src/HOL/Library/Multiset.thy
author wenzelm
Sat Apr 08 22:51:06 2006 +0200 (2006-04-08)
changeset 19363 667b5ea637dd
parent 19086 1b3780be6cc2
child 19564 d3e2f532459a
permissions -rw-r--r--
refined 'abbreviation';
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(*  Title:      HOL/Library/Multiset.thy
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    ID:         $Id$
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    Author:     Tobias Nipkow, Markus Wenzel, Lawrence C Paulson, Norbert Voelker
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*)
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header {* Multisets *}
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theory Multiset
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imports Accessible_Part
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begin
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subsection {* The type of multisets *}
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typedef 'a multiset = "{f::'a => nat. finite {x . 0 < f x}}"
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proof
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  show "(\<lambda>x. 0::nat) \<in> ?multiset" by simp
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qed
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lemmas multiset_typedef [simp] =
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    Abs_multiset_inverse Rep_multiset_inverse Rep_multiset
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  and [simp] = Rep_multiset_inject [symmetric]
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definition
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  Mempty :: "'a multiset"    ("{#}")
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  "{#} = Abs_multiset (\<lambda>a. 0)"
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  single :: "'a => 'a multiset"    ("{#_#}")
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  "{#a#} = Abs_multiset (\<lambda>b. if b = a then 1 else 0)"
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  count :: "'a multiset => 'a => nat"
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  "count = Rep_multiset"
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  MCollect :: "'a multiset => ('a => bool) => 'a multiset"
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  "MCollect M P = Abs_multiset (\<lambda>x. if P x then Rep_multiset M x else 0)"
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abbreviation
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  Melem :: "'a => 'a multiset => bool"    ("(_/ :# _)" [50, 51] 50)
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  "a :# M == 0 < count M a"
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syntax
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  "_MCollect" :: "pttrn => 'a multiset => bool => 'a multiset"    ("(1{# _ : _./ _#})")
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translations
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  "{#x:M. P#}" == "MCollect M (\<lambda>x. P)"
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definition
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  set_of :: "'a multiset => 'a set"
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  "set_of M = {x. x :# M}"
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instance multiset :: (type) "{plus, minus, zero}" ..
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defs (overloaded)
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  union_def: "M + N == Abs_multiset (\<lambda>a. Rep_multiset M a + Rep_multiset N a)"
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  diff_def: "M - N == Abs_multiset (\<lambda>a. Rep_multiset M a - Rep_multiset N a)"
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  Zero_multiset_def [simp]: "0 == {#}"
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  size_def: "size M == setsum (count M) (set_of M)"
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definition
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  multiset_inter :: "'a multiset \<Rightarrow> 'a multiset \<Rightarrow> 'a multiset" (infixl "#\<inter>" 70)
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  "multiset_inter A B = A - (A - B)"
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text {*
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 \medskip Preservation of the representing set @{term multiset}.
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*}
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lemma const0_in_multiset [simp]: "(\<lambda>a. 0) \<in> multiset"
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  by (simp add: multiset_def)
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lemma only1_in_multiset [simp]: "(\<lambda>b. if b = a then 1 else 0) \<in> multiset"
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  by (simp add: multiset_def)
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lemma union_preserves_multiset [simp]:
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    "M \<in> multiset ==> N \<in> multiset ==> (\<lambda>a. M a + N a) \<in> multiset"
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  apply (simp add: multiset_def)
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  apply (drule (1) finite_UnI)
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  apply (simp del: finite_Un add: Un_def)
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  done
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lemma diff_preserves_multiset [simp]:
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    "M \<in> multiset ==> (\<lambda>a. M a - N a) \<in> multiset"
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  apply (simp add: multiset_def)
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  apply (rule finite_subset)
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   apply auto
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  done
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subsection {* Algebraic properties of multisets *}
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subsubsection {* Union *}
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lemma union_empty [simp]: "M + {#} = M \<and> {#} + M = M"
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  by (simp add: union_def Mempty_def)
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lemma union_commute: "M + N = N + (M::'a multiset)"
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  by (simp add: union_def add_ac)
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lemma union_assoc: "(M + N) + K = M + (N + (K::'a multiset))"
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  by (simp add: union_def add_ac)
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lemma union_lcomm: "M + (N + K) = N + (M + (K::'a multiset))"
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proof -
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  have "M + (N + K) = (N + K) + M"
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    by (rule union_commute)
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  also have "\<dots> = N + (K + M)"
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    by (rule union_assoc)
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  also have "K + M = M + K"
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    by (rule union_commute)
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  finally show ?thesis .
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qed
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lemmas union_ac = union_assoc union_commute union_lcomm
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instance multiset :: (type) comm_monoid_add
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proof
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  fix a b c :: "'a multiset"
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  show "(a + b) + c = a + (b + c)" by (rule union_assoc)
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  show "a + b = b + a" by (rule union_commute)
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  show "0 + a = a" by simp
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qed
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subsubsection {* Difference *}
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lemma diff_empty [simp]: "M - {#} = M \<and> {#} - M = {#}"
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  by (simp add: Mempty_def diff_def)
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lemma diff_union_inverse2 [simp]: "M + {#a#} - {#a#} = M"
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  by (simp add: union_def diff_def)
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subsubsection {* Count of elements *}
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lemma count_empty [simp]: "count {#} a = 0"
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  by (simp add: count_def Mempty_def)
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lemma count_single [simp]: "count {#b#} a = (if b = a then 1 else 0)"
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  by (simp add: count_def single_def)
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lemma count_union [simp]: "count (M + N) a = count M a + count N a"
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  by (simp add: count_def union_def)
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lemma count_diff [simp]: "count (M - N) a = count M a - count N a"
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  by (simp add: count_def diff_def)
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subsubsection {* Set of elements *}
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lemma set_of_empty [simp]: "set_of {#} = {}"
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  by (simp add: set_of_def)
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lemma set_of_single [simp]: "set_of {#b#} = {b}"
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  by (simp add: set_of_def)
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lemma set_of_union [simp]: "set_of (M + N) = set_of M \<union> set_of N"
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  by (auto simp add: set_of_def)
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lemma set_of_eq_empty_iff [simp]: "(set_of M = {}) = (M = {#})"
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  by (auto simp add: set_of_def Mempty_def count_def expand_fun_eq)
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lemma mem_set_of_iff [simp]: "(x \<in> set_of M) = (x :# M)"
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  by (auto simp add: set_of_def)
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subsubsection {* Size *}
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lemma size_empty [simp]: "size {#} = 0"
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  by (simp add: size_def)
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lemma size_single [simp]: "size {#b#} = 1"
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  by (simp add: size_def)
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lemma finite_set_of [iff]: "finite (set_of M)"
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  using Rep_multiset [of M]
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  by (simp add: multiset_def set_of_def count_def)
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lemma setsum_count_Int:
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    "finite A ==> setsum (count N) (A \<inter> set_of N) = setsum (count N) A"
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  apply (induct rule: finite_induct)
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   apply simp
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  apply (simp add: Int_insert_left set_of_def)
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  done
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lemma size_union [simp]: "size (M + N::'a multiset) = size M + size N"
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  apply (unfold size_def)
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  apply (subgoal_tac "count (M + N) = (\<lambda>a. count M a + count N a)")
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   prefer 2
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   apply (rule ext, simp)
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  apply (simp (no_asm_simp) add: setsum_Un_nat setsum_addf setsum_count_Int)
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  apply (subst Int_commute)
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  apply (simp (no_asm_simp) add: setsum_count_Int)
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  done
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lemma size_eq_0_iff_empty [iff]: "(size M = 0) = (M = {#})"
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  apply (unfold size_def Mempty_def count_def, auto)
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  apply (simp add: set_of_def count_def expand_fun_eq)
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  done
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lemma size_eq_Suc_imp_elem: "size M = Suc n ==> \<exists>a. a :# M"
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  apply (unfold size_def)
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  apply (drule setsum_SucD, auto)
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  done
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subsubsection {* Equality of multisets *}
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lemma multiset_eq_conv_count_eq: "(M = N) = (\<forall>a. count M a = count N a)"
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  by (simp add: count_def expand_fun_eq)
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lemma single_not_empty [simp]: "{#a#} \<noteq> {#} \<and> {#} \<noteq> {#a#}"
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  by (simp add: single_def Mempty_def expand_fun_eq)
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lemma single_eq_single [simp]: "({#a#} = {#b#}) = (a = b)"
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  by (auto simp add: single_def expand_fun_eq)
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lemma union_eq_empty [iff]: "(M + N = {#}) = (M = {#} \<and> N = {#})"
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  by (auto simp add: union_def Mempty_def expand_fun_eq)
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lemma empty_eq_union [iff]: "({#} = M + N) = (M = {#} \<and> N = {#})"
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  by (auto simp add: union_def Mempty_def expand_fun_eq)
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lemma union_right_cancel [simp]: "(M + K = N + K) = (M = (N::'a multiset))"
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  by (simp add: union_def expand_fun_eq)
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lemma union_left_cancel [simp]: "(K + M = K + N) = (M = (N::'a multiset))"
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  by (simp add: union_def expand_fun_eq)
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lemma union_is_single:
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    "(M + N = {#a#}) = (M = {#a#} \<and> N={#} \<or> M = {#} \<and> N = {#a#})"
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  apply (simp add: Mempty_def single_def union_def add_is_1 expand_fun_eq)
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  apply blast
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  done
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lemma single_is_union:
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     "({#a#} = M + N) = ({#a#} = M \<and> N = {#} \<or> M = {#} \<and> {#a#} = N)"
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  apply (unfold Mempty_def single_def union_def)
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  apply (simp add: add_is_1 one_is_add expand_fun_eq)
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  apply (blast dest: sym)
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  done
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ML"reset use_neq_simproc"
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lemma add_eq_conv_diff:
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  "(M + {#a#} = N + {#b#}) =
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   (M = N \<and> a = b \<or> M = N - {#a#} + {#b#} \<and> N = M - {#b#} + {#a#})"
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  apply (unfold single_def union_def diff_def)
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  apply (simp (no_asm) add: expand_fun_eq)
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  apply (rule conjI, force, safe, simp_all)
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  apply (simp add: eq_sym_conv)
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  done
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ML"set use_neq_simproc"
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declare Rep_multiset_inject [symmetric, simp del]
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subsubsection {* Intersection *}
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lemma multiset_inter_count:
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    "count (A #\<inter> B) x = min (count A x) (count B x)"
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  by (simp add: multiset_inter_def min_def)
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lemma multiset_inter_commute: "A #\<inter> B = B #\<inter> A"
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  by (simp add: multiset_eq_conv_count_eq multiset_inter_count
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    min_max.below_inf.inf_commute)
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lemma multiset_inter_assoc: "A #\<inter> (B #\<inter> C) = A #\<inter> B #\<inter> C"
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  by (simp add: multiset_eq_conv_count_eq multiset_inter_count
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    min_max.below_inf.inf_assoc)
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lemma multiset_inter_left_commute: "A #\<inter> (B #\<inter> C) = B #\<inter> (A #\<inter> C)"
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  by (simp add: multiset_eq_conv_count_eq multiset_inter_count min_def)
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lemmas multiset_inter_ac =
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  multiset_inter_commute
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  multiset_inter_assoc
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  multiset_inter_left_commute
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lemma multiset_union_diff_commute: "B #\<inter> C = {#} \<Longrightarrow> A + B - C = A - C + B"
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  apply (simp add: multiset_eq_conv_count_eq multiset_inter_count min_def
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    split: split_if_asm)
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  apply clarsimp
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  apply (erule_tac x = a in allE)
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  apply auto
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  done
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subsection {* Induction over multisets *}
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lemma setsum_decr:
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  "finite F ==> (0::nat) < f a ==>
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    setsum (f (a := f a - 1)) F = (if a\<in>F then setsum f F - 1 else setsum f F)"
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  apply (induct rule: finite_induct)
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   apply auto
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  apply (drule_tac a = a in mk_disjoint_insert, auto)
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  done
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lemma rep_multiset_induct_aux:
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  assumes 1: "P (\<lambda>a. (0::nat))"
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    and 2: "!!f b. f \<in> multiset ==> P f ==> P (f (b := f b + 1))"
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  shows "\<forall>f. f \<in> multiset --> setsum f {x. 0 < f x} = n --> P f"
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  apply (unfold multiset_def)
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  apply (induct_tac n, simp, clarify)
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   apply (subgoal_tac "f = (\<lambda>a.0)")
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    apply simp
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    apply (rule 1)
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   apply (rule ext, force, clarify)
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  apply (frule setsum_SucD, clarify)
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  apply (rename_tac a)
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  apply (subgoal_tac "finite {x. 0 < (f (a := f a - 1)) x}")
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   prefer 2
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   apply (rule finite_subset)
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    prefer 2
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    apply assumption
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   apply simp
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   apply blast
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  apply (subgoal_tac "f = (f (a := f a - 1))(a := (f (a := f a - 1)) a + 1)")
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   prefer 2
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   apply (rule ext)
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   apply (simp (no_asm_simp))
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   apply (erule ssubst, rule 2 [unfolded multiset_def], blast)
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  apply (erule allE, erule impE, erule_tac [2] mp, blast)
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  apply (simp (no_asm_simp) add: setsum_decr del: fun_upd_apply One_nat_def)
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  apply (subgoal_tac "{x. x \<noteq> a --> 0 < f x} = {x. 0 < f x}")
wenzelm@18730
   322
   prefer 2
wenzelm@18730
   323
   apply blast
wenzelm@18730
   324
  apply (subgoal_tac "{x. x \<noteq> a \<and> 0 < f x} = {x. 0 < f x} - {a}")
wenzelm@18730
   325
   prefer 2
wenzelm@18730
   326
   apply blast
wenzelm@18730
   327
  apply (simp add: le_imp_diff_is_add setsum_diff1_nat cong: conj_cong)
wenzelm@18730
   328
  done
wenzelm@10249
   329
wenzelm@10313
   330
theorem rep_multiset_induct:
nipkow@11464
   331
  "f \<in> multiset ==> P (\<lambda>a. 0) ==>
wenzelm@11701
   332
    (!!f b. f \<in> multiset ==> P f ==> P (f (b := f b + 1))) ==> P f"
wenzelm@17161
   333
  using rep_multiset_induct_aux by blast
wenzelm@10249
   334
wenzelm@18258
   335
theorem multiset_induct [case_names empty add, induct type: multiset]:
wenzelm@18258
   336
  assumes empty: "P {#}"
wenzelm@18258
   337
    and add: "!!M x. P M ==> P (M + {#x#})"
wenzelm@17161
   338
  shows "P M"
wenzelm@10249
   339
proof -
wenzelm@10249
   340
  note defns = union_def single_def Mempty_def
wenzelm@10249
   341
  show ?thesis
wenzelm@10249
   342
    apply (rule Rep_multiset_inverse [THEN subst])
wenzelm@10313
   343
    apply (rule Rep_multiset [THEN rep_multiset_induct])
wenzelm@18258
   344
     apply (rule empty [unfolded defns])
paulson@15072
   345
    apply (subgoal_tac "f(b := f b + 1) = (\<lambda>a. f a + (if a=b then 1 else 0))")
wenzelm@10249
   346
     prefer 2
wenzelm@10249
   347
     apply (simp add: expand_fun_eq)
wenzelm@10249
   348
    apply (erule ssubst)
wenzelm@17200
   349
    apply (erule Abs_multiset_inverse [THEN subst])
wenzelm@18258
   350
    apply (erule add [unfolded defns, simplified])
wenzelm@10249
   351
    done
wenzelm@10249
   352
qed
wenzelm@10249
   353
wenzelm@10249
   354
lemma MCollect_preserves_multiset:
nipkow@11464
   355
    "M \<in> multiset ==> (\<lambda>x. if P x then M x else 0) \<in> multiset"
wenzelm@10249
   356
  apply (simp add: multiset_def)
paulson@15072
   357
  apply (rule finite_subset, auto)
wenzelm@10249
   358
  done
wenzelm@10249
   359
wenzelm@17161
   360
lemma count_MCollect [simp]:
wenzelm@10249
   361
    "count {# x:M. P x #} a = (if P a then count M a else 0)"
paulson@15072
   362
  by (simp add: count_def MCollect_def MCollect_preserves_multiset)
wenzelm@10249
   363
wenzelm@17161
   364
lemma set_of_MCollect [simp]: "set_of {# x:M. P x #} = set_of M \<inter> {x. P x}"
wenzelm@17161
   365
  by (auto simp add: set_of_def)
wenzelm@10249
   366
wenzelm@17161
   367
lemma multiset_partition: "M = {# x:M. P x #} + {# x:M. \<not> P x #}"
wenzelm@17161
   368
  by (subst multiset_eq_conv_count_eq, auto)
wenzelm@10249
   369
wenzelm@17161
   370
lemma add_eq_conv_ex:
wenzelm@17161
   371
  "(M + {#a#} = N + {#b#}) =
wenzelm@17161
   372
    (M = N \<and> a = b \<or> (\<exists>K. M = K + {#b#} \<and> N = K + {#a#}))"
paulson@15072
   373
  by (auto simp add: add_eq_conv_diff)
wenzelm@10249
   374
kleing@15869
   375
declare multiset_typedef [simp del]
wenzelm@10249
   376
wenzelm@17161
   377
wenzelm@10249
   378
subsection {* Multiset orderings *}
wenzelm@10249
   379
wenzelm@10249
   380
subsubsection {* Well-foundedness *}
wenzelm@10249
   381
wenzelm@19086
   382
definition
nipkow@11464
   383
  mult1 :: "('a \<times> 'a) set => ('a multiset \<times> 'a multiset) set"
wenzelm@19086
   384
  "mult1 r =
nipkow@11464
   385
    {(N, M). \<exists>a M0 K. M = M0 + {#a#} \<and> N = M0 + K \<and>
nipkow@11464
   386
      (\<forall>b. b :# K --> (b, a) \<in> r)}"
wenzelm@10249
   387
nipkow@11464
   388
  mult :: "('a \<times> 'a) set => ('a multiset \<times> 'a multiset) set"
wenzelm@19086
   389
  "mult r = (mult1 r)\<^sup>+"
wenzelm@10249
   390
nipkow@11464
   391
lemma not_less_empty [iff]: "(M, {#}) \<notin> mult1 r"
wenzelm@10277
   392
  by (simp add: mult1_def)
wenzelm@10249
   393
nipkow@11464
   394
lemma less_add: "(N, M0 + {#a#}) \<in> mult1 r ==>
nipkow@11464
   395
    (\<exists>M. (M, M0) \<in> mult1 r \<and> N = M + {#a#}) \<or>
nipkow@11464
   396
    (\<exists>K. (\<forall>b. b :# K --> (b, a) \<in> r) \<and> N = M0 + K)"
nipkow@11464
   397
  (concl is "?case1 (mult1 r) \<or> ?case2")
wenzelm@10249
   398
proof (unfold mult1_def)
nipkow@11464
   399
  let ?r = "\<lambda>K a. \<forall>b. b :# K --> (b, a) \<in> r"
nipkow@11464
   400
  let ?R = "\<lambda>N M. \<exists>a M0 K. M = M0 + {#a#} \<and> N = M0 + K \<and> ?r K a"
wenzelm@10249
   401
  let ?case1 = "?case1 {(N, M). ?R N M}"
wenzelm@10249
   402
nipkow@11464
   403
  assume "(N, M0 + {#a#}) \<in> {(N, M). ?R N M}"
wenzelm@18258
   404
  then have "\<exists>a' M0' K.
nipkow@11464
   405
      M0 + {#a#} = M0' + {#a'#} \<and> N = M0' + K \<and> ?r K a'" by simp
wenzelm@18258
   406
  then show "?case1 \<or> ?case2"
wenzelm@10249
   407
  proof (elim exE conjE)
wenzelm@10249
   408
    fix a' M0' K
wenzelm@10249
   409
    assume N: "N = M0' + K" and r: "?r K a'"
wenzelm@10249
   410
    assume "M0 + {#a#} = M0' + {#a'#}"
wenzelm@18258
   411
    then have "M0 = M0' \<and> a = a' \<or>
nipkow@11464
   412
        (\<exists>K'. M0 = K' + {#a'#} \<and> M0' = K' + {#a#})"
wenzelm@10249
   413
      by (simp only: add_eq_conv_ex)
wenzelm@18258
   414
    then show ?thesis
wenzelm@10249
   415
    proof (elim disjE conjE exE)
wenzelm@10249
   416
      assume "M0 = M0'" "a = a'"
nipkow@11464
   417
      with N r have "?r K a \<and> N = M0 + K" by simp
wenzelm@18258
   418
      then have ?case2 .. then show ?thesis ..
wenzelm@10249
   419
    next
wenzelm@10249
   420
      fix K'
wenzelm@10249
   421
      assume "M0' = K' + {#a#}"
wenzelm@10249
   422
      with N have n: "N = K' + K + {#a#}" by (simp add: union_ac)
wenzelm@10249
   423
wenzelm@10249
   424
      assume "M0 = K' + {#a'#}"
wenzelm@10249
   425
      with r have "?R (K' + K) M0" by blast
wenzelm@18258
   426
      with n have ?case1 by simp then show ?thesis ..
wenzelm@10249
   427
    qed
wenzelm@10249
   428
  qed
wenzelm@10249
   429
qed
wenzelm@10249
   430
nipkow@11464
   431
lemma all_accessible: "wf r ==> \<forall>M. M \<in> acc (mult1 r)"
wenzelm@10249
   432
proof
wenzelm@10249
   433
  let ?R = "mult1 r"
wenzelm@10249
   434
  let ?W = "acc ?R"
wenzelm@10249
   435
  {
wenzelm@10249
   436
    fix M M0 a
nipkow@11464
   437
    assume M0: "M0 \<in> ?W"
wenzelm@12399
   438
      and wf_hyp: "!!b. (b, a) \<in> r ==> (\<forall>M \<in> ?W. M + {#b#} \<in> ?W)"
nipkow@11464
   439
      and acc_hyp: "\<forall>M. (M, M0) \<in> ?R --> M + {#a#} \<in> ?W"
nipkow@11464
   440
    have "M0 + {#a#} \<in> ?W"
wenzelm@10249
   441
    proof (rule accI [of "M0 + {#a#}"])
wenzelm@10249
   442
      fix N
nipkow@11464
   443
      assume "(N, M0 + {#a#}) \<in> ?R"
wenzelm@18258
   444
      then have "((\<exists>M. (M, M0) \<in> ?R \<and> N = M + {#a#}) \<or>
nipkow@11464
   445
          (\<exists>K. (\<forall>b. b :# K --> (b, a) \<in> r) \<and> N = M0 + K))"
wenzelm@10249
   446
        by (rule less_add)
wenzelm@18258
   447
      then show "N \<in> ?W"
wenzelm@10249
   448
      proof (elim exE disjE conjE)
nipkow@11464
   449
        fix M assume "(M, M0) \<in> ?R" and N: "N = M + {#a#}"
nipkow@11464
   450
        from acc_hyp have "(M, M0) \<in> ?R --> M + {#a#} \<in> ?W" ..
wenzelm@18258
   451
        then have "M + {#a#} \<in> ?W" ..
wenzelm@18258
   452
        then show "N \<in> ?W" by (simp only: N)
wenzelm@10249
   453
      next
wenzelm@10249
   454
        fix K
wenzelm@10249
   455
        assume N: "N = M0 + K"
nipkow@11464
   456
        assume "\<forall>b. b :# K --> (b, a) \<in> r"
wenzelm@18730
   457
        then have "M0 + K \<in> ?W"
wenzelm@10249
   458
        proof (induct K)
wenzelm@18730
   459
          case empty
wenzelm@18258
   460
          from M0 show "M0 + {#} \<in> ?W" by simp
wenzelm@18730
   461
        next
wenzelm@18730
   462
          case (add K x)
wenzelm@18730
   463
          from add.prems have "(x, a) \<in> r" by simp
wenzelm@18258
   464
          with wf_hyp have "\<forall>M \<in> ?W. M + {#x#} \<in> ?W" by blast
wenzelm@18730
   465
          moreover from add have "M0 + K \<in> ?W" by simp
wenzelm@18258
   466
          ultimately have "(M0 + K) + {#x#} \<in> ?W" ..
wenzelm@18258
   467
          then show "M0 + (K + {#x#}) \<in> ?W" by (simp only: union_assoc)
wenzelm@10249
   468
        qed
wenzelm@18730
   469
        then show "N \<in> ?W" by (simp only: N)
wenzelm@10249
   470
      qed
wenzelm@10249
   471
    qed
wenzelm@10249
   472
  } note tedious_reasoning = this
wenzelm@10249
   473
wenzelm@10249
   474
  assume wf: "wf r"
wenzelm@10249
   475
  fix M
nipkow@11464
   476
  show "M \<in> ?W"
wenzelm@10249
   477
  proof (induct M)
nipkow@11464
   478
    show "{#} \<in> ?W"
wenzelm@10249
   479
    proof (rule accI)
nipkow@11464
   480
      fix b assume "(b, {#}) \<in> ?R"
nipkow@11464
   481
      with not_less_empty show "b \<in> ?W" by contradiction
wenzelm@10249
   482
    qed
wenzelm@10249
   483
nipkow@11464
   484
    fix M a assume "M \<in> ?W"
nipkow@11464
   485
    from wf have "\<forall>M \<in> ?W. M + {#a#} \<in> ?W"
wenzelm@10249
   486
    proof induct
wenzelm@10249
   487
      fix a
wenzelm@12399
   488
      assume "!!b. (b, a) \<in> r ==> (\<forall>M \<in> ?W. M + {#b#} \<in> ?W)"
nipkow@11464
   489
      show "\<forall>M \<in> ?W. M + {#a#} \<in> ?W"
wenzelm@10249
   490
      proof
nipkow@11464
   491
        fix M assume "M \<in> ?W"
wenzelm@18258
   492
        then show "M + {#a#} \<in> ?W"
wenzelm@10249
   493
          by (rule acc_induct) (rule tedious_reasoning)
wenzelm@10249
   494
      qed
wenzelm@10249
   495
    qed
wenzelm@18258
   496
    then show "M + {#a#} \<in> ?W" ..
wenzelm@10249
   497
  qed
wenzelm@10249
   498
qed
wenzelm@10249
   499
wenzelm@10249
   500
theorem wf_mult1: "wf r ==> wf (mult1 r)"
wenzelm@10249
   501
  by (rule acc_wfI, rule all_accessible)
wenzelm@10249
   502
wenzelm@10249
   503
theorem wf_mult: "wf r ==> wf (mult r)"
wenzelm@10249
   504
  by (unfold mult_def, rule wf_trancl, rule wf_mult1)
wenzelm@10249
   505
wenzelm@10249
   506
wenzelm@10249
   507
subsubsection {* Closure-free presentation *}
wenzelm@10249
   508
wenzelm@10249
   509
(*Badly needed: a linear arithmetic procedure for multisets*)
wenzelm@10249
   510
wenzelm@10249
   511
lemma diff_union_single_conv: "a :# J ==> I + J - {#a#} = I + (J - {#a#})"
paulson@15072
   512
by (simp add: multiset_eq_conv_count_eq)
wenzelm@10249
   513
wenzelm@10249
   514
text {* One direction. *}
wenzelm@10249
   515
wenzelm@10249
   516
lemma mult_implies_one_step:
nipkow@11464
   517
  "trans r ==> (M, N) \<in> mult r ==>
nipkow@11464
   518
    \<exists>I J K. N = I + J \<and> M = I + K \<and> J \<noteq> {#} \<and>
nipkow@11464
   519
    (\<forall>k \<in> set_of K. \<exists>j \<in> set_of J. (k, j) \<in> r)"
wenzelm@10249
   520
  apply (unfold mult_def mult1_def set_of_def)
paulson@15072
   521
  apply (erule converse_trancl_induct, clarify)
paulson@15072
   522
   apply (rule_tac x = M0 in exI, simp, clarify)
wenzelm@10249
   523
  apply (case_tac "a :# K")
wenzelm@10249
   524
   apply (rule_tac x = I in exI)
wenzelm@10249
   525
   apply (simp (no_asm))
wenzelm@10249
   526
   apply (rule_tac x = "(K - {#a#}) + Ka" in exI)
wenzelm@10249
   527
   apply (simp (no_asm_simp) add: union_assoc [symmetric])
nipkow@11464
   528
   apply (drule_tac f = "\<lambda>M. M - {#a#}" in arg_cong)
wenzelm@10249
   529
   apply (simp add: diff_union_single_conv)
wenzelm@10249
   530
   apply (simp (no_asm_use) add: trans_def)
wenzelm@10249
   531
   apply blast
wenzelm@10249
   532
  apply (subgoal_tac "a :# I")
wenzelm@10249
   533
   apply (rule_tac x = "I - {#a#}" in exI)
wenzelm@10249
   534
   apply (rule_tac x = "J + {#a#}" in exI)
wenzelm@10249
   535
   apply (rule_tac x = "K + Ka" in exI)
wenzelm@10249
   536
   apply (rule conjI)
wenzelm@10249
   537
    apply (simp add: multiset_eq_conv_count_eq split: nat_diff_split)
wenzelm@10249
   538
   apply (rule conjI)
paulson@15072
   539
    apply (drule_tac f = "\<lambda>M. M - {#a#}" in arg_cong, simp)
wenzelm@10249
   540
    apply (simp add: multiset_eq_conv_count_eq split: nat_diff_split)
wenzelm@10249
   541
   apply (simp (no_asm_use) add: trans_def)
wenzelm@10249
   542
   apply blast
wenzelm@10277
   543
  apply (subgoal_tac "a :# (M0 + {#a#})")
wenzelm@10249
   544
   apply simp
wenzelm@10249
   545
  apply (simp (no_asm))
wenzelm@10249
   546
  done
wenzelm@10249
   547
wenzelm@10249
   548
lemma elem_imp_eq_diff_union: "a :# M ==> M = M - {#a#} + {#a#}"
paulson@15072
   549
by (simp add: multiset_eq_conv_count_eq)
wenzelm@10249
   550
nipkow@11464
   551
lemma size_eq_Suc_imp_eq_union: "size M = Suc n ==> \<exists>a N. M = N + {#a#}"
wenzelm@10249
   552
  apply (erule size_eq_Suc_imp_elem [THEN exE])
paulson@15072
   553
  apply (drule elem_imp_eq_diff_union, auto)
wenzelm@10249
   554
  done
wenzelm@10249
   555
wenzelm@10249
   556
lemma one_step_implies_mult_aux:
wenzelm@10249
   557
  "trans r ==>
nipkow@11464
   558
    \<forall>I J K. (size J = n \<and> J \<noteq> {#} \<and> (\<forall>k \<in> set_of K. \<exists>j \<in> set_of J. (k, j) \<in> r))
nipkow@11464
   559
      --> (I + K, I + J) \<in> mult r"
paulson@15072
   560
  apply (induct_tac n, auto)
paulson@15072
   561
  apply (frule size_eq_Suc_imp_eq_union, clarify)
paulson@15072
   562
  apply (rename_tac "J'", simp)
paulson@15072
   563
  apply (erule notE, auto)
wenzelm@10249
   564
  apply (case_tac "J' = {#}")
wenzelm@10249
   565
   apply (simp add: mult_def)
wenzelm@10249
   566
   apply (rule r_into_trancl)
paulson@15072
   567
   apply (simp add: mult1_def set_of_def, blast)
nipkow@11464
   568
  txt {* Now we know @{term "J' \<noteq> {#}"}. *}
nipkow@11464
   569
  apply (cut_tac M = K and P = "\<lambda>x. (x, a) \<in> r" in multiset_partition)
nipkow@11464
   570
  apply (erule_tac P = "\<forall>k \<in> set_of K. ?P k" in rev_mp)
wenzelm@10249
   571
  apply (erule ssubst)
paulson@15072
   572
  apply (simp add: Ball_def, auto)
wenzelm@10249
   573
  apply (subgoal_tac
nipkow@11464
   574
    "((I + {# x : K. (x, a) \<in> r #}) + {# x : K. (x, a) \<notin> r #},
nipkow@11464
   575
      (I + {# x : K. (x, a) \<in> r #}) + J') \<in> mult r")
wenzelm@10249
   576
   prefer 2
wenzelm@10249
   577
   apply force
wenzelm@10249
   578
  apply (simp (no_asm_use) add: union_assoc [symmetric] mult_def)
wenzelm@10249
   579
  apply (erule trancl_trans)
wenzelm@10249
   580
  apply (rule r_into_trancl)
wenzelm@10249
   581
  apply (simp add: mult1_def set_of_def)
wenzelm@10249
   582
  apply (rule_tac x = a in exI)
wenzelm@10249
   583
  apply (rule_tac x = "I + J'" in exI)
wenzelm@10249
   584
  apply (simp add: union_ac)
wenzelm@10249
   585
  done
wenzelm@10249
   586
wenzelm@17161
   587
lemma one_step_implies_mult:
nipkow@11464
   588
  "trans r ==> J \<noteq> {#} ==> \<forall>k \<in> set_of K. \<exists>j \<in> set_of J. (k, j) \<in> r
nipkow@11464
   589
    ==> (I + K, I + J) \<in> mult r"
paulson@15072
   590
  apply (insert one_step_implies_mult_aux, blast)
wenzelm@10249
   591
  done
wenzelm@10249
   592
wenzelm@10249
   593
wenzelm@10249
   594
subsubsection {* Partial-order properties *}
wenzelm@10249
   595
wenzelm@12338
   596
instance multiset :: (type) ord ..
wenzelm@10249
   597
wenzelm@10249
   598
defs (overloaded)
nipkow@11464
   599
  less_multiset_def: "M' < M == (M', M) \<in> mult {(x', x). x' < x}"
nipkow@11464
   600
  le_multiset_def: "M' <= M == M' = M \<or> M' < (M::'a multiset)"
wenzelm@10249
   601
wenzelm@10249
   602
lemma trans_base_order: "trans {(x', x). x' < (x::'a::order)}"
wenzelm@18730
   603
  unfolding trans_def by (blast intro: order_less_trans)
wenzelm@10249
   604
wenzelm@10249
   605
text {*
wenzelm@10249
   606
 \medskip Irreflexivity.
wenzelm@10249
   607
*}
wenzelm@10249
   608
wenzelm@10249
   609
lemma mult_irrefl_aux:
wenzelm@18258
   610
    "finite A ==> (\<forall>x \<in> A. \<exists>y \<in> A. x < (y::'a::order)) \<Longrightarrow> A = {}"
wenzelm@18258
   611
  apply (induct rule: finite_induct)
wenzelm@10249
   612
   apply (auto intro: order_less_trans)
wenzelm@10249
   613
  done
wenzelm@10249
   614
wenzelm@17161
   615
lemma mult_less_not_refl: "\<not> M < (M::'a::order multiset)"
paulson@15072
   616
  apply (unfold less_multiset_def, auto)
paulson@15072
   617
  apply (drule trans_base_order [THEN mult_implies_one_step], auto)
wenzelm@10249
   618
  apply (drule finite_set_of [THEN mult_irrefl_aux [rule_format (no_asm)]])
wenzelm@10249
   619
  apply (simp add: set_of_eq_empty_iff)
wenzelm@10249
   620
  done
wenzelm@10249
   621
wenzelm@10249
   622
lemma mult_less_irrefl [elim!]: "M < (M::'a::order multiset) ==> R"
paulson@15072
   623
by (insert mult_less_not_refl, fast)
wenzelm@10249
   624
wenzelm@10249
   625
wenzelm@10249
   626
text {* Transitivity. *}
wenzelm@10249
   627
wenzelm@10249
   628
theorem mult_less_trans: "K < M ==> M < N ==> K < (N::'a::order multiset)"
wenzelm@10249
   629
  apply (unfold less_multiset_def mult_def)
wenzelm@10249
   630
  apply (blast intro: trancl_trans)
wenzelm@10249
   631
  done
wenzelm@10249
   632
wenzelm@10249
   633
text {* Asymmetry. *}
wenzelm@10249
   634
nipkow@11464
   635
theorem mult_less_not_sym: "M < N ==> \<not> N < (M::'a::order multiset)"
wenzelm@10249
   636
  apply auto
wenzelm@10249
   637
  apply (rule mult_less_not_refl [THEN notE])
paulson@15072
   638
  apply (erule mult_less_trans, assumption)
wenzelm@10249
   639
  done
wenzelm@10249
   640
wenzelm@10249
   641
theorem mult_less_asym:
nipkow@11464
   642
    "M < N ==> (\<not> P ==> N < (M::'a::order multiset)) ==> P"
paulson@15072
   643
  by (insert mult_less_not_sym, blast)
wenzelm@10249
   644
wenzelm@10249
   645
theorem mult_le_refl [iff]: "M <= (M::'a::order multiset)"
wenzelm@18730
   646
  unfolding le_multiset_def by auto
wenzelm@10249
   647
wenzelm@10249
   648
text {* Anti-symmetry. *}
wenzelm@10249
   649
wenzelm@10249
   650
theorem mult_le_antisym:
wenzelm@10249
   651
    "M <= N ==> N <= M ==> M = (N::'a::order multiset)"
wenzelm@18730
   652
  unfolding le_multiset_def by (blast dest: mult_less_not_sym)
wenzelm@10249
   653
wenzelm@10249
   654
text {* Transitivity. *}
wenzelm@10249
   655
wenzelm@10249
   656
theorem mult_le_trans:
wenzelm@10249
   657
    "K <= M ==> M <= N ==> K <= (N::'a::order multiset)"
wenzelm@18730
   658
  unfolding le_multiset_def by (blast intro: mult_less_trans)
wenzelm@10249
   659
wenzelm@11655
   660
theorem mult_less_le: "(M < N) = (M <= N \<and> M \<noteq> (N::'a::order multiset))"
wenzelm@18730
   661
  unfolding le_multiset_def by auto
wenzelm@10249
   662
wenzelm@10277
   663
text {* Partial order. *}
wenzelm@10277
   664
wenzelm@10277
   665
instance multiset :: (order) order
wenzelm@10277
   666
  apply intro_classes
wenzelm@10277
   667
     apply (rule mult_le_refl)
paulson@15072
   668
    apply (erule mult_le_trans, assumption)
paulson@15072
   669
   apply (erule mult_le_antisym, assumption)
wenzelm@10277
   670
  apply (rule mult_less_le)
wenzelm@10277
   671
  done
wenzelm@10277
   672
wenzelm@10249
   673
wenzelm@10249
   674
subsubsection {* Monotonicity of multiset union *}
wenzelm@10249
   675
wenzelm@17161
   676
lemma mult1_union:
nipkow@11464
   677
    "(B, D) \<in> mult1 r ==> trans r ==> (C + B, C + D) \<in> mult1 r"
paulson@15072
   678
  apply (unfold mult1_def, auto)
wenzelm@10249
   679
  apply (rule_tac x = a in exI)
wenzelm@10249
   680
  apply (rule_tac x = "C + M0" in exI)
wenzelm@10249
   681
  apply (simp add: union_assoc)
wenzelm@10249
   682
  done
wenzelm@10249
   683
wenzelm@10249
   684
lemma union_less_mono2: "B < D ==> C + B < C + (D::'a::order multiset)"
wenzelm@10249
   685
  apply (unfold less_multiset_def mult_def)
wenzelm@10249
   686
  apply (erule trancl_induct)
wenzelm@10249
   687
   apply (blast intro: mult1_union transI order_less_trans r_into_trancl)
wenzelm@10249
   688
  apply (blast intro: mult1_union transI order_less_trans r_into_trancl trancl_trans)
wenzelm@10249
   689
  done
wenzelm@10249
   690
wenzelm@10249
   691
lemma union_less_mono1: "B < D ==> B + C < D + (C::'a::order multiset)"
wenzelm@10249
   692
  apply (subst union_commute [of B C])
wenzelm@10249
   693
  apply (subst union_commute [of D C])
wenzelm@10249
   694
  apply (erule union_less_mono2)
wenzelm@10249
   695
  done
wenzelm@10249
   696
wenzelm@17161
   697
lemma union_less_mono:
wenzelm@10249
   698
    "A < C ==> B < D ==> A + B < C + (D::'a::order multiset)"
wenzelm@10249
   699
  apply (blast intro!: union_less_mono1 union_less_mono2 mult_less_trans)
wenzelm@10249
   700
  done
wenzelm@10249
   701
wenzelm@17161
   702
lemma union_le_mono:
wenzelm@10249
   703
    "A <= C ==> B <= D ==> A + B <= C + (D::'a::order multiset)"
wenzelm@18730
   704
  unfolding le_multiset_def
wenzelm@18730
   705
  by (blast intro: union_less_mono union_less_mono1 union_less_mono2)
wenzelm@10249
   706
wenzelm@17161
   707
lemma empty_leI [iff]: "{#} <= (M::'a::order multiset)"
wenzelm@10249
   708
  apply (unfold le_multiset_def less_multiset_def)
wenzelm@10249
   709
  apply (case_tac "M = {#}")
wenzelm@10249
   710
   prefer 2
nipkow@11464
   711
   apply (subgoal_tac "({#} + {#}, {#} + M) \<in> mult (Collect (split op <))")
wenzelm@10249
   712
    prefer 2
wenzelm@10249
   713
    apply (rule one_step_implies_mult)
paulson@15072
   714
      apply (simp only: trans_def, auto)
wenzelm@10249
   715
  done
wenzelm@10249
   716
wenzelm@17161
   717
lemma union_upper1: "A <= A + (B::'a::order multiset)"
paulson@15072
   718
proof -
wenzelm@17200
   719
  have "A + {#} <= A + B" by (blast intro: union_le_mono)
wenzelm@18258
   720
  then show ?thesis by simp
paulson@15072
   721
qed
paulson@15072
   722
wenzelm@17161
   723
lemma union_upper2: "B <= A + (B::'a::order multiset)"
wenzelm@18258
   724
  by (subst union_commute) (rule union_upper1)
paulson@15072
   725
paulson@15072
   726
wenzelm@17200
   727
subsection {* Link with lists *}
paulson@15072
   728
wenzelm@17200
   729
consts
paulson@15072
   730
  multiset_of :: "'a list \<Rightarrow> 'a multiset"
paulson@15072
   731
primrec
paulson@15072
   732
  "multiset_of [] = {#}"
paulson@15072
   733
  "multiset_of (a # x) = multiset_of x + {# a #}"
paulson@15072
   734
paulson@15072
   735
lemma multiset_of_zero_iff[simp]: "(multiset_of x = {#}) = (x = [])"
wenzelm@18258
   736
  by (induct x) auto
paulson@15072
   737
paulson@15072
   738
lemma multiset_of_zero_iff_right[simp]: "({#} = multiset_of x) = (x = [])"
wenzelm@18258
   739
  by (induct x) auto
paulson@15072
   740
paulson@15072
   741
lemma set_of_multiset_of[simp]: "set_of(multiset_of x) = set x"
wenzelm@18258
   742
  by (induct x) auto
kleing@15867
   743
kleing@15867
   744
lemma mem_set_multiset_eq: "x \<in> set xs = (x :# multiset_of xs)"
kleing@15867
   745
  by (induct xs) auto
paulson@15072
   746
wenzelm@18258
   747
lemma multiset_of_append [simp]:
wenzelm@18258
   748
    "multiset_of (xs @ ys) = multiset_of xs + multiset_of ys"
wenzelm@18258
   749
  by (induct xs fixing: ys) (auto simp: union_ac)
wenzelm@18730
   750
paulson@15072
   751
lemma surj_multiset_of: "surj multiset_of"
wenzelm@17200
   752
  apply (unfold surj_def, rule allI)
wenzelm@17200
   753
  apply (rule_tac M=y in multiset_induct, auto)
wenzelm@17200
   754
  apply (rule_tac x = "x # xa" in exI, auto)
wenzelm@10249
   755
  done
wenzelm@10249
   756
paulson@15072
   757
lemma set_count_greater_0: "set x = {a. 0 < count (multiset_of x) a}"
wenzelm@18258
   758
  by (induct x) auto
paulson@15072
   759
wenzelm@17200
   760
lemma distinct_count_atmost_1:
paulson@15072
   761
   "distinct x = (! a. count (multiset_of x) a = (if a \<in> set x then 1 else 0))"
wenzelm@18258
   762
   apply (induct x, simp, rule iffI, simp_all)
wenzelm@17200
   763
   apply (rule conjI)
wenzelm@17200
   764
   apply (simp_all add: set_of_multiset_of [THEN sym] del: set_of_multiset_of)
paulson@15072
   765
   apply (erule_tac x=a in allE, simp, clarify)
wenzelm@17200
   766
   apply (erule_tac x=aa in allE, simp)
paulson@15072
   767
   done
paulson@15072
   768
wenzelm@17200
   769
lemma multiset_of_eq_setD:
kleing@15867
   770
  "multiset_of xs = multiset_of ys \<Longrightarrow> set xs = set ys"
kleing@15867
   771
  by (rule) (auto simp add:multiset_eq_conv_count_eq set_count_greater_0)
kleing@15867
   772
wenzelm@17200
   773
lemma set_eq_iff_multiset_of_eq_distinct:
wenzelm@17200
   774
  "\<lbrakk>distinct x; distinct y\<rbrakk>
paulson@15072
   775
   \<Longrightarrow> (set x = set y) = (multiset_of x = multiset_of y)"
wenzelm@17200
   776
  by (auto simp: multiset_eq_conv_count_eq distinct_count_atmost_1)
paulson@15072
   777
wenzelm@17200
   778
lemma set_eq_iff_multiset_of_remdups_eq:
paulson@15072
   779
   "(set x = set y) = (multiset_of (remdups x) = multiset_of (remdups y))"
wenzelm@17200
   780
  apply (rule iffI)
wenzelm@17200
   781
  apply (simp add: set_eq_iff_multiset_of_eq_distinct[THEN iffD1])
wenzelm@17200
   782
  apply (drule distinct_remdups[THEN distinct_remdups
wenzelm@17200
   783
                      [THEN set_eq_iff_multiset_of_eq_distinct[THEN iffD2]]])
paulson@15072
   784
  apply simp
wenzelm@10249
   785
  done
wenzelm@10249
   786
wenzelm@18258
   787
lemma multiset_of_compl_union [simp]:
wenzelm@18258
   788
    "multiset_of [x\<in>xs. P x] + multiset_of [x\<in>xs. \<not>P x] = multiset_of xs"
kleing@15630
   789
  by (induct xs) (auto simp: union_ac)
paulson@15072
   790
wenzelm@17200
   791
lemma count_filter:
wenzelm@18258
   792
    "count (multiset_of xs) x = length [y \<in> xs. y = x]"
wenzelm@18258
   793
  by (induct xs) auto
kleing@15867
   794
kleing@15867
   795
paulson@15072
   796
subsection {* Pointwise ordering induced by count *}
paulson@15072
   797
wenzelm@19086
   798
definition
wenzelm@19086
   799
  mset_le :: "['a multiset, 'a multiset] \<Rightarrow> bool"   ("_ \<le># _"  [50,51] 50)
wenzelm@19086
   800
  "(xs \<le># ys) = (\<forall>a. count xs a \<le> count ys a)"
paulson@15072
   801
paulson@15072
   802
lemma mset_le_refl[simp]: "xs \<le># xs"
wenzelm@18730
   803
  unfolding mset_le_def by auto
paulson@15072
   804
paulson@15072
   805
lemma mset_le_trans: "\<lbrakk> xs \<le># ys; ys \<le># zs \<rbrakk> \<Longrightarrow> xs \<le># zs"
wenzelm@18730
   806
  unfolding mset_le_def by (fast intro: order_trans)
paulson@15072
   807
paulson@15072
   808
lemma mset_le_antisym: "\<lbrakk> xs\<le># ys; ys \<le># xs\<rbrakk> \<Longrightarrow> xs = ys"
wenzelm@17200
   809
  apply (unfold mset_le_def)
wenzelm@17200
   810
  apply (rule multiset_eq_conv_count_eq[THEN iffD2])
paulson@15072
   811
  apply (blast intro: order_antisym)
paulson@15072
   812
  done
paulson@15072
   813
wenzelm@17200
   814
lemma mset_le_exists_conv:
wenzelm@17200
   815
  "(xs \<le># ys) = (\<exists>zs. ys = xs + zs)"
wenzelm@17200
   816
  apply (unfold mset_le_def, rule iffI, rule_tac x = "ys - xs" in exI)
paulson@15072
   817
  apply (auto intro: multiset_eq_conv_count_eq [THEN iffD2])
paulson@15072
   818
  done
paulson@15072
   819
paulson@15072
   820
lemma mset_le_mono_add_right_cancel[simp]: "(xs + zs \<le># ys + zs) = (xs \<le># ys)"
wenzelm@18730
   821
  unfolding mset_le_def by auto
paulson@15072
   822
paulson@15072
   823
lemma mset_le_mono_add_left_cancel[simp]: "(zs + xs \<le># zs + ys) = (xs \<le># ys)"
wenzelm@18730
   824
  unfolding mset_le_def by auto
paulson@15072
   825
wenzelm@17200
   826
lemma mset_le_mono_add: "\<lbrakk> xs \<le># ys; vs \<le># ws \<rbrakk> \<Longrightarrow> xs + vs \<le># ys + ws"
wenzelm@17200
   827
  apply (unfold mset_le_def)
wenzelm@17200
   828
  apply auto
paulson@15072
   829
  apply (erule_tac x=a in allE)+
paulson@15072
   830
  apply auto
paulson@15072
   831
  done
paulson@15072
   832
paulson@15072
   833
lemma mset_le_add_left[simp]: "xs \<le># xs + ys"
wenzelm@18730
   834
  unfolding mset_le_def by auto
paulson@15072
   835
paulson@15072
   836
lemma mset_le_add_right[simp]: "ys \<le># xs + ys"
wenzelm@18730
   837
  unfolding mset_le_def by auto
paulson@15072
   838
paulson@15072
   839
lemma multiset_of_remdups_le: "multiset_of (remdups x) \<le># multiset_of x"
wenzelm@17200
   840
  apply (induct x)
wenzelm@17200
   841
   apply auto
wenzelm@17200
   842
  apply (rule mset_le_trans)
wenzelm@17200
   843
   apply auto
wenzelm@17200
   844
  done
paulson@15072
   845
wenzelm@10249
   846
end