src/HOL/Complete_Partial_Order.thy
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(* Title:    HOL/Complete_Partial_Order.thy
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   Author:   Brian Huffman, Portland State University
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   Author:   Alexander Krauss, TU Muenchen
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*)
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section {* Chain-complete partial orders and their fixpoints *}
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theory Complete_Partial_Order
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imports Product_Type
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begin
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subsection {* Monotone functions *}
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text {* Dictionary-passing version of @{const Orderings.mono}. *}
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definition monotone :: "('a \<Rightarrow> 'a \<Rightarrow> bool) \<Rightarrow> ('b \<Rightarrow> 'b \<Rightarrow> bool) \<Rightarrow> ('a \<Rightarrow> 'b) \<Rightarrow> bool"
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where "monotone orda ordb f \<longleftrightarrow> (\<forall>x y. orda x y \<longrightarrow> ordb (f x) (f y))"
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lemma monotoneI[intro?]: "(\<And>x y. orda x y \<Longrightarrow> ordb (f x) (f y))
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 \<Longrightarrow> monotone orda ordb f"
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unfolding monotone_def by iprover
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lemma monotoneD[dest?]: "monotone orda ordb f \<Longrightarrow> orda x y \<Longrightarrow> ordb (f x) (f y)"
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unfolding monotone_def by iprover
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subsection {* Chains *}
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text {* A chain is a totally-ordered set. Chains are parameterized over
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  the order for maximal flexibility, since type classes are not enough.
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*}
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definition
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  chain :: "('a \<Rightarrow> 'a \<Rightarrow> bool) \<Rightarrow> 'a set \<Rightarrow> bool"
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where
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  "chain ord S \<longleftrightarrow> (\<forall>x\<in>S. \<forall>y\<in>S. ord x y \<or> ord y x)"
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lemma chainI:
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  assumes "\<And>x y. x \<in> S \<Longrightarrow> y \<in> S \<Longrightarrow> ord x y \<or> ord y x"
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  shows "chain ord S"
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using assms unfolding chain_def by fast
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lemma chainD:
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  assumes "chain ord S" and "x \<in> S" and "y \<in> S"
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  shows "ord x y \<or> ord y x"
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using assms unfolding chain_def by fast
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lemma chainE:
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  assumes "chain ord S" and "x \<in> S" and "y \<in> S"
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  obtains "ord x y" | "ord y x"
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using assms unfolding chain_def by fast
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lemma chain_empty: "chain ord {}"
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by(simp add: chain_def)
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lemma chain_equality: "chain op = A \<longleftrightarrow> (\<forall>x\<in>A. \<forall>y\<in>A. x = y)"
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by(auto simp add: chain_def)
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lemma chain_subset:
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  "\<lbrakk> chain ord A; B \<subseteq> A \<rbrakk>
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  \<Longrightarrow> chain ord B"
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by(rule chainI)(blast dest: chainD)
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lemma chain_imageI: 
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  assumes chain: "chain le_a Y"
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  and mono: "\<And>x y. \<lbrakk> x \<in> Y; y \<in> Y; le_a x y \<rbrakk> \<Longrightarrow> le_b (f x) (f y)"
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  shows "chain le_b (f ` Y)"
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by(blast intro: chainI dest: chainD[OF chain] mono)
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subsection {* Chain-complete partial orders *}
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text {*
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  A ccpo has a least upper bound for any chain.  In particular, the
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  empty set is a chain, so every ccpo must have a bottom element.
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*}
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class ccpo = order + Sup +
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  assumes ccpo_Sup_upper: "\<lbrakk>chain (op \<le>) A; x \<in> A\<rbrakk> \<Longrightarrow> x \<le> Sup A"
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  assumes ccpo_Sup_least: "\<lbrakk>chain (op \<le>) A; \<And>x. x \<in> A \<Longrightarrow> x \<le> z\<rbrakk> \<Longrightarrow> Sup A \<le> z"
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begin
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lemma chain_singleton: "Complete_Partial_Order.chain op \<le> {x}"
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by(rule chainI) simp
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lemma ccpo_Sup_singleton [simp]: "\<Squnion>{x} = x"
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by(rule antisym)(auto intro: ccpo_Sup_least ccpo_Sup_upper simp add: chain_singleton)
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subsection {* Transfinite iteration of a function *}
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inductive_set iterates :: "('a \<Rightarrow> 'a) \<Rightarrow> 'a set"
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for f :: "'a \<Rightarrow> 'a"
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where
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  step: "x \<in> iterates f \<Longrightarrow> f x \<in> iterates f"
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| Sup: "chain (op \<le>) M \<Longrightarrow> \<forall>x\<in>M. x \<in> iterates f \<Longrightarrow> Sup M \<in> iterates f"
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lemma iterates_le_f:
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  "x \<in> iterates f \<Longrightarrow> monotone (op \<le>) (op \<le>) f \<Longrightarrow> x \<le> f x"
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by (induct x rule: iterates.induct)
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  (force dest: monotoneD intro!: ccpo_Sup_upper ccpo_Sup_least)+
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lemma chain_iterates:
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  assumes f: "monotone (op \<le>) (op \<le>) f"
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  shows "chain (op \<le>) (iterates f)" (is "chain _ ?C")
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proof (rule chainI)
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  fix x y assume "x \<in> ?C" "y \<in> ?C"
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  then show "x \<le> y \<or> y \<le> x"
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  proof (induct x arbitrary: y rule: iterates.induct)
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    fix x y assume y: "y \<in> ?C"
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    and IH: "\<And>z. z \<in> ?C \<Longrightarrow> x \<le> z \<or> z \<le> x"
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    from y show "f x \<le> y \<or> y \<le> f x"
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    proof (induct y rule: iterates.induct)
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      case (step y) with IH f show ?case by (auto dest: monotoneD)
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    next
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      case (Sup M)
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      then have chM: "chain (op \<le>) M"
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        and IH': "\<And>z. z \<in> M \<Longrightarrow> f x \<le> z \<or> z \<le> f x" by auto
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      show "f x \<le> Sup M \<or> Sup M \<le> f x"
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      proof (cases "\<exists>z\<in>M. f x \<le> z")
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        case True then have "f x \<le> Sup M"
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          apply rule
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          apply (erule order_trans)
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          by (rule ccpo_Sup_upper[OF chM])
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        thus ?thesis ..
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      next
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        case False with IH'
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        show ?thesis by (auto intro: ccpo_Sup_least[OF chM])
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      qed
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    qed
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  next
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    case (Sup M y)
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    show ?case
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    proof (cases "\<exists>x\<in>M. y \<le> x")
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      case True then have "y \<le> Sup M"
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        apply rule
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        apply (erule order_trans)
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1e3ff542e83e remove constant 'ccpo.lub', re-use constant 'Sup' instead
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   136
        by (rule ccpo_Sup_upper[OF Sup(1)])
40106
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
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diff changeset
   137
      thus ?thesis ..
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
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diff changeset
   138
    next
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1e3ff542e83e remove constant 'ccpo.lub', re-use constant 'Sup' instead
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diff changeset
   139
      case False with Sup
1e3ff542e83e remove constant 'ccpo.lub', re-use constant 'Sup' instead
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   140
      show ?thesis by (auto intro: ccpo_Sup_least)
40106
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
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diff changeset
   141
    qed
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
parents:
diff changeset
   142
  qed
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
parents:
diff changeset
   143
qed
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
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diff changeset
   144
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   145
lemma bot_in_iterates: "Sup {} \<in> iterates f"
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   146
by(auto intro: iterates.Sup simp add: chain_empty)
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   147
40106
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
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   148
subsection {* Fixpoint combinator *}
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
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   149
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
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   150
definition
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
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   151
  fixp :: "('a \<Rightarrow> 'a) \<Rightarrow> 'a"
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
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   152
where
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1e3ff542e83e remove constant 'ccpo.lub', re-use constant 'Sup' instead
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   153
  "fixp f = Sup (iterates f)"
40106
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
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diff changeset
   154
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
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diff changeset
   155
lemma iterates_fixp:
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
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   156
  assumes f: "monotone (op \<le>) (op \<le>) f" shows "fixp f \<in> iterates f"
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
parents:
diff changeset
   157
unfolding fixp_def
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1e3ff542e83e remove constant 'ccpo.lub', re-use constant 'Sup' instead
huffman
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diff changeset
   158
by (simp add: iterates.Sup chain_iterates f)
40106
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
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diff changeset
   159
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
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diff changeset
   160
lemma fixp_unfold:
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
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diff changeset
   161
  assumes f: "monotone (op \<le>) (op \<le>) f"
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
parents:
diff changeset
   162
  shows "fixp f = f (fixp f)"
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
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diff changeset
   163
proof (rule antisym)
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
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diff changeset
   164
  show "fixp f \<le> f (fixp f)"
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
parents:
diff changeset
   165
    by (intro iterates_le_f iterates_fixp f)
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1e3ff542e83e remove constant 'ccpo.lub', re-use constant 'Sup' instead
huffman
parents: 40252
diff changeset
   166
  have "f (fixp f) \<le> Sup (iterates f)"
1e3ff542e83e remove constant 'ccpo.lub', re-use constant 'Sup' instead
huffman
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diff changeset
   167
    by (intro ccpo_Sup_upper chain_iterates f iterates.step iterates_fixp)
40106
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
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diff changeset
   168
  thus "f (fixp f) \<le> fixp f"
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
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diff changeset
   169
    unfolding fixp_def .
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
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diff changeset
   170
qed
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
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diff changeset
   171
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
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   172
lemma fixp_lowerbound:
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
parents:
diff changeset
   173
  assumes f: "monotone (op \<le>) (op \<le>) f" and z: "f z \<le> z" shows "fixp f \<le> z"
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
parents:
diff changeset
   174
unfolding fixp_def
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1e3ff542e83e remove constant 'ccpo.lub', re-use constant 'Sup' instead
huffman
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diff changeset
   175
proof (rule ccpo_Sup_least[OF chain_iterates[OF f]])
40106
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
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diff changeset
   176
  fix x assume "x \<in> iterates f"
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
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diff changeset
   177
  thus "x \<le> z"
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
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diff changeset
   178
  proof (induct x rule: iterates.induct)
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
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diff changeset
   179
    fix x assume "x \<le> z" with f have "f x \<le> f z" by (rule monotoneD)
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
parents:
diff changeset
   180
    also note z finally show "f x \<le> z" .
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1e3ff542e83e remove constant 'ccpo.lub', re-use constant 'Sup' instead
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diff changeset
   181
  qed (auto intro: ccpo_Sup_least)
40106
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
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diff changeset
   182
qed
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
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diff changeset
   183
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   184
end
40106
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
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diff changeset
   185
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
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diff changeset
   186
subsection {* Fixpoint induction *}
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
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diff changeset
   187
53361
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   188
setup {* Sign.map_naming (Name_Space.mandatory_path "ccpo") *}
1cb7d3c0cf31 move admissible out of class ccpo to avoid unnecessary class predicate in foundational theorems
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diff changeset
   189
1cb7d3c0cf31 move admissible out of class ccpo to avoid unnecessary class predicate in foundational theorems
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diff changeset
   190
definition admissible :: "('a set \<Rightarrow> 'a) \<Rightarrow> ('a \<Rightarrow> 'a \<Rightarrow> bool) \<Rightarrow> ('a \<Rightarrow> bool) \<Rightarrow> bool"
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9061af4d5ebc restrict admissibility to non-empty chains to allow more syntax-directed proof rules
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diff changeset
   191
where "admissible lub ord P = (\<forall>A. chain ord A \<longrightarrow> (A \<noteq> {}) \<longrightarrow> (\<forall>x\<in>A. P x) \<longrightarrow> P (lub A))"
40106
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
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diff changeset
   192
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
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diff changeset
   193
lemma admissibleI:
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   194
  assumes "\<And>A. chain ord A \<Longrightarrow> A \<noteq> {} \<Longrightarrow> \<forall>x\<in>A. P x \<Longrightarrow> P (lub A)"
53361
1cb7d3c0cf31 move admissible out of class ccpo to avoid unnecessary class predicate in foundational theorems
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diff changeset
   195
  shows "ccpo.admissible lub ord P"
1cb7d3c0cf31 move admissible out of class ccpo to avoid unnecessary class predicate in foundational theorems
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diff changeset
   196
using assms unfolding ccpo.admissible_def by fast
40106
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
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diff changeset
   197
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
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diff changeset
   198
lemma admissibleD:
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1cb7d3c0cf31 move admissible out of class ccpo to avoid unnecessary class predicate in foundational theorems
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   199
  assumes "ccpo.admissible lub ord P"
1cb7d3c0cf31 move admissible out of class ccpo to avoid unnecessary class predicate in foundational theorems
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diff changeset
   200
  assumes "chain ord A"
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9061af4d5ebc restrict admissibility to non-empty chains to allow more syntax-directed proof rules
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diff changeset
   201
  assumes "A \<noteq> {}"
40106
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
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diff changeset
   202
  assumes "\<And>x. x \<in> A \<Longrightarrow> P x"
53361
1cb7d3c0cf31 move admissible out of class ccpo to avoid unnecessary class predicate in foundational theorems
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diff changeset
   203
  shows "P (lub A)"
1cb7d3c0cf31 move admissible out of class ccpo to avoid unnecessary class predicate in foundational theorems
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diff changeset
   204
using assms by (auto simp: ccpo.admissible_def)
40106
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
parents:
diff changeset
   205
53361
1cb7d3c0cf31 move admissible out of class ccpo to avoid unnecessary class predicate in foundational theorems
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diff changeset
   206
setup {* Sign.map_naming Name_Space.parent_path *}
1cb7d3c0cf31 move admissible out of class ccpo to avoid unnecessary class predicate in foundational theorems
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diff changeset
   207
1cb7d3c0cf31 move admissible out of class ccpo to avoid unnecessary class predicate in foundational theorems
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diff changeset
   208
lemma (in ccpo) fixp_induct:
1cb7d3c0cf31 move admissible out of class ccpo to avoid unnecessary class predicate in foundational theorems
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diff changeset
   209
  assumes adm: "ccpo.admissible Sup (op \<le>) P"
40106
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
parents:
diff changeset
   210
  assumes mono: "monotone (op \<le>) (op \<le>) f"
54630
9061af4d5ebc restrict admissibility to non-empty chains to allow more syntax-directed proof rules
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diff changeset
   211
  assumes bot: "P (Sup {})"
40106
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
parents:
diff changeset
   212
  assumes step: "\<And>x. P x \<Longrightarrow> P (f x)"
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
parents:
diff changeset
   213
  shows "P (fixp f)"
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
parents:
diff changeset
   214
unfolding fixp_def using adm chain_iterates[OF mono]
53361
1cb7d3c0cf31 move admissible out of class ccpo to avoid unnecessary class predicate in foundational theorems
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diff changeset
   215
proof (rule ccpo.admissibleD)
54630
9061af4d5ebc restrict admissibility to non-empty chains to allow more syntax-directed proof rules
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diff changeset
   216
  show "iterates f \<noteq> {}" using bot_in_iterates by auto
40106
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
parents:
diff changeset
   217
  fix x assume "x \<in> iterates f"
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
parents:
diff changeset
   218
  thus "P x"
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
parents:
diff changeset
   219
    by (induct rule: iterates.induct)
54630
9061af4d5ebc restrict admissibility to non-empty chains to allow more syntax-directed proof rules
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parents: 53361
diff changeset
   220
      (case_tac "M = {}", auto intro: step bot ccpo.admissibleD adm)
40106
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
parents:
diff changeset
   221
qed
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
parents:
diff changeset
   222
53361
1cb7d3c0cf31 move admissible out of class ccpo to avoid unnecessary class predicate in foundational theorems
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diff changeset
   223
lemma admissible_True: "ccpo.admissible lub ord (\<lambda>x. True)"
1cb7d3c0cf31 move admissible out of class ccpo to avoid unnecessary class predicate in foundational theorems
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parents: 46041
diff changeset
   224
unfolding ccpo.admissible_def by simp
40106
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
parents:
diff changeset
   225
54630
9061af4d5ebc restrict admissibility to non-empty chains to allow more syntax-directed proof rules
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diff changeset
   226
(*lemma admissible_False: "\<not> ccpo.admissible lub ord (\<lambda>x. False)"
53361
1cb7d3c0cf31 move admissible out of class ccpo to avoid unnecessary class predicate in foundational theorems
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diff changeset
   227
unfolding ccpo.admissible_def chain_def by simp
54630
9061af4d5ebc restrict admissibility to non-empty chains to allow more syntax-directed proof rules
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diff changeset
   228
*)
9061af4d5ebc restrict admissibility to non-empty chains to allow more syntax-directed proof rules
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diff changeset
   229
lemma admissible_const: "ccpo.admissible lub ord (\<lambda>x. t)"
9061af4d5ebc restrict admissibility to non-empty chains to allow more syntax-directed proof rules
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diff changeset
   230
by(auto intro: ccpo.admissibleI)
40106
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
parents:
diff changeset
   231
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
parents:
diff changeset
   232
lemma admissible_conj:
53361
1cb7d3c0cf31 move admissible out of class ccpo to avoid unnecessary class predicate in foundational theorems
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diff changeset
   233
  assumes "ccpo.admissible lub ord (\<lambda>x. P x)"
1cb7d3c0cf31 move admissible out of class ccpo to avoid unnecessary class predicate in foundational theorems
Andreas Lochbihler
parents: 46041
diff changeset
   234
  assumes "ccpo.admissible lub ord (\<lambda>x. Q x)"
1cb7d3c0cf31 move admissible out of class ccpo to avoid unnecessary class predicate in foundational theorems
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parents: 46041
diff changeset
   235
  shows "ccpo.admissible lub ord (\<lambda>x. P x \<and> Q x)"
1cb7d3c0cf31 move admissible out of class ccpo to avoid unnecessary class predicate in foundational theorems
Andreas Lochbihler
parents: 46041
diff changeset
   236
using assms unfolding ccpo.admissible_def by simp
40106
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
parents:
diff changeset
   237
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
parents:
diff changeset
   238
lemma admissible_all:
53361
1cb7d3c0cf31 move admissible out of class ccpo to avoid unnecessary class predicate in foundational theorems
Andreas Lochbihler
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diff changeset
   239
  assumes "\<And>y. ccpo.admissible lub ord (\<lambda>x. P x y)"
1cb7d3c0cf31 move admissible out of class ccpo to avoid unnecessary class predicate in foundational theorems
Andreas Lochbihler
parents: 46041
diff changeset
   240
  shows "ccpo.admissible lub ord (\<lambda>x. \<forall>y. P x y)"
1cb7d3c0cf31 move admissible out of class ccpo to avoid unnecessary class predicate in foundational theorems
Andreas Lochbihler
parents: 46041
diff changeset
   241
using assms unfolding ccpo.admissible_def by fast
40106
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
parents:
diff changeset
   242
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
parents:
diff changeset
   243
lemma admissible_ball:
53361
1cb7d3c0cf31 move admissible out of class ccpo to avoid unnecessary class predicate in foundational theorems
Andreas Lochbihler
parents: 46041
diff changeset
   244
  assumes "\<And>y. y \<in> A \<Longrightarrow> ccpo.admissible lub ord (\<lambda>x. P x y)"
1cb7d3c0cf31 move admissible out of class ccpo to avoid unnecessary class predicate in foundational theorems
Andreas Lochbihler
parents: 46041
diff changeset
   245
  shows "ccpo.admissible lub ord (\<lambda>x. \<forall>y\<in>A. P x y)"
1cb7d3c0cf31 move admissible out of class ccpo to avoid unnecessary class predicate in foundational theorems
Andreas Lochbihler
parents: 46041
diff changeset
   246
using assms unfolding ccpo.admissible_def by fast
40106
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
parents:
diff changeset
   247
53361
1cb7d3c0cf31 move admissible out of class ccpo to avoid unnecessary class predicate in foundational theorems
Andreas Lochbihler
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diff changeset
   248
lemma chain_compr: "chain ord A \<Longrightarrow> chain ord {x \<in> A. P x}"
40106
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
parents:
diff changeset
   249
unfolding chain_def by fast
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
parents:
diff changeset
   250
53361
1cb7d3c0cf31 move admissible out of class ccpo to avoid unnecessary class predicate in foundational theorems
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diff changeset
   251
context ccpo begin
1cb7d3c0cf31 move admissible out of class ccpo to avoid unnecessary class predicate in foundational theorems
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diff changeset
   252
40106
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
parents:
diff changeset
   253
lemma admissible_disj_lemma:
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
parents:
diff changeset
   254
  assumes A: "chain (op \<le>)A"
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
parents:
diff changeset
   255
  assumes P: "\<forall>x\<in>A. \<exists>y\<in>A. x \<le> y \<and> P y"
46041
1e3ff542e83e remove constant 'ccpo.lub', re-use constant 'Sup' instead
huffman
parents: 40252
diff changeset
   256
  shows "Sup A = Sup {x \<in> A. P x}"
40106
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
parents:
diff changeset
   257
proof (rule antisym)
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
parents:
diff changeset
   258
  have *: "chain (op \<le>) {x \<in> A. P x}"
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
parents:
diff changeset
   259
    by (rule chain_compr [OF A])
46041
1e3ff542e83e remove constant 'ccpo.lub', re-use constant 'Sup' instead
huffman
parents: 40252
diff changeset
   260
  show "Sup A \<le> Sup {x \<in> A. P x}"
1e3ff542e83e remove constant 'ccpo.lub', re-use constant 'Sup' instead
huffman
parents: 40252
diff changeset
   261
    apply (rule ccpo_Sup_least [OF A])
40106
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
parents:
diff changeset
   262
    apply (drule P [rule_format], clarify)
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
parents:
diff changeset
   263
    apply (erule order_trans)
46041
1e3ff542e83e remove constant 'ccpo.lub', re-use constant 'Sup' instead
huffman
parents: 40252
diff changeset
   264
    apply (simp add: ccpo_Sup_upper [OF *])
40106
c58951943cba Complete_Partial_Order.thy: complete partial orders over arbitrary chains, with fixpoint theorem
krauss
parents:
diff changeset
   265
    done
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  show "Sup {x \<in> A. P x} \<le> Sup A"
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    apply (rule ccpo_Sup_least [OF *])
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    apply clarify
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    apply (simp add: ccpo_Sup_upper [OF A])
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    done
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qed
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lemma admissible_disj:
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  fixes P Q :: "'a \<Rightarrow> bool"
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  assumes P: "ccpo.admissible Sup (op \<le>) (\<lambda>x. P x)"
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  assumes Q: "ccpo.admissible Sup (op \<le>) (\<lambda>x. Q x)"
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  shows "ccpo.admissible Sup (op \<le>) (\<lambda>x. P x \<or> Q x)"
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proof (rule ccpo.admissibleI)
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  fix A :: "'a set" assume A: "chain (op \<le>) A"
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  assume "A \<noteq> {}"
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    and "\<forall>x\<in>A. P x \<or> Q x"
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  hence "(\<exists>x\<in>A. P x) \<and> (\<forall>x\<in>A. \<exists>y\<in>A. x \<le> y \<and> P y) \<or> (\<exists>x\<in>A. Q x) \<and> (\<forall>x\<in>A. \<exists>y\<in>A. x \<le> y \<and> Q y)"
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    using chainD[OF A] by blast
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  hence "(\<exists>x. x \<in> A \<and> P x) \<and> Sup A = Sup {x \<in> A. P x} \<or> (\<exists>x. x \<in> A \<and> Q x) \<and> Sup A = Sup {x \<in> A. Q x}"
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    using admissible_disj_lemma [OF A] by blast
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  thus "P (Sup A) \<or> Q (Sup A)"
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    apply (rule disjE, simp_all)
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    apply (rule disjI1, rule ccpo.admissibleD [OF P chain_compr [OF A]], simp, simp)
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    apply (rule disjI2, rule ccpo.admissibleD [OF Q chain_compr [OF A]], simp, simp)
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    done
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qed
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end
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instance complete_lattice \<subseteq> ccpo
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  by default (fast intro: Sup_upper Sup_least)+
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lemma lfp_eq_fixp:
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  assumes f: "mono f" shows "lfp f = fixp f"
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proof (rule antisym)
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  from f have f': "monotone (op \<le>) (op \<le>) f"
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    unfolding mono_def monotone_def .
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  show "lfp f \<le> fixp f"
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    by (rule lfp_lowerbound, subst fixp_unfold [OF f'], rule order_refl)
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  show "fixp f \<le> lfp f"
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    by (rule fixp_lowerbound [OF f'], subst lfp_unfold [OF f], rule order_refl)
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qed
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hide_const (open) iterates fixp
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end