < place x})", simp)
huffman@30505
   650
apply (rule finite_vimageI [OF _ inj_place])
huffman@27411
   651
apply (simp add: lessThan_def [symmetric])
huffman@27411
   652
done
huffman@27411
   653
huffman@30505
   654
lemma fin2: "finite (basis_emb ` {y. place y < place x \<and> x \<sqsubseteq> y})"
huffman@27411
   655
by (rule finite_imageI [OF fin1])
huffman@27411
   656
huffman@30505
   657
lemma rank_place_mono:
huffman@30505
   658
  "\<lbrakk>place x < place y; x \<sqsubseteq> y\<rbrakk> \<Longrightarrow> rank x < rank y"
huffman@30505
   659
apply (rule linorder_cases, assumption)
huffman@30505
   660
apply (simp add: place_def cong: rank_lt_cong rank_eq_cong)
huffman@30505
   661
apply (drule choose_pos_lessD)
huffman@30505
   662
apply (rule finite_rank_eq)
huffman@30505
   663
apply (simp add: rank_eq_def)
huffman@30505
   664
apply (simp add: rank_eq_def)
huffman@30505
   665
apply simp
huffman@30505
   666
apply (drule place_rank_mono, simp)
huffman@30505
   667
done
huffman@30505
   668
huffman@30505
   669
lemma basis_emb_mono:
huffman@30505
   670
  "x \<sqsubseteq> y \<Longrightarrow> ubasis_le (basis_emb x) (basis_emb y)"
berghofe@34915
   671
proof (induct "max (place x) (place y)" arbitrary: x y rule: less_induct)
berghofe@34915
   672
  case less
huffman@30505
   673
  show ?case proof (rule linorder_cases)
huffman@30505
   674
    assume "place x < place y"
huffman@30505
   675
    then have "rank x < rank y"
huffman@30505
   676
      using `x \<sqsubseteq> y` by (rule rank_place_mono)
huffman@30505
   677
    with `place x < place y` show ?case
huffman@30505
   678
      apply (case_tac "y = compact_bot", simp)
huffman@30505
   679
      apply (simp add: basis_emb.simps [of y])
huffman@30505
   680
      apply (rule ubasis_le_trans [OF _ ubasis_le_lower [OF fin2]])
berghofe@34915
   681
      apply (rule less)
huffman@30505
   682
       apply (simp add: less_max_iff_disj)
huffman@30505
   683
       apply (erule place_sub_less)
huffman@30505
   684
      apply (erule rank_less_imp_below_sub [OF `x \<sqsubseteq> y`])
huffman@27411
   685
      done
huffman@30505
   686
  next
huffman@30505
   687
    assume "place x = place y"
huffman@30505
   688
    hence "x = y" by (rule place_eqD)
huffman@30505
   689
    thus ?case by (simp add: ubasis_le_refl)
huffman@30505
   690
  next
huffman@30505
   691
    assume "place x > place y"
huffman@30505
   692
    with `x \<sqsubseteq> y` show ?case
huffman@30505
   693
      apply (case_tac "x = compact_bot", simp add: ubasis_le_minimal)
huffman@30505
   694
      apply (simp add: basis_emb.simps [of x])
huffman@30505
   695
      apply (rule ubasis_le_upper [OF fin2], simp)
berghofe@34915
   696
      apply (rule less)
huffman@30505
   697
       apply (simp add: less_max_iff_disj)
huffman@30505
   698
       apply (erule place_sub_less)
huffman@31076
   699
      apply (erule rev_below_trans)
huffman@30505
   700
      apply (rule sub_below)
huffman@30505
   701
      done
huffman@27411
   702
  qed
huffman@27411
   703
qed
huffman@27411
   704
huffman@27411
   705
lemma inj_basis_emb: "inj basis_emb"
huffman@27411
   706
 apply (rule inj_onI)
huffman@27411
   707
 apply (case_tac "x = compact_bot")
huffman@27411
   708
  apply (case_tac [!] "y = compact_bot")
huffman@27411
   709
    apply simp
huffman@27411
   710
   apply (simp add: basis_emb.simps)
huffman@27411
   711
  apply (simp add: basis_emb.simps)
huffman@27411
   712
 apply (simp add: basis_emb.simps)
huffman@30505
   713
 apply (simp add: fin2 inj_eq [OF inj_place])
huffman@27411
   714
done
huffman@27411
   715
huffman@27411
   716
definition
huffman@30505
   717
  basis_prj :: "ubasis \<Rightarrow> 'a compact_basis"
huffman@27411
   718
where
huffman@27411
   719
  "basis_prj x = inv basis_emb
huffman@30505
   720
    (ubasis_until (\<lambda>x. x \<in> range (basis_emb :: 'a compact_basis \<Rightarrow> ubasis)) x)"
huffman@27411
   721
huffman@27411
   722
lemma basis_prj_basis_emb: "\<And>x. basis_prj (basis_emb x) = x"
huffman@27411
   723
unfolding basis_prj_def
huffman@27411
   724
 apply (subst ubasis_until_same)
huffman@27411
   725
  apply (rule rangeI)
huffman@27411
   726
 apply (rule inv_f_f)
huffman@27411
   727
 apply (rule inj_basis_emb)
huffman@27411
   728
done
huffman@27411
   729
huffman@27411
   730
lemma basis_prj_node:
huffman@30505
   731
  "\<lbrakk>finite S; node i a S \<notin> range (basis_emb :: 'a compact_basis \<Rightarrow> nat)\<rbrakk>
huffman@30505
   732
    \<Longrightarrow> basis_prj (node i a S) = (basis_prj a :: 'a compact_basis)"
huffman@27411
   733
unfolding basis_prj_def by simp
huffman@27411
   734
huffman@27411
   735
lemma basis_prj_0: "basis_prj 0 = compact_bot"
huffman@27411
   736
apply (subst basis_emb_compact_bot [symmetric])
huffman@27411
   737
apply (rule basis_prj_basis_emb)
huffman@27411
   738
done
huffman@27411
   739
huffman@30505
   740
lemma node_eq_basis_emb_iff:
huffman@30505
   741
  "finite S \<Longrightarrow> node i a S = basis_emb x \<longleftrightarrow>
huffman@30505
   742
    x \<noteq> compact_bot \<and> i = place x \<and> a = basis_emb (sub x) \<and>
huffman@30505
   743
        S = basis_emb ` {y. place y < place x \<and> x \<sqsubseteq> y}"
huffman@30505
   744
apply (cases "x = compact_bot", simp)
huffman@30505
   745
apply (simp add: basis_emb.simps [of x])
huffman@30505
   746
apply (simp add: fin2)
huffman@27411
   747
done
huffman@27411
   748
huffman@30505
   749
lemma basis_prj_mono: "ubasis_le a b \<Longrightarrow> basis_prj a \<sqsubseteq> basis_prj b"
huffman@30505
   750
proof (induct a b rule: ubasis_le.induct)
huffman@31076
   751
  case (ubasis_le_refl a) show ?case by (rule below_refl)
huffman@30505
   752
next
huffman@31076
   753
  case (ubasis_le_trans a b c) thus ?case by - (rule below_trans)
huffman@30505
   754
next
huffman@30505
   755
  case (ubasis_le_lower S a i) thus ?case
huffman@30561
   756
    apply (cases "node i a S \<in> range (basis_emb :: 'a compact_basis \<Rightarrow> nat)")
huffman@30505
   757
     apply (erule rangeE, rename_tac x)
huffman@30505
   758
     apply (simp add: basis_prj_basis_emb)
huffman@30505
   759
     apply (simp add: node_eq_basis_emb_iff)
huffman@30505
   760
     apply (simp add: basis_prj_basis_emb)
huffman@30505
   761
     apply (rule sub_below)
huffman@30505
   762
    apply (simp add: basis_prj_node)
huffman@30505
   763
    done
huffman@30505
   764
next
huffman@30505
   765
  case (ubasis_le_upper S b a i) thus ?case
huffman@30561
   766
    apply (cases "node i a S \<in> range (basis_emb :: 'a compact_basis \<Rightarrow> nat)")
huffman@30505
   767
     apply (erule rangeE, rename_tac x)
huffman@30505
   768
     apply (simp add: basis_prj_basis_emb)
huffman@30505
   769
     apply (clarsimp simp add: node_eq_basis_emb_iff)
huffman@30505
   770
     apply (simp add: basis_prj_basis_emb)
huffman@30505
   771
    apply (simp add: basis_prj_node)
huffman@30505
   772
    done
huffman@30505
   773
qed
huffman@30505
   774
huffman@27411
   775
lemma basis_emb_prj_less: "ubasis_le (basis_emb (basis_prj x)) x"
huffman@27411
   776
unfolding basis_prj_def
wenzelm@33071
   777
 apply (subst f_inv_into_f [where f=basis_emb])
huffman@27411
   778
  apply (rule ubasis_until)
huffman@27411
   779
  apply (rule range_eqI [where x=compact_bot])
huffman@27411
   780
  apply simp
huffman@27411
   781
 apply (rule ubasis_until_less)
huffman@27411
   782
done
huffman@27411
   783
huffman@41286
   784
lemma ideal_completion:
huffman@41286
   785
  "ideal_completion below Rep_compact_basis (approximants :: 'a \<Rightarrow> _)"
huffman@39974
   786
proof
huffman@39974
   787
  fix w :: "'a"
huffman@39974
   788
  show "below.ideal (approximants w)"
huffman@39974
   789
  proof (rule below.idealI)
huffman@41370
   790
    have "Abs_compact_basis (approx 0\<cdot>w) \<in> approximants w"
huffman@41370
   791
      by (simp add: approximants_def approx_below)
huffman@41370
   792
    thus "\<exists>x. x \<in> approximants w" ..
huffman@39974
   793
  next
huffman@39974
   794
    fix x y :: "'a compact_basis"
huffman@41370
   795
    assume x: "x \<in> approximants w" and y: "y \<in> approximants w"
huffman@41370
   796
    obtain i where i: "approx i\<cdot>(Rep_compact_basis x) = Rep_compact_basis x"
huffman@41370
   797
      using compact_eq_approx Rep_compact_basis' by fast
huffman@41370
   798
    obtain j where j: "approx j\<cdot>(Rep_compact_basis y) = Rep_compact_basis y"
huffman@41370
   799
      using compact_eq_approx Rep_compact_basis' by fast
huffman@41370
   800
    let ?z = "Abs_compact_basis (approx (max i j)\<cdot>w)"
huffman@41370
   801
    have "?z \<in> approximants w"
huffman@41370
   802
      by (simp add: approximants_def approx_below)
huffman@41370
   803
    moreover from x y have "x \<sqsubseteq> ?z \<and> y \<sqsubseteq> ?z"
huffman@41370
   804
      by (simp add: approximants_def compact_le_def)
huffman@41370
   805
         (metis i j monofun_cfun chain_mono chain_approx le_maxI1 le_maxI2)
huffman@41370
   806
    ultimately show "\<exists>z \<in> approximants w. x \<sqsubseteq> z \<and> y \<sqsubseteq> z" ..
huffman@39974
   807
  next
huffman@39974
   808
    fix x y :: "'a compact_basis"
huffman@39974
   809
    assume "x \<sqsubseteq> y" "y \<in> approximants w" thus "x \<in> approximants w"
huffman@41370
   810
      unfolding approximants_def compact_le_def
huffman@41370
   811
      by (auto elim: below_trans)
huffman@39974
   812
  qed
huffman@39974
   813
next
huffman@39974
   814
  fix Y :: "nat \<Rightarrow> 'a"
huffman@41370
   815
  assume "chain Y"
huffman@41370
   816
  thus "approximants (\<Squnion>i. Y i) = (\<Union>i. approximants (Y i))"
huffman@39974
   817
    unfolding approximants_def
huffman@41370
   818
    by (auto simp add: compact_below_lub_iff)
huffman@39974
   819
next
huffman@39974
   820
  fix a :: "'a compact_basis"
huffman@39974
   821
  show "approximants (Rep_compact_basis a) = {b. b \<sqsubseteq> a}"
huffman@39974
   822
    unfolding approximants_def compact_le_def ..
huffman@39974
   823
next
huffman@39974
   824
  fix x y :: "'a"
huffman@41370
   825
  assume "approximants x \<subseteq> approximants y"
huffman@41370
   826
  hence "\<forall>z. compact z \<longrightarrow> z \<sqsubseteq> x \<longrightarrow> z \<sqsubseteq> y"
huffman@41370
   827
    by (simp add: approximants_def subset_eq)
huffman@41370
   828
       (metis Abs_compact_basis_inverse')
huffman@41370
   829
  hence "(\<Squnion>i. approx i\<cdot>x) \<sqsubseteq> y"
huffman@41370
   830
    by (simp add: lub_below approx_below)
huffman@41370
   831
  thus "x \<sqsubseteq> y"
huffman@41370
   832
    by (simp add: lub_distribs)
huffman@39974
   833
next
huffman@39974
   834
  show "\<exists>f::'a compact_basis \<Rightarrow> nat. inj f"
huffman@39974
   835
    by (rule exI, rule inj_place)
huffman@39974
   836
qed
huffman@27411
   837
huffman@41286
   838
end
huffman@41286
   839
huffman@41286
   840
interpretation compact_basis!:
huffman@41286
   841
  ideal_completion below Rep_compact_basis
huffman@41286
   842
    "approximants :: 'a::bifinite \<Rightarrow> 'a compact_basis set"
huffman@41286
   843
proof -
huffman@41286
   844
  obtain a :: "nat \<Rightarrow> 'a \<rightarrow> 'a" where "approx_chain a"
huffman@41286
   845
    using bifinite ..
huffman@41286
   846
  hence "bifinite_approx_chain a"
huffman@41286
   847
    unfolding bifinite_approx_chain_def .
huffman@41286
   848
  thus "ideal_completion below Rep_compact_basis (approximants :: 'a \<Rightarrow> _)"
huffman@41286
   849
    by (rule bifinite_approx_chain.ideal_completion)
huffman@41286
   850
qed
huffman@41286
   851
huffman@35900
   852
subsubsection {* EP-pair from any bifinite domain into \emph{udom} *}
huffman@27411
   853
huffman@41286
   854
context bifinite_approx_chain begin
huffman@39974
   855
huffman@27411
   856
definition
huffman@39974
   857
  udom_emb :: "'a \<rightarrow> udom"
huffman@27411
   858
where
huffman@41394
   859
  "udom_emb = compact_basis.extension (\<lambda>x. udom_principal (basis_emb x))"
huffman@27411
   860
huffman@27411
   861
definition
huffman@39974
   862
  udom_prj :: "udom \<rightarrow> 'a"
huffman@27411
   863
where
huffman@41394
   864
  "udom_prj = udom.extension (\<lambda>x. Rep_compact_basis (basis_prj x))"
huffman@27411
   865
huffman@27411
   866
lemma udom_emb_principal:
huffman@27411
   867
  "udom_emb\<cdot>(Rep_compact_basis x) = udom_principal (basis_emb x)"
huffman@27411
   868
unfolding udom_emb_def
huffman@41394
   869
apply (rule compact_basis.extension_principal)
huffman@27411
   870
apply (rule udom.principal_mono)
huffman@27411
   871
apply (erule basis_emb_mono)
huffman@27411
   872
done
huffman@27411
   873
huffman@27411
   874
lemma udom_prj_principal:
huffman@27411
   875
  "udom_prj\<cdot>(udom_principal x) = Rep_compact_basis (basis_prj x)"
huffman@27411
   876
unfolding udom_prj_def
huffman@41394
   877
apply (rule udom.extension_principal)
huffman@27411
   878
apply (rule compact_basis.principal_mono)
huffman@27411
   879
apply (erule basis_prj_mono)
huffman@27411
   880
done
huffman@27411
   881
huffman@27411
   882
lemma ep_pair_udom: "ep_pair udom_emb udom_prj"
huffman@27411
   883
 apply default
huffman@27411
   884
  apply (rule compact_basis.principal_induct, simp)
huffman@27411
   885
  apply (simp add: udom_emb_principal udom_prj_principal)
huffman@27411
   886
  apply (simp add: basis_prj_basis_emb)
huffman@27411
   887
 apply (rule udom.principal_induct, simp)
huffman@27411
   888
 apply (simp add: udom_emb_principal udom_prj_principal)
huffman@27411
   889
 apply (rule basis_emb_prj_less)
huffman@27411
   890
done
huffman@27411
   891
huffman@27411
   892
end
huffman@39974
   893
huffman@41286
   894
abbreviation "udom_emb \<equiv> bifinite_approx_chain.udom_emb"
huffman@41286
   895
abbreviation "udom_prj \<equiv> bifinite_approx_chain.udom_prj"
huffman@39974
   896
huffman@41286
   897
lemmas ep_pair_udom =
huffman@41286
   898
  bifinite_approx_chain.ep_pair_udom [unfolded bifinite_approx_chain_def]
huffman@39974
   899
huffman@39974
   900
subsection {* Chain of approx functions for type \emph{udom} *}
huffman@39974
   901
huffman@39974
   902
definition
huffman@39974
   903
  udom_approx :: "nat \<Rightarrow> udom \<rightarrow> udom"
huffman@39974
   904
where
huffman@39974
   905
  "udom_approx i =
huffman@41394
   906
    udom.extension (\<lambda>x. udom_principal (ubasis_until (\<lambda>y. y \<le> i) x))"
huffman@39974
   907
huffman@39974
   908
lemma udom_approx_mono:
huffman@39974
   909
  "ubasis_le a b \<Longrightarrow>
huffman@39974
   910
    udom_principal (ubasis_until (\<lambda>y. y \<le> i) a) \<sqsubseteq>
huffman@39974
   911
    udom_principal (ubasis_until (\<lambda>y. y \<le> i) b)"
huffman@39974
   912
apply (rule udom.principal_mono)
huffman@39974
   913
apply (rule ubasis_until_mono)
huffman@39974
   914
apply (frule (2) order_less_le_trans [OF node_gt2])
huffman@39974
   915
apply (erule order_less_imp_le)
huffman@39974
   916
apply assumption
huffman@39974
   917
done
huffman@39974
   918
huffman@39974
   919
lemma adm_mem_finite: "\<lbrakk>cont f; finite S\<rbrakk> \<Longrightarrow> adm (\<lambda>x. f x \<in> S)"
huffman@39974
   920
by (erule adm_subst, induct set: finite, simp_all)
huffman@39974
   921
huffman@39974
   922
lemma udom_approx_principal:
huffman@39974
   923
  "udom_approx i\<cdot>(udom_principal x) =
huffman@39974
   924
    udom_principal (ubasis_until (\<lambda>y. y \<le> i) x)"
huffman@39974
   925
unfolding udom_approx_def
huffman@41394
   926
apply (rule udom.extension_principal)
huffman@39974
   927
apply (erule udom_approx_mono)
huffman@39974
   928
done
huffman@39974
   929
huffman@39974
   930
lemma finite_deflation_udom_approx: "finite_deflation (udom_approx i)"
huffman@39974
   931
proof
huffman@39974
   932
  fix x show "udom_approx i\<cdot>(udom_approx i\<cdot>x) = udom_approx i\<cdot>x"
huffman@39974
   933
    by (induct x rule: udom.principal_induct, simp)
huffman@39974
   934
       (simp add: udom_approx_principal ubasis_until_idem)
huffman@39974
   935
next
huffman@39974
   936
  fix x show "udom_approx i\<cdot>x \<sqsubseteq> x"
huffman@39974
   937
    by (induct x rule: udom.principal_induct, simp)
huffman@39974
   938
       (simp add: udom_approx_principal ubasis_until_less)
huffman@39974
   939
next
huffman@39974
   940
  have *: "finite (range (\<lambda>x. udom_principal (ubasis_until (\<lambda>y. y \<le> i) x)))"
huffman@39974
   941
    apply (subst range_composition [where f=udom_principal])
huffman@39974
   942
    apply (simp add: finite_range_ubasis_until)
huffman@39974
   943
    done
huffman@39974
   944
  show "finite {x. udom_approx i\<cdot>x = x}"
huffman@39974
   945
    apply (rule finite_range_imp_finite_fixes)
huffman@39974
   946
    apply (rule rev_finite_subset [OF *])
huffman@39974
   947
    apply (clarsimp, rename_tac x)
huffman@39974
   948
    apply (induct_tac x rule: udom.principal_induct)
huffman@39974
   949
    apply (simp add: adm_mem_finite *)
huffman@39974
   950
    apply (simp add: udom_approx_principal)
huffman@39974
   951
    done
huffman@39974
   952
qed
huffman@39974
   953
huffman@39974
   954
interpretation udom_approx: finite_deflation "udom_approx i"
huffman@39974
   955
by (rule finite_deflation_udom_approx)
huffman@39974
   956
huffman@39974
   957
lemma chain_udom_approx [simp]: "chain (\<lambda>i. udom_approx i)"
huffman@39974
   958
unfolding udom_approx_def
huffman@39974
   959
apply (rule chainI)
huffman@41394
   960
apply (rule udom.extension_mono)
huffman@39974
   961
apply (erule udom_approx_mono)
huffman@39974
   962
apply (erule udom_approx_mono)
huffman@39974
   963
apply (rule udom.principal_mono)
huffman@39974
   964
apply (rule ubasis_until_chain, simp)
huffman@39974
   965
done
huffman@39974
   966
huffman@39974
   967
lemma lub_udom_approx [simp]: "(\<Squnion>i. udom_approx i) = ID"
huffman@40002
   968
apply (rule cfun_eqI, simp add: contlub_cfun_fun)
huffman@39974
   969
apply (rule below_antisym)
huffman@40500
   970
apply (rule lub_below)
huffman@39974
   971
apply (simp)
huffman@39974
   972
apply (rule udom_approx.below)
huffman@39974
   973
apply (rule_tac x=x in udom.principal_induct)
huffman@39974
   974
apply (simp add: lub_distribs)
huffman@40500
   975
apply (rule_tac i=a in below_lub)
huffman@39974
   976
apply simp
huffman@39974
   977
apply (simp add: udom_approx_principal)
huffman@39974
   978
apply (simp add: ubasis_until_same ubasis_le_refl)
huffman@39974
   979
done
huffman@39974
   980
 
huffman@41286
   981
lemma udom_approx [simp]: "approx_chain udom_approx"
huffman@39974
   982
proof
huffman@39974
   983
  show "chain (\<lambda>i. udom_approx i)"
huffman@39974
   984
    by (rule chain_udom_approx)
huffman@39974
   985
  show "(\<Squnion>i. udom_approx i) = ID"
huffman@39974
   986
    by (rule lub_udom_approx)
huffman@39974
   987
qed
huffman@39974
   988
huffman@41286
   989
instance udom :: bifinite
huffman@41286
   990
  by default (fast intro: udom_approx)
huffman@41286
   991
huffman@39974
   992
hide_const (open) node
huffman@39974
   993
huffman@39974
   994
end