nipkow@45963
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(* Author: Tobias Nipkow *)
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nipkow@45963
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nipkow@48465
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theory Abs_Int1_ITP
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nipkow@48465
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imports Abs_State_ITP
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begin
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subsection "Computable Abstract Interpretation"
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text{* Abstract interpretation over type @{text st} instead of
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functions. *}
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context Gamma
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begin
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fun aval' :: "aexp \<Rightarrow> 'av st \<Rightarrow> 'av" where
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"aval' (N n) S = num' n" |
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"aval' (V x) S = lookup S x" |
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"aval' (Plus a1 a2) S = plus' (aval' a1 S) (aval' a2 S)"
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wenzelm@54152
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lemma aval'_sound: "s : \<gamma>\<^sub>f S \<Longrightarrow> aval a s : \<gamma>(aval' a S)"
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by (induction a) (auto simp: gamma_num' gamma_plus' \<gamma>_st_def lookup_def)
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end
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text{* The for-clause (here and elsewhere) only serves the purpose of fixing
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the name of the type parameter @{typ 'av} which would otherwise be renamed to
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@{typ 'a}. *}
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locale Abs_Int = Gamma where \<gamma>=\<gamma> for \<gamma> :: "'av::SL_top \<Rightarrow> val set"
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begin
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fun step' :: "'av st option \<Rightarrow> 'av st option acom \<Rightarrow> 'av st option acom" where
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"step' S (SKIP {P}) = (SKIP {S})" |
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"step' S (x ::= e {P}) =
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x ::= e {case S of None \<Rightarrow> None | Some S \<Rightarrow> Some(update S x (aval' e S))}" |
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"step' S (c1;; c2) = step' S c1;; step' (post c1) c2" |
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"step' S (IF b THEN c1 ELSE c2 {P}) =
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(let c1' = step' S c1; c2' = step' S c2
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in IF b THEN c1' ELSE c2' {post c1 \<squnion> post c2})" |
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"step' S ({Inv} WHILE b DO c {P}) =
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{S \<squnion> post c} WHILE b DO step' Inv c {Inv}"
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definition AI :: "com \<Rightarrow> 'av st option acom option" where
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wenzelm@54152
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"AI = lpfp\<^sub>c (step' \<top>)"
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nipkow@45998
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lemma strip_step'[simp]: "strip(step' S c) = strip c"
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by(induct c arbitrary: S) (simp_all add: Let_def)
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text{* Soundness: *}
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lemma in_gamma_update:
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wenzelm@54152
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"\<lbrakk> s : \<gamma>\<^sub>f S; i : \<gamma> a \<rbrakk> \<Longrightarrow> s(x := i) : \<gamma>\<^sub>f(update S x a)"
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by(simp add: \<gamma>_st_def lookup_update)
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text{* The soundness proofs are textually identical to the ones for the step
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function operating on states as functions. *}
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lemma step_preserves_le:
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wenzelm@54152
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"\<lbrakk> S \<subseteq> \<gamma>\<^sub>o S'; c \<le> \<gamma>\<^sub>c c' \<rbrakk> \<Longrightarrow> step S c \<le> \<gamma>\<^sub>c (step' S' c')"
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proof(induction c arbitrary: c' S S')
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case SKIP thus ?case by(auto simp:SKIP_le map_acom_SKIP)
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next
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case Assign thus ?case
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by (fastforce simp: Assign_le map_acom_Assign intro: aval'_sound in_gamma_update
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split: option.splits del:subsetD)
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next
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case Seq thus ?case apply (auto simp: Seq_le map_acom_Seq)
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by (metis le_post post_map_acom)
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next
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case (If b c1 c2 P)
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then obtain c1' c2' P' where
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"c' = IF b THEN c1' ELSE c2' {P'}"
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wenzelm@54152
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"P \<subseteq> \<gamma>\<^sub>o P'" "c1 \<le> \<gamma>\<^sub>c c1'" "c2 \<le> \<gamma>\<^sub>c c2'"
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by (fastforce simp: If_le map_acom_If)
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wenzelm@54152
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moreover have "post c1 \<subseteq> \<gamma>\<^sub>o(post c1' \<squnion> post c2')"
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wenzelm@54152
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by (metis (no_types) `c1 \<le> \<gamma>\<^sub>c c1'` join_ge1 le_post mono_gamma_o order_trans post_map_acom)
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wenzelm@54152
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moreover have "post c2 \<subseteq> \<gamma>\<^sub>o(post c1' \<squnion> post c2')"
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wenzelm@54152
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by (metis (no_types) `c2 \<le> \<gamma>\<^sub>c c2'` join_ge2 le_post mono_gamma_o order_trans post_map_acom)
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wenzelm@54152
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ultimately show ?case using `S \<subseteq> \<gamma>\<^sub>o S'` by (simp add: If.IH subset_iff)
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next
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nipkow@47162
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case (While I b c1 P)
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then obtain c1' I' P' where
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"c' = {I'} WHILE b DO c1' {P'}"
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wenzelm@54152
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"I \<subseteq> \<gamma>\<^sub>o I'" "P \<subseteq> \<gamma>\<^sub>o P'" "c1 \<le> \<gamma>\<^sub>c c1'"
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by (fastforce simp: map_acom_While While_le)
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moreover have "S \<union> post c1 \<subseteq> \<gamma>\<^sub>o (S' \<squnion> post c1')"
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wenzelm@54152
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using `S \<subseteq> \<gamma>\<^sub>o S'` le_post[OF `c1 \<le> \<gamma>\<^sub>c c1'`, simplified]
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by (metis (no_types) join_ge1 join_ge2 le_sup_iff mono_gamma_o order_trans)
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ultimately show ?case by (simp add: While.IH subset_iff)
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qed
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lemma AI_sound: "AI c = Some c' \<Longrightarrow> CS c \<le> \<gamma>\<^sub>c c'"
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proof(simp add: CS_def AI_def)
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assume 1: "lpfp\<^sub>c (step' \<top>) c = Some c'"
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have 2: "step' \<top> c' \<sqsubseteq> c'" by(rule lpfpc_pfp[OF 1])
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wenzelm@54152
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have 3: "strip (\<gamma>\<^sub>c (step' \<top> c')) = c"
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nipkow@46494
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by(simp add: strip_lpfpc[OF _ 1])
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wenzelm@54152
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have "lfp (step UNIV) c \<le> \<gamma>\<^sub>c (step' \<top> c')"
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nipkow@46770
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proof(rule lfp_lowerbound[simplified,OF 3])
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wenzelm@54152
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show "step UNIV (\<gamma>\<^sub>c (step' \<top> c')) \<le> \<gamma>\<^sub>c (step' \<top> c')"
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nipkow@46939
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proof(rule step_preserves_le[OF _ _])
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wenzelm@54152
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show "UNIV \<subseteq> \<gamma>\<^sub>o \<top>" by simp
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wenzelm@54152
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show "\<gamma>\<^sub>c (step' \<top> c') \<le> \<gamma>\<^sub>c c'" by(rule mono_gamma_c[OF 2])
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qed
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qed
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wenzelm@54152
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from this 2 show "lfp (step UNIV) c \<le> \<gamma>\<^sub>c c'"
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by (blast intro: mono_gamma_c order_trans)
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qed
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end
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subsubsection "Monotonicity"
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locale Abs_Int_mono = Abs_Int +
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assumes mono_plus': "a1 \<sqsubseteq> b1 \<Longrightarrow> a2 \<sqsubseteq> b2 \<Longrightarrow> plus' a1 a2 \<sqsubseteq> plus' b1 b2"
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begin
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lemma mono_aval': "S \<sqsubseteq> S' \<Longrightarrow> aval' e S \<sqsubseteq> aval' e S'"
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by(induction e) (auto simp: le_st_def lookup_def mono_plus')
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lemma mono_update: "a \<sqsubseteq> a' \<Longrightarrow> S \<sqsubseteq> S' \<Longrightarrow> update S x a \<sqsubseteq> update S' x a'"
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by(auto simp add: le_st_def lookup_def update_def)
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lemma mono_step': "S \<sqsubseteq> S' \<Longrightarrow> c \<sqsubseteq> c' \<Longrightarrow> step' S c \<sqsubseteq> step' S' c'"
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nipkow@47024
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apply(induction c c' arbitrary: S S' rule: le_acom.induct)
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nipkow@47024
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apply (auto simp: Let_def mono_update mono_aval' mono_post le_join_disj
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split: option.split)
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done
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end
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subsubsection "Ascending Chain Condition"
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abbreviation "strict r == r \<inter> -(r^-1)"
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abbreviation "acc r == wf((strict r)^-1)"
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lemma strict_inv_image: "strict(inv_image r f) = inv_image (strict r) f"
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by(auto simp: inv_image_def)
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lemma acc_inv_image:
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"acc r \<Longrightarrow> acc (inv_image r f)"
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by (metis converse_inv_image strict_inv_image wf_inv_image)
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text{* ACC for option type: *}
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lemma acc_option: assumes "acc {(x,y::'a::preord). x \<sqsubseteq> y}"
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shows "acc {(x,y::'a::preord option). x \<sqsubseteq> y}"
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proof(auto simp: wf_eq_minimal)
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fix xo :: "'a option" and Qo assume "xo : Qo"
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let ?Q = "{x. Some x \<in> Qo}"
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show "\<exists>yo\<in>Qo. \<forall>zo. yo \<sqsubseteq> zo \<and> ~ zo \<sqsubseteq> yo \<longrightarrow> zo \<notin> Qo" (is "\<exists>zo\<in>Qo. ?P zo")
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proof cases
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assume "?Q = {}"
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hence "?P None" by auto
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moreover have "None \<in> Qo" using `?Q = {}` `xo : Qo`
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by auto (metis not_Some_eq)
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ultimately show ?thesis by blast
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next
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assume "?Q \<noteq> {}"
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with assms show ?thesis
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apply(auto simp: wf_eq_minimal)
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apply(erule_tac x="?Q" in allE)
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apply auto
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apply(rule_tac x = "Some z" in bexI)
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by auto
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qed
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qed
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text{* ACC for abstract states, via measure functions. *}
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(*FIXME mv*)
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lemma setsum_strict_mono1:
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fixes f :: "'a \<Rightarrow> 'b::{comm_monoid_add, ordered_cancel_ab_semigroup_add}"
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assumes "finite A" and "ALL x:A. f x \<le> g x" and "EX a:A. f a < g a"
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shows "setsum f A < setsum g A"
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proof-
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from assms(3) obtain a where a: "a:A" "f a < g a" by blast
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have "setsum f A = setsum f ((A-{a}) \<union> {a})"
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by(simp add:insert_absorb[OF `a:A`])
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also have "\<dots> = setsum f (A-{a}) + setsum f {a}"
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using `finite A` by(subst setsum_Un_disjoint) auto
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also have "setsum f (A-{a}) \<le> setsum g (A-{a})"
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by(rule setsum_mono)(simp add: assms(2))
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nipkow@47029
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also have "setsum f {a} < setsum g {a}" using a by simp
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nipkow@47029
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also have "setsum g (A - {a}) + setsum g {a} = setsum g((A-{a}) \<union> {a})"
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nipkow@47029
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using `finite A` by(subst setsum_Un_disjoint[symmetric]) auto
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nipkow@47029
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also have "\<dots> = setsum g A" by(simp add:insert_absorb[OF `a:A`])
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nipkow@47029
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finally show ?thesis by (metis add_right_mono add_strict_left_mono)
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qed
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nipkow@47029
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nipkow@47029
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lemma measure_st: assumes "(strict{(x,y::'a::SL_top). x \<sqsubseteq> y})^-1 <= measure m"
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nipkow@47183
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and "\<forall>x y::'a::SL_top. x \<sqsubseteq> y \<and> y \<sqsubseteq> x \<longrightarrow> m x = m y"
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nipkow@47183
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shows "(strict{(S,S'::'a::SL_top st). S \<sqsubseteq> S'})^-1 \<subseteq>
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nipkow@47029
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measure(%fd. \<Sum>x| x\<in>set(dom fd) \<and> ~ \<top> \<sqsubseteq> fun fd x. m(fun fd x)+1)"
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proof-
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{ fix S S' :: "'a st" assume "S \<sqsubseteq> S'" "~ S' \<sqsubseteq> S"
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nipkow@47029
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let ?X = "set(dom S)" let ?Y = "set(dom S')"
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nipkow@47029
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let ?f = "fun S" let ?g = "fun S'"
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let ?X' = "{x:?X. ~ \<top> \<sqsubseteq> ?f x}" let ?Y' = "{y:?Y. ~ \<top> \<sqsubseteq> ?g y}"
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nipkow@47029
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from `S \<sqsubseteq> S'` have "ALL y:?Y'\<inter>?X. ?f y \<sqsubseteq> ?g y"
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nipkow@47029
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by(auto simp: le_st_def lookup_def)
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nipkow@47029
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hence 1: "ALL y:?Y'\<inter>?X. m(?g y)+1 \<le> m(?f y)+1"
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nipkow@47029
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using assms(1,2) by(fastforce)
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nipkow@47029
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from `~ S' \<sqsubseteq> S` obtain u where u: "u : ?X" "~ lookup S' u \<sqsubseteq> ?f u"
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nipkow@47029
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by(auto simp: le_st_def)
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nipkow@47029
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hence "u : ?X'" by simp (metis preord_class.le_trans top)
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nipkow@47029
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have "?Y'-?X = {}" using `S \<sqsubseteq> S'` by(fastforce simp: le_st_def lookup_def)
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nipkow@47029
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have "?Y'\<inter>?X <= ?X'" apply auto
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nipkow@47029
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apply (metis `S \<sqsubseteq> S'` le_st_def lookup_def preord_class.le_trans)
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nipkow@47029
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done
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nipkow@47029
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have "(\<Sum>y\<in>?Y'. m(?g y)+1) = (\<Sum>y\<in>(?Y'-?X) \<union> (?Y'\<inter>?X). m(?g y)+1)"
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nipkow@47029
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by (metis Un_Diff_Int)
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nipkow@47029
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also have "\<dots> = (\<Sum>y\<in>?Y'\<inter>?X. m(?g y)+1)"
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nipkow@47029
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using `?Y'-?X = {}` by (metis Un_empty_left)
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nipkow@47029
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also have "\<dots> < (\<Sum>x\<in>?X'. m(?f x)+1)"
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nipkow@47029
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proof cases
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nipkow@47029
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assume "u \<in> ?Y'"
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nipkow@47029
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hence "m(?g u) < m(?f u)" using assms(1) `S \<sqsubseteq> S'` u
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nipkow@47029
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by (fastforce simp: le_st_def lookup_def)
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nipkow@47029
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have "(\<Sum>y\<in>?Y'\<inter>?X. m(?g y)+1) < (\<Sum>y\<in>?Y'\<inter>?X. m(?f y)+1)"
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nipkow@47029
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using `u:?X` `u:?Y'` `m(?g u) < m(?f u)`
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nipkow@47029
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by(fastforce intro!: setsum_strict_mono1[OF _ 1])
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nipkow@47029
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also have "\<dots> \<le> (\<Sum>y\<in>?X'. m(?f y)+1)"
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nipkow@47029
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by(simp add: setsum_mono3[OF _ `?Y'\<inter>?X <= ?X'`])
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nipkow@47029
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finally show ?thesis .
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nipkow@47029
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next
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nipkow@47029
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assume "u \<notin> ?Y'"
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nipkow@47029
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with `?Y'\<inter>?X <= ?X'` have "?Y'\<inter>?X - {u} <= ?X' - {u}" by blast
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nipkow@47029
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have "(\<Sum>y\<in>?Y'\<inter>?X. m(?g y)+1) = (\<Sum>y\<in>?Y'\<inter>?X - {u}. m(?g y)+1)"
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nipkow@47029
|
234 |
proof-
|
nipkow@47029
|
235 |
have "?Y'\<inter>?X = ?Y'\<inter>?X - {u}" using `u \<notin> ?Y'` by auto
|
nipkow@47029
|
236 |
thus ?thesis by metis
|
nipkow@47029
|
237 |
qed
|
nipkow@47029
|
238 |
also have "\<dots> < (\<Sum>y\<in>?Y'\<inter>?X-{u}. m(?g y)+1) + (\<Sum>y\<in>{u}. m(?f y)+1)" by simp
|
nipkow@47029
|
239 |
also have "(\<Sum>y\<in>?Y'\<inter>?X-{u}. m(?g y)+1) \<le> (\<Sum>y\<in>?Y'\<inter>?X-{u}. m(?f y)+1)"
|
nipkow@47029
|
240 |
using 1 by(blast intro: setsum_mono)
|
nipkow@47029
|
241 |
also have "\<dots> \<le> (\<Sum>y\<in>?X'-{u}. m(?f y)+1)"
|
nipkow@47029
|
242 |
by(simp add: setsum_mono3[OF _ `?Y'\<inter>?X-{u} <= ?X'-{u}`])
|
nipkow@47029
|
243 |
also have "\<dots> + (\<Sum>y\<in>{u}. m(?f y)+1)= (\<Sum>y\<in>(?X'-{u}) \<union> {u}. m(?f y)+1)"
|
nipkow@47029
|
244 |
using `u:?X'` by(subst setsum_Un_disjoint[symmetric]) auto
|
nipkow@47029
|
245 |
also have "\<dots> = (\<Sum>x\<in>?X'. m(?f x)+1)"
|
nipkow@47029
|
246 |
using `u : ?X'` by(simp add:insert_absorb)
|
nipkow@47029
|
247 |
finally show ?thesis by (blast intro: add_right_mono)
|
nipkow@47029
|
248 |
qed
|
nipkow@47029
|
249 |
finally have "(\<Sum>y\<in>?Y'. m(?g y)+1) < (\<Sum>x\<in>?X'. m(?f x)+1)" .
|
nipkow@47029
|
250 |
} thus ?thesis by(auto simp add: measure_def inv_image_def)
|
nipkow@47029
|
251 |
qed
|
nipkow@47029
|
252 |
|
nipkow@47029
|
253 |
text{* ACC for acom. First the ordering on acom is related to an ordering on
|
nipkow@47029
|
254 |
lists of annotations. *}
|
nipkow@47029
|
255 |
|
nipkow@47029
|
256 |
(* FIXME mv and add [simp] *)
|
nipkow@47029
|
257 |
lemma listrel_Cons_iff:
|
nipkow@47029
|
258 |
"(x#xs, y#ys) : listrel r \<longleftrightarrow> (x,y) \<in> r \<and> (xs,ys) \<in> listrel r"
|
nipkow@47029
|
259 |
by (blast intro:listrel.Cons)
|
nipkow@47029
|
260 |
|
nipkow@47029
|
261 |
lemma listrel_app: "(xs1,ys1) : listrel r \<Longrightarrow> (xs2,ys2) : listrel r
|
nipkow@47029
|
262 |
\<Longrightarrow> (xs1@xs2, ys1@ys2) : listrel r"
|
nipkow@47029
|
263 |
by(auto simp add: listrel_iff_zip)
|
nipkow@47029
|
264 |
|
nipkow@47029
|
265 |
lemma listrel_app_same_size: "size xs1 = size ys1 \<Longrightarrow> size xs2 = size ys2 \<Longrightarrow>
|
nipkow@47029
|
266 |
(xs1@xs2, ys1@ys2) : listrel r \<longleftrightarrow>
|
nipkow@47029
|
267 |
(xs1,ys1) : listrel r \<and> (xs2,ys2) : listrel r"
|
nipkow@47029
|
268 |
by(auto simp add: listrel_iff_zip)
|
nipkow@47029
|
269 |
|
nipkow@47029
|
270 |
lemma listrel_converse: "listrel(r^-1) = (listrel r)^-1"
|
nipkow@47029
|
271 |
proof-
|
nipkow@47029
|
272 |
{ fix xs ys
|
nipkow@47029
|
273 |
have "(xs,ys) : listrel(r^-1) \<longleftrightarrow> (ys,xs) : listrel r"
|
nipkow@47029
|
274 |
apply(induct xs arbitrary: ys)
|
nipkow@47029
|
275 |
apply (fastforce simp: listrel.Nil)
|
nipkow@47029
|
276 |
apply (fastforce simp: listrel_Cons_iff)
|
nipkow@47029
|
277 |
done
|
nipkow@47029
|
278 |
} thus ?thesis by auto
|
nipkow@47029
|
279 |
qed
|
nipkow@47029
|
280 |
|
nipkow@47029
|
281 |
(* It would be nice to get rid of refl & trans and build them into the proof *)
|
nipkow@47029
|
282 |
lemma acc_listrel: fixes r :: "('a*'a)set" assumes "refl r" and "trans r"
|
nipkow@47029
|
283 |
and "acc r" shows "acc (listrel r - {([],[])})"
|
nipkow@47029
|
284 |
proof-
|
nipkow@47029
|
285 |
have refl: "!!x. (x,x) : r" using `refl r` unfolding refl_on_def by blast
|
nipkow@47029
|
286 |
have trans: "!!x y z. (x,y) : r \<Longrightarrow> (y,z) : r \<Longrightarrow> (x,z) : r"
|
nipkow@47029
|
287 |
using `trans r` unfolding trans_def by blast
|
nipkow@47029
|
288 |
from assms(3) obtain mx :: "'a set \<Rightarrow> 'a" where
|
nipkow@47029
|
289 |
mx: "!!S x. x:S \<Longrightarrow> mx S : S \<and> (\<forall>y. (mx S,y) : strict r \<longrightarrow> y \<notin> S)"
|
nipkow@47029
|
290 |
by(simp add: wf_eq_minimal) metis
|
nipkow@47029
|
291 |
let ?R = "listrel r - {([], [])}"
|
nipkow@47029
|
292 |
{ fix Q and xs :: "'a list"
|
nipkow@47029
|
293 |
have "xs \<in> Q \<Longrightarrow> \<exists>ys. ys\<in>Q \<and> (\<forall>zs. (ys, zs) \<in> strict ?R \<longrightarrow> zs \<notin> Q)"
|
nipkow@47029
|
294 |
(is "_ \<Longrightarrow> \<exists>ys. ?P Q ys")
|
nipkow@47029
|
295 |
proof(induction xs arbitrary: Q rule: length_induct)
|
nipkow@47029
|
296 |
case (1 xs)
|
nipkow@47029
|
297 |
{ have "!!ys Q. size ys < size xs \<Longrightarrow> ys : Q \<Longrightarrow> EX ms. ?P Q ms"
|
nipkow@47029
|
298 |
using "1.IH" by blast
|
nipkow@47029
|
299 |
} note IH = this
|
nipkow@47029
|
300 |
show ?case
|
nipkow@47029
|
301 |
proof(cases xs)
|
nipkow@47029
|
302 |
case Nil with `xs : Q` have "?P Q []" by auto
|
nipkow@47029
|
303 |
thus ?thesis by blast
|
nipkow@47029
|
304 |
next
|
nipkow@47029
|
305 |
case (Cons x ys)
|
nipkow@47029
|
306 |
let ?Q1 = "{a. \<exists>bs. size bs = size ys \<and> a#bs : Q}"
|
nipkow@47029
|
307 |
have "x : ?Q1" using `xs : Q` Cons by auto
|
nipkow@47029
|
308 |
from mx[OF this] obtain m1 where
|
nipkow@47029
|
309 |
1: "m1 \<in> ?Q1 \<and> (\<forall>y. (m1,y) \<in> strict r \<longrightarrow> y \<notin> ?Q1)" by blast
|
nipkow@47029
|
310 |
then obtain ms1 where "size ms1 = size ys" "m1#ms1 : Q" by blast+
|
nipkow@47029
|
311 |
hence "size ms1 < size xs" using Cons by auto
|
nipkow@47029
|
312 |
let ?Q2 = "{bs. \<exists>m1'. (m1',m1):r \<and> (m1,m1'):r \<and> m1'#bs : Q \<and> size bs = size ms1}"
|
nipkow@47029
|
313 |
have "ms1 : ?Q2" using `m1#ms1 : Q` by(blast intro: refl)
|
nipkow@47029
|
314 |
from IH[OF `size ms1 < size xs` this]
|
nipkow@47029
|
315 |
obtain ms where 2: "?P ?Q2 ms" by auto
|
nipkow@47029
|
316 |
then obtain m1' where m1': "(m1',m1) : r \<and> (m1,m1') : r \<and> m1'#ms : Q"
|
nipkow@47029
|
317 |
by blast
|
nipkow@47029
|
318 |
hence "\<forall>ab. (m1'#ms,ab) : strict ?R \<longrightarrow> ab \<notin> Q" using 1 2
|
nipkow@47029
|
319 |
apply (auto simp: listrel_Cons_iff)
|
nipkow@47029
|
320 |
apply (metis `length ms1 = length ys` listrel_eq_len trans)
|
nipkow@47029
|
321 |
by (metis `length ms1 = length ys` listrel_eq_len trans)
|
nipkow@47029
|
322 |
with m1' show ?thesis by blast
|
nipkow@47029
|
323 |
qed
|
nipkow@47029
|
324 |
qed
|
nipkow@47029
|
325 |
}
|
nipkow@47029
|
326 |
thus ?thesis unfolding wf_eq_minimal by (metis converse_iff)
|
nipkow@47029
|
327 |
qed
|
nipkow@47029
|
328 |
|
nipkow@47029
|
329 |
|
nipkow@47029
|
330 |
lemma le_iff_le_annos: "c1 \<sqsubseteq> c2 \<longleftrightarrow>
|
nipkow@47029
|
331 |
(annos c1, annos c2) : listrel{(x,y). x \<sqsubseteq> y} \<and> strip c1 = strip c2"
|
nipkow@47029
|
332 |
apply(induct c1 c2 rule: le_acom.induct)
|
nipkow@47117
|
333 |
apply (auto simp: listrel.Nil listrel_Cons_iff listrel_app size_annos_same2)
|
nipkow@47029
|
334 |
apply (metis listrel_app_same_size size_annos_same)+
|
nipkow@47029
|
335 |
done
|
nipkow@47029
|
336 |
|
nipkow@47029
|
337 |
lemma le_acom_subset_same_annos:
|
nipkow@47029
|
338 |
"(strict{(c,c'::'a::preord acom). c \<sqsubseteq> c'})^-1 \<subseteq>
|
nipkow@47029
|
339 |
(strict(inv_image (listrel{(a,a'::'a). a \<sqsubseteq> a'} - {([],[])}) annos))^-1"
|
nipkow@47029
|
340 |
by(auto simp: le_iff_le_annos)
|
nipkow@47029
|
341 |
|
nipkow@47029
|
342 |
lemma acc_acom: "acc {(a,a'::'a::preord). a \<sqsubseteq> a'} \<Longrightarrow>
|
nipkow@47029
|
343 |
acc {(c,c'::'a acom). c \<sqsubseteq> c'}"
|
nipkow@47029
|
344 |
apply(rule wf_subset[OF _ le_acom_subset_same_annos])
|
nipkow@47029
|
345 |
apply(rule acc_inv_image[OF acc_listrel])
|
nipkow@47029
|
346 |
apply(auto simp: refl_on_def trans_def intro: le_trans)
|
nipkow@47029
|
347 |
done
|
nipkow@47029
|
348 |
|
nipkow@47029
|
349 |
text{* Termination of the fixed-point finders, assuming monotone functions: *}
|
nipkow@47029
|
350 |
|
nipkow@47029
|
351 |
lemma pfp_termination:
|
nipkow@47029
|
352 |
fixes x0 :: "'a::preord"
|
nipkow@47029
|
353 |
assumes mono: "\<And>x y. x \<sqsubseteq> y \<Longrightarrow> f x \<sqsubseteq> f y" and "acc {(x::'a,y). x \<sqsubseteq> y}"
|
nipkow@47029
|
354 |
and "x0 \<sqsubseteq> f x0" shows "EX x. pfp f x0 = Some x"
|
nipkow@47029
|
355 |
proof(simp add: pfp_def, rule wf_while_option_Some[where P = "%x. x \<sqsubseteq> f x"])
|
nipkow@47029
|
356 |
show "wf {(x, s). (s \<sqsubseteq> f s \<and> \<not> f s \<sqsubseteq> s) \<and> x = f s}"
|
nipkow@47029
|
357 |
by(rule wf_subset[OF assms(2)]) auto
|
nipkow@47029
|
358 |
next
|
nipkow@47029
|
359 |
show "x0 \<sqsubseteq> f x0" by(rule assms)
|
nipkow@47029
|
360 |
next
|
nipkow@47029
|
361 |
fix x assume "x \<sqsubseteq> f x" thus "f x \<sqsubseteq> f(f x)" by(rule mono)
|
nipkow@47029
|
362 |
qed
|
nipkow@47029
|
363 |
|
nipkow@47029
|
364 |
lemma lpfpc_termination:
|
nipkow@47029
|
365 |
fixes f :: "(('a::SL_top)option acom \<Rightarrow> 'a option acom)"
|
nipkow@47029
|
366 |
assumes "acc {(x::'a,y). x \<sqsubseteq> y}" and "\<And>x y. x \<sqsubseteq> y \<Longrightarrow> f x \<sqsubseteq> f y"
|
nipkow@47029
|
367 |
and "\<And>c. strip(f c) = strip c"
|
wenzelm@54152
|
368 |
shows "\<exists>c'. lpfp\<^sub>c f c = Some c'"
|
wenzelm@54152
|
369 |
unfolding lpfp\<^sub>c_def
|
nipkow@47029
|
370 |
apply(rule pfp_termination)
|
nipkow@47029
|
371 |
apply(erule assms(2))
|
nipkow@47029
|
372 |
apply(rule acc_acom[OF acc_option[OF assms(1)]])
|
nipkow@47029
|
373 |
apply(simp add: bot_acom assms(3))
|
nipkow@47029
|
374 |
done
|
nipkow@47029
|
375 |
|
nipkow@47162
|
376 |
context Abs_Int_mono
|
nipkow@47162
|
377 |
begin
|
nipkow@47162
|
378 |
|
nipkow@47162
|
379 |
lemma AI_Some_measure:
|
nipkow@47162
|
380 |
assumes "(strict{(x,y::'a). x \<sqsubseteq> y})^-1 <= measure m"
|
nipkow@47162
|
381 |
and "\<forall>x y::'a. x \<sqsubseteq> y \<and> y \<sqsubseteq> x \<longrightarrow> m x = m y"
|
nipkow@47162
|
382 |
shows "\<exists>c'. AI c = Some c'"
|
nipkow@47162
|
383 |
unfolding AI_def
|
nipkow@47162
|
384 |
apply(rule lpfpc_termination)
|
nipkow@47162
|
385 |
apply(rule wf_subset[OF wf_measure measure_st[OF assms]])
|
nipkow@47162
|
386 |
apply(erule mono_step'[OF le_refl])
|
nipkow@47162
|
387 |
apply(rule strip_step')
|
nipkow@47162
|
388 |
done
|
nipkow@47029
|
389 |
|
nipkow@45998
|
390 |
end
|
nipkow@47162
|
391 |
|
nipkow@47162
|
392 |
end
|