src/HOL/Finite_Set.thy
author haftmann
Fri Mar 02 15:43:19 2007 +0100 (2007-03-02)
changeset 22388 14098da702e0
parent 22316 f662831459de
child 22398 dfe146d65b14
permissions -rw-r--r--
added code theorems for UNIV
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(*  Title:      HOL/Finite_Set.thy
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    ID:         $Id$
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    Author:     Tobias Nipkow, Lawrence C Paulson and Markus Wenzel
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                with contributions by Jeremy Avigad
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*)
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header {* Finite sets *}
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theory Finite_Set
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imports Power Divides Inductive Lattices
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begin
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subsection {* Definition and basic properties *}
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inductive2 finite :: "'a set => bool"
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  where
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    emptyI [simp, intro!]: "finite {}"
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  | insertI [simp, intro!]: "finite A ==> finite (insert a A)"
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lemma ex_new_if_finite: -- "does not depend on def of finite at all"
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  assumes "\<not> finite (UNIV :: 'a set)" and "finite A"
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  shows "\<exists>a::'a. a \<notin> A"
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proof -
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  from prems have "A \<noteq> UNIV" by blast
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  thus ?thesis by blast
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qed
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lemma finite_induct [case_names empty insert, induct set: finite]:
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  "finite F ==>
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    P {} ==> (!!x F. finite F ==> x \<notin> F ==> P F ==> P (insert x F)) ==> P F"
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  -- {* Discharging @{text "x \<notin> F"} entails extra work. *}
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proof -
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  assume "P {}" and
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    insert: "!!x F. finite F ==> x \<notin> F ==> P F ==> P (insert x F)"
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  assume "finite F"
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  thus "P F"
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  proof induct
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    show "P {}" .
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    fix x F assume F: "finite F" and P: "P F"
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    show "P (insert x F)"
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    proof cases
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      assume "x \<in> F"
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      hence "insert x F = F" by (rule insert_absorb)
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      with P show ?thesis by (simp only:)
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    next
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      assume "x \<notin> F"
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      from F this P show ?thesis by (rule insert)
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    qed
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  qed
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qed
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lemma finite_ne_induct[case_names singleton insert, consumes 2]:
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assumes fin: "finite F" shows "F \<noteq> {} \<Longrightarrow>
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 \<lbrakk> \<And>x. P{x};
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   \<And>x F. \<lbrakk> finite F; F \<noteq> {}; x \<notin> F; P F \<rbrakk> \<Longrightarrow> P (insert x F) \<rbrakk>
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 \<Longrightarrow> P F"
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using fin
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proof induct
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  case empty thus ?case by simp
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next
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  case (insert x F)
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  show ?case
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  proof cases
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    assume "F = {}" thus ?thesis using insert(4) by simp
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  next
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    assume "F \<noteq> {}" thus ?thesis using insert by blast
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  qed
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qed
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lemma finite_subset_induct [consumes 2, case_names empty insert]:
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  "finite F ==> F \<subseteq> A ==>
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    P {} ==> (!!a F. finite F ==> a \<in> A ==> a \<notin> F ==> P F ==> P (insert a F)) ==>
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    P F"
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proof -
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  assume "P {}" and insert:
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    "!!a F. finite F ==> a \<in> A ==> a \<notin> F ==> P F ==> P (insert a F)"
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  assume "finite F"
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  thus "F \<subseteq> A ==> P F"
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  proof induct
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    show "P {}" .
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    fix x F assume "finite F" and "x \<notin> F"
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      and P: "F \<subseteq> A ==> P F" and i: "insert x F \<subseteq> A"
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    show "P (insert x F)"
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    proof (rule insert)
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      from i show "x \<in> A" by blast
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      from i have "F \<subseteq> A" by blast
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      with P show "P F" .
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    qed
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  qed
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qed
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text{* Finite sets are the images of initial segments of natural numbers: *}
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lemma finite_imp_nat_seg_image_inj_on:
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  assumes fin: "finite A" 
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  shows "\<exists> (n::nat) f. A = f ` {i. i<n} & inj_on f {i. i<n}"
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using fin
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proof induct
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  case empty
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  show ?case  
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  proof show "\<exists>f. {} = f ` {i::nat. i < 0} & inj_on f {i. i<0}" by simp 
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  qed
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next
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  case (insert a A)
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  have notinA: "a \<notin> A" .
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  from insert.hyps obtain n f
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    where "A = f ` {i::nat. i < n}" "inj_on f {i. i < n}" by blast
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  hence "insert a A = f(n:=a) ` {i. i < Suc n}"
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        "inj_on (f(n:=a)) {i. i < Suc n}" using notinA
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    by (auto simp add: image_def Ball_def inj_on_def less_Suc_eq)
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  thus ?case by blast
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qed
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lemma nat_seg_image_imp_finite:
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  "!!f A. A = f ` {i::nat. i<n} \<Longrightarrow> finite A"
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proof (induct n)
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  case 0 thus ?case by simp
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next
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  case (Suc n)
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  let ?B = "f ` {i. i < n}"
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  have finB: "finite ?B" by(rule Suc.hyps[OF refl])
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  show ?case
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  proof cases
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    assume "\<exists>k<n. f n = f k"
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    hence "A = ?B" using Suc.prems by(auto simp:less_Suc_eq)
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    thus ?thesis using finB by simp
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  next
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    assume "\<not>(\<exists> k<n. f n = f k)"
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    hence "A = insert (f n) ?B" using Suc.prems by(auto simp:less_Suc_eq)
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    thus ?thesis using finB by simp
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  qed
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qed
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lemma finite_conv_nat_seg_image:
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  "finite A = (\<exists> (n::nat) f. A = f ` {i::nat. i<n})"
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by(blast intro: nat_seg_image_imp_finite dest: finite_imp_nat_seg_image_inj_on)
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subsubsection{* Finiteness and set theoretic constructions *}
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lemma finite_UnI: "finite F ==> finite G ==> finite (F Un G)"
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  -- {* The union of two finite sets is finite. *}
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  by (induct set: finite) simp_all
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lemma finite_subset: "A \<subseteq> B ==> finite B ==> finite A"
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  -- {* Every subset of a finite set is finite. *}
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proof -
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  assume "finite B"
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  thus "!!A. A \<subseteq> B ==> finite A"
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  proof induct
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    case empty
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    thus ?case by simp
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  next
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    case (insert x F A)
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    have A: "A \<subseteq> insert x F" and r: "A - {x} \<subseteq> F ==> finite (A - {x})" .
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    show "finite A"
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    proof cases
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      assume x: "x \<in> A"
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      with A have "A - {x} \<subseteq> F" by (simp add: subset_insert_iff)
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      with r have "finite (A - {x})" .
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      hence "finite (insert x (A - {x}))" ..
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      also have "insert x (A - {x}) = A" by (rule insert_Diff)
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      finally show ?thesis .
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    next
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      show "A \<subseteq> F ==> ?thesis" .
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      assume "x \<notin> A"
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      with A show "A \<subseteq> F" by (simp add: subset_insert_iff)
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    qed
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  qed
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qed
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lemma finite_Collect_subset[simp]: "finite A \<Longrightarrow> finite{x \<in> A. P x}"
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using finite_subset[of "{x \<in> A. P x}" "A"] by blast
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lemma finite_Un [iff]: "finite (F Un G) = (finite F & finite G)"
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  by (blast intro: finite_subset [of _ "X Un Y", standard] finite_UnI)
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lemma finite_Int [simp, intro]: "finite F | finite G ==> finite (F Int G)"
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  -- {* The converse obviously fails. *}
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  by (blast intro: finite_subset)
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lemma finite_insert [simp]: "finite (insert a A) = finite A"
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  apply (subst insert_is_Un)
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  apply (simp only: finite_Un, blast)
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  done
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lemma finite_Union[simp, intro]:
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 "\<lbrakk> finite A; !!M. M \<in> A \<Longrightarrow> finite M \<rbrakk> \<Longrightarrow> finite(\<Union>A)"
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by (induct rule:finite_induct) simp_all
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lemma finite_empty_induct:
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  "finite A ==>
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  P A ==> (!!a A. finite A ==> a:A ==> P A ==> P (A - {a})) ==> P {}"
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proof -
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  assume "finite A"
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    and "P A" and "!!a A. finite A ==> a:A ==> P A ==> P (A - {a})"
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  have "P (A - A)"
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  proof -
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    fix c b :: "'a set"
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    presume c: "finite c" and b: "finite b"
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      and P1: "P b" and P2: "!!x y. finite y ==> x \<in> y ==> P y ==> P (y - {x})"
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    from c show "c \<subseteq> b ==> P (b - c)"
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    proof induct
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      case empty
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      from P1 show ?case by simp
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    next
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      case (insert x F)
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      have "P (b - F - {x})"
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      proof (rule P2)
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        from _ b show "finite (b - F)" by (rule finite_subset) blast
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        from insert show "x \<in> b - F" by simp
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        from insert show "P (b - F)" by simp
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      qed
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      also have "b - F - {x} = b - insert x F" by (rule Diff_insert [symmetric])
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      finally show ?case .
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    qed
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  next
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    show "A \<subseteq> A" ..
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  qed
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  thus "P {}" by simp
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qed
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lemma finite_Diff [simp]: "finite B ==> finite (B - Ba)"
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  by (rule Diff_subset [THEN finite_subset])
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lemma finite_Diff_insert [iff]: "finite (A - insert a B) = finite (A - B)"
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  apply (subst Diff_insert)
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  apply (case_tac "a : A - B")
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   apply (rule finite_insert [symmetric, THEN trans])
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   apply (subst insert_Diff, simp_all)
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  done
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lemma finite_Diff_singleton [simp]: "finite (A - {a}) = finite A"
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  by simp
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text {* Image and Inverse Image over Finite Sets *}
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lemma finite_imageI[simp]: "finite F ==> finite (h ` F)"
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  -- {* The image of a finite set is finite. *}
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  by (induct set: finite) simp_all
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lemma finite_surj: "finite A ==> B <= f ` A ==> finite B"
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  apply (frule finite_imageI)
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  apply (erule finite_subset, assumption)
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  done
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lemma finite_range_imageI:
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    "finite (range g) ==> finite (range (%x. f (g x)))"
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  apply (drule finite_imageI, simp)
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  done
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lemma finite_imageD: "finite (f`A) ==> inj_on f A ==> finite A"
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proof -
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  have aux: "!!A. finite (A - {}) = finite A" by simp
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  fix B :: "'a set"
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  assume "finite B"
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  thus "!!A. f`A = B ==> inj_on f A ==> finite A"
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    apply induct
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     apply simp
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    apply (subgoal_tac "EX y:A. f y = x & F = f ` (A - {y})")
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     apply clarify
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     apply (simp (no_asm_use) add: inj_on_def)
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     apply (blast dest!: aux [THEN iffD1], atomize)
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    apply (erule_tac V = "ALL A. ?PP (A)" in thin_rl)
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    apply (frule subsetD [OF equalityD2 insertI1], clarify)
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    apply (rule_tac x = xa in bexI)
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     apply (simp_all add: inj_on_image_set_diff)
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    done
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qed (rule refl)
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lemma inj_vimage_singleton: "inj f ==> f-`{a} \<subseteq> {THE x. f x = a}"
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  -- {* The inverse image of a singleton under an injective function
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         is included in a singleton. *}
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  apply (auto simp add: inj_on_def)
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  apply (blast intro: the_equality [symmetric])
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  done
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lemma finite_vimageI: "[|finite F; inj h|] ==> finite (h -` F)"
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  -- {* The inverse image of a finite set under an injective function
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         is finite. *}
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  apply (induct set: finite)
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   apply simp_all
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  apply (subst vimage_insert)
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  apply (simp add: finite_Un finite_subset [OF inj_vimage_singleton])
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  done
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text {* The finite UNION of finite sets *}
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lemma finite_UN_I: "finite A ==> (!!a. a:A ==> finite (B a)) ==> finite (UN a:A. B a)"
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  by (induct set: finite) simp_all
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text {*
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  Strengthen RHS to
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  @{prop "((ALL x:A. finite (B x)) & finite {x. x:A & B x \<noteq> {}})"}?
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  We'd need to prove
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  @{prop "finite C ==> ALL A B. (UNION A B) <= C --> finite {x. x:A & B x \<noteq> {}}"}
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  by induction. *}
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lemma finite_UN [simp]: "finite A ==> finite (UNION A B) = (ALL x:A. finite (B x))"
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  by (blast intro: finite_UN_I finite_subset)
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lemma finite_Plus: "[| finite A; finite B |] ==> finite (A <+> B)"
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by (simp add: Plus_def)
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text {* Sigma of finite sets *}
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lemma finite_SigmaI [simp]:
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    "finite A ==> (!!a. a:A ==> finite (B a)) ==> finite (SIGMA a:A. B a)"
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  by (unfold Sigma_def) (blast intro!: finite_UN_I)
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lemma finite_cartesian_product: "[| finite A; finite B |] ==>
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    finite (A <*> B)"
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  by (rule finite_SigmaI)
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lemma finite_Prod_UNIV:
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    "finite (UNIV::'a set) ==> finite (UNIV::'b set) ==> finite (UNIV::('a * 'b) set)"
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  apply (subgoal_tac "(UNIV:: ('a * 'b) set) = Sigma UNIV (%x. UNIV)")
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   apply (erule ssubst)
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   apply (erule finite_SigmaI, auto)
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  done
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lemma finite_cartesian_productD1:
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     "[| finite (A <*> B); B \<noteq> {} |] ==> finite A"
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apply (auto simp add: finite_conv_nat_seg_image) 
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apply (drule_tac x=n in spec) 
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   330
apply (drule_tac x="fst o f" in spec) 
paulson@15409
   331
apply (auto simp add: o_def) 
paulson@15409
   332
 prefer 2 apply (force dest!: equalityD2) 
paulson@15409
   333
apply (drule equalityD1) 
paulson@15409
   334
apply (rename_tac y x)
paulson@15409
   335
apply (subgoal_tac "\<exists>k. k<n & f k = (x,y)") 
paulson@15409
   336
 prefer 2 apply force
paulson@15409
   337
apply clarify
paulson@15409
   338
apply (rule_tac x=k in image_eqI, auto)
paulson@15409
   339
done
paulson@15409
   340
paulson@15409
   341
lemma finite_cartesian_productD2:
paulson@15409
   342
     "[| finite (A <*> B); A \<noteq> {} |] ==> finite B"
paulson@15409
   343
apply (auto simp add: finite_conv_nat_seg_image) 
paulson@15409
   344
apply (drule_tac x=n in spec) 
paulson@15409
   345
apply (drule_tac x="snd o f" in spec) 
paulson@15409
   346
apply (auto simp add: o_def) 
paulson@15409
   347
 prefer 2 apply (force dest!: equalityD2) 
paulson@15409
   348
apply (drule equalityD1)
paulson@15409
   349
apply (rename_tac x y)
paulson@15409
   350
apply (subgoal_tac "\<exists>k. k<n & f k = (x,y)") 
paulson@15409
   351
 prefer 2 apply force
paulson@15409
   352
apply clarify
paulson@15409
   353
apply (rule_tac x=k in image_eqI, auto)
paulson@15409
   354
done
paulson@15409
   355
paulson@15409
   356
nipkow@15392
   357
text {* The powerset of a finite set *}
wenzelm@12396
   358
wenzelm@12396
   359
lemma finite_Pow_iff [iff]: "finite (Pow A) = finite A"
wenzelm@12396
   360
proof
wenzelm@12396
   361
  assume "finite (Pow A)"
wenzelm@12396
   362
  with _ have "finite ((%x. {x}) ` A)" by (rule finite_subset) blast
wenzelm@12396
   363
  thus "finite A" by (rule finite_imageD [unfolded inj_on_def]) simp
wenzelm@12396
   364
next
wenzelm@12396
   365
  assume "finite A"
wenzelm@12396
   366
  thus "finite (Pow A)"
wenzelm@12396
   367
    by induct (simp_all add: finite_UnI finite_imageI Pow_insert)
wenzelm@12396
   368
qed
wenzelm@12396
   369
nipkow@15392
   370
nipkow@15392
   371
lemma finite_UnionD: "finite(\<Union>A) \<Longrightarrow> finite A"
nipkow@15392
   372
by(blast intro: finite_subset[OF subset_Pow_Union])
nipkow@15392
   373
nipkow@15392
   374
wenzelm@12396
   375
lemma finite_converse [iff]: "finite (r^-1) = finite r"
wenzelm@12396
   376
  apply (subgoal_tac "r^-1 = (%(x,y). (y,x))`r")
wenzelm@12396
   377
   apply simp
wenzelm@12396
   378
   apply (rule iffI)
wenzelm@12396
   379
    apply (erule finite_imageD [unfolded inj_on_def])
wenzelm@12396
   380
    apply (simp split add: split_split)
wenzelm@12396
   381
   apply (erule finite_imageI)
paulson@14208
   382
  apply (simp add: converse_def image_def, auto)
wenzelm@12396
   383
  apply (rule bexI)
wenzelm@12396
   384
   prefer 2 apply assumption
wenzelm@12396
   385
  apply simp
wenzelm@12396
   386
  done
wenzelm@12396
   387
paulson@14430
   388
nipkow@15392
   389
text {* \paragraph{Finiteness of transitive closure} (Thanks to Sidi
nipkow@15392
   390
Ehmety) *}
wenzelm@12396
   391
wenzelm@12396
   392
lemma finite_Field: "finite r ==> finite (Field r)"
wenzelm@12396
   393
  -- {* A finite relation has a finite field (@{text "= domain \<union> range"}. *}
berghofe@22262
   394
  apply (induct set: finite)
wenzelm@12396
   395
   apply (auto simp add: Field_def Domain_insert Range_insert)
wenzelm@12396
   396
  done
wenzelm@12396
   397
wenzelm@12396
   398
lemma trancl_subset_Field2: "r^+ <= Field r \<times> Field r"
wenzelm@12396
   399
  apply clarify
wenzelm@12396
   400
  apply (erule trancl_induct)
wenzelm@12396
   401
   apply (auto simp add: Field_def)
wenzelm@12396
   402
  done
wenzelm@12396
   403
wenzelm@12396
   404
lemma finite_trancl: "finite (r^+) = finite r"
wenzelm@12396
   405
  apply auto
wenzelm@12396
   406
   prefer 2
wenzelm@12396
   407
   apply (rule trancl_subset_Field2 [THEN finite_subset])
wenzelm@12396
   408
   apply (rule finite_SigmaI)
wenzelm@12396
   409
    prefer 3
berghofe@13704
   410
    apply (blast intro: r_into_trancl' finite_subset)
wenzelm@12396
   411
   apply (auto simp add: finite_Field)
wenzelm@12396
   412
  done
wenzelm@12396
   413
wenzelm@12396
   414
nipkow@15392
   415
subsection {* A fold functional for finite sets *}
nipkow@15392
   416
nipkow@15392
   417
text {* The intended behaviour is
nipkow@15480
   418
@{text "fold f g z {x\<^isub>1, ..., x\<^isub>n} = f (g x\<^isub>1) (\<dots> (f (g x\<^isub>n) z)\<dots>)"}
nipkow@15392
   419
if @{text f} is associative-commutative. For an application of @{text fold}
nipkow@15392
   420
se the definitions of sums and products over finite sets.
nipkow@15392
   421
*}
nipkow@15392
   422
berghofe@22262
   423
inductive2
berghofe@22262
   424
  foldSet :: "('a => 'a => 'a) => ('b => 'a) => 'a => 'b set => 'a => bool"
berghofe@22262
   425
  for f ::  "'a => 'a => 'a"
berghofe@22262
   426
  and g :: "'b => 'a"
berghofe@22262
   427
  and z :: 'a
berghofe@22262
   428
where
berghofe@22262
   429
  emptyI [intro]: "foldSet f g z {} z"
berghofe@22262
   430
| insertI [intro]:
berghofe@22262
   431
     "\<lbrakk> x \<notin> A; foldSet f g z A y \<rbrakk>
berghofe@22262
   432
      \<Longrightarrow> foldSet f g z (insert x A) (f (g x) y)"
berghofe@22262
   433
berghofe@22262
   434
inductive_cases2 empty_foldSetE [elim!]: "foldSet f g z {} x"
nipkow@15392
   435
nipkow@15392
   436
constdefs
nipkow@21733
   437
  fold :: "('a => 'a => 'a) => ('b => 'a) => 'a => 'b set => 'a"
berghofe@22262
   438
  "fold f g z A == THE x. foldSet f g z A x"
nipkow@15392
   439
paulson@15498
   440
text{*A tempting alternative for the definiens is
berghofe@22262
   441
@{term "if finite A then THE x. foldSet f g e A x else e"}.
paulson@15498
   442
It allows the removal of finiteness assumptions from the theorems
paulson@15498
   443
@{text fold_commute}, @{text fold_reindex} and @{text fold_distrib}.
paulson@15498
   444
The proofs become ugly, with @{text rule_format}. It is not worth the effort.*}
paulson@15498
   445
paulson@15498
   446
nipkow@15392
   447
lemma Diff1_foldSet:
berghofe@22262
   448
  "foldSet f g z (A - {x}) y ==> x: A ==> foldSet f g z A (f (g x) y)"
nipkow@15392
   449
by (erule insert_Diff [THEN subst], rule foldSet.intros, auto)
nipkow@15392
   450
berghofe@22262
   451
lemma foldSet_imp_finite: "foldSet f g z A x==> finite A"
nipkow@15392
   452
  by (induct set: foldSet) auto
nipkow@15392
   453
berghofe@22262
   454
lemma finite_imp_foldSet: "finite A ==> EX x. foldSet f g z A x"
berghofe@22262
   455
  by (induct set: finite) auto
nipkow@15392
   456
nipkow@15392
   457
nipkow@15392
   458
subsubsection {* Commutative monoids *}
nipkow@15480
   459
nipkow@15392
   460
locale ACf =
nipkow@15392
   461
  fixes f :: "'a => 'a => 'a"    (infixl "\<cdot>" 70)
nipkow@15392
   462
  assumes commute: "x \<cdot> y = y \<cdot> x"
nipkow@15392
   463
    and assoc: "(x \<cdot> y) \<cdot> z = x \<cdot> (y \<cdot> z)"
nipkow@15392
   464
nipkow@15392
   465
locale ACe = ACf +
nipkow@15392
   466
  fixes e :: 'a
nipkow@15392
   467
  assumes ident [simp]: "x \<cdot> e = x"
nipkow@15392
   468
nipkow@15480
   469
locale ACIf = ACf +
nipkow@15480
   470
  assumes idem: "x \<cdot> x = x"
nipkow@15480
   471
nipkow@15392
   472
lemma (in ACf) left_commute: "x \<cdot> (y \<cdot> z) = y \<cdot> (x \<cdot> z)"
nipkow@15392
   473
proof -
nipkow@15392
   474
  have "x \<cdot> (y \<cdot> z) = (y \<cdot> z) \<cdot> x" by (simp only: commute)
nipkow@15392
   475
  also have "... = y \<cdot> (z \<cdot> x)" by (simp only: assoc)
nipkow@15392
   476
  also have "z \<cdot> x = x \<cdot> z" by (simp only: commute)
nipkow@15392
   477
  finally show ?thesis .
nipkow@15392
   478
qed
nipkow@15392
   479
nipkow@15392
   480
lemmas (in ACf) AC = assoc commute left_commute
nipkow@15392
   481
nipkow@15392
   482
lemma (in ACe) left_ident [simp]: "e \<cdot> x = x"
nipkow@15392
   483
proof -
nipkow@15392
   484
  have "x \<cdot> e = x" by (rule ident)
nipkow@15392
   485
  thus ?thesis by (subst commute)
nipkow@15392
   486
qed
nipkow@15392
   487
nipkow@15497
   488
lemma (in ACIf) idem2: "x \<cdot> (x \<cdot> y) = x \<cdot> y"
nipkow@15497
   489
proof -
nipkow@15497
   490
  have "x \<cdot> (x \<cdot> y) = (x \<cdot> x) \<cdot> y" by(simp add:assoc)
nipkow@15497
   491
  also have "\<dots> = x \<cdot> y" by(simp add:idem)
nipkow@15497
   492
  finally show ?thesis .
nipkow@15497
   493
qed
nipkow@15497
   494
nipkow@15497
   495
lemmas (in ACIf) ACI = AC idem idem2
nipkow@15497
   496
ballarin@15765
   497
text{* Interpretation of locales: *}
ballarin@15765
   498
ballarin@15765
   499
interpretation AC_add: ACe ["op +" "0::'a::comm_monoid_add"]
ballarin@19984
   500
  by unfold_locales (auto intro: add_assoc add_commute)
nipkow@15402
   501
ballarin@15765
   502
interpretation AC_mult: ACe ["op *" "1::'a::comm_monoid_mult"]
ballarin@19984
   503
  by unfold_locales (auto intro: mult_assoc mult_commute)
nipkow@15402
   504
nipkow@15392
   505
subsubsection{*From @{term foldSet} to @{term fold}*}
nipkow@15392
   506
paulson@15510
   507
lemma image_less_Suc: "h ` {i. i < Suc m} = insert (h m) (h ` {i. i < m})"
wenzelm@19868
   508
  by (auto simp add: less_Suc_eq) 
paulson@15510
   509
paulson@15510
   510
lemma insert_image_inj_on_eq:
paulson@15510
   511
     "[|insert (h m) A = h ` {i. i < Suc m}; h m \<notin> A; 
paulson@15510
   512
        inj_on h {i. i < Suc m}|] 
paulson@15510
   513
      ==> A = h ` {i. i < m}"
paulson@15510
   514
apply (auto simp add: image_less_Suc inj_on_def)
paulson@15510
   515
apply (blast intro: less_trans) 
paulson@15510
   516
done
paulson@15510
   517
paulson@15510
   518
lemma insert_inj_onE:
paulson@15510
   519
  assumes aA: "insert a A = h`{i::nat. i<n}" and anot: "a \<notin> A" 
paulson@15510
   520
      and inj_on: "inj_on h {i::nat. i<n}"
paulson@15510
   521
  shows "\<exists>hm m. inj_on hm {i::nat. i<m} & A = hm ` {i. i<m} & m < n"
paulson@15510
   522
proof (cases n)
paulson@15510
   523
  case 0 thus ?thesis using aA by auto
paulson@15510
   524
next
paulson@15510
   525
  case (Suc m)
paulson@15510
   526
  have nSuc: "n = Suc m" . 
paulson@15510
   527
  have mlessn: "m<n" by (simp add: nSuc)
paulson@15532
   528
  from aA obtain k where hkeq: "h k = a" and klessn: "k<n" by (blast elim!: equalityE)
paulson@15520
   529
  let ?hm = "swap k m h"
paulson@15520
   530
  have inj_hm: "inj_on ?hm {i. i < n}" using klessn mlessn 
paulson@15520
   531
    by (simp add: inj_on_swap_iff inj_on)
paulson@15510
   532
  show ?thesis
paulson@15520
   533
  proof (intro exI conjI)
paulson@15520
   534
    show "inj_on ?hm {i. i < m}" using inj_hm
paulson@15510
   535
      by (auto simp add: nSuc less_Suc_eq intro: subset_inj_on)
paulson@15520
   536
    show "m<n" by (rule mlessn)
paulson@15520
   537
    show "A = ?hm ` {i. i < m}" 
paulson@15520
   538
    proof (rule insert_image_inj_on_eq)
paulson@15520
   539
      show "inj_on (swap k m h) {i. i < Suc m}" using inj_hm nSuc by simp
paulson@15520
   540
      show "?hm m \<notin> A" by (simp add: swap_def hkeq anot) 
paulson@15520
   541
      show "insert (?hm m) A = ?hm ` {i. i < Suc m}"
paulson@15520
   542
	using aA hkeq nSuc klessn
paulson@15520
   543
	by (auto simp add: swap_def image_less_Suc fun_upd_image 
paulson@15520
   544
			   less_Suc_eq inj_on_image_set_diff [OF inj_on])
nipkow@15479
   545
    qed
nipkow@15479
   546
  qed
nipkow@15479
   547
qed
nipkow@15479
   548
nipkow@15392
   549
lemma (in ACf) foldSet_determ_aux:
paulson@15510
   550
  "!!A x x' h. \<lbrakk> A = h`{i::nat. i<n}; inj_on h {i. i<n}; 
berghofe@22262
   551
                foldSet f g z A x; foldSet f g z A x' \<rbrakk>
nipkow@15392
   552
   \<Longrightarrow> x' = x"
paulson@15510
   553
proof (induct n rule: less_induct)
paulson@15510
   554
  case (less n)
paulson@15510
   555
    have IH: "!!m h A x x'. 
paulson@15510
   556
               \<lbrakk>m<n; A = h ` {i. i<m}; inj_on h {i. i<m}; 
berghofe@22262
   557
                foldSet f g z A x; foldSet f g z A x'\<rbrakk> \<Longrightarrow> x' = x" .
berghofe@22262
   558
    have Afoldx: "foldSet f g z A x" and Afoldx': "foldSet f g z A x'"
paulson@15510
   559
     and A: "A = h`{i. i<n}" and injh: "inj_on h {i. i<n}" .
paulson@15510
   560
    show ?case
paulson@15510
   561
    proof (rule foldSet.cases [OF Afoldx])
berghofe@22262
   562
      assume "A = {}" and "x = z"
paulson@15510
   563
      with Afoldx' show "x' = x" by blast
nipkow@15392
   564
    next
paulson@15510
   565
      fix B b u
berghofe@22262
   566
      assume AbB: "A = insert b B" and x: "x = g b \<cdot> u"
berghofe@22262
   567
         and notinB: "b \<notin> B" and Bu: "foldSet f g z B u"
paulson@15510
   568
      show "x'=x" 
paulson@15510
   569
      proof (rule foldSet.cases [OF Afoldx'])
berghofe@22262
   570
        assume "A = {}" and "x' = z"
paulson@15510
   571
        with AbB show "x' = x" by blast
nipkow@15392
   572
      next
paulson@15510
   573
	fix C c v
berghofe@22262
   574
	assume AcC: "A = insert c C" and x': "x' = g c \<cdot> v"
berghofe@22262
   575
           and notinC: "c \<notin> C" and Cv: "foldSet f g z C v"
paulson@15510
   576
	from A AbB have Beq: "insert b B = h`{i. i<n}" by simp
paulson@15510
   577
        from insert_inj_onE [OF Beq notinB injh]
paulson@15510
   578
        obtain hB mB where inj_onB: "inj_on hB {i. i < mB}" 
paulson@15510
   579
                     and Beq: "B = hB ` {i. i < mB}"
paulson@15510
   580
                     and lessB: "mB < n" by auto 
paulson@15510
   581
	from A AcC have Ceq: "insert c C = h`{i. i<n}" by simp
paulson@15510
   582
        from insert_inj_onE [OF Ceq notinC injh]
paulson@15510
   583
        obtain hC mC where inj_onC: "inj_on hC {i. i < mC}"
paulson@15510
   584
                       and Ceq: "C = hC ` {i. i < mC}"
paulson@15510
   585
                       and lessC: "mC < n" by auto 
paulson@15510
   586
	show "x'=x"
nipkow@15392
   587
	proof cases
paulson@15510
   588
          assume "b=c"
paulson@15510
   589
	  then moreover have "B = C" using AbB AcC notinB notinC by auto
paulson@15510
   590
	  ultimately show ?thesis  using Bu Cv x x' IH[OF lessC Ceq inj_onC]
paulson@15510
   591
            by auto
nipkow@15392
   592
	next
nipkow@15392
   593
	  assume diff: "b \<noteq> c"
nipkow@15392
   594
	  let ?D = "B - {c}"
nipkow@15392
   595
	  have B: "B = insert c ?D" and C: "C = insert b ?D"
paulson@15510
   596
	    using AbB AcC notinB notinC diff by(blast elim!:equalityE)+
nipkow@15402
   597
	  have "finite A" by(rule foldSet_imp_finite[OF Afoldx])
paulson@15510
   598
	  with AbB have "finite ?D" by simp
berghofe@22262
   599
	  then obtain d where Dfoldd: "foldSet f g z ?D d"
nipkow@17589
   600
	    using finite_imp_foldSet by iprover
paulson@15506
   601
	  moreover have cinB: "c \<in> B" using B by auto
berghofe@22262
   602
	  ultimately have "foldSet f g z B (g c \<cdot> d)"
nipkow@15392
   603
	    by(rule Diff1_foldSet)
paulson@15510
   604
	  hence "g c \<cdot> d = u" by (rule IH [OF lessB Beq inj_onB Bu]) 
paulson@15510
   605
          moreover have "g b \<cdot> d = v"
paulson@15510
   606
	  proof (rule IH[OF lessC Ceq inj_onC Cv])
berghofe@22262
   607
	    show "foldSet f g z C (g b \<cdot> d)" using C notinB Dfoldd
nipkow@15392
   608
	      by fastsimp
nipkow@15392
   609
	  qed
paulson@15510
   610
	  ultimately show ?thesis using x x' by (auto simp: AC)
nipkow@15392
   611
	qed
nipkow@15392
   612
      qed
nipkow@15392
   613
    qed
nipkow@15392
   614
  qed
nipkow@15392
   615
nipkow@15392
   616
nipkow@15392
   617
lemma (in ACf) foldSet_determ:
berghofe@22262
   618
  "foldSet f g z A x ==> foldSet f g z A y ==> y = x"
paulson@15510
   619
apply (frule foldSet_imp_finite [THEN finite_imp_nat_seg_image_inj_on]) 
paulson@15510
   620
apply (blast intro: foldSet_determ_aux [rule_format])
nipkow@15392
   621
done
nipkow@15392
   622
berghofe@22262
   623
lemma (in ACf) fold_equality: "foldSet f g z A y ==> fold f g z A = y"
nipkow@15392
   624
  by (unfold fold_def) (blast intro: foldSet_determ)
nipkow@15392
   625
nipkow@15392
   626
text{* The base case for @{text fold}: *}
nipkow@15392
   627
nipkow@15480
   628
lemma fold_empty [simp]: "fold f g z {} = z"
nipkow@15392
   629
  by (unfold fold_def) blast
nipkow@15392
   630
nipkow@15392
   631
lemma (in ACf) fold_insert_aux: "x \<notin> A ==>
berghofe@22262
   632
    (foldSet f g z (insert x A) v) =
berghofe@22262
   633
    (EX y. foldSet f g z A y & v = f (g x) y)"
nipkow@15392
   634
  apply auto
nipkow@15392
   635
  apply (rule_tac A1 = A and f1 = f in finite_imp_foldSet [THEN exE])
nipkow@15392
   636
   apply (fastsimp dest: foldSet_imp_finite)
nipkow@15392
   637
  apply (blast intro: foldSet_determ)
nipkow@15392
   638
  done
nipkow@15392
   639
nipkow@15392
   640
text{* The recursion equation for @{text fold}: *}
nipkow@15392
   641
nipkow@15392
   642
lemma (in ACf) fold_insert[simp]:
nipkow@15480
   643
    "finite A ==> x \<notin> A ==> fold f g z (insert x A) = f (g x) (fold f g z A)"
nipkow@15392
   644
  apply (unfold fold_def)
nipkow@15392
   645
  apply (simp add: fold_insert_aux)
nipkow@15392
   646
  apply (rule the_equality)
nipkow@15392
   647
  apply (auto intro: finite_imp_foldSet
nipkow@15392
   648
    cong add: conj_cong simp add: fold_def [symmetric] fold_equality)
nipkow@15392
   649
  done
nipkow@15392
   650
nipkow@15535
   651
lemma (in ACf) fold_rec:
nipkow@15535
   652
assumes fin: "finite A" and a: "a:A"
nipkow@15535
   653
shows "fold f g z A = f (g a) (fold f g z (A - {a}))"
nipkow@15535
   654
proof-
nipkow@15535
   655
  have A: "A = insert a (A - {a})" using a by blast
nipkow@15535
   656
  hence "fold f g z A = fold f g z (insert a (A - {a}))" by simp
nipkow@15535
   657
  also have "\<dots> = f (g a) (fold f g z (A - {a}))"
nipkow@15535
   658
    by(rule fold_insert) (simp add:fin)+
nipkow@15535
   659
  finally show ?thesis .
nipkow@15535
   660
qed
nipkow@15535
   661
nipkow@15392
   662
nipkow@15480
   663
text{* A simplified version for idempotent functions: *}
nipkow@15480
   664
paulson@15509
   665
lemma (in ACIf) fold_insert_idem:
nipkow@15480
   666
assumes finA: "finite A"
paulson@15508
   667
shows "fold f g z (insert a A) = g a \<cdot> fold f g z A"
nipkow@15480
   668
proof cases
nipkow@15480
   669
  assume "a \<in> A"
nipkow@15480
   670
  then obtain B where A: "A = insert a B" and disj: "a \<notin> B"
nipkow@15480
   671
    by(blast dest: mk_disjoint_insert)
nipkow@15480
   672
  show ?thesis
nipkow@15480
   673
  proof -
nipkow@15480
   674
    from finA A have finB: "finite B" by(blast intro: finite_subset)
nipkow@15480
   675
    have "fold f g z (insert a A) = fold f g z (insert a B)" using A by simp
nipkow@15480
   676
    also have "\<dots> = (g a) \<cdot> (fold f g z B)"
paulson@15506
   677
      using finB disj by simp
nipkow@15480
   678
    also have "\<dots> = g a \<cdot> fold f g z A"
nipkow@15480
   679
      using A finB disj by(simp add:idem assoc[symmetric])
nipkow@15480
   680
    finally show ?thesis .
nipkow@15480
   681
  qed
nipkow@15480
   682
next
nipkow@15480
   683
  assume "a \<notin> A"
nipkow@15480
   684
  with finA show ?thesis by simp
nipkow@15480
   685
qed
nipkow@15480
   686
nipkow@15484
   687
lemma (in ACIf) foldI_conv_id:
nipkow@15484
   688
  "finite A \<Longrightarrow> fold f g z A = fold f id z (g ` A)"
paulson@15509
   689
by(erule finite_induct)(simp_all add: fold_insert_idem del: fold_insert)
nipkow@15484
   690
nipkow@15392
   691
subsubsection{*Lemmas about @{text fold}*}
nipkow@15392
   692
nipkow@15392
   693
lemma (in ACf) fold_commute:
paulson@15487
   694
  "finite A ==> (!!z. f x (fold f g z A) = fold f g (f x z) A)"
berghofe@22262
   695
  apply (induct set: finite)
wenzelm@21575
   696
   apply simp
paulson@15487
   697
  apply (simp add: left_commute [of x])
nipkow@15392
   698
  done
nipkow@15392
   699
nipkow@15392
   700
lemma (in ACf) fold_nest_Un_Int:
nipkow@15392
   701
  "finite A ==> finite B
nipkow@15480
   702
    ==> fold f g (fold f g z B) A = fold f g (fold f g z (A Int B)) (A Un B)"
berghofe@22262
   703
  apply (induct set: finite)
wenzelm@21575
   704
   apply simp
nipkow@15392
   705
  apply (simp add: fold_commute Int_insert_left insert_absorb)
nipkow@15392
   706
  done
nipkow@15392
   707
nipkow@15392
   708
lemma (in ACf) fold_nest_Un_disjoint:
nipkow@15392
   709
  "finite A ==> finite B ==> A Int B = {}
nipkow@15480
   710
    ==> fold f g z (A Un B) = fold f g (fold f g z B) A"
nipkow@15392
   711
  by (simp add: fold_nest_Un_Int)
nipkow@15392
   712
nipkow@15392
   713
lemma (in ACf) fold_reindex:
paulson@15487
   714
assumes fin: "finite A"
paulson@15487
   715
shows "inj_on h A \<Longrightarrow> fold f g z (h ` A) = fold f (g \<circ> h) z A"
paulson@15506
   716
using fin apply induct
nipkow@15392
   717
 apply simp
nipkow@15392
   718
apply simp
nipkow@15392
   719
done
nipkow@15392
   720
nipkow@15392
   721
lemma (in ACe) fold_Un_Int:
nipkow@15392
   722
  "finite A ==> finite B ==>
nipkow@15392
   723
    fold f g e A \<cdot> fold f g e B =
nipkow@15392
   724
    fold f g e (A Un B) \<cdot> fold f g e (A Int B)"
berghofe@22262
   725
  apply (induct set: finite, simp)
nipkow@15392
   726
  apply (simp add: AC insert_absorb Int_insert_left)
nipkow@15392
   727
  done
nipkow@15392
   728
nipkow@15392
   729
corollary (in ACe) fold_Un_disjoint:
nipkow@15392
   730
  "finite A ==> finite B ==> A Int B = {} ==>
nipkow@15392
   731
    fold f g e (A Un B) = fold f g e A \<cdot> fold f g e B"
nipkow@15392
   732
  by (simp add: fold_Un_Int)
nipkow@15392
   733
nipkow@15392
   734
lemma (in ACe) fold_UN_disjoint:
nipkow@15392
   735
  "\<lbrakk> finite I; ALL i:I. finite (A i);
nipkow@15392
   736
     ALL i:I. ALL j:I. i \<noteq> j --> A i Int A j = {} \<rbrakk>
nipkow@15392
   737
   \<Longrightarrow> fold f g e (UNION I A) =
nipkow@15392
   738
       fold f (%i. fold f g e (A i)) e I"
berghofe@22262
   739
  apply (induct set: finite, simp, atomize)
nipkow@15392
   740
  apply (subgoal_tac "ALL i:F. x \<noteq> i")
nipkow@15392
   741
   prefer 2 apply blast
nipkow@15392
   742
  apply (subgoal_tac "A x Int UNION F A = {}")
nipkow@15392
   743
   prefer 2 apply blast
nipkow@15392
   744
  apply (simp add: fold_Un_disjoint)
nipkow@15392
   745
  done
nipkow@15392
   746
paulson@15506
   747
text{*Fusion theorem, as described in
paulson@15506
   748
Graham Hutton's paper,
paulson@15506
   749
A Tutorial on the Universality and Expressiveness of Fold,
paulson@15506
   750
JFP 9:4 (355-372), 1999.*}
paulson@15506
   751
lemma (in ACf) fold_fusion:
paulson@15506
   752
      includes ACf g
paulson@15506
   753
      shows
paulson@15506
   754
	"finite A ==> 
paulson@15506
   755
	 (!!x y. h (g x y) = f x (h y)) ==>
paulson@15506
   756
         h (fold g j w A) = fold f j (h w) A"
berghofe@22262
   757
  by (induct set: finite) simp_all
paulson@15506
   758
nipkow@15392
   759
lemma (in ACf) fold_cong:
nipkow@15480
   760
  "finite A \<Longrightarrow> (!!x. x:A ==> g x = h x) ==> fold f g z A = fold f h z A"
nipkow@15480
   761
  apply (subgoal_tac "ALL C. C <= A --> (ALL x:C. g x = h x) --> fold f g z C = fold f h z C")
nipkow@15392
   762
   apply simp
nipkow@15392
   763
  apply (erule finite_induct, simp)
nipkow@15392
   764
  apply (simp add: subset_insert_iff, clarify)
nipkow@15392
   765
  apply (subgoal_tac "finite C")
nipkow@15392
   766
   prefer 2 apply (blast dest: finite_subset [COMP swap_prems_rl])
nipkow@15392
   767
  apply (subgoal_tac "C = insert x (C - {x})")
nipkow@15392
   768
   prefer 2 apply blast
nipkow@15392
   769
  apply (erule ssubst)
nipkow@15392
   770
  apply (drule spec)
nipkow@15392
   771
  apply (erule (1) notE impE)
nipkow@15392
   772
  apply (simp add: Ball_def del: insert_Diff_single)
nipkow@15392
   773
  done
nipkow@15392
   774
nipkow@15392
   775
lemma (in ACe) fold_Sigma: "finite A ==> ALL x:A. finite (B x) ==>
nipkow@15392
   776
  fold f (%x. fold f (g x) e (B x)) e A =
nipkow@15392
   777
  fold f (split g) e (SIGMA x:A. B x)"
nipkow@15392
   778
apply (subst Sigma_def)
paulson@15506
   779
apply (subst fold_UN_disjoint, assumption, simp)
nipkow@15392
   780
 apply blast
nipkow@15392
   781
apply (erule fold_cong)
paulson@15506
   782
apply (subst fold_UN_disjoint, simp, simp)
nipkow@15392
   783
 apply blast
paulson@15506
   784
apply simp
nipkow@15392
   785
done
nipkow@15392
   786
nipkow@15392
   787
lemma (in ACe) fold_distrib: "finite A \<Longrightarrow>
nipkow@15392
   788
   fold f (%x. f (g x) (h x)) e A = f (fold f g e A) (fold f h e A)"
paulson@15506
   789
apply (erule finite_induct, simp)
nipkow@15392
   790
apply (simp add:AC)
nipkow@15392
   791
done
nipkow@15392
   792
nipkow@15392
   793
nipkow@15402
   794
subsection {* Generalized summation over a set *}
nipkow@15402
   795
nipkow@15402
   796
constdefs
nipkow@15402
   797
  setsum :: "('a => 'b) => 'a set => 'b::comm_monoid_add"
nipkow@15402
   798
  "setsum f A == if finite A then fold (op +) f 0 A else 0"
nipkow@15402
   799
wenzelm@19535
   800
abbreviation
wenzelm@21404
   801
  Setsum  ("\<Sum>_" [1000] 999) where
wenzelm@19535
   802
  "\<Sum>A == setsum (%x. x) A"
wenzelm@19535
   803
nipkow@15402
   804
text{* Now: lot's of fancy syntax. First, @{term "setsum (%x. e) A"} is
nipkow@15402
   805
written @{text"\<Sum>x\<in>A. e"}. *}
nipkow@15402
   806
nipkow@15402
   807
syntax
paulson@17189
   808
  "_setsum" :: "pttrn => 'a set => 'b => 'b::comm_monoid_add"    ("(3SUM _:_. _)" [0, 51, 10] 10)
nipkow@15402
   809
syntax (xsymbols)
paulson@17189
   810
  "_setsum" :: "pttrn => 'a set => 'b => 'b::comm_monoid_add"    ("(3\<Sum>_\<in>_. _)" [0, 51, 10] 10)
nipkow@15402
   811
syntax (HTML output)
paulson@17189
   812
  "_setsum" :: "pttrn => 'a set => 'b => 'b::comm_monoid_add"    ("(3\<Sum>_\<in>_. _)" [0, 51, 10] 10)
nipkow@15402
   813
nipkow@15402
   814
translations -- {* Beware of argument permutation! *}
nipkow@15402
   815
  "SUM i:A. b" == "setsum (%i. b) A"
nipkow@15402
   816
  "\<Sum>i\<in>A. b" == "setsum (%i. b) A"
nipkow@15402
   817
nipkow@15402
   818
text{* Instead of @{term"\<Sum>x\<in>{x. P}. e"} we introduce the shorter
nipkow@15402
   819
 @{text"\<Sum>x|P. e"}. *}
nipkow@15402
   820
nipkow@15402
   821
syntax
paulson@17189
   822
  "_qsetsum" :: "pttrn \<Rightarrow> bool \<Rightarrow> 'a \<Rightarrow> 'a" ("(3SUM _ |/ _./ _)" [0,0,10] 10)
nipkow@15402
   823
syntax (xsymbols)
paulson@17189
   824
  "_qsetsum" :: "pttrn \<Rightarrow> bool \<Rightarrow> 'a \<Rightarrow> 'a" ("(3\<Sum>_ | (_)./ _)" [0,0,10] 10)
nipkow@15402
   825
syntax (HTML output)
paulson@17189
   826
  "_qsetsum" :: "pttrn \<Rightarrow> bool \<Rightarrow> 'a \<Rightarrow> 'a" ("(3\<Sum>_ | (_)./ _)" [0,0,10] 10)
nipkow@15402
   827
nipkow@15402
   828
translations
nipkow@15402
   829
  "SUM x|P. t" => "setsum (%x. t) {x. P}"
nipkow@15402
   830
  "\<Sum>x|P. t" => "setsum (%x. t) {x. P}"
nipkow@15402
   831
nipkow@15402
   832
print_translation {*
nipkow@15402
   833
let
wenzelm@19535
   834
  fun setsum_tr' [Abs(x,Tx,t), Const ("Collect",_) $ Abs(y,Ty,P)] = 
wenzelm@19535
   835
    if x<>y then raise Match
wenzelm@19535
   836
    else let val x' = Syntax.mark_bound x
wenzelm@19535
   837
             val t' = subst_bound(x',t)
wenzelm@19535
   838
             val P' = subst_bound(x',P)
wenzelm@19535
   839
         in Syntax.const "_qsetsum" $ Syntax.mark_bound x $ P' $ t' end
wenzelm@19535
   840
in [("setsum", setsum_tr')] end
nipkow@15402
   841
*}
nipkow@15402
   842
wenzelm@19535
   843
nipkow@15402
   844
lemma setsum_empty [simp]: "setsum f {} = 0"
nipkow@15402
   845
  by (simp add: setsum_def)
nipkow@15402
   846
nipkow@15402
   847
lemma setsum_insert [simp]:
nipkow@15402
   848
    "finite F ==> a \<notin> F ==> setsum f (insert a F) = f a + setsum f F"
ballarin@15765
   849
  by (simp add: setsum_def)
nipkow@15402
   850
paulson@15409
   851
lemma setsum_infinite [simp]: "~ finite A ==> setsum f A = 0"
paulson@15409
   852
  by (simp add: setsum_def)
paulson@15409
   853
nipkow@15402
   854
lemma setsum_reindex:
nipkow@15402
   855
     "inj_on f B ==> setsum h (f ` B) = setsum (h \<circ> f) B"
ballarin@15765
   856
by(auto simp add: setsum_def AC_add.fold_reindex dest!:finite_imageD)
nipkow@15402
   857
nipkow@15402
   858
lemma setsum_reindex_id:
nipkow@15402
   859
     "inj_on f B ==> setsum f B = setsum id (f ` B)"
nipkow@15402
   860
by (auto simp add: setsum_reindex)
nipkow@15402
   861
nipkow@15402
   862
lemma setsum_cong:
nipkow@15402
   863
  "A = B ==> (!!x. x:B ==> f x = g x) ==> setsum f A = setsum g B"
ballarin@15765
   864
by(fastsimp simp: setsum_def intro: AC_add.fold_cong)
nipkow@15402
   865
nipkow@16733
   866
lemma strong_setsum_cong[cong]:
nipkow@16733
   867
  "A = B ==> (!!x. x:B =simp=> f x = g x)
nipkow@16733
   868
   ==> setsum (%x. f x) A = setsum (%x. g x) B"
berghofe@16632
   869
by(fastsimp simp: simp_implies_def setsum_def intro: AC_add.fold_cong)
berghofe@16632
   870
nipkow@15554
   871
lemma setsum_cong2: "\<lbrakk>\<And>x. x \<in> A \<Longrightarrow> f x = g x\<rbrakk> \<Longrightarrow> setsum f A = setsum g A";
nipkow@15554
   872
  by (rule setsum_cong[OF refl], auto);
nipkow@15554
   873
nipkow@15402
   874
lemma setsum_reindex_cong:
nipkow@15554
   875
     "[|inj_on f A; B = f ` A; !!a. a:A \<Longrightarrow> g a = h (f a)|] 
nipkow@15402
   876
      ==> setsum h B = setsum g A"
nipkow@15402
   877
  by (simp add: setsum_reindex cong: setsum_cong)
nipkow@15402
   878
nipkow@15542
   879
lemma setsum_0[simp]: "setsum (%i. 0) A = 0"
nipkow@15402
   880
apply (clarsimp simp: setsum_def)
ballarin@15765
   881
apply (erule finite_induct, auto)
nipkow@15402
   882
done
nipkow@15402
   883
nipkow@15543
   884
lemma setsum_0': "ALL a:A. f a = 0 ==> setsum f A = 0"
nipkow@15543
   885
by(simp add:setsum_cong)
nipkow@15402
   886
nipkow@15402
   887
lemma setsum_Un_Int: "finite A ==> finite B ==>
nipkow@15402
   888
  setsum g (A Un B) + setsum g (A Int B) = setsum g A + setsum g B"
nipkow@15402
   889
  -- {* The reversed orientation looks more natural, but LOOPS as a simprule! *}
ballarin@15765
   890
by(simp add: setsum_def AC_add.fold_Un_Int [symmetric])
nipkow@15402
   891
nipkow@15402
   892
lemma setsum_Un_disjoint: "finite A ==> finite B
nipkow@15402
   893
  ==> A Int B = {} ==> setsum g (A Un B) = setsum g A + setsum g B"
nipkow@15402
   894
by (subst setsum_Un_Int [symmetric], auto)
nipkow@15402
   895
paulson@15409
   896
(*But we can't get rid of finite I. If infinite, although the rhs is 0, 
paulson@15409
   897
  the lhs need not be, since UNION I A could still be finite.*)
nipkow@15402
   898
lemma setsum_UN_disjoint:
nipkow@15402
   899
    "finite I ==> (ALL i:I. finite (A i)) ==>
nipkow@15402
   900
        (ALL i:I. ALL j:I. i \<noteq> j --> A i Int A j = {}) ==>
nipkow@15402
   901
      setsum f (UNION I A) = (\<Sum>i\<in>I. setsum f (A i))"
ballarin@15765
   902
by(simp add: setsum_def AC_add.fold_UN_disjoint cong: setsum_cong)
nipkow@15402
   903
paulson@15409
   904
text{*No need to assume that @{term C} is finite.  If infinite, the rhs is
paulson@15409
   905
directly 0, and @{term "Union C"} is also infinite, hence the lhs is also 0.*}
nipkow@15402
   906
lemma setsum_Union_disjoint:
paulson@15409
   907
  "[| (ALL A:C. finite A);
paulson@15409
   908
      (ALL A:C. ALL B:C. A \<noteq> B --> A Int B = {}) |]
paulson@15409
   909
   ==> setsum f (Union C) = setsum (setsum f) C"
paulson@15409
   910
apply (cases "finite C") 
paulson@15409
   911
 prefer 2 apply (force dest: finite_UnionD simp add: setsum_def)
nipkow@15402
   912
  apply (frule setsum_UN_disjoint [of C id f])
paulson@15409
   913
 apply (unfold Union_def id_def, assumption+)
paulson@15409
   914
done
nipkow@15402
   915
paulson@15409
   916
(*But we can't get rid of finite A. If infinite, although the lhs is 0, 
paulson@15409
   917
  the rhs need not be, since SIGMA A B could still be finite.*)
nipkow@15402
   918
lemma setsum_Sigma: "finite A ==> ALL x:A. finite (B x) ==>
paulson@17189
   919
    (\<Sum>x\<in>A. (\<Sum>y\<in>B x. f x y)) = (\<Sum>(x,y)\<in>(SIGMA x:A. B x). f x y)"
ballarin@15765
   920
by(simp add:setsum_def AC_add.fold_Sigma split_def cong:setsum_cong)
nipkow@15402
   921
paulson@15409
   922
text{*Here we can eliminate the finiteness assumptions, by cases.*}
paulson@15409
   923
lemma setsum_cartesian_product: 
paulson@17189
   924
   "(\<Sum>x\<in>A. (\<Sum>y\<in>B. f x y)) = (\<Sum>(x,y) \<in> A <*> B. f x y)"
paulson@15409
   925
apply (cases "finite A") 
paulson@15409
   926
 apply (cases "finite B") 
paulson@15409
   927
  apply (simp add: setsum_Sigma)
paulson@15409
   928
 apply (cases "A={}", simp)
nipkow@15543
   929
 apply (simp) 
paulson@15409
   930
apply (auto simp add: setsum_def
paulson@15409
   931
            dest: finite_cartesian_productD1 finite_cartesian_productD2) 
paulson@15409
   932
done
nipkow@15402
   933
nipkow@15402
   934
lemma setsum_addf: "setsum (%x. f x + g x) A = (setsum f A + setsum g A)"
ballarin@15765
   935
by(simp add:setsum_def AC_add.fold_distrib)
nipkow@15402
   936
nipkow@15402
   937
nipkow@15402
   938
subsubsection {* Properties in more restricted classes of structures *}
nipkow@15402
   939
nipkow@15402
   940
lemma setsum_SucD: "setsum f A = Suc n ==> EX a:A. 0 < f a"
nipkow@15402
   941
  apply (case_tac "finite A")
nipkow@15402
   942
   prefer 2 apply (simp add: setsum_def)
nipkow@15402
   943
  apply (erule rev_mp)
nipkow@15402
   944
  apply (erule finite_induct, auto)
nipkow@15402
   945
  done
nipkow@15402
   946
nipkow@15402
   947
lemma setsum_eq_0_iff [simp]:
nipkow@15402
   948
    "finite F ==> (setsum f F = 0) = (ALL a:F. f a = (0::nat))"
berghofe@22262
   949
  by (induct set: finite) auto
nipkow@15402
   950
nipkow@15402
   951
lemma setsum_Un_nat: "finite A ==> finite B ==>
nipkow@15402
   952
    (setsum f (A Un B) :: nat) = setsum f A + setsum f B - setsum f (A Int B)"
nipkow@15402
   953
  -- {* For the natural numbers, we have subtraction. *}
nipkow@15402
   954
  by (subst setsum_Un_Int [symmetric], auto simp add: ring_eq_simps)
nipkow@15402
   955
nipkow@15402
   956
lemma setsum_Un: "finite A ==> finite B ==>
nipkow@15402
   957
    (setsum f (A Un B) :: 'a :: ab_group_add) =
nipkow@15402
   958
      setsum f A + setsum f B - setsum f (A Int B)"
nipkow@15402
   959
  by (subst setsum_Un_Int [symmetric], auto simp add: ring_eq_simps)
nipkow@15402
   960
nipkow@15402
   961
lemma setsum_diff1_nat: "(setsum f (A - {a}) :: nat) =
nipkow@15402
   962
    (if a:A then setsum f A - f a else setsum f A)"
nipkow@15402
   963
  apply (case_tac "finite A")
nipkow@15402
   964
   prefer 2 apply (simp add: setsum_def)
nipkow@15402
   965
  apply (erule finite_induct)
nipkow@15402
   966
   apply (auto simp add: insert_Diff_if)
nipkow@15402
   967
  apply (drule_tac a = a in mk_disjoint_insert, auto)
nipkow@15402
   968
  done
nipkow@15402
   969
nipkow@15402
   970
lemma setsum_diff1: "finite A \<Longrightarrow>
nipkow@15402
   971
  (setsum f (A - {a}) :: ('a::ab_group_add)) =
nipkow@15402
   972
  (if a:A then setsum f A - f a else setsum f A)"
nipkow@15402
   973
  by (erule finite_induct) (auto simp add: insert_Diff_if)
nipkow@15402
   974
obua@15552
   975
lemma setsum_diff1'[rule_format]: "finite A \<Longrightarrow> a \<in> A \<longrightarrow> (\<Sum> x \<in> A. f x) = f a + (\<Sum> x \<in> (A - {a}). f x)"
obua@15552
   976
  apply (erule finite_induct[where F=A and P="% A. (a \<in> A \<longrightarrow> (\<Sum> x \<in> A. f x) = f a + (\<Sum> x \<in> (A - {a}). f x))"])
obua@15552
   977
  apply (auto simp add: insert_Diff_if add_ac)
obua@15552
   978
  done
obua@15552
   979
nipkow@15402
   980
(* By Jeremy Siek: *)
nipkow@15402
   981
nipkow@15402
   982
lemma setsum_diff_nat: 
wenzelm@19535
   983
  assumes "finite B"
wenzelm@19535
   984
    and "B \<subseteq> A"
wenzelm@19535
   985
  shows "(setsum f (A - B) :: nat) = (setsum f A) - (setsum f B)"
wenzelm@19535
   986
  using prems
wenzelm@19535
   987
proof induct
nipkow@15402
   988
  show "setsum f (A - {}) = (setsum f A) - (setsum f {})" by simp
nipkow@15402
   989
next
nipkow@15402
   990
  fix F x assume finF: "finite F" and xnotinF: "x \<notin> F"
nipkow@15402
   991
    and xFinA: "insert x F \<subseteq> A"
nipkow@15402
   992
    and IH: "F \<subseteq> A \<Longrightarrow> setsum f (A - F) = setsum f A - setsum f F"
nipkow@15402
   993
  from xnotinF xFinA have xinAF: "x \<in> (A - F)" by simp
nipkow@15402
   994
  from xinAF have A: "setsum f ((A - F) - {x}) = setsum f (A - F) - f x"
nipkow@15402
   995
    by (simp add: setsum_diff1_nat)
nipkow@15402
   996
  from xFinA have "F \<subseteq> A" by simp
nipkow@15402
   997
  with IH have "setsum f (A - F) = setsum f A - setsum f F" by simp
nipkow@15402
   998
  with A have B: "setsum f ((A - F) - {x}) = setsum f A - setsum f F - f x"
nipkow@15402
   999
    by simp
nipkow@15402
  1000
  from xnotinF have "A - insert x F = (A - F) - {x}" by auto
nipkow@15402
  1001
  with B have C: "setsum f (A - insert x F) = setsum f A - setsum f F - f x"
nipkow@15402
  1002
    by simp
nipkow@15402
  1003
  from finF xnotinF have "setsum f (insert x F) = setsum f F + f x" by simp
nipkow@15402
  1004
  with C have "setsum f (A - insert x F) = setsum f A - setsum f (insert x F)"
nipkow@15402
  1005
    by simp
nipkow@15402
  1006
  thus "setsum f (A - insert x F) = setsum f A - setsum f (insert x F)" by simp
nipkow@15402
  1007
qed
nipkow@15402
  1008
nipkow@15402
  1009
lemma setsum_diff:
nipkow@15402
  1010
  assumes le: "finite A" "B \<subseteq> A"
nipkow@15402
  1011
  shows "setsum f (A - B) = setsum f A - ((setsum f B)::('a::ab_group_add))"
nipkow@15402
  1012
proof -
nipkow@15402
  1013
  from le have finiteB: "finite B" using finite_subset by auto
nipkow@15402
  1014
  show ?thesis using finiteB le
wenzelm@21575
  1015
  proof induct
wenzelm@19535
  1016
    case empty
wenzelm@19535
  1017
    thus ?case by auto
wenzelm@19535
  1018
  next
wenzelm@19535
  1019
    case (insert x F)
wenzelm@19535
  1020
    thus ?case using le finiteB 
wenzelm@19535
  1021
      by (simp add: Diff_insert[where a=x and B=F] setsum_diff1 insert_absorb)
nipkow@15402
  1022
  qed
wenzelm@19535
  1023
qed
nipkow@15402
  1024
nipkow@15402
  1025
lemma setsum_mono:
nipkow@15402
  1026
  assumes le: "\<And>i. i\<in>K \<Longrightarrow> f (i::'a) \<le> ((g i)::('b::{comm_monoid_add, pordered_ab_semigroup_add}))"
nipkow@15402
  1027
  shows "(\<Sum>i\<in>K. f i) \<le> (\<Sum>i\<in>K. g i)"
nipkow@15402
  1028
proof (cases "finite K")
nipkow@15402
  1029
  case True
nipkow@15402
  1030
  thus ?thesis using le
wenzelm@19535
  1031
  proof induct
nipkow@15402
  1032
    case empty
nipkow@15402
  1033
    thus ?case by simp
nipkow@15402
  1034
  next
nipkow@15402
  1035
    case insert
wenzelm@19535
  1036
    thus ?case using add_mono by fastsimp
nipkow@15402
  1037
  qed
nipkow@15402
  1038
next
nipkow@15402
  1039
  case False
nipkow@15402
  1040
  thus ?thesis
nipkow@15402
  1041
    by (simp add: setsum_def)
nipkow@15402
  1042
qed
nipkow@15402
  1043
nipkow@15554
  1044
lemma setsum_strict_mono:
wenzelm@19535
  1045
  fixes f :: "'a \<Rightarrow> 'b::{pordered_cancel_ab_semigroup_add,comm_monoid_add}"
wenzelm@19535
  1046
  assumes "finite A"  "A \<noteq> {}"
wenzelm@19535
  1047
    and "!!x. x:A \<Longrightarrow> f x < g x"
wenzelm@19535
  1048
  shows "setsum f A < setsum g A"
wenzelm@19535
  1049
  using prems
nipkow@15554
  1050
proof (induct rule: finite_ne_induct)
nipkow@15554
  1051
  case singleton thus ?case by simp
nipkow@15554
  1052
next
nipkow@15554
  1053
  case insert thus ?case by (auto simp: add_strict_mono)
nipkow@15554
  1054
qed
nipkow@15554
  1055
nipkow@15535
  1056
lemma setsum_negf:
wenzelm@19535
  1057
  "setsum (%x. - (f x)::'a::ab_group_add) A = - setsum f A"
nipkow@15535
  1058
proof (cases "finite A")
berghofe@22262
  1059
  case True thus ?thesis by (induct set: finite) auto
nipkow@15535
  1060
next
nipkow@15535
  1061
  case False thus ?thesis by (simp add: setsum_def)
nipkow@15535
  1062
qed
nipkow@15402
  1063
nipkow@15535
  1064
lemma setsum_subtractf:
wenzelm@19535
  1065
  "setsum (%x. ((f x)::'a::ab_group_add) - g x) A =
wenzelm@19535
  1066
    setsum f A - setsum g A"
nipkow@15535
  1067
proof (cases "finite A")
nipkow@15535
  1068
  case True thus ?thesis by (simp add: diff_minus setsum_addf setsum_negf)
nipkow@15535
  1069
next
nipkow@15535
  1070
  case False thus ?thesis by (simp add: setsum_def)
nipkow@15535
  1071
qed
nipkow@15402
  1072
nipkow@15535
  1073
lemma setsum_nonneg:
wenzelm@19535
  1074
  assumes nn: "\<forall>x\<in>A. (0::'a::{pordered_ab_semigroup_add,comm_monoid_add}) \<le> f x"
wenzelm@19535
  1075
  shows "0 \<le> setsum f A"
nipkow@15535
  1076
proof (cases "finite A")
nipkow@15535
  1077
  case True thus ?thesis using nn
wenzelm@21575
  1078
  proof induct
wenzelm@19535
  1079
    case empty then show ?case by simp
wenzelm@19535
  1080
  next
wenzelm@19535
  1081
    case (insert x F)
wenzelm@19535
  1082
    then have "0 + 0 \<le> f x + setsum f F" by (blast intro: add_mono)
wenzelm@19535
  1083
    with insert show ?case by simp
wenzelm@19535
  1084
  qed
nipkow@15535
  1085
next
nipkow@15535
  1086
  case False thus ?thesis by (simp add: setsum_def)
nipkow@15535
  1087
qed
nipkow@15402
  1088
nipkow@15535
  1089
lemma setsum_nonpos:
wenzelm@19535
  1090
  assumes np: "\<forall>x\<in>A. f x \<le> (0::'a::{pordered_ab_semigroup_add,comm_monoid_add})"
wenzelm@19535
  1091
  shows "setsum f A \<le> 0"
nipkow@15535
  1092
proof (cases "finite A")
nipkow@15535
  1093
  case True thus ?thesis using np
wenzelm@21575
  1094
  proof induct
wenzelm@19535
  1095
    case empty then show ?case by simp
wenzelm@19535
  1096
  next
wenzelm@19535
  1097
    case (insert x F)
wenzelm@19535
  1098
    then have "f x + setsum f F \<le> 0 + 0" by (blast intro: add_mono)
wenzelm@19535
  1099
    with insert show ?case by simp
wenzelm@19535
  1100
  qed
nipkow@15535
  1101
next
nipkow@15535
  1102
  case False thus ?thesis by (simp add: setsum_def)
nipkow@15535
  1103
qed
nipkow@15402
  1104
nipkow@15539
  1105
lemma setsum_mono2:
nipkow@15539
  1106
fixes f :: "'a \<Rightarrow> 'b :: {pordered_ab_semigroup_add_imp_le,comm_monoid_add}"
nipkow@15539
  1107
assumes fin: "finite B" and sub: "A \<subseteq> B" and nn: "\<And>b. b \<in> B-A \<Longrightarrow> 0 \<le> f b"
nipkow@15539
  1108
shows "setsum f A \<le> setsum f B"
nipkow@15539
  1109
proof -
nipkow@15539
  1110
  have "setsum f A \<le> setsum f A + setsum f (B-A)"
nipkow@15539
  1111
    by(simp add: add_increasing2[OF setsum_nonneg] nn Ball_def)
nipkow@15539
  1112
  also have "\<dots> = setsum f (A \<union> (B-A))" using fin finite_subset[OF sub fin]
nipkow@15539
  1113
    by (simp add:setsum_Un_disjoint del:Un_Diff_cancel)
nipkow@15539
  1114
  also have "A \<union> (B-A) = B" using sub by blast
nipkow@15539
  1115
  finally show ?thesis .
nipkow@15539
  1116
qed
nipkow@15542
  1117
avigad@16775
  1118
lemma setsum_mono3: "finite B ==> A <= B ==> 
avigad@16775
  1119
    ALL x: B - A. 
avigad@16775
  1120
      0 <= ((f x)::'a::{comm_monoid_add,pordered_ab_semigroup_add}) ==>
avigad@16775
  1121
        setsum f A <= setsum f B"
avigad@16775
  1122
  apply (subgoal_tac "setsum f B = setsum f A + setsum f (B - A)")
avigad@16775
  1123
  apply (erule ssubst)
avigad@16775
  1124
  apply (subgoal_tac "setsum f A + 0 <= setsum f A + setsum f (B - A)")
avigad@16775
  1125
  apply simp
avigad@16775
  1126
  apply (rule add_left_mono)
avigad@16775
  1127
  apply (erule setsum_nonneg)
avigad@16775
  1128
  apply (subst setsum_Un_disjoint [THEN sym])
avigad@16775
  1129
  apply (erule finite_subset, assumption)
avigad@16775
  1130
  apply (rule finite_subset)
avigad@16775
  1131
  prefer 2
avigad@16775
  1132
  apply assumption
avigad@16775
  1133
  apply auto
avigad@16775
  1134
  apply (rule setsum_cong)
avigad@16775
  1135
  apply auto
avigad@16775
  1136
done
avigad@16775
  1137
ballarin@19279
  1138
lemma setsum_right_distrib: 
nipkow@15402
  1139
  fixes f :: "'a => ('b::semiring_0_cancel)"
nipkow@15402
  1140
  shows "r * setsum f A = setsum (%n. r * f n) A"
nipkow@15402
  1141
proof (cases "finite A")
nipkow@15402
  1142
  case True
nipkow@15402
  1143
  thus ?thesis
wenzelm@21575
  1144
  proof induct
nipkow@15402
  1145
    case empty thus ?case by simp
nipkow@15402
  1146
  next
nipkow@15402
  1147
    case (insert x A) thus ?case by (simp add: right_distrib)
nipkow@15402
  1148
  qed
nipkow@15402
  1149
next
nipkow@15402
  1150
  case False thus ?thesis by (simp add: setsum_def)
nipkow@15402
  1151
qed
nipkow@15402
  1152
ballarin@17149
  1153
lemma setsum_left_distrib:
ballarin@17149
  1154
  "setsum f A * (r::'a::semiring_0_cancel) = (\<Sum>n\<in>A. f n * r)"
ballarin@17149
  1155
proof (cases "finite A")
ballarin@17149
  1156
  case True
ballarin@17149
  1157
  then show ?thesis
ballarin@17149
  1158
  proof induct
ballarin@17149
  1159
    case empty thus ?case by simp
ballarin@17149
  1160
  next
ballarin@17149
  1161
    case (insert x A) thus ?case by (simp add: left_distrib)
ballarin@17149
  1162
  qed
ballarin@17149
  1163
next
ballarin@17149
  1164
  case False thus ?thesis by (simp add: setsum_def)
ballarin@17149
  1165
qed
ballarin@17149
  1166
ballarin@17149
  1167
lemma setsum_divide_distrib:
ballarin@17149
  1168
  "setsum f A / (r::'a::field) = (\<Sum>n\<in>A. f n / r)"
ballarin@17149
  1169
proof (cases "finite A")
ballarin@17149
  1170
  case True
ballarin@17149
  1171
  then show ?thesis
ballarin@17149
  1172
  proof induct
ballarin@17149
  1173
    case empty thus ?case by simp
ballarin@17149
  1174
  next
ballarin@17149
  1175
    case (insert x A) thus ?case by (simp add: add_divide_distrib)
ballarin@17149
  1176
  qed
ballarin@17149
  1177
next
ballarin@17149
  1178
  case False thus ?thesis by (simp add: setsum_def)
ballarin@17149
  1179
qed
ballarin@17149
  1180
nipkow@15535
  1181
lemma setsum_abs[iff]: 
nipkow@15402
  1182
  fixes f :: "'a => ('b::lordered_ab_group_abs)"
nipkow@15402
  1183
  shows "abs (setsum f A) \<le> setsum (%i. abs(f i)) A"
nipkow@15535
  1184
proof (cases "finite A")
nipkow@15535
  1185
  case True
nipkow@15535
  1186
  thus ?thesis
wenzelm@21575
  1187
  proof induct
nipkow@15535
  1188
    case empty thus ?case by simp
nipkow@15535
  1189
  next
nipkow@15535
  1190
    case (insert x A)
nipkow@15535
  1191
    thus ?case by (auto intro: abs_triangle_ineq order_trans)
nipkow@15535
  1192
  qed
nipkow@15402
  1193
next
nipkow@15535
  1194
  case False thus ?thesis by (simp add: setsum_def)
nipkow@15402
  1195
qed
nipkow@15402
  1196
nipkow@15535
  1197
lemma setsum_abs_ge_zero[iff]: 
nipkow@15402
  1198
  fixes f :: "'a => ('b::lordered_ab_group_abs)"
nipkow@15402
  1199
  shows "0 \<le> setsum (%i. abs(f i)) A"
nipkow@15535
  1200
proof (cases "finite A")
nipkow@15535
  1201
  case True
nipkow@15535
  1202
  thus ?thesis
wenzelm@21575
  1203
  proof induct
nipkow@15535
  1204
    case empty thus ?case by simp
nipkow@15535
  1205
  next
nipkow@21733
  1206
    case (insert x A) thus ?case by (auto simp: add_nonneg_nonneg)
nipkow@15535
  1207
  qed
nipkow@15402
  1208
next
nipkow@15535
  1209
  case False thus ?thesis by (simp add: setsum_def)
nipkow@15402
  1210
qed
nipkow@15402
  1211
nipkow@15539
  1212
lemma abs_setsum_abs[simp]: 
nipkow@15539
  1213
  fixes f :: "'a => ('b::lordered_ab_group_abs)"
nipkow@15539
  1214
  shows "abs (\<Sum>a\<in>A. abs(f a)) = (\<Sum>a\<in>A. abs(f a))"
nipkow@15539
  1215
proof (cases "finite A")
nipkow@15539
  1216
  case True
nipkow@15539
  1217
  thus ?thesis
wenzelm@21575
  1218
  proof induct
nipkow@15539
  1219
    case empty thus ?case by simp
nipkow@15539
  1220
  next
nipkow@15539
  1221
    case (insert a A)
nipkow@15539
  1222
    hence "\<bar>\<Sum>a\<in>insert a A. \<bar>f a\<bar>\<bar> = \<bar>\<bar>f a\<bar> + (\<Sum>a\<in>A. \<bar>f a\<bar>)\<bar>" by simp
nipkow@15539
  1223
    also have "\<dots> = \<bar>\<bar>f a\<bar> + \<bar>\<Sum>a\<in>A. \<bar>f a\<bar>\<bar>\<bar>"  using insert by simp
avigad@16775
  1224
    also have "\<dots> = \<bar>f a\<bar> + \<bar>\<Sum>a\<in>A. \<bar>f a\<bar>\<bar>"
avigad@16775
  1225
      by (simp del: abs_of_nonneg)
nipkow@15539
  1226
    also have "\<dots> = (\<Sum>a\<in>insert a A. \<bar>f a\<bar>)" using insert by simp
nipkow@15539
  1227
    finally show ?case .
nipkow@15539
  1228
  qed
nipkow@15539
  1229
next
nipkow@15539
  1230
  case False thus ?thesis by (simp add: setsum_def)
nipkow@15539
  1231
qed
nipkow@15539
  1232
nipkow@15402
  1233
ballarin@17149
  1234
text {* Commuting outer and inner summation *}
ballarin@17149
  1235
ballarin@17149
  1236
lemma swap_inj_on:
ballarin@17149
  1237
  "inj_on (%(i, j). (j, i)) (A \<times> B)"
ballarin@17149
  1238
  by (unfold inj_on_def) fast
ballarin@17149
  1239
ballarin@17149
  1240
lemma swap_product:
ballarin@17149
  1241
  "(%(i, j). (j, i)) ` (A \<times> B) = B \<times> A"
ballarin@17149
  1242
  by (simp add: split_def image_def) blast
ballarin@17149
  1243
ballarin@17149
  1244
lemma setsum_commute:
ballarin@17149
  1245
  "(\<Sum>i\<in>A. \<Sum>j\<in>B. f i j) = (\<Sum>j\<in>B. \<Sum>i\<in>A. f i j)"
ballarin@17149
  1246
proof (simp add: setsum_cartesian_product)
paulson@17189
  1247
  have "(\<Sum>(x,y) \<in> A <*> B. f x y) =
paulson@17189
  1248
    (\<Sum>(y,x) \<in> (%(i, j). (j, i)) ` (A \<times> B). f x y)"
ballarin@17149
  1249
    (is "?s = _")
ballarin@17149
  1250
    apply (simp add: setsum_reindex [where f = "%(i, j). (j, i)"] swap_inj_on)
ballarin@17149
  1251
    apply (simp add: split_def)
ballarin@17149
  1252
    done
paulson@17189
  1253
  also have "... = (\<Sum>(y,x)\<in>B \<times> A. f x y)"
ballarin@17149
  1254
    (is "_ = ?t")
ballarin@17149
  1255
    apply (simp add: swap_product)
ballarin@17149
  1256
    done
ballarin@17149
  1257
  finally show "?s = ?t" .
ballarin@17149
  1258
qed
ballarin@17149
  1259
ballarin@19279
  1260
lemma setsum_product:
ballarin@19279
  1261
  fixes f :: "nat => ('a::semiring_0_cancel)"
ballarin@19279
  1262
  shows "setsum f A * setsum g B = (\<Sum>i\<in>A. \<Sum>j\<in>B. f i * g j)"
ballarin@19279
  1263
  by (simp add: setsum_right_distrib setsum_left_distrib) (rule setsum_commute)
ballarin@19279
  1264
ballarin@17149
  1265
nipkow@15402
  1266
subsection {* Generalized product over a set *}
nipkow@15402
  1267
nipkow@15402
  1268
constdefs
nipkow@15402
  1269
  setprod :: "('a => 'b) => 'a set => 'b::comm_monoid_mult"
nipkow@15402
  1270
  "setprod f A == if finite A then fold (op *) f 1 A else 1"
nipkow@15402
  1271
wenzelm@19535
  1272
abbreviation
wenzelm@21404
  1273
  Setprod  ("\<Prod>_" [1000] 999) where
wenzelm@19535
  1274
  "\<Prod>A == setprod (%x. x) A"
wenzelm@19535
  1275
nipkow@15402
  1276
syntax
paulson@17189
  1277
  "_setprod" :: "pttrn => 'a set => 'b => 'b::comm_monoid_mult"  ("(3PROD _:_. _)" [0, 51, 10] 10)
nipkow@15402
  1278
syntax (xsymbols)
paulson@17189
  1279
  "_setprod" :: "pttrn => 'a set => 'b => 'b::comm_monoid_mult"  ("(3\<Prod>_\<in>_. _)" [0, 51, 10] 10)
nipkow@15402
  1280
syntax (HTML output)
paulson@17189
  1281
  "_setprod" :: "pttrn => 'a set => 'b => 'b::comm_monoid_mult"  ("(3\<Prod>_\<in>_. _)" [0, 51, 10] 10)
nipkow@16550
  1282
nipkow@16550
  1283
translations -- {* Beware of argument permutation! *}
nipkow@16550
  1284
  "PROD i:A. b" == "setprod (%i. b) A" 
nipkow@16550
  1285
  "\<Prod>i\<in>A. b" == "setprod (%i. b) A" 
nipkow@16550
  1286
nipkow@16550
  1287
text{* Instead of @{term"\<Prod>x\<in>{x. P}. e"} we introduce the shorter
nipkow@16550
  1288
 @{text"\<Prod>x|P. e"}. *}
nipkow@16550
  1289
nipkow@16550
  1290
syntax
paulson@17189
  1291
  "_qsetprod" :: "pttrn \<Rightarrow> bool \<Rightarrow> 'a \<Rightarrow> 'a" ("(3PROD _ |/ _./ _)" [0,0,10] 10)
nipkow@16550
  1292
syntax (xsymbols)
paulson@17189
  1293
  "_qsetprod" :: "pttrn \<Rightarrow> bool \<Rightarrow> 'a \<Rightarrow> 'a" ("(3\<Prod>_ | (_)./ _)" [0,0,10] 10)
nipkow@16550
  1294
syntax (HTML output)
paulson@17189
  1295
  "_qsetprod" :: "pttrn \<Rightarrow> bool \<Rightarrow> 'a \<Rightarrow> 'a" ("(3\<Prod>_ | (_)./ _)" [0,0,10] 10)
nipkow@16550
  1296
nipkow@15402
  1297
translations
nipkow@16550
  1298
  "PROD x|P. t" => "setprod (%x. t) {x. P}"
nipkow@16550
  1299
  "\<Prod>x|P. t" => "setprod (%x. t) {x. P}"
nipkow@16550
  1300
nipkow@15402
  1301
nipkow@15402
  1302
lemma setprod_empty [simp]: "setprod f {} = 1"
nipkow@15402
  1303
  by (auto simp add: setprod_def)
nipkow@15402
  1304
nipkow@15402
  1305
lemma setprod_insert [simp]: "[| finite A; a \<notin> A |] ==>
nipkow@15402
  1306
    setprod f (insert a A) = f a * setprod f A"
ballarin@19931
  1307
  by (simp add: setprod_def)
nipkow@15402
  1308
paulson@15409
  1309
lemma setprod_infinite [simp]: "~ finite A ==> setprod f A = 1"
paulson@15409
  1310
  by (simp add: setprod_def)
paulson@15409
  1311
nipkow@15402
  1312
lemma setprod_reindex:
nipkow@15402
  1313
     "inj_on f B ==> setprod h (f ` B) = setprod (h \<circ> f) B"
ballarin@15765
  1314
by(auto simp: setprod_def AC_mult.fold_reindex dest!:finite_imageD)
nipkow@15402
  1315
nipkow@15402
  1316
lemma setprod_reindex_id: "inj_on f B ==> setprod f B = setprod id (f ` B)"
nipkow@15402
  1317
by (auto simp add: setprod_reindex)
nipkow@15402
  1318
nipkow@15402
  1319
lemma setprod_cong:
nipkow@15402
  1320
  "A = B ==> (!!x. x:B ==> f x = g x) ==> setprod f A = setprod g B"
ballarin@15765
  1321
by(fastsimp simp: setprod_def intro: AC_mult.fold_cong)
nipkow@15402
  1322
berghofe@16632
  1323
lemma strong_setprod_cong:
berghofe@16632
  1324
  "A = B ==> (!!x. x:B =simp=> f x = g x) ==> setprod f A = setprod g B"
berghofe@16632
  1325
by(fastsimp simp: simp_implies_def setprod_def intro: AC_mult.fold_cong)
berghofe@16632
  1326
nipkow@15402
  1327
lemma setprod_reindex_cong: "inj_on f A ==>
nipkow@15402
  1328
    B = f ` A ==> g = h \<circ> f ==> setprod h B = setprod g A"
nipkow@15402
  1329
  by (frule setprod_reindex, simp)
nipkow@15402
  1330
nipkow@15402
  1331
nipkow@15402
  1332
lemma setprod_1: "setprod (%i. 1) A = 1"
nipkow@15402
  1333
  apply (case_tac "finite A")
nipkow@15402
  1334
  apply (erule finite_induct, auto simp add: mult_ac)
nipkow@15402
  1335
  done
nipkow@15402
  1336
nipkow@15402
  1337
lemma setprod_1': "ALL a:F. f a = 1 ==> setprod f F = 1"
nipkow@15402
  1338
  apply (subgoal_tac "setprod f F = setprod (%x. 1) F")
nipkow@15402
  1339
  apply (erule ssubst, rule setprod_1)
nipkow@15402
  1340
  apply (rule setprod_cong, auto)
nipkow@15402
  1341
  done
nipkow@15402
  1342
nipkow@15402
  1343
lemma setprod_Un_Int: "finite A ==> finite B
nipkow@15402
  1344
    ==> setprod g (A Un B) * setprod g (A Int B) = setprod g A * setprod g B"
ballarin@15765
  1345
by(simp add: setprod_def AC_mult.fold_Un_Int[symmetric])
nipkow@15402
  1346
nipkow@15402
  1347
lemma setprod_Un_disjoint: "finite A ==> finite B
nipkow@15402
  1348
  ==> A Int B = {} ==> setprod g (A Un B) = setprod g A * setprod g B"
nipkow@15402
  1349
by (subst setprod_Un_Int [symmetric], auto)
nipkow@15402
  1350
nipkow@15402
  1351
lemma setprod_UN_disjoint:
nipkow@15402
  1352
    "finite I ==> (ALL i:I. finite (A i)) ==>
nipkow@15402
  1353
        (ALL i:I. ALL j:I. i \<noteq> j --> A i Int A j = {}) ==>
nipkow@15402
  1354
      setprod f (UNION I A) = setprod (%i. setprod f (A i)) I"
ballarin@15765
  1355
by(simp add: setprod_def AC_mult.fold_UN_disjoint cong: setprod_cong)
nipkow@15402
  1356
nipkow@15402
  1357
lemma setprod_Union_disjoint:
paulson@15409
  1358
  "[| (ALL A:C. finite A);
paulson@15409
  1359
      (ALL A:C. ALL B:C. A \<noteq> B --> A Int B = {}) |] 
paulson@15409
  1360
   ==> setprod f (Union C) = setprod (setprod f) C"
paulson@15409
  1361
apply (cases "finite C") 
paulson@15409
  1362
 prefer 2 apply (force dest: finite_UnionD simp add: setprod_def)
nipkow@15402
  1363
  apply (frule setprod_UN_disjoint [of C id f])
paulson@15409
  1364
 apply (unfold Union_def id_def, assumption+)
paulson@15409
  1365
done
nipkow@15402
  1366
nipkow@15402
  1367
lemma setprod_Sigma: "finite A ==> ALL x:A. finite (B x) ==>
nipkow@16550
  1368
    (\<Prod>x\<in>A. (\<Prod>y\<in> B x. f x y)) =
paulson@17189
  1369
    (\<Prod>(x,y)\<in>(SIGMA x:A. B x). f x y)"
ballarin@15765
  1370
by(simp add:setprod_def AC_mult.fold_Sigma split_def cong:setprod_cong)
nipkow@15402
  1371
paulson@15409
  1372
text{*Here we can eliminate the finiteness assumptions, by cases.*}
paulson@15409
  1373
lemma setprod_cartesian_product: 
paulson@17189
  1374
     "(\<Prod>x\<in>A. (\<Prod>y\<in> B. f x y)) = (\<Prod>(x,y)\<in>(A <*> B). f x y)"
paulson@15409
  1375
apply (cases "finite A") 
paulson@15409
  1376
 apply (cases "finite B") 
paulson@15409
  1377
  apply (simp add: setprod_Sigma)
paulson@15409
  1378
 apply (cases "A={}", simp)
paulson@15409
  1379
 apply (simp add: setprod_1) 
paulson@15409
  1380
apply (auto simp add: setprod_def
paulson@15409
  1381
            dest: finite_cartesian_productD1 finite_cartesian_productD2) 
paulson@15409
  1382
done
nipkow@15402
  1383
nipkow@15402
  1384
lemma setprod_timesf:
paulson@15409
  1385
     "setprod (%x. f x * g x) A = (setprod f A * setprod g A)"
ballarin@15765
  1386
by(simp add:setprod_def AC_mult.fold_distrib)
nipkow@15402
  1387
nipkow@15402
  1388
nipkow@15402
  1389
subsubsection {* Properties in more restricted classes of structures *}
nipkow@15402
  1390
nipkow@15402
  1391
lemma setprod_eq_1_iff [simp]:
nipkow@15402
  1392
    "finite F ==> (setprod f F = 1) = (ALL a:F. f a = (1::nat))"
berghofe@22262
  1393
  by (induct set: finite) auto
nipkow@15402
  1394
nipkow@15402
  1395
lemma setprod_zero:
nipkow@15402
  1396
     "finite A ==> EX x: A. f x = (0::'a::comm_semiring_1_cancel) ==> setprod f A = 0"
berghofe@22262
  1397
  apply (induct set: finite, force, clarsimp)
nipkow@15402
  1398
  apply (erule disjE, auto)
nipkow@15402
  1399
  done
nipkow@15402
  1400
nipkow@15402
  1401
lemma setprod_nonneg [rule_format]:
nipkow@15402
  1402
     "(ALL x: A. (0::'a::ordered_idom) \<le> f x) --> 0 \<le> setprod f A"
nipkow@15402
  1403
  apply (case_tac "finite A")
berghofe@22262
  1404
  apply (induct set: finite, force, clarsimp)
nipkow@15402
  1405
  apply (subgoal_tac "0 * 0 \<le> f x * setprod f F", force)
nipkow@15402
  1406
  apply (rule mult_mono, assumption+)
nipkow@15402
  1407
  apply (auto simp add: setprod_def)
nipkow@15402
  1408
  done
nipkow@15402
  1409
nipkow@15402
  1410
lemma setprod_pos [rule_format]: "(ALL x: A. (0::'a::ordered_idom) < f x)
nipkow@15402
  1411
     --> 0 < setprod f A"
nipkow@15402
  1412
  apply (case_tac "finite A")
berghofe@22262
  1413
  apply (induct set: finite, force, clarsimp)
nipkow@15402
  1414
  apply (subgoal_tac "0 * 0 < f x * setprod f F", force)
nipkow@15402
  1415
  apply (rule mult_strict_mono, assumption+)
nipkow@15402
  1416
  apply (auto simp add: setprod_def)
nipkow@15402
  1417
  done
nipkow@15402
  1418
nipkow@15402
  1419
lemma setprod_nonzero [rule_format]:
nipkow@15402
  1420
    "(ALL x y. (x::'a::comm_semiring_1_cancel) * y = 0 --> x = 0 | y = 0) ==>
nipkow@15402
  1421
      finite A ==> (ALL x: A. f x \<noteq> (0::'a)) --> setprod f A \<noteq> 0"
nipkow@15402
  1422
  apply (erule finite_induct, auto)
nipkow@15402
  1423
  done
nipkow@15402
  1424
nipkow@15402
  1425
lemma setprod_zero_eq:
nipkow@15402
  1426
    "(ALL x y. (x::'a::comm_semiring_1_cancel) * y = 0 --> x = 0 | y = 0) ==>
nipkow@15402
  1427
     finite A ==> (setprod f A = (0::'a)) = (EX x: A. f x = 0)"
nipkow@15402
  1428
  apply (insert setprod_zero [of A f] setprod_nonzero [of A f], blast)
nipkow@15402
  1429
  done
nipkow@15402
  1430
nipkow@15402
  1431
lemma setprod_nonzero_field:
nipkow@15402
  1432
    "finite A ==> (ALL x: A. f x \<noteq> (0::'a::field)) ==> setprod f A \<noteq> 0"
nipkow@15402
  1433
  apply (rule setprod_nonzero, auto)
nipkow@15402
  1434
  done
nipkow@15402
  1435
nipkow@15402
  1436
lemma setprod_zero_eq_field:
nipkow@15402
  1437
    "finite A ==> (setprod f A = (0::'a::field)) = (EX x: A. f x = 0)"
nipkow@15402
  1438
  apply (rule setprod_zero_eq, auto)
nipkow@15402
  1439
  done
nipkow@15402
  1440
nipkow@15402
  1441
lemma setprod_Un: "finite A ==> finite B ==> (ALL x: A Int B. f x \<noteq> 0) ==>
nipkow@15402
  1442
    (setprod f (A Un B) :: 'a ::{field})
nipkow@15402
  1443
      = setprod f A * setprod f B / setprod f (A Int B)"
nipkow@15402
  1444
  apply (subst setprod_Un_Int [symmetric], auto)
nipkow@15402
  1445
  apply (subgoal_tac "finite (A Int B)")
nipkow@15402
  1446
  apply (frule setprod_nonzero_field [of "A Int B" f], assumption)
nipkow@15402
  1447
  apply (subst times_divide_eq_right [THEN sym], auto simp add: divide_self)
nipkow@15402
  1448
  done
nipkow@15402
  1449
nipkow@15402
  1450
lemma setprod_diff1: "finite A ==> f a \<noteq> 0 ==>
nipkow@15402
  1451
    (setprod f (A - {a}) :: 'a :: {field}) =
nipkow@15402
  1452
      (if a:A then setprod f A / f a else setprod f A)"
nipkow@15402
  1453
  apply (erule finite_induct)
nipkow@15402
  1454
   apply (auto simp add: insert_Diff_if)
nipkow@15402
  1455
  apply (subgoal_tac "f a * setprod f F / f a = setprod f F * f a / f a")
nipkow@15402
  1456
  apply (erule ssubst)
nipkow@15402
  1457
  apply (subst times_divide_eq_right [THEN sym])
nipkow@15402
  1458
  apply (auto simp add: mult_ac times_divide_eq_right divide_self)
nipkow@15402
  1459
  done
nipkow@15402
  1460
nipkow@15402
  1461
lemma setprod_inversef: "finite A ==>
nipkow@15402
  1462
    ALL x: A. f x \<noteq> (0::'a::{field,division_by_zero}) ==>
nipkow@15402
  1463
      setprod (inverse \<circ> f) A = inverse (setprod f A)"
nipkow@15402
  1464
  apply (erule finite_induct)
nipkow@15402
  1465
  apply (simp, simp)
nipkow@15402
  1466
  done
nipkow@15402
  1467
nipkow@15402
  1468
lemma setprod_dividef:
nipkow@15402
  1469
     "[|finite A;
nipkow@15402
  1470
        \<forall>x \<in> A. g x \<noteq> (0::'a::{field,division_by_zero})|]
nipkow@15402
  1471
      ==> setprod (%x. f x / g x) A = setprod f A / setprod g A"
nipkow@15402
  1472
  apply (subgoal_tac
nipkow@15402
  1473
         "setprod (%x. f x / g x) A = setprod (%x. f x * (inverse \<circ> g) x) A")
nipkow@15402
  1474
  apply (erule ssubst)
nipkow@15402
  1475
  apply (subst divide_inverse)
nipkow@15402
  1476
  apply (subst setprod_timesf)
nipkow@15402
  1477
  apply (subst setprod_inversef, assumption+, rule refl)
nipkow@15402
  1478
  apply (rule setprod_cong, rule refl)
nipkow@15402
  1479
  apply (subst divide_inverse, auto)
nipkow@15402
  1480
  done
nipkow@15402
  1481
wenzelm@12396
  1482
subsection {* Finite cardinality *}
wenzelm@12396
  1483
nipkow@15402
  1484
text {* This definition, although traditional, is ugly to work with:
nipkow@15402
  1485
@{text "card A == LEAST n. EX f. A = {f i | i. i < n}"}.
nipkow@15402
  1486
But now that we have @{text setsum} things are easy:
wenzelm@12396
  1487
*}
wenzelm@12396
  1488
wenzelm@12396
  1489
constdefs
wenzelm@12396
  1490
  card :: "'a set => nat"
nipkow@15402
  1491
  "card A == setsum (%x. 1::nat) A"
wenzelm@12396
  1492
wenzelm@12396
  1493
lemma card_empty [simp]: "card {} = 0"
nipkow@15402
  1494
  by (simp add: card_def)
nipkow@15402
  1495
paulson@15409
  1496
lemma card_infinite [simp]: "~ finite A ==> card A = 0"
paulson@15409
  1497
  by (simp add: card_def)
paulson@15409
  1498
nipkow@15402
  1499
lemma card_eq_setsum: "card A = setsum (%x. 1) A"
nipkow@15402
  1500
by (simp add: card_def)
wenzelm@12396
  1501
wenzelm@12396
  1502
lemma card_insert_disjoint [simp]:
wenzelm@12396
  1503
  "finite A ==> x \<notin> A ==> card (insert x A) = Suc(card A)"
ballarin@15765
  1504
by(simp add: card_def)
nipkow@15402
  1505
nipkow@15402
  1506
lemma card_insert_if:
nipkow@15402
  1507
    "finite A ==> card (insert x A) = (if x:A then card A else Suc(card(A)))"
nipkow@15402
  1508
  by (simp add: insert_absorb)
wenzelm@12396
  1509
wenzelm@12396
  1510
lemma card_0_eq [simp]: "finite A ==> (card A = 0) = (A = {})"
wenzelm@12396
  1511
  apply auto
paulson@15506
  1512
  apply (drule_tac a = x in mk_disjoint_insert, clarify, auto)
wenzelm@12396
  1513
  done
wenzelm@12396
  1514
paulson@15409
  1515
lemma card_eq_0_iff: "(card A = 0) = (A = {} | ~ finite A)"
paulson@15409
  1516
by auto
paulson@15409
  1517
wenzelm@12396
  1518
lemma card_Suc_Diff1: "finite A ==> x: A ==> Suc (card (A - {x})) = card A"
nipkow@14302
  1519
apply(rule_tac t = A in insert_Diff [THEN subst], assumption)
nipkow@14302
  1520
apply(simp del:insert_Diff_single)
nipkow@14302
  1521
done
wenzelm@12396
  1522
wenzelm@12396
  1523
lemma card_Diff_singleton:
wenzelm@12396
  1524
    "finite A ==> x: A ==> card (A - {x}) = card A - 1"
wenzelm@12396
  1525
  by (simp add: card_Suc_Diff1 [symmetric])
wenzelm@12396
  1526
wenzelm@12396
  1527
lemma card_Diff_singleton_if:
wenzelm@12396
  1528
    "finite A ==> card (A-{x}) = (if x : A then card A - 1 else card A)"
wenzelm@12396
  1529
  by (simp add: card_Diff_singleton)
wenzelm@12396
  1530
wenzelm@12396
  1531
lemma card_insert: "finite A ==> card (insert x A) = Suc (card (A - {x}))"
wenzelm@12396
  1532
  by (simp add: card_insert_if card_Suc_Diff1)
wenzelm@12396
  1533
wenzelm@12396
  1534
lemma card_insert_le: "finite A ==> card A <= card (insert x A)"
wenzelm@12396
  1535
  by (simp add: card_insert_if)
wenzelm@12396
  1536
nipkow@15402
  1537
lemma card_mono: "\<lbrakk> finite B; A \<subseteq> B \<rbrakk> \<Longrightarrow> card A \<le> card B"
nipkow@15539
  1538
by (simp add: card_def setsum_mono2)
nipkow@15402
  1539
wenzelm@12396
  1540
lemma card_seteq: "finite B ==> (!!A. A <= B ==> card B <= card A ==> A = B)"
berghofe@22262
  1541
  apply (induct set: finite, simp, clarify)
wenzelm@12396
  1542
  apply (subgoal_tac "finite A & A - {x} <= F")
paulson@14208
  1543
   prefer 2 apply (blast intro: finite_subset, atomize)
wenzelm@12396
  1544
  apply (drule_tac x = "A - {x}" in spec)
wenzelm@12396
  1545
  apply (simp add: card_Diff_singleton_if split add: split_if_asm)
paulson@14208
  1546
  apply (case_tac "card A", auto)
wenzelm@12396
  1547
  done
wenzelm@12396
  1548
wenzelm@12396
  1549
lemma psubset_card_mono: "finite B ==> A < B ==> card A < card B"
wenzelm@12396
  1550
  apply (simp add: psubset_def linorder_not_le [symmetric])
wenzelm@12396
  1551
  apply (blast dest: card_seteq)
wenzelm@12396
  1552
  done
wenzelm@12396
  1553
wenzelm@12396
  1554
lemma card_Un_Int: "finite A ==> finite B
wenzelm@12396
  1555
    ==> card A + card B = card (A Un B) + card (A Int B)"
nipkow@15402
  1556
by(simp add:card_def setsum_Un_Int)
wenzelm@12396
  1557
wenzelm@12396
  1558
lemma card_Un_disjoint: "finite A ==> finite B
wenzelm@12396
  1559
    ==> A Int B = {} ==> card (A Un B) = card A + card B"
wenzelm@12396
  1560
  by (simp add: card_Un_Int)
wenzelm@12396
  1561
wenzelm@12396
  1562
lemma card_Diff_subset:
nipkow@15402
  1563
  "finite B ==> B <= A ==> card (A - B) = card A - card B"
nipkow@15402
  1564
by(simp add:card_def setsum_diff_nat)
wenzelm@12396
  1565
wenzelm@12396
  1566
lemma card_Diff1_less: "finite A ==> x: A ==> card (A - {x}) < card A"
wenzelm@12396
  1567
  apply (rule Suc_less_SucD)
wenzelm@12396
  1568
  apply (simp add: card_Suc_Diff1)
wenzelm@12396
  1569
  done
wenzelm@12396
  1570
wenzelm@12396
  1571
lemma card_Diff2_less:
wenzelm@12396
  1572
    "finite A ==> x: A ==> y: A ==> card (A - {x} - {y}) < card A"
wenzelm@12396
  1573
  apply (case_tac "x = y")
wenzelm@12396
  1574
   apply (simp add: card_Diff1_less)
wenzelm@12396
  1575
  apply (rule less_trans)
wenzelm@12396
  1576
   prefer 2 apply (auto intro!: card_Diff1_less)
wenzelm@12396
  1577
  done
wenzelm@12396
  1578
wenzelm@12396
  1579
lemma card_Diff1_le: "finite A ==> card (A - {x}) <= card A"
wenzelm@12396
  1580
  apply (case_tac "x : A")
wenzelm@12396
  1581
   apply (simp_all add: card_Diff1_less less_imp_le)
wenzelm@12396
  1582
  done
wenzelm@12396
  1583
wenzelm@12396
  1584
lemma card_psubset: "finite B ==> A \<subseteq> B ==> card A < card B ==> A < B"
paulson@14208
  1585
by (erule psubsetI, blast)
wenzelm@12396
  1586
paulson@14889
  1587
lemma insert_partition:
nipkow@15402
  1588
  "\<lbrakk> x \<notin> F; \<forall>c1 \<in> insert x F. \<forall>c2 \<in> insert x F. c1 \<noteq> c2 \<longrightarrow> c1 \<inter> c2 = {} \<rbrakk>
nipkow@15402
  1589
  \<Longrightarrow> x \<inter> \<Union> F = {}"
paulson@14889
  1590
by auto
paulson@14889
  1591
paulson@19793
  1592
text{* main cardinality theorem *}
paulson@14889
  1593
lemma card_partition [rule_format]:
paulson@14889
  1594
     "finite C ==>  
paulson@14889
  1595
        finite (\<Union> C) -->  
paulson@14889
  1596
        (\<forall>c\<in>C. card c = k) -->   
paulson@14889
  1597
        (\<forall>c1 \<in> C. \<forall>c2 \<in> C. c1 \<noteq> c2 --> c1 \<inter> c2 = {}) -->  
paulson@14889
  1598
        k * card(C) = card (\<Union> C)"
paulson@14889
  1599
apply (erule finite_induct, simp)
paulson@14889
  1600
apply (simp add: card_insert_disjoint card_Un_disjoint insert_partition 
paulson@14889
  1601
       finite_subset [of _ "\<Union> (insert x F)"])
paulson@14889
  1602
done
paulson@14889
  1603
wenzelm@12396
  1604
paulson@19793
  1605
text{*The form of a finite set of given cardinality*}
paulson@19793
  1606
paulson@19793
  1607
lemma card_eq_SucD:
paulson@19793
  1608
  assumes cardeq: "card A = Suc k" and fin: "finite A" 
paulson@19793
  1609
  shows "\<exists>b B. A = insert b B & b \<notin> B & card B = k"
paulson@19793
  1610
proof -
paulson@19793
  1611
  have "card A \<noteq> 0" using cardeq by auto
paulson@19793
  1612
  then obtain b where b: "b \<in> A" using fin by auto
paulson@19793
  1613
  show ?thesis
paulson@19793
  1614
  proof (intro exI conjI)
paulson@19793
  1615
    show "A = insert b (A-{b})" using b by blast
paulson@19793
  1616
    show "b \<notin> A - {b}" by blast
paulson@19793
  1617
    show "card (A - {b}) = k" by (simp add: fin cardeq b card_Diff_singleton) 
paulson@19793
  1618
  qed
paulson@19793
  1619
qed
paulson@19793
  1620
paulson@19793
  1621
paulson@19793
  1622
lemma card_Suc_eq:
paulson@19793
  1623
  "finite A ==>
paulson@19793
  1624
   (card A = Suc k) = (\<exists>b B. A = insert b B & b \<notin> B & card B = k)"
paulson@19793
  1625
by (auto dest!: card_eq_SucD) 
paulson@19793
  1626
paulson@19793
  1627
lemma card_1_eq:
paulson@19793
  1628
  "finite A ==> (card A = Suc 0) = (\<exists>x. A = {x})"
paulson@19793
  1629
by (auto dest!: card_eq_SucD) 
paulson@19793
  1630
paulson@19793
  1631
lemma card_2_eq:
paulson@19793
  1632
  "finite A ==> (card A = Suc(Suc 0)) = (\<exists>x y. x\<noteq>y & A = {x,y})" 
paulson@19793
  1633
by (auto dest!: card_eq_SucD, blast) 
paulson@19793
  1634
paulson@19793
  1635
nipkow@15539
  1636
lemma setsum_constant [simp]: "(\<Sum>x \<in> A. y) = of_nat(card A) * y"
nipkow@15539
  1637
apply (cases "finite A")
nipkow@15539
  1638
apply (erule finite_induct)
nipkow@15539
  1639
apply (auto simp add: ring_distrib add_ac)
paulson@15409
  1640
done
nipkow@15402
  1641
nipkow@15539
  1642
krauss@21199
  1643
lemma setprod_constant: "finite A ==> (\<Prod>x\<in> A. (y::'a::{recpower, comm_monoid_mult})) = y^(card A)"
nipkow@15402
  1644
  apply (erule finite_induct)
nipkow@15402
  1645
  apply (auto simp add: power_Suc)
nipkow@15402
  1646
  done
nipkow@15402
  1647
nipkow@15542
  1648
lemma setsum_bounded:
nipkow@15542
  1649
  assumes le: "\<And>i. i\<in>A \<Longrightarrow> f i \<le> (K::'a::{comm_semiring_1_cancel, pordered_ab_semigroup_add})"
nipkow@15542
  1650
  shows "setsum f A \<le> of_nat(card A) * K"
nipkow@15542
  1651
proof (cases "finite A")
nipkow@15542
  1652
  case True
nipkow@15542
  1653
  thus ?thesis using le setsum_mono[where K=A and g = "%x. K"] by simp
nipkow@15542
  1654
next
nipkow@15542
  1655
  case False thus ?thesis by (simp add: setsum_def)
nipkow@15542
  1656
qed
nipkow@15542
  1657
nipkow@15402
  1658
nipkow@15402
  1659
subsubsection {* Cardinality of unions *}
nipkow@15402
  1660
nipkow@15539
  1661
lemma of_nat_id[simp]: "(of_nat n :: nat) = n"
wenzelm@21575
  1662
by(induct n) auto
nipkow@15539
  1663
nipkow@15402
  1664
lemma card_UN_disjoint:
nipkow@15402
  1665
    "finite I ==> (ALL i:I. finite (A i)) ==>
nipkow@15402
  1666
        (ALL i:I. ALL j:I. i \<noteq> j --> A i Int A j = {}) ==>
nipkow@15402
  1667
      card (UNION I A) = (\<Sum>i\<in>I. card(A i))"
nipkow@15539
  1668
  apply (simp add: card_def del: setsum_constant)
nipkow@15402
  1669
  apply (subgoal_tac
nipkow@15402
  1670
           "setsum (%i. card (A i)) I = setsum (%i. (setsum (%x. 1) (A i))) I")
nipkow@15539
  1671
  apply (simp add: setsum_UN_disjoint del: setsum_constant)
nipkow@15539
  1672
  apply (simp cong: setsum_cong)
nipkow@15402
  1673
  done
nipkow@15402
  1674
nipkow@15402
  1675
lemma card_Union_disjoint:
nipkow@15402
  1676
  "finite C ==> (ALL A:C. finite A) ==>
nipkow@15402
  1677
        (ALL A:C. ALL B:C. A \<noteq> B --> A Int B = {}) ==>
nipkow@15402
  1678
      card (Union C) = setsum card C"
nipkow@15402
  1679
  apply (frule card_UN_disjoint [of C id])
nipkow@15402
  1680
  apply (unfold Union_def id_def, assumption+)
nipkow@15402
  1681
  done
nipkow@15402
  1682
wenzelm@12396
  1683
subsubsection {* Cardinality of image *}
wenzelm@12396
  1684
paulson@15447
  1685
text{*The image of a finite set can be expressed using @{term fold}.*}
paulson@15447
  1686
lemma image_eq_fold: "finite A ==> f ` A = fold (op Un) (%x. {f x}) {} A"
paulson@15447
  1687
  apply (erule finite_induct, simp)
paulson@15447
  1688
  apply (subst ACf.fold_insert) 
paulson@15447
  1689
  apply (auto simp add: ACf_def) 
paulson@15447
  1690
  done
paulson@15447
  1691
wenzelm@12396
  1692
lemma card_image_le: "finite A ==> card (f ` A) <= card A"
berghofe@22262
  1693
  apply (induct set: finite)
wenzelm@21575
  1694
   apply simp
wenzelm@12396
  1695
  apply (simp add: le_SucI finite_imageI card_insert_if)
wenzelm@12396
  1696
  done
wenzelm@12396
  1697
nipkow@15402
  1698
lemma card_image: "inj_on f A ==> card (f ` A) = card A"
nipkow@15539
  1699
by(simp add:card_def setsum_reindex o_def del:setsum_constant)
wenzelm@12396
  1700
wenzelm@12396
  1701
lemma endo_inj_surj: "finite A ==> f ` A \<subseteq> A ==> inj_on f A ==> f ` A = A"
wenzelm@12396
  1702
  by (simp add: card_seteq card_image)
wenzelm@12396
  1703
nipkow@15111
  1704
lemma eq_card_imp_inj_on:
nipkow@15111
  1705
  "[| finite A; card(f ` A) = card A |] ==> inj_on f A"
wenzelm@21575
  1706
apply (induct rule:finite_induct)
wenzelm@21575
  1707
apply simp
nipkow@15111
  1708
apply(frule card_image_le[where f = f])
nipkow@15111
  1709
apply(simp add:card_insert_if split:if_splits)
nipkow@15111
  1710
done
nipkow@15111
  1711
nipkow@15111
  1712
lemma inj_on_iff_eq_card:
nipkow@15111
  1713
  "finite A ==> inj_on f A = (card(f ` A) = card A)"
nipkow@15111
  1714
by(blast intro: card_image eq_card_imp_inj_on)
nipkow@15111
  1715
wenzelm@12396
  1716
nipkow@15402
  1717
lemma card_inj_on_le:
nipkow@15402
  1718
    "[|inj_on f A; f ` A \<subseteq> B; finite B |] ==> card A \<le> card B"
nipkow@15402
  1719
apply (subgoal_tac "finite A") 
nipkow@15402
  1720
 apply (force intro: card_mono simp add: card_image [symmetric])
nipkow@15402
  1721
apply (blast intro: finite_imageD dest: finite_subset) 
nipkow@15402
  1722
done
nipkow@15402
  1723
nipkow@15402
  1724
lemma card_bij_eq:
nipkow@15402
  1725
    "[|inj_on f A; f ` A \<subseteq> B; inj_on g B; g ` B \<subseteq> A;
nipkow@15402
  1726
       finite A; finite B |] ==> card A = card B"
nipkow@15402
  1727
  by (auto intro: le_anti_sym card_inj_on_le)
nipkow@15402
  1728
nipkow@15402
  1729
nipkow@15402
  1730
subsubsection {* Cardinality of products *}
nipkow@15402
  1731
nipkow@15402
  1732
(*
nipkow@15402
  1733
lemma SigmaI_insert: "y \<notin> A ==>
nipkow@15402
  1734
  (SIGMA x:(insert y A). B x) = (({y} <*> (B y)) \<union> (SIGMA x: A. B x))"
nipkow@15402
  1735
  by auto
nipkow@15402
  1736
*)
nipkow@15402
  1737
nipkow@15402
  1738
lemma card_SigmaI [simp]:
nipkow@15402
  1739
  "\<lbrakk> finite A; ALL a:A. finite (B a) \<rbrakk>
nipkow@15402
  1740
  \<Longrightarrow> card (SIGMA x: A. B x) = (\<Sum>a\<in>A. card (B a))"
nipkow@15539
  1741
by(simp add:card_def setsum_Sigma del:setsum_constant)
nipkow@15402
  1742
paulson@15409
  1743
lemma card_cartesian_product: "card (A <*> B) = card(A) * card(B)"
paulson@15409
  1744
apply (cases "finite A") 
paulson@15409
  1745
apply (cases "finite B") 
paulson@15409
  1746
apply (auto simp add: card_eq_0_iff
nipkow@15539
  1747
            dest: finite_cartesian_productD1 finite_cartesian_productD2)
paulson@15409
  1748
done
nipkow@15402
  1749
nipkow@15402
  1750
lemma card_cartesian_product_singleton:  "card({x} <*> A) = card(A)"
nipkow@15539
  1751
by (simp add: card_cartesian_product)
paulson@15409
  1752
nipkow@15402
  1753
nipkow@15402
  1754
wenzelm@12396
  1755
subsubsection {* Cardinality of the Powerset *}
wenzelm@12396
  1756
wenzelm@12396
  1757
lemma card_Pow: "finite A ==> card (Pow A) = Suc (Suc 0) ^ card A"  (* FIXME numeral 2 (!?) *)
berghofe@22262
  1758
  apply (induct set: finite)
wenzelm@12396
  1759
   apply (simp_all add: Pow_insert)
paulson@14208
  1760
  apply (subst card_Un_disjoint, blast)
paulson@14208
  1761
    apply (blast intro: finite_imageI, blast)
wenzelm@12396
  1762
  apply (subgoal_tac "inj_on (insert x) (Pow F)")
wenzelm@12396
  1763
   apply (simp add: card_image Pow_insert)
wenzelm@12396
  1764
  apply (unfold inj_on_def)
wenzelm@12396
  1765
  apply (blast elim!: equalityE)
wenzelm@12396
  1766
  done
wenzelm@12396
  1767
nipkow@15392
  1768
text {* Relates to equivalence classes.  Based on a theorem of
nipkow@15392
  1769
F. Kammüller's.  *}
wenzelm@12396
  1770
wenzelm@12396
  1771
lemma dvd_partition:
nipkow@15392
  1772
  "finite (Union C) ==>
wenzelm@12396
  1773
    ALL c : C. k dvd card c ==>
paulson@14430
  1774
    (ALL c1: C. ALL c2: C. c1 \<noteq> c2 --> c1 Int c2 = {}) ==>
wenzelm@12396
  1775
  k dvd card (Union C)"
nipkow@15392
  1776
apply(frule finite_UnionD)
nipkow@15392
  1777
apply(rotate_tac -1)
berghofe@22262
  1778
  apply (induct set: finite, simp_all, clarify)
wenzelm@12396
  1779
  apply (subst card_Un_disjoint)
wenzelm@12396
  1780
  apply (auto simp add: dvd_add disjoint_eq_subset_Compl)
wenzelm@12396
  1781
  done
wenzelm@12396
  1782
wenzelm@12396
  1783
nipkow@15392
  1784
subsection{* A fold functional for non-empty sets *}
nipkow@15392
  1785
nipkow@15392
  1786
text{* Does not require start value. *}
wenzelm@12396
  1787
berghofe@22262
  1788
inductive2
berghofe@22262
  1789
  fold1Set :: "('a => 'a => 'a) => 'a set => 'a => bool"
berghofe@22262
  1790
  for f :: "'a => 'a => 'a"
berghofe@22262
  1791
where
paulson@15506
  1792
  fold1Set_insertI [intro]:
berghofe@22262
  1793
   "\<lbrakk> foldSet f id a A x; a \<notin> A \<rbrakk> \<Longrightarrow> fold1Set f (insert a A) x"
wenzelm@12396
  1794
nipkow@15392
  1795
constdefs
nipkow@15392
  1796
  fold1 :: "('a => 'a => 'a) => 'a set => 'a"
berghofe@22262
  1797
  "fold1 f A == THE x. fold1Set f A x"
paulson@15506
  1798
paulson@15506
  1799
lemma fold1Set_nonempty:
berghofe@22262
  1800
 "fold1Set f A x \<Longrightarrow> A \<noteq> {}"
paulson@15506
  1801
by(erule fold1Set.cases, simp_all) 
paulson@15506
  1802
nipkow@15392
  1803
berghofe@22262
  1804
inductive_cases2 empty_fold1SetE [elim!]: "fold1Set f {} x"
berghofe@22262
  1805
berghofe@22262
  1806
inductive_cases2 insert_fold1SetE [elim!]: "fold1Set f (insert a X) x"
berghofe@22262
  1807
berghofe@22262
  1808
berghofe@22262
  1809
lemma fold1Set_sing [iff]: "(fold1Set f {a} b) = (a = b)"
paulson@15506
  1810
  by (blast intro: foldSet.intros elim: foldSet.cases)
nipkow@15392
  1811
paulson@15508
  1812
lemma fold1_singleton[simp]: "fold1 f {a} = a"
paulson@15508
  1813
  by (unfold fold1_def) blast
wenzelm@12396
  1814
paulson@15508
  1815
lemma finite_nonempty_imp_fold1Set:
berghofe@22262
  1816
  "\<lbrakk> finite A; A \<noteq> {} \<rbrakk> \<Longrightarrow> EX x. fold1Set f A x"
paulson@15508
  1817
apply (induct A rule: finite_induct)
paulson@15508
  1818
apply (auto dest: finite_imp_foldSet [of _ f id])  
paulson@15508
  1819
done
paulson@15506
  1820
paulson@15506
  1821
text{*First, some lemmas about @{term foldSet}.*}
nipkow@15392
  1822
paulson@15508
  1823
lemma (in ACf) foldSet_insert_swap:
berghofe@22262
  1824
assumes fold: "foldSet f id b A y"
berghofe@22262
  1825
shows "b \<notin> A \<Longrightarrow> foldSet f id z (insert b A) (z \<cdot> y)"
paulson@15508
  1826
using fold
paulson@15508
  1827
proof (induct rule: foldSet.induct)
paulson@15508
  1828
  case emptyI thus ?case by (force simp add: fold_insert_aux commute)
paulson@15508
  1829
next
berghofe@22262
  1830
  case (insertI x A y)
berghofe@22262
  1831
    have "foldSet f (\<lambda>u. u) z (insert x (insert b A)) (x \<cdot> (z \<cdot> y))"
paulson@15521
  1832
      using insertI by force  --{*how does @{term id} get unfolded?*}
paulson@15508
  1833
    thus ?case by (simp add: insert_commute AC)
paulson@15508
  1834
qed
paulson@15508
  1835
paulson@15508
  1836
lemma (in ACf) foldSet_permute_diff:
berghofe@22262
  1837
assumes fold: "foldSet f id b A x"
berghofe@22262
  1838
shows "!!a. \<lbrakk>a \<in> A; b \<notin> A\<rbrakk> \<Longrightarrow> foldSet f id a (insert b (A-{a})) x"
paulson@15508
  1839
using fold
paulson@15508
  1840
proof (induct rule: foldSet.induct)
paulson@15508
  1841
  case emptyI thus ?case by simp
paulson@15508
  1842
next
berghofe@22262
  1843
  case (insertI x A y)
paulson@15521
  1844
  have "a = x \<or> a \<in> A" using insertI by simp
paulson@15521
  1845
  thus ?case
paulson@15521
  1846
  proof
paulson@15521
  1847
    assume "a = x"
paulson@15521
  1848
    with insertI show ?thesis
paulson@15521
  1849
      by (simp add: id_def [symmetric], blast intro: foldSet_insert_swap) 
paulson@15521
  1850
  next
paulson@15521
  1851
    assume ainA: "a \<in> A"
berghofe@22262
  1852
    hence "foldSet f id a (insert x (insert b (A - {a}))) (x \<cdot> y)"
paulson@15521
  1853
      using insertI by (force simp: id_def)
paulson@15521
  1854
    moreover
paulson@15521
  1855
    have "insert x (insert b (A - {a})) = insert b (insert x A - {a})"
paulson@15521
  1856
      using ainA insertI by blast
paulson@15521
  1857
    ultimately show ?thesis by (simp add: id_def)
paulson@15508
  1858
  qed
paulson@15508
  1859
qed
paulson@15508
  1860
paulson@15508
  1861
lemma (in ACf) fold1_eq_fold:
paulson@15508
  1862
     "[|finite A; a \<notin> A|] ==> fold1 f (insert a A) = fold f id a A"
paulson@15508
  1863
apply (simp add: fold1_def fold_def) 
paulson@15508
  1864
apply (rule the_equality)
paulson@15508
  1865
apply (best intro: foldSet_determ theI dest: finite_imp_foldSet [of _ f id]) 
paulson@15508
  1866
apply (rule sym, clarify)
paulson@15508
  1867
apply (case_tac "Aa=A")
paulson@15508
  1868
 apply (best intro: the_equality foldSet_determ)  
berghofe@22262
  1869
apply (subgoal_tac "foldSet f id a A x")
paulson@15508
  1870
 apply (best intro: the_equality foldSet_determ)  
paulson@15508
  1871
apply (subgoal_tac "insert aa (Aa - {a}) = A") 
paulson@15508
  1872
 prefer 2 apply (blast elim: equalityE) 
paulson@15508
  1873
apply (auto dest: foldSet_permute_diff [where a=a]) 
paulson@15508
  1874
done
paulson@15508
  1875
paulson@15521
  1876
lemma nonempty_iff: "(A \<noteq> {}) = (\<exists>x B. A = insert x B & x \<notin> B)"
paulson@15521
  1877
apply safe
paulson@15521
  1878
apply simp 
paulson@15521
  1879
apply (drule_tac x=x in spec)
paulson@15521
  1880
apply (drule_tac x="A-{x}" in spec, auto) 
paulson@15508
  1881
done
paulson@15508
  1882
paulson@15521
  1883
lemma (in ACf) fold1_insert:
paulson@15521
  1884
  assumes nonempty: "A \<noteq> {}" and A: "finite A" "x \<notin> A"
paulson@15521
  1885
  shows "fold1 f (insert x A) = f x (fold1 f A)"
paulson@15521
  1886
proof -
paulson@15521
  1887
  from nonempty obtain a A' where "A = insert a A' & a ~: A'" 
paulson@15521
  1888
    by (auto simp add: nonempty_iff)
paulson@15521
  1889
  with A show ?thesis
paulson@15521
  1890
    by (simp add: insert_commute [of x] fold1_eq_fold eq_commute) 
paulson@15521
  1891
qed
paulson@15521
  1892
paulson@15509
  1893
lemma (in ACIf) fold1_insert_idem [simp]:
paulson@15521
  1894
  assumes nonempty: "A \<noteq> {}" and A: "finite A" 
paulson@15521
  1895
  shows "fold1 f (insert x A) = f x (fold1 f A)"
paulson@15521
  1896
proof -
paulson@15521
  1897
  from nonempty obtain a A' where A': "A = insert a A' & a ~: A'" 
paulson@15521
  1898
    by (auto simp add: nonempty_iff)
paulson@15521
  1899
  show ?thesis
paulson@15521
  1900
  proof cases
paulson@15521
  1901
    assume "a = x"
paulson@15521
  1902
    thus ?thesis 
paulson@15521
  1903
    proof cases
paulson@15521
  1904
      assume "A' = {}"
paulson@15521
  1905
      with prems show ?thesis by (simp add: idem) 
paulson@15521
  1906
    next
paulson@15521
  1907
      assume "A' \<noteq> {}"
paulson@15521
  1908
      with prems show ?thesis
paulson@15521
  1909
	by (simp add: fold1_insert assoc [symmetric] idem) 
paulson@15521
  1910
    qed
paulson@15521
  1911
  next
paulson@15521
  1912
    assume "a \<noteq> x"
paulson@15521
  1913
    with prems show ?thesis
paulson@15521
  1914
      by (simp add: insert_commute fold1_eq_fold fold_insert_idem)
paulson@15521
  1915
  qed
paulson@15521
  1916
qed
paulson@15506
  1917
paulson@15506
  1918
paulson@15508
  1919
text{* Now the recursion rules for definitions: *}
paulson@15508
  1920
paulson@15508
  1921
lemma fold1_singleton_def: "g \<equiv> fold1 f \<Longrightarrow> g {a} = a"
paulson@15508
  1922
by(simp add:fold1_singleton)
paulson@15508
  1923
paulson@15508
  1924
lemma (in ACf) fold1_insert_def:
paulson@15508
  1925
  "\<lbrakk> g \<equiv> fold1 f; finite A; x \<notin> A; A \<noteq> {} \<rbrakk> \<Longrightarrow> g(insert x A) = x \<cdot> (g A)"
paulson@15508
  1926
by(simp add:fold1_insert)
paulson@15508
  1927
paulson@15509
  1928
lemma (in ACIf) fold1_insert_idem_def:
paulson@15508
  1929
  "\<lbrakk> g \<equiv> fold1 f; finite A; A \<noteq> {} \<rbrakk> \<Longrightarrow> g(insert x A) = x \<cdot> (g A)"
paulson@15509
  1930
by(simp add:fold1_insert_idem)
paulson@15508
  1931
paulson@15508
  1932
subsubsection{* Determinacy for @{term fold1Set} *}
paulson@15508
  1933
paulson@15508
  1934
text{*Not actually used!!*}
wenzelm@12396
  1935
paulson@15506
  1936
lemma (in ACf) foldSet_permute:
berghofe@22262
  1937
  "[|foldSet f id b (insert a A) x; a \<notin> A; b \<notin> A|]
berghofe@22262
  1938
   ==> foldSet f id a (insert b A) x"
paulson@15506
  1939
apply (case_tac "a=b") 
paulson@15506
  1940
apply (auto dest: foldSet_permute_diff) 
paulson@15506
  1941
done
nipkow@15376
  1942
paulson@15506
  1943
lemma (in ACf) fold1Set_determ:
berghofe@22262
  1944
  "fold1Set f A x ==> fold1Set f A y ==> y = x"
paulson@15506
  1945
proof (clarify elim!: fold1Set.cases)
paulson@15506
  1946
  fix A x B y a b
berghofe@22262
  1947
  assume Ax: "foldSet f id a A x"
berghofe@22262
  1948
  assume By: "foldSet f id b B y"
paulson@15506
  1949
  assume anotA:  "a \<notin> A"
paulson@15506
  1950
  assume bnotB:  "b \<notin> B"
paulson@15506
  1951
  assume eq: "insert a A = insert b B"
paulson@15506
  1952
  show "y=x"
paulson@15506
  1953
  proof cases
paulson@15506
  1954
    assume same: "a=b"
paulson@15506
  1955
    hence "A=B" using anotA bnotB eq by (blast elim!: equalityE)
paulson@15506
  1956
    thus ?thesis using Ax By same by (blast intro: foldSet_determ)
nipkow@15392
  1957
  next
paulson@15506
  1958
    assume diff: "a\<noteq>b"
paulson@15506
  1959
    let ?D = "B - {a}"
paulson@15506
  1960
    have B: "B = insert a ?D" and A: "A = insert b ?D"
paulson@15506
  1961
     and aB: "a \<in> B" and bA: "b \<in> A"
paulson@15506
  1962
      using eq anotA bnotB diff by (blast elim!:equalityE)+
paulson@15506
  1963
    with aB bnotB By
berghofe@22262
  1964
    have "foldSet f id a (insert b ?D) y" 
paulson@15506
  1965
      by (auto intro: foldSet_permute simp add: insert_absorb)
paulson@15506
  1966
    moreover
berghofe@22262
  1967
    have "foldSet f id a (insert b ?D) x"
paulson@15506
  1968
      by (simp add: A [symmetric] Ax) 
paulson@15506
  1969
    ultimately show ?thesis by (blast intro: foldSet_determ) 
nipkow@15392
  1970
  qed
wenzelm@12396
  1971
qed
wenzelm@12396
  1972
berghofe@22262
  1973
lemma (in ACf) fold1Set_equality: "fold1Set f A y ==> fold1 f A = y"
paulson@15506
  1974
  by (unfold fold1_def) (blast intro: fold1Set_determ)
paulson@15506
  1975
paulson@15506
  1976
declare
paulson@15506
  1977
  empty_foldSetE [rule del]   foldSet.intros [rule del]
paulson@15506
  1978
  empty_fold1SetE [rule del]  insert_fold1SetE [rule del]
ballarin@19931
  1979
  -- {* No more proofs involve these relations. *}
nipkow@15376
  1980
nipkow@15497
  1981
subsubsection{* Semi-Lattices *}
nipkow@15497
  1982
nipkow@15497
  1983
locale ACIfSL = ACIf +
nipkow@15500
  1984
  fixes below :: "'a \<Rightarrow> 'a \<Rightarrow> bool" (infixl "\<sqsubseteq>" 50)
nipkow@18493
  1985
  and strict_below :: "'a \<Rightarrow> 'a \<Rightarrow> bool" (infixl "\<sqsubset>" 50)
nipkow@15500
  1986
  assumes below_def: "(x \<sqsubseteq> y) = (x\<cdot>y = x)"
nipkow@18493
  1987
  defines strict_below_def:  "(x \<sqsubset> y) \<equiv> (x \<sqsubseteq> y \<and> x \<noteq> y)"
nipkow@15497
  1988
nipkow@15497
  1989
locale ACIfSLlin = ACIfSL +
nipkow@15497
  1990
  assumes lin: "x\<cdot>y \<in> {x,y}"
nipkow@15497
  1991
nipkow@15500
  1992
lemma (in ACIfSL) below_refl[simp]: "x \<sqsubseteq> x"
nipkow@15497
  1993
by(simp add: below_def idem)
nipkow@15497
  1994
nipkow@15500
  1995
lemma (in ACIfSL) below_f_conv[simp]: "x \<sqsubseteq> y \<cdot> z = (x \<sqsubseteq> y \<and> x \<sqsubseteq> z)"
nipkow@15497
  1996
proof
nipkow@15500
  1997
  assume "x \<sqsubseteq> y \<cdot> z"
nipkow@15497
  1998
  hence xyzx: "x \<cdot> (y \<cdot> z) = x"  by(simp add: below_def)
nipkow@15497
  1999
  have "x \<cdot> y = x"
nipkow@15497
  2000
  proof -
nipkow@15497
  2001
    have "x \<cdot> y = (x \<cdot> (y \<cdot> z)) \<cdot> y" by(rule subst[OF xyzx], rule refl)
nipkow@15497
  2002
    also have "\<dots> = x \<cdot> (y \<cdot> z)" by(simp add:ACI)
nipkow@15497
  2003
    also have "\<dots> = x" by(rule xyzx)
nipkow@15497
  2004
    finally show ?thesis .
nipkow@15497
  2005
  qed
nipkow@15497
  2006
  moreover have "x \<cdot> z = x"
nipkow@15497
  2007
  proof -
nipkow@15497
  2008
    have "x \<cdot> z = (x \<cdot> (y \<cdot> z)) \<cdot> z" by(rule subst[OF xyzx], rule refl)
nipkow@15497
  2009
    also have "\<dots> = x \<cdot> (y \<cdot> z)" by(simp add:ACI)
nipkow@15497
  2010
    also have "\<dots> = x" by(rule xyzx)
nipkow@15497
  2011
    finally show ?thesis .
nipkow@15497
  2012
  qed
nipkow@15500
  2013
  ultimately show "x \<sqsubseteq> y \<and> x \<sqsubseteq> z" by(simp add: below_def)
nipkow@15497
  2014
next
nipkow@15500
  2015
  assume a: "x \<sqsubseteq> y \<and> x \<sqsubseteq> z"
nipkow@15497
  2016
  hence y: "x \<cdot> y = x" and z: "x \<cdot> z = x" by(simp_all add: below_def)
nipkow@15497
  2017
  have "x \<cdot> (y \<cdot> z) = (x \<cdot> y) \<cdot> z" by(simp add:assoc)
nipkow@15497
  2018
  also have "x \<cdot> y = x" using a by(simp_all add: below_def)
nipkow@15497
  2019
  also have "x \<cdot> z = x" using a by(simp_all add: below_def)
nipkow@15500
  2020
  finally show "x \<sqsubseteq> y \<cdot> z" by(simp_all add: below_def)
nipkow@15497
  2021
qed
nipkow@15497
  2022
nipkow@15497
  2023
lemma (in ACIfSLlin) above_f_conv:
nipkow@15500
  2024
 "x \<cdot> y \<sqsubseteq> z = (x \<sqsubseteq> z \<or> y \<sqsubseteq> z)"
nipkow@15497
  2025
proof
nipkow@15500
  2026
  assume a: "x \<cdot> y \<sqsubseteq> z"
nipkow@15497
  2027
  have "x \<cdot> y = x \<or> x \<cdot> y = y" using lin[of x y] by simp
nipkow@15500
  2028
  thus "x \<sqsubseteq> z \<or> y \<sqsubseteq> z"
nipkow@15497
  2029
  proof
nipkow@15500
  2030
    assume "x \<cdot> y = x" hence "x \<sqsubseteq> z" by(rule subst)(rule a) thus ?thesis ..
nipkow@15497
  2031
  next
nipkow@15500
  2032
    assume "x \<cdot> y = y" hence "y \<sqsubseteq> z" by(rule subst)(rule a) thus ?thesis ..
nipkow@15497
  2033
  qed
nipkow@15497
  2034
next
nipkow@15500
  2035
  assume "x \<sqsubseteq> z \<or> y \<sqsubseteq> z"
nipkow@15500
  2036
  thus "x \<cdot> y \<sqsubseteq> z"
nipkow@15497
  2037
  proof
nipkow@15500
  2038
    assume a: "x \<sqsubseteq> z"
nipkow@15497
  2039
    have "(x \<cdot> y) \<cdot> z = (x \<cdot> z) \<cdot> y" by(simp add:ACI)
nipkow@15497
  2040
    also have "x \<cdot> z = x" using a by(simp add:below_def)
nipkow@15500
  2041
    finally show "x \<cdot> y \<sqsubseteq> z" by(simp add:below_def)
nipkow@15497
  2042
  next
nipkow@15500
  2043
    assume a: "y \<sqsubseteq> z"
nipkow@15497
  2044
    have "(x \<cdot> y) \<cdot> z = x \<cdot> (y \<cdot> z)" by(simp add:ACI)
nipkow@15497
  2045
    also have "y \<cdot> z = y" using a by(simp add:below_def)
nipkow@15500
  2046
    finally show "x \<cdot> y \<sqsubseteq> z" by(simp add:below_def)
nipkow@15497
  2047
  qed
nipkow@15497
  2048
qed
nipkow@15497
  2049
nipkow@15497
  2050
nipkow@18493
  2051
lemma (in ACIfSLlin) strict_below_f_conv[simp]: "x \<sqsubset> y \<cdot> z = (x \<sqsubset> y \<and> x \<sqsubset> z)"
nipkow@18493
  2052
apply(simp add: strict_below_def)
nipkow@18493
  2053
using lin[of y z] by (auto simp:below_def ACI)
nipkow@18493
  2054
nipkow@18493
  2055
nipkow@18493
  2056
lemma (in ACIfSLlin) strict_above_f_conv:
ballarin@19931
  2057
  "x \<cdot> y \<sqsubset> z = (x \<sqsubset> z \<or> y \<sqsubset> z)"
nipkow@18493
  2058
apply(simp add: strict_below_def above_f_conv)
nipkow@18493
  2059
using lin[of y z] lin[of x z] by (auto simp:below_def ACI)
nipkow@18493
  2060
nipkow@18493
  2061
nipkow@15502
  2062
subsubsection{* Lemmas about @{text fold1} *}
nipkow@15484
  2063
nipkow@15484
  2064
lemma (in ACf) fold1_Un:
nipkow@15484
  2065
assumes A: "finite A" "A \<noteq> {}"
nipkow@15484
  2066
shows "finite B \<Longrightarrow> B \<noteq> {} \<Longrightarrow> A Int B = {} \<Longrightarrow>
nipkow@15484
  2067
       fold1 f (A Un B) = f (fold1 f A) (fold1 f B)"
nipkow@15484
  2068
using A
nipkow@15484
  2069
proof(induct rule:finite_ne_induct)
nipkow@15484
  2070
  case singleton thus ?case by(simp add:fold1_insert)
nipkow@15484
  2071
next
nipkow@15484
  2072
  case insert thus ?case by (simp add:fold1_insert assoc)
nipkow@15484
  2073
qed
nipkow@15484
  2074
nipkow@15484
  2075
lemma (in ACIf) fold1_Un2:
nipkow@15484
  2076
assumes A: "finite A" "A \<noteq> {}"
nipkow@15484
  2077
shows "finite B \<Longrightarrow> B \<noteq> {} \<Longrightarrow>
nipkow@15484
  2078
       fold1 f (A Un B) = f (fold1 f A) (fold1 f B)"
nipkow@15484
  2079
using A
nipkow@15484
  2080
proof(induct rule:finite_ne_induct)
paulson@15509
  2081
  case singleton thus ?case by(simp add:fold1_insert_idem)
nipkow@15484
  2082
next
paulson@15509
  2083
  case insert thus ?case by (simp add:fold1_insert_idem assoc)
nipkow@15484
  2084
qed
nipkow@15484
  2085
nipkow@15484
  2086
lemma (in ACf) fold1_in:
nipkow@15484
  2087
  assumes A: "finite (A)" "A \<noteq> {}" and elem: "\<And>x y. x\<cdot>y \<in> {x,y}"
nipkow@15484
  2088
  shows "fold1 f A \<in> A"
nipkow@15484
  2089
using A
nipkow@15484
  2090
proof (induct rule:finite_ne_induct)
paulson@15506
  2091
  case singleton thus ?case by simp
nipkow@15484
  2092
next
nipkow@15484
  2093
  case insert thus ?case using elem by (force simp add:fold1_insert)
nipkow@15484
  2094
qed
nipkow@15484
  2095
nipkow@15497
  2096
lemma (in ACIfSL) below_fold1_iff:
nipkow@15497
  2097
assumes A: "finite A" "A \<noteq> {}"
nipkow@15500
  2098
shows "x \<sqsubseteq> fold1 f A = (\<forall>a\<in>A. x \<sqsubseteq> a)"
nipkow@15497
  2099
using A
nipkow@15497
  2100
by(induct rule:finite_ne_induct) simp_all
nipkow@15497
  2101
nipkow@18493
  2102
lemma (in ACIfSLlin) strict_below_fold1_iff:
nipkow@18493
  2103
  "finite A \<Longrightarrow> A \<noteq> {} \<Longrightarrow> x \<sqsubset> fold1 f A = (\<forall>a\<in>A. x \<sqsubset> a)"
nipkow@18493
  2104
by(induct rule:finite_ne_induct) simp_all
nipkow@18493
  2105
nipkow@18493
  2106
nipkow@15497
  2107
lemma (in ACIfSL) fold1_belowI:
nipkow@15497
  2108
assumes A: "finite A" "A \<noteq> {}"
nipkow@15500
  2109
shows "a \<in> A \<Longrightarrow> fold1 f A \<sqsubseteq> a"
nipkow@15484
  2110
using A
nipkow@15484
  2111
proof (induct rule:finite_ne_induct)
nipkow@15497
  2112
  case singleton thus ?case by simp
nipkow@15484
  2113
next
nipkow@15497
  2114
  case (insert x F)
berghofe@15517
  2115
  from insert(5) have "a = x \<or> a \<in> F" by simp
nipkow@15497
  2116
  thus ?case
nipkow@15497
  2117
  proof
nipkow@15497
  2118
    assume "a = x" thus ?thesis using insert by(simp add:below_def ACI)
nipkow@15497
  2119
  next
nipkow@15497
  2120
    assume "a \<in> F"
paulson@15508
  2121
    hence bel: "fold1 f F \<sqsubseteq> a" by(rule insert)
paulson@15508
  2122
    have "fold1 f (insert x F) \<cdot> a = x \<cdot> (fold1 f F \<cdot> a)"
nipkow@15497
  2123
      using insert by(simp add:below_def ACI)
paulson@15508
  2124
    also have "fold1 f F \<cdot> a = fold1 f F"
nipkow@15497
  2125
      using bel  by(simp add:below_def ACI)
paulson@15508
  2126
    also have "x \<cdot> \<dots> = fold1 f (insert x F)"
nipkow@15497
  2127
      using insert by(simp add:below_def ACI)
nipkow@15497
  2128
    finally show ?thesis  by(simp add:below_def)
nipkow@15497
  2129
  qed
nipkow@15484
  2130
qed
nipkow@15484
  2131
nipkow@18493
  2132
nipkow@15497
  2133
lemma (in ACIfSLlin) fold1_below_iff:
nipkow@15497
  2134
assumes A: "finite A" "A \<noteq> {}"
nipkow@15500
  2135
shows "fold1 f A \<sqsubseteq> x = (\<exists>a\<in>A. a \<sqsubseteq> x)"
nipkow@15484
  2136
using A
nipkow@15497
  2137
by(induct rule:finite_ne_induct)(simp_all add:above_f_conv)
nipkow@15484
  2138
nipkow@18493
  2139
lemma (in ACIfSLlin) fold1_strict_below_iff:
nipkow@18493
  2140
assumes A: "finite A" "A \<noteq> {}"
nipkow@18493
  2141
shows "fold1 f A \<sqsubset> x = (\<exists>a\<in>A. a \<sqsubset> x)"
nipkow@18493
  2142
using A
nipkow@18493
  2143
by(induct rule:finite_ne_induct)(simp_all add:strict_above_f_conv)
nipkow@18493
  2144
nipkow@15512
  2145
nipkow@18423
  2146
lemma (in ACIfSLlin) fold1_antimono:
nipkow@18423
  2147
assumes "A \<noteq> {}" and "A \<subseteq> B" and "finite B"
nipkow@18423
  2148
shows "fold1 f B \<sqsubseteq> fold1 f A"
nipkow@18423
  2149
proof(cases)
nipkow@18423
  2150
  assume "A = B" thus ?thesis by simp
nipkow@18423
  2151
next
nipkow@18423
  2152
  assume "A \<noteq> B"
nipkow@18423
  2153
  have B: "B = A \<union> (B-A)" using `A \<subseteq> B` by blast
nipkow@18423
  2154
  have "fold1 f B = fold1 f (A \<union> (B-A))" by(subst B)(rule refl)
nipkow@18423
  2155
  also have "\<dots> = f (fold1 f A) (fold1 f (B-A))"
nipkow@18423
  2156
  proof -
nipkow@18423
  2157
    have "finite A" by(rule finite_subset[OF `A \<subseteq> B` `finite B`])
nipkow@18493
  2158
    moreover have "finite(B-A)" by(rule finite_Diff[OF `finite B`]) (* by(blast intro:finite_Diff prems) fails *)
nipkow@18423
  2159
    moreover have "(B-A) \<noteq> {}" using prems by blast
nipkow@18423
  2160
    moreover have "A Int (B-A) = {}" using prems by blast
nipkow@18423
  2161
    ultimately show ?thesis using `A \<noteq> {}` by(rule_tac fold1_Un)
nipkow@18423
  2162
  qed
nipkow@18423
  2163
  also have "\<dots> \<sqsubseteq> fold1 f A" by(simp add: above_f_conv)
nipkow@18423
  2164
  finally show ?thesis .
nipkow@18423
  2165
qed
nipkow@18423
  2166
nipkow@18423
  2167
nipkow@18493
  2168
nipkow@15500
  2169
subsubsection{* Lattices *}
nipkow@15500
  2170
nipkow@15512
  2171
locale Lattice = lattice +
nipkow@15512
  2172
  fixes Inf :: "'a set \<Rightarrow> 'a" ("\<Sqinter>_" [900] 900)
nipkow@15500
  2173
  and Sup :: "'a set \<Rightarrow> 'a" ("\<Squnion>_" [900] 900)
nipkow@15500
  2174
  defines "Inf == fold1 inf"  and "Sup == fold1 sup"
nipkow@15500
  2175
nipkow@15512
  2176
locale Distrib_Lattice = distrib_lattice + Lattice
nipkow@15504
  2177
nipkow@15500
  2178
text{* Lattices are semilattices *}
nipkow@15500
  2179
nipkow@15500
  2180
lemma (in Lattice) ACf_inf: "ACf inf"
nipkow@15512
  2181
by(blast intro: ACf.intro inf_commute inf_assoc)
nipkow@15500
  2182
nipkow@15500
  2183
lemma (in Lattice) ACf_sup: "ACf sup"
nipkow@15512
  2184
by(blast intro: ACf.intro sup_commute sup_assoc)
nipkow@15500
  2185
nipkow@15500
  2186
lemma (in Lattice) ACIf_inf: "ACIf inf"
nipkow@15500
  2187
apply(rule ACIf.intro)
nipkow@15500
  2188
apply(rule ACf_inf)
nipkow@15500
  2189
apply(rule ACIf_axioms.intro)
nipkow@15500
  2190
apply(rule inf_idem)
nipkow@15500
  2191
done
nipkow@15500
  2192
nipkow@15500
  2193
lemma (in Lattice) ACIf_sup: "ACIf sup"
nipkow@15500
  2194
apply(rule ACIf.intro)
nipkow@15500
  2195
apply(rule ACf_sup)
nipkow@15500
  2196
apply(rule ACIf_axioms.intro)
nipkow@15500
  2197
apply(rule sup_idem)
nipkow@15500
  2198
done
nipkow@15500
  2199
nipkow@15500
  2200
lemma (in Lattice) ACIfSL_inf: "ACIfSL inf (op \<sqsubseteq>)"
nipkow@15500
  2201
apply(rule ACIfSL.intro)
ballarin@19931
  2202
apply(rule ACIf.intro)
nipkow@15500
  2203
apply(rule ACf_inf)
nipkow@15500
  2204
apply(rule ACIf.axioms[OF ACIf_inf])
nipkow@15500
  2205
apply(rule ACIfSL_axioms.intro)
nipkow@15500
  2206
apply(rule iffI)
nipkow@21733
  2207
 apply(blast intro: antisym inf_le1 inf_le2 inf_greatest refl)
nipkow@15500
  2208
apply(erule subst)
nipkow@15500
  2209
apply(rule inf_le2)
nipkow@15500
  2210
done
nipkow@15500
  2211
nipkow@15500
  2212
lemma (in Lattice) ACIfSL_sup: "ACIfSL sup (%x y. y \<sqsubseteq> x)"
ballarin@19984
  2213
(* FIXME: insert ACf_sup and use unfold_locales *)
nipkow@15500
  2214
apply(rule ACIfSL.intro)
ballarin@19931
  2215
apply(rule ACIf.intro)
nipkow@15500
  2216
apply(rule ACf_sup)
nipkow@15500
  2217
apply(rule ACIf.axioms[OF ACIf_sup])
nipkow@15500
  2218
apply(rule ACIfSL_axioms.intro)
nipkow@15500
  2219
apply(rule iffI)
nipkow@21733
  2220
 apply(blast intro: antisym sup_ge1 sup_ge2 sup_least refl)
nipkow@15500
  2221
apply(erule subst)
nipkow@15500
  2222
apply(rule sup_ge2)
nipkow@15500
  2223
done
nipkow@15500
  2224
nipkow@15505
  2225
nipkow@15505
  2226
subsubsection{* Fold laws in lattices *}
nipkow@15500
  2227
nipkow@15780
  2228
lemma (in Lattice) Inf_le_Sup[simp]: "\<lbrakk> finite A; A \<noteq> {} \<rbrakk> \<Longrightarrow> \<Sqinter>A \<sqsubseteq> \<Squnion>A"
nipkow@15500
  2229
apply(unfold Sup_def Inf_def)
nipkow@15500
  2230
apply(subgoal_tac "EX a. a:A")
nipkow@15500
  2231
prefer 2 apply blast
nipkow@15500
  2232
apply(erule exE)
haftmann@22388
  2233
apply(rule order_trans)
nipkow@15500
  2234
apply(erule (2) ACIfSL.fold1_belowI[OF ACIfSL_inf])
nipkow@15500
  2235
apply(erule (2) ACIfSL.fold1_belowI[OF ACIfSL_sup])
nipkow@15500
  2236
done
nipkow@15500
  2237
nipkow@15780
  2238
lemma (in Lattice) sup_Inf_absorb[simp]:
nipkow@15504
  2239
  "\<lbrakk> finite A; A \<noteq> {}; a \<in> A \<rbrakk> \<Longrightarrow> (a \<squnion> \<Sqinter>A) = a"
nipkow@15512
  2240
apply(subst sup_commute)
nipkow@21733
  2241
apply(simp add:Inf_def sup_absorb2 ACIfSL.fold1_belowI[OF ACIfSL_inf])
nipkow@15504
  2242
done
nipkow@15504
  2243
nipkow@15780
  2244
lemma (in Lattice) inf_Sup_absorb[simp]:
nipkow@15504
  2245
  "\<lbrakk> finite A; A \<noteq> {}; a \<in> A \<rbrakk> \<Longrightarrow> (a \<sqinter> \<Squnion>A) = a"
nipkow@21733
  2246
by(simp add:Sup_def inf_absorb1 ACIfSL.fold1_belowI[OF ACIfSL_sup])
nipkow@15504
  2247
nipkow@15504
  2248
nipkow@18423
  2249
lemma (in ACIf) hom_fold1_commute:
nipkow@18423
  2250
assumes hom: "!!x y. h(f x y) = f (h x) (h y)"
nipkow@18423
  2251
and N: "finite N" "N \<noteq> {}" shows "h(fold1 f N) = fold1 f (h ` N)"
nipkow@18423
  2252
using N proof (induct rule: finite_ne_induct)
nipkow@18423
  2253
  case singleton thus ?case by simp
nipkow@15500
  2254
next
nipkow@18423
  2255
  case (insert n N)
nipkow@18423
  2256
  have "h(fold1 f (insert n N)) = h(f n (fold1 f N))" using insert by(simp)
nipkow@18423
  2257
  also have "\<dots> = f (h n) (h(fold1 f N))" by(rule hom)
nipkow@18423
  2258
  also have "h(fold1 f N) = fold1 f (h ` N)" by(rule insert)
nipkow@18423
  2259
  also have "f (h n) \<dots> = fold1 f (insert (h n) (h ` N))"
nipkow@18423
  2260
    using insert by(simp)
nipkow@18423
  2261
  also have "insert (h n) (h ` N) = h ` insert n N" by simp
nipkow@15500
  2262
  finally show ?case .
nipkow@15500
  2263
qed
nipkow@15500
  2264
nipkow@18423
  2265
lemma (in Distrib_Lattice) sup_Inf1_distrib:
nipkow@18423
  2266
 "finite A \<Longrightarrow> A \<noteq> {} \<Longrightarrow> (x \<squnion> \<Sqinter>A) = \<Sqinter>{x \<squnion> a|a. a \<in> A}"
nipkow@18423
  2267
apply(simp add:Inf_def image_def
nipkow@18423
  2268
  ACIf.hom_fold1_commute[OF ACIf_inf, where h="sup x", OF sup_inf_distrib1])
nipkow@18423
  2269
apply(rule arg_cong, blast)
nipkow@18423
  2270
done
nipkow@18423
  2271
nipkow@18423
  2272
nipkow@15512
  2273
lemma (in Distrib_Lattice) sup_Inf2_distrib:
nipkow@15500
  2274
assumes A: "finite A" "A \<noteq> {}" and B: "finite B" "B \<noteq> {}"
nipkow@15500
  2275
shows "(\<Sqinter>A \<squnion> \<Sqinter>B) = \<Sqinter>{a \<squnion> b|a b. a \<in> A \<and> b \<in> B}"
nipkow@15500
  2276
using A
nipkow@15500
  2277
proof (induct rule: finite_ne_induct)
nipkow@15500
  2278
  case singleton thus ?case
nipkow@15500
  2279
    by(simp add: sup_Inf1_distrib[OF B] fold1_singleton_def[OF Inf_def])
nipkow@15500
  2280
next
nipkow@15500
  2281
  case (insert x A)
nipkow@15500
  2282
  have finB: "finite {x \<squnion> b |b. b \<in> B}"
nipkow@21733
  2283
    by(rule finite_surj[where f = "%b. x \<squnion> b", OF B(1)], auto)
nipkow@15500
  2284
  have finAB: "finite {a \<squnion> b |a b. a \<in> A \<and> b \<in> B}"
nipkow@15500
  2285
  proof -
nipkow@15500
  2286
    have "{a \<squnion> b |a b. a \<in> A \<and> b \<in> B} = (UN a:A. UN b:B. {a \<squnion> b})"
nipkow@15500
  2287
      by blast
berghofe@15517
  2288
    thus ?thesis by(simp add: insert(1) B(1))
nipkow@15500
  2289
  qed
nipkow@15500
  2290
  have ne: "{a \<squnion> b |a b. a \<in> A \<and> b \<in> B} \<noteq> {}" using insert B by blast
nipkow@15500
  2291
  have "\<Sqinter>(insert x A) \<squnion> \<Sqinter>B = (x \<sqinter> \<Sqinter>A) \<squnion> \<Sqinter>B"
paulson@15509
  2292
    using insert by(simp add:ACIf.fold1_insert_idem_def[OF ACIf_inf Inf_def])
nipkow@15500
  2293
  also have "\<dots> = (x \<squnion> \<Sqinter>B) \<sqinter> (\<Sqinter>A \<squnion> \<Sqinter>B)" by(rule sup_inf_distrib2)
nipkow@15500
  2294
  also have "\<dots> = \<Sqinter>{x \<squnion> b|b. b \<in> B} \<sqinter> \<Sqinter>{a \<squnion> b|a b. a \<in> A \<and> b \<in> B}"
nipkow@15500
  2295
    using insert by(simp add:sup_Inf1_distrib[OF B])
nipkow@15500
  2296
  also have "\<dots> = \<Sqinter>({x\<squnion>b |b. b \<in> B} \<union> {a\<squnion>b |a b. a \<in> A \<and> b \<in> B})"
nipkow@15500
  2297
    (is "_ = \<Sqinter>?M")
nipkow@15500
  2298
    using B insert
nipkow@15500
  2299
    by(simp add:Inf_def ACIf.fold1_Un2[OF ACIf_inf finB _ finAB ne])
nipkow@15500
  2300
  also have "?M = {a \<squnion> b |a b. a \<in> insert x A \<and> b \<in> B}"
nipkow@15500
  2301
    by blast
nipkow@15500
  2302
  finally show ?case .
nipkow@15500
  2303
qed
nipkow@15500
  2304
nipkow@15484
  2305
nipkow@18423
  2306
lemma (in Distrib_Lattice) inf_Sup1_distrib:
nipkow@18423
  2307
 "finite A \<Longrightarrow> A \<noteq> {} \<Longrightarrow> (x \<sqinter> \<Squnion>A) = \<Squnion>{x \<sqinter> a|a. a \<in> A}"
nipkow@18423
  2308
apply(simp add:Sup_def image_def
nipkow@18423
  2309
  ACIf.hom_fold1_commute[OF ACIf_sup, where h="inf x", OF inf_sup_distrib1])
nipkow@18423
  2310
apply(rule arg_cong, blast)
nipkow@18423
  2311
done
nipkow@18423
  2312
nipkow@18423
  2313
nipkow@18423
  2314
lemma (in Distrib_Lattice) inf_Sup2_distrib:
nipkow@18423
  2315
assumes A: "finite A" "A \<noteq> {}" and B: "finite B" "B \<noteq> {}"
nipkow@18423
  2316
shows "(\<Squnion>A \<sqinter> \<Squnion>B) = \<Squnion>{a \<sqinter> b|a b. a \<in> A \<and> b \<in> B}"
nipkow@18423
  2317
using A
nipkow@18423
  2318
proof (induct rule: finite_ne_induct)
nipkow@18423
  2319
  case singleton thus ?case
nipkow@18423
  2320
    by(simp add: inf_Sup1_distrib[OF B] fold1_singleton_def[OF Sup_def])
nipkow@18423
  2321
next
nipkow@18423
  2322
  case (insert x A)
nipkow@18423
  2323
  have finB: "finite {x \<sqinter> b |b. b \<in> B}"
nipkow@21733
  2324
    by(rule finite_surj[where f = "%b. x \<sqinter> b", OF B(1)], auto)
nipkow@18423
  2325
  have finAB: "finite {a \<sqinter> b |a b. a \<in> A \<and> b \<in> B}"
nipkow@18423
  2326
  proof -
nipkow@18423
  2327
    have "{a \<sqinter> b |a b. a \<in> A \<and> b \<in> B} = (UN a:A. UN b:B. {a \<sqinter> b})"
nipkow@18423
  2328
      by blast
nipkow@18423
  2329
    thus ?thesis by(simp add: insert(1) B(1))
nipkow@18423
  2330
  qed
nipkow@18423
  2331
  have ne: "{a \<sqinter> b |a b. a \<in> A \<and> b \<in> B} \<noteq> {}" using insert B by blast
nipkow@18423
  2332
  have "\<Squnion>(insert x A) \<sqinter> \<Squnion>B = (x \<squnion> \<Squnion>A) \<sqinter> \<Squnion>B"
nipkow@18423
  2333
    using insert by(simp add:ACIf.fold1_insert_idem_def[OF ACIf_sup Sup_def])
nipkow@18423
  2334
  also have "\<dots> = (x \<sqinter> \<Squnion>B) \<squnion> (\<Squnion>A \<sqinter> \<Squnion>B)" by(rule inf_sup_distrib2)
nipkow@18423
  2335
  also have "\<dots> = \<Squnion>{x \<sqinter> b|b. b \<in> B} \<squnion> \<Squnion>{a \<sqinter> b|a b. a \<in> A \<and> b \<in> B}"
nipkow@18423
  2336
    using insert by(simp add:inf_Sup1_distrib[OF B])
nipkow@18423
  2337
  also have "\<dots> = \<Squnion>({x\<sqinter>b |b. b \<in> B} \<union> {a\<sqinter>b |a b. a \<in> A \<and> b \<in> B})"
nipkow@18423
  2338
    (is "_ = \<Squnion>?M")
nipkow@18423
  2339
    using B insert
nipkow@18423
  2340
    by(simp add:Sup_def ACIf.fold1_Un2[OF ACIf_sup finB _ finAB ne])
nipkow@18423
  2341
  also have "?M = {a \<sqinter> b |a b. a \<in> insert x A \<and> b \<in> B}"
nipkow@18423
  2342
    by blast
nipkow@18423
  2343
  finally show ?case .
nipkow@18423
  2344
qed
nipkow@18423
  2345
nipkow@18423
  2346
nipkow@15392
  2347
subsection{*Min and Max*}
nipkow@15392
  2348
nipkow@15392
  2349
text{* As an application of @{text fold1} we define the minimal and
nipkow@15497
  2350
maximal element of a (non-empty) set over a linear order. *}
nipkow@15497
  2351
nipkow@15497
  2352
constdefs
nipkow@15497
  2353
  Min :: "('a::linorder)set => 'a"
nipkow@15497
  2354
  "Min  ==  fold1 min"
nipkow@15497
  2355
nipkow@15497
  2356
  Max :: "('a::linorder)set => 'a"
nipkow@15497
  2357
  "Max  ==  fold1 max"
nipkow@15497
  2358
nipkow@15497
  2359
nipkow@15497
  2360
text{* Before we can do anything, we need to show that @{text min} and
nipkow@15497
  2361
@{text max} are ACI and the ordering is linear: *}
nipkow@15392
  2362
ballarin@15837
  2363
interpretation min: ACf ["min:: 'a::linorder \<Rightarrow> 'a \<Rightarrow> 'a"]
nipkow@15392
  2364
apply(rule ACf.intro)
nipkow@15392
  2365
apply(auto simp:min_def)
nipkow@15392
  2366
done
nipkow@15392
  2367
ballarin@15837
  2368
interpretation min: ACIf ["min:: 'a::linorder \<Rightarrow> 'a \<Rightarrow> 'a"]
ballarin@19984
  2369
apply unfold_locales
nipkow@15392
  2370
apply(auto simp:min_def)
nipkow@15376
  2371
done
nipkow@15376
  2372
ballarin@15837
  2373
interpretation max: ACf ["max :: 'a::linorder \<Rightarrow> 'a \<Rightarrow> 'a"]
ballarin@19984
  2374
apply unfold_locales
nipkow@15392
  2375
apply(auto simp:max_def)
nipkow@15392
  2376
done
nipkow@15392
  2377
ballarin@15837
  2378
interpretation max: ACIf ["max:: 'a::linorder \<Rightarrow> 'a \<Rightarrow> 'a"]
ballarin@19984
  2379
apply unfold_locales
nipkow@15392
  2380
apply(auto simp:max_def)
nipkow@15376
  2381
done
wenzelm@12396
  2382
ballarin@15837
  2383
interpretation min:
nipkow@18493
  2384
  ACIfSL ["min:: 'a::linorder \<Rightarrow> 'a \<Rightarrow> 'a" "op \<le>" "op <"]
nipkow@18493
  2385
apply(simp add:order_less_le)
ballarin@19984
  2386
apply unfold_locales
nipkow@15497
  2387
apply(auto simp:min_def)
nipkow@15497
  2388
done
nipkow@15497
  2389
ballarin@15837
  2390
interpretation min:
nipkow@18493
  2391
  ACIfSLlin ["min :: 'a::linorder \<Rightarrow> 'a \<Rightarrow> 'a" "op \<le>" "op <"]
ballarin@19984
  2392
apply unfold_locales
nipkow@15497
  2393
apply(auto simp:min_def)
nipkow@15497
  2394
done
nipkow@15392
  2395
ballarin@15837
  2396
interpretation max:
nipkow@18493
  2397
  ACIfSL ["max :: 'a::linorder \<Rightarrow> 'a \<Rightarrow> 'a" "%x y. y\<le>x" "%x y. y<x"]
nipkow@18493
  2398
apply(simp add:order_less_le eq_sym_conv)
ballarin@19984
  2399
apply unfold_locales
nipkow@15497
  2400
apply(auto simp:max_def)
nipkow@15497
  2401
done
nipkow@15392
  2402
ballarin@15837
  2403
interpretation max:
nipkow@18493
  2404
  ACIfSLlin ["max :: 'a::linorder \<Rightarrow> 'a \<Rightarrow> 'a" "%x y. y\<le>x" "%x y. y<x"]
ballarin@19984
  2405
apply unfold_locales
nipkow@15497
  2406
apply(auto simp:max_def)
nipkow@15497
  2407
done
nipkow@15392
  2408
ballarin@15837
  2409
interpretation min_max:
haftmann@21215
  2410
  Lattice ["op \<le>" "op <" "min :: 'a::linorder \<Rightarrow> 'a \<Rightarrow> 'a" "max" "Min" "Max"]
nipkow@15780
  2411
apply -
nipkow@15780
  2412
apply(rule Min_def)
nipkow@15780
  2413
apply(rule Max_def)
ballarin@19984
  2414
apply unfold_locales
nipkow@15507
  2415
done
nipkow@15500
  2416
nipkow@15500
  2417
ballarin@15837
  2418
interpretation min_max:
haftmann@21215
  2419
  Distrib_Lattice ["op \<le>" "op <" "min :: 'a::linorder \<Rightarrow> 'a \<Rightarrow> 'a" "max" "Min" "Max"]
ballarin@19984
  2420
  by unfold_locales
ballarin@19931
  2421
ballarin@15765
  2422
nipkow@15402
  2423
text{* Now we instantiate the recursion equations and declare them
nipkow@15392
  2424
simplification rules: *}
nipkow@15392
  2425
paulson@17085
  2426
(* Making Min or Max a defined parameter of a locale, suitably
paulson@17085
  2427
  extending ACIf, could make the following interpretations more automatic. *)
ballarin@15765
  2428
paulson@17085
  2429
lemmas Min_singleton = fold1_singleton_def [OF Min_def]
paulson@17085
  2430
lemmas Max_singleton = fold1_singleton_def [OF Max_def]
paulson@17085
  2431
lemmas Min_insert = min.fold1_insert_idem_def [OF Min_def]
paulson@17085
  2432
lemmas Max_insert = max.fold1_insert_idem_def [OF Max_def]
paulson@17085
  2433
paulson@17085
  2434
declare Min_singleton [simp]  Max_singleton [simp]
paulson@17085
  2435
declare Min_insert [simp]  Max_insert [simp]
paulson@17085
  2436
nipkow@15392
  2437
nipkow@15484
  2438
text{* Now we instantiate some @{text fold1} properties: *}
nipkow@15392
  2439
nipkow@15392
  2440
lemma Min_in [simp]:
nipkow@15484
  2441
  shows "finite A \<Longrightarrow> A \<noteq> {} \<Longrightarrow> Min A \<in> A"
nipkow@15791
  2442
using min.fold1_in
nipkow@15484
  2443
by(fastsimp simp: Min_def min_def)
nipkow@15392
  2444
nipkow@15392
  2445
lemma Max_in [simp]:
nipkow@15484
  2446
  shows "finite A \<Longrightarrow> A \<noteq> {} \<Longrightarrow> Max A \<in> A"
nipkow@15791
  2447
using max.fold1_in
nipkow@15484
  2448
by(fastsimp simp: Max_def max_def)
nipkow@15392
  2449
nipkow@18423
  2450
lemma Min_antimono: "\<lbrakk> M \<subseteq> N; M \<noteq> {}; finite N \<rbrakk> \<Longrightarrow> Min N \<le> Min M"
nipkow@18423
  2451
by(simp add:Finite_Set.Min_def min.fold1_antimono)
nipkow@18423
  2452
nipkow@18423
  2453
lemma Max_mono: "\<lbrakk> M \<subseteq> N; M \<noteq> {}; finite N \<rbrakk> \<Longrightarrow> Max M \<le> Max N"
nipkow@18423
  2454
by(simp add:Max_def max.fold1_antimono)
nipkow@18423
  2455
nipkow@15484
  2456
lemma Min_le [simp]: "\<lbrakk> finite A; A \<noteq> {}; x \<in> A \<rbrakk> \<Longrightarrow> Min A \<le> x"
nipkow@15791
  2457
by(simp add: Min_def min.fold1_belowI)
nipkow@15392
  2458
nipkow@15484
  2459
lemma Max_ge [simp]: "\<lbrakk> finite A; A \<noteq> {}; x \<in> A \<rbrakk> \<Longrightarrow> x \<le> Max A"
nipkow@15791
  2460
by(simp add: Max_def max.fold1_belowI)
nipkow@15497
  2461
nipkow@15497
  2462
lemma Min_ge_iff[simp]:
nipkow@15497
  2463
  "\<lbrakk> finite A; A \<noteq> {} \<rbrakk> \<Longrightarrow> (x \<le> Min A) = (\<forall>a\<in>A. x \<le> a)"
nipkow@15791
  2464
by(simp add: Min_def min.below_fold1_iff)
nipkow@15497
  2465
nipkow@15497
  2466
lemma Max_le_iff[simp]:
nipkow@15497
  2467
  "\<lbrakk> finite A; A \<noteq> {} \<rbrakk> \<Longrightarrow> (Max A \<le> x) = (\<forall>a\<in>A. a \<le> x)"
nipkow@15791
  2468
by(simp add: Max_def max.below_fold1_iff)
nipkow@15497
  2469
nipkow@18493
  2470
lemma Min_gr_iff[simp]:
nipkow@18493
  2471
  "\<lbrakk> finite A; A \<noteq> {} \<rbrakk> \<Longrightarrow> (x < Min A) = (\<forall>a\<in>A. x < a)"
nipkow@18493
  2472
by(simp add: Min_def min.strict_below_fold1_iff)
nipkow@18493
  2473
nipkow@18493
  2474
lemma Max_less_iff[simp]:
nipkow@18493
  2475
  "\<lbrakk> finite A; A \<noteq> {} \<rbrakk> \<Longrightarrow> (Max A < x) = (\<forall>a\<in>A. a < x)"
nipkow@18493
  2476
by(simp add: Max_def max.strict_below_fold1_iff)
nipkow@18493
  2477
nipkow@15497
  2478
lemma Min_le_iff:
nipkow@15497
  2479
  "\<lbrakk> finite A; A \<noteq> {} \<rbrakk> \<Longrightarrow> (Min A \<le> x) = (\<exists>a\<in>A. a \<le> x)"
nipkow@15791
  2480
by(simp add: Min_def min.fold1_below_iff)
nipkow@15497
  2481
nipkow@15497
  2482
lemma Max_ge_iff:
nipkow@15497
  2483
  "\<lbrakk> finite A; A \<noteq> {} \<rbrakk> \<Longrightarrow> (x \<le> Max A) = (\<exists>a\<in>A. x \<le> a)"
nipkow@15791
  2484
by(simp add: Max_def max.fold1_below_iff)
wenzelm@12396
  2485
nipkow@18493
  2486
lemma Min_le_iff:
nipkow@18493
  2487
  "\<lbrakk> finite A; A \<noteq> {} \<rbrakk> \<Longrightarrow> (Min A < x) = (\<exists>a\<in>A. a < x)"
nipkow@18493
  2488
by(simp add: Min_def min.fold1_strict_below_iff)
nipkow@18493
  2489
nipkow@18493
  2490
lemma Max_ge_iff:
nipkow@18493
  2491
  "\<lbrakk> finite A; A \<noteq> {} \<rbrakk> \<Longrightarrow> (x < Max A) = (\<exists>a\<in>A. x < a)"
nipkow@18493
  2492
by(simp add: Max_def max.fold1_strict_below_iff)
nipkow@18493
  2493
nipkow@18423
  2494
lemma Min_Un: "\<lbrakk>finite A; A \<noteq> {}; finite B; B \<noteq> {}\<rbrakk>
nipkow@18423
  2495
  \<Longrightarrow> Min (A \<union> B) = min (Min A) (Min B)"
nipkow@18423
  2496
by(simp add:Min_def min.f.fold1_Un2)
nipkow@18423
  2497
nipkow@18423
  2498
lemma Max_Un: "\<lbrakk>finite A; A \<noteq> {}; finite B; B \<noteq> {}\<rbrakk>
nipkow@18423
  2499
  \<Longrightarrow> Max (A \<union> B) = max (Max A) (Max B)"
nipkow@18423
  2500
by(simp add:Max_def max.f.fold1_Un2)
nipkow@18423
  2501
nipkow@18423
  2502
nipkow@18423
  2503
lemma hom_Min_commute:
nipkow@18423
  2504
 "(!!x y::'a::linorder. h(min x y) = min (h x) (h y::'a))
nipkow@18423
  2505
  \<Longrightarrow> finite N \<Longrightarrow> N \<noteq> {} \<Longrightarrow> h(Min N) = Min(h ` N)"
nipkow@18423
  2506
by(simp add:Finite_Set.Min_def min.hom_fold1_commute)
nipkow@18423
  2507
nipkow@18423
  2508
lemma hom_Max_commute:
nipkow@18423
  2509
 "(!!x y::'a::linorder. h(max x y) = max (h x) (h y::'a))
nipkow@18423
  2510
  \<Longrightarrow> finite N \<Longrightarrow> N \<noteq> {} \<Longrightarrow> h(Max N) = Max(h ` N)"
nipkow@18423
  2511
by(simp add:Max_def max.hom_fold1_commute)
nipkow@18423
  2512
nipkow@18423
  2513
nipkow@18423
  2514
lemma add_Min_commute: fixes k::"'a::{pordered_ab_semigroup_add,linorder}"
nipkow@18423
  2515
 shows "finite N \<Longrightarrow> N \<noteq> {} \<Longrightarrow> k + Min N = Min {k+m|m. m \<in> N}"
nipkow@18423
  2516
apply(subgoal_tac "!!x y. k + min x y = min (k + x) (k + y)")
nipkow@18423
  2517
using hom_Min_commute[of "op + k" N]
nipkow@18423
  2518
apply simp apply(rule arg_cong[where f = Min]) apply blast
nipkow@18423
  2519
apply(simp add:min_def linorder_not_le)
haftmann@22388
  2520
apply(blast intro: antisym order_less_imp_le add_left_mono)
nipkow@18423
  2521
done
nipkow@18423
  2522
nipkow@18423
  2523
lemma add_Max_commute: fixes k::"'a::{pordered_ab_semigroup_add,linorder}"
nipkow@18423
  2524
 shows "finite N \<Longrightarrow> N \<noteq> {} \<Longrightarrow> k + Max N = Max {k+m|m. m \<in> N}"
nipkow@18423
  2525
apply(subgoal_tac "!!x y. k + max x y = max (k + x) (k + y)")
nipkow@18423
  2526
using hom_Max_commute[of "op + k" N]
nipkow@18423
  2527
apply simp apply(rule arg_cong[where f = Max]) apply blast
nipkow@18423
  2528
apply(simp add:max_def linorder_not_le)
haftmann@22388
  2529
apply(blast intro: antisym order_less_imp_le add_left_mono)
nipkow@18423
  2530
done
nipkow@18423
  2531
nipkow@18423
  2532
haftmann@22388
  2533
subsection {* Class @{text finite} *}
haftmann@22388
  2534
haftmann@22388
  2535
class finite (attach UNIV) =
haftmann@22388
  2536
  assumes finite: "finite UNIV"
nipkow@17022
  2537
nipkow@17022
  2538
lemma finite_set: "finite (A::'a::finite set)"
haftmann@22388
  2539
  by (rule finite_subset [OF subset_UNIV finite])
haftmann@22388
  2540
haftmann@22388
  2541
lemma univ_unit:
haftmann@22388
  2542
  "UNIV = {()}" by auto
nipkow@17022
  2543
nipkow@17022
  2544
instance unit :: finite
nipkow@17022
  2545
proof
nipkow@17022
  2546
  have "finite {()}" by simp
haftmann@22388
  2547
  also note univ_unit [symmetric]
nipkow@17022
  2548
  finally show "finite (UNIV :: unit set)" .
nipkow@17022
  2549
qed
nipkow@17022
  2550
haftmann@22388
  2551
lemmas [code func] = univ_unit
haftmann@22388
  2552
haftmann@22388
  2553
lemma univ_bool:
haftmann@22388
  2554
  "UNIV = {False, True}" by auto
haftmann@22388
  2555
nipkow@17022
  2556
instance bool :: finite
nipkow@17022
  2557
proof
haftmann@22388
  2558
  have "finite {False, True}" by simp
haftmann@22388
  2559
  also note univ_bool [symmetric]
nipkow@17022
  2560
  finally show "finite (UNIV :: bool set)" .
nipkow@17022
  2561
qed
nipkow@17022
  2562
haftmann@22388
  2563
lemmas [code func] = univ_bool
nipkow@17022
  2564
nipkow@17022
  2565
instance * :: (finite, finite) finite
nipkow@17022
  2566
proof
nipkow@17022
  2567
  show "finite (UNIV :: ('a \<times> 'b) set)"
nipkow@17022
  2568
  proof (rule finite_Prod_UNIV)
nipkow@17022
  2569
    show "finite (UNIV :: 'a set)" by (rule finite)
nipkow@17022
  2570
    show "finite (UNIV :: 'b set)" by (rule finite)
nipkow@17022
  2571
  qed
nipkow@17022
  2572
qed
nipkow@17022
  2573
haftmann@22388
  2574
lemma univ_prod [code func]:
haftmann@22388
  2575
  "UNIV = (UNIV \<Colon> 'a\<Colon>finite set) \<times> (UNIV \<Colon> 'b\<Colon>finite set)"
haftmann@22388
  2576
  unfolding UNIV_Times_UNIV ..
haftmann@22388
  2577
nipkow@17022
  2578
instance "+" :: (finite, finite) finite
nipkow@17022
  2579
proof
nipkow@17022
  2580
  have a: "finite (UNIV :: 'a set)" by (rule finite)
nipkow@17022
  2581
  have b: "finite (UNIV :: 'b set)" by (rule finite)
nipkow@17022
  2582
  from a b have "finite ((UNIV :: 'a set) <+> (UNIV :: 'b set))"
nipkow@17022
  2583
    by (rule finite_Plus)
nipkow@17022
  2584
  thus "finite (UNIV :: ('a + 'b) set)" by simp
nipkow@17022
  2585
qed
nipkow@17022
  2586
haftmann@22388
  2587
lemma univ_sum [code func]:
haftmann@22388
  2588
  "UNIV = (UNIV \<Colon> 'a\<Colon>finite set) <+> (UNIV \<Colon> 'b\<Colon>finite set)"
haftmann@22388
  2589
  unfolding UNIV_Plus_UNIV ..
nipkow@17022
  2590
nipkow@17022
  2591
instance set :: (finite) finite
nipkow@17022
  2592
proof
nipkow@17022
  2593
  have "finite (UNIV :: 'a set)" by (rule finite)
nipkow@17022
  2594
  hence "finite (Pow (UNIV :: 'a set))"
nipkow@17022
  2595
    by (rule finite_Pow_iff [THEN iffD2])
nipkow@17022
  2596
  thus "finite (UNIV :: 'a set set)" by simp
nipkow@17022
  2597
qed
nipkow@17022
  2598
haftmann@22388
  2599
lemma univ_set [code func]:
haftmann@22388
  2600
  "UNIV = Pow (UNIV \<Colon> 'a\<Colon>finite set)" unfolding Pow_UNIV ..
haftmann@22388
  2601
nipkow@17022
  2602
lemma inj_graph: "inj (%f. {(x, y). y = f x})"
haftmann@22388
  2603
  by (rule inj_onI, auto simp add: expand_set_eq expand_fun_eq)
nipkow@17022
  2604
haftmann@21215
  2605
instance "fun" :: (finite, finite) finite
nipkow@17022
  2606
proof
nipkow@17022
  2607
  show "finite (UNIV :: ('a => 'b) set)"
nipkow@17022
  2608
  proof (rule finite_imageD)
nipkow@17022
  2609
    let ?graph = "%f::'a => 'b. {(x, y). y = f x}"
nipkow@17022
  2610
    show "finite (range ?graph)" by (rule finite_set)
nipkow@17022
  2611
    show "inj ?graph" by (rule inj_graph)
nipkow@17022
  2612
  qed
nipkow@17022
  2613
qed
nipkow@17022
  2614
haftmann@22388
  2615
haftmann@22388
  2616
subsection {* Equality on functions *}
haftmann@22388
  2617
haftmann@22388
  2618
instance "fun" :: (finite, eq) eq ..
haftmann@22388
  2619
<