src/HOL/Library/Multiset.thy
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```     1 (*  Title:      HOL/Library/Multiset.thy
```
```     2     Author:     Tobias Nipkow, Markus Wenzel, Lawrence C Paulson, Norbert Voelker
```
```     3 *)
```
```     4
```
```     5 header {* (Finite) multisets *}
```
```     6
```
```     7 theory Multiset
```
```     8 imports Main DAList
```
```     9 begin
```
```    10
```
```    11 subsection {* The type of multisets *}
```
```    12
```
```    13 definition "multiset = {f :: 'a => nat. finite {x. f x > 0}}"
```
```    14
```
```    15 typedef (open) 'a multiset = "multiset :: ('a => nat) set"
```
```    16   morphisms count Abs_multiset
```
```    17   unfolding multiset_def
```
```    18 proof
```
```    19   show "(\<lambda>x. 0::nat) \<in> {f. finite {x. f x > 0}}" by simp
```
```    20 qed
```
```    21
```
```    22 setup_lifting type_definition_multiset
```
```    23
```
```    24 abbreviation Melem :: "'a => 'a multiset => bool"  ("(_/ :# _)" [50, 51] 50) where
```
```    25   "a :# M == 0 < count M a"
```
```    26
```
```    27 notation (xsymbols)
```
```    28   Melem (infix "\<in>#" 50)
```
```    29
```
```    30 lemma multiset_eq_iff:
```
```    31   "M = N \<longleftrightarrow> (\<forall>a. count M a = count N a)"
```
```    32   by (simp only: count_inject [symmetric] fun_eq_iff)
```
```    33
```
```    34 lemma multiset_eqI:
```
```    35   "(\<And>x. count A x = count B x) \<Longrightarrow> A = B"
```
```    36   using multiset_eq_iff by auto
```
```    37
```
```    38 text {*
```
```    39  \medskip Preservation of the representing set @{term multiset}.
```
```    40 *}
```
```    41
```
```    42 lemma const0_in_multiset:
```
```    43   "(\<lambda>a. 0) \<in> multiset"
```
```    44   by (simp add: multiset_def)
```
```    45
```
```    46 lemma only1_in_multiset:
```
```    47   "(\<lambda>b. if b = a then n else 0) \<in> multiset"
```
```    48   by (simp add: multiset_def)
```
```    49
```
```    50 lemma union_preserves_multiset:
```
```    51   "M \<in> multiset \<Longrightarrow> N \<in> multiset \<Longrightarrow> (\<lambda>a. M a + N a) \<in> multiset"
```
```    52   by (simp add: multiset_def)
```
```    53
```
```    54 lemma diff_preserves_multiset:
```
```    55   assumes "M \<in> multiset"
```
```    56   shows "(\<lambda>a. M a - N a) \<in> multiset"
```
```    57 proof -
```
```    58   have "{x. N x < M x} \<subseteq> {x. 0 < M x}"
```
```    59     by auto
```
```    60   with assms show ?thesis
```
```    61     by (auto simp add: multiset_def intro: finite_subset)
```
```    62 qed
```
```    63
```
```    64 lemma filter_preserves_multiset:
```
```    65   assumes "M \<in> multiset"
```
```    66   shows "(\<lambda>x. if P x then M x else 0) \<in> multiset"
```
```    67 proof -
```
```    68   have "{x. (P x \<longrightarrow> 0 < M x) \<and> P x} \<subseteq> {x. 0 < M x}"
```
```    69     by auto
```
```    70   with assms show ?thesis
```
```    71     by (auto simp add: multiset_def intro: finite_subset)
```
```    72 qed
```
```    73
```
```    74 lemmas in_multiset = const0_in_multiset only1_in_multiset
```
```    75   union_preserves_multiset diff_preserves_multiset filter_preserves_multiset
```
```    76
```
```    77
```
```    78 subsection {* Representing multisets *}
```
```    79
```
```    80 text {* Multiset enumeration *}
```
```    81
```
```    82 instantiation multiset :: (type) cancel_comm_monoid_add
```
```    83 begin
```
```    84
```
```    85 lift_definition zero_multiset :: "'a multiset" is "\<lambda>a. 0"
```
```    86 by (rule const0_in_multiset)
```
```    87
```
```    88 abbreviation Mempty :: "'a multiset" ("{#}") where
```
```    89   "Mempty \<equiv> 0"
```
```    90
```
```    91 lift_definition plus_multiset :: "'a multiset => 'a multiset => 'a multiset" is "\<lambda>M N. (\<lambda>a. M a + N a)"
```
```    92 by (rule union_preserves_multiset)
```
```    93
```
```    94 instance
```
```    95 by default (transfer, simp add: fun_eq_iff)+
```
```    96
```
```    97 end
```
```    98
```
```    99 lift_definition single :: "'a => 'a multiset" is "\<lambda>a b. if b = a then 1 else 0"
```
```   100 by (rule only1_in_multiset)
```
```   101
```
```   102 syntax
```
```   103   "_multiset" :: "args => 'a multiset"    ("{#(_)#}")
```
```   104 translations
```
```   105   "{#x, xs#}" == "{#x#} + {#xs#}"
```
```   106   "{#x#}" == "CONST single x"
```
```   107
```
```   108 lemma count_empty [simp]: "count {#} a = 0"
```
```   109   by (simp add: zero_multiset.rep_eq)
```
```   110
```
```   111 lemma count_single [simp]: "count {#b#} a = (if b = a then 1 else 0)"
```
```   112   by (simp add: single.rep_eq)
```
```   113
```
```   114
```
```   115 subsection {* Basic operations *}
```
```   116
```
```   117 subsubsection {* Union *}
```
```   118
```
```   119 lemma count_union [simp]: "count (M + N) a = count M a + count N a"
```
```   120   by (simp add: plus_multiset.rep_eq)
```
```   121
```
```   122
```
```   123 subsubsection {* Difference *}
```
```   124
```
```   125 instantiation multiset :: (type) comm_monoid_diff
```
```   126 begin
```
```   127
```
```   128 lift_definition minus_multiset :: "'a multiset => 'a multiset => 'a multiset" is "\<lambda> M N. \<lambda>a. M a - N a"
```
```   129 by (rule diff_preserves_multiset)
```
```   130
```
```   131 instance
```
```   132 by default (transfer, simp add: fun_eq_iff)+
```
```   133
```
```   134 end
```
```   135
```
```   136 lemma count_diff [simp]: "count (M - N) a = count M a - count N a"
```
```   137   by (simp add: minus_multiset.rep_eq)
```
```   138
```
```   139 lemma diff_empty [simp]: "M - {#} = M \<and> {#} - M = {#}"
```
```   140 by(simp add: multiset_eq_iff)
```
```   141
```
```   142 lemma diff_cancel[simp]: "A - A = {#}"
```
```   143 by (rule multiset_eqI) simp
```
```   144
```
```   145 lemma diff_union_cancelR [simp]: "M + N - N = (M::'a multiset)"
```
```   146 by(simp add: multiset_eq_iff)
```
```   147
```
```   148 lemma diff_union_cancelL [simp]: "N + M - N = (M::'a multiset)"
```
```   149 by(simp add: multiset_eq_iff)
```
```   150
```
```   151 lemma insert_DiffM:
```
```   152   "x \<in># M \<Longrightarrow> {#x#} + (M - {#x#}) = M"
```
```   153   by (clarsimp simp: multiset_eq_iff)
```
```   154
```
```   155 lemma insert_DiffM2 [simp]:
```
```   156   "x \<in># M \<Longrightarrow> M - {#x#} + {#x#} = M"
```
```   157   by (clarsimp simp: multiset_eq_iff)
```
```   158
```
```   159 lemma diff_right_commute:
```
```   160   "(M::'a multiset) - N - Q = M - Q - N"
```
```   161   by (auto simp add: multiset_eq_iff)
```
```   162
```
```   163 lemma diff_add:
```
```   164   "(M::'a multiset) - (N + Q) = M - N - Q"
```
```   165 by (simp add: multiset_eq_iff)
```
```   166
```
```   167 lemma diff_union_swap:
```
```   168   "a \<noteq> b \<Longrightarrow> M - {#a#} + {#b#} = M + {#b#} - {#a#}"
```
```   169   by (auto simp add: multiset_eq_iff)
```
```   170
```
```   171 lemma diff_union_single_conv:
```
```   172   "a \<in># J \<Longrightarrow> I + J - {#a#} = I + (J - {#a#})"
```
```   173   by (simp add: multiset_eq_iff)
```
```   174
```
```   175
```
```   176 subsubsection {* Equality of multisets *}
```
```   177
```
```   178 lemma single_not_empty [simp]: "{#a#} \<noteq> {#} \<and> {#} \<noteq> {#a#}"
```
```   179   by (simp add: multiset_eq_iff)
```
```   180
```
```   181 lemma single_eq_single [simp]: "{#a#} = {#b#} \<longleftrightarrow> a = b"
```
```   182   by (auto simp add: multiset_eq_iff)
```
```   183
```
```   184 lemma union_eq_empty [iff]: "M + N = {#} \<longleftrightarrow> M = {#} \<and> N = {#}"
```
```   185   by (auto simp add: multiset_eq_iff)
```
```   186
```
```   187 lemma empty_eq_union [iff]: "{#} = M + N \<longleftrightarrow> M = {#} \<and> N = {#}"
```
```   188   by (auto simp add: multiset_eq_iff)
```
```   189
```
```   190 lemma multi_self_add_other_not_self [simp]: "M = M + {#x#} \<longleftrightarrow> False"
```
```   191   by (auto simp add: multiset_eq_iff)
```
```   192
```
```   193 lemma diff_single_trivial:
```
```   194   "\<not> x \<in># M \<Longrightarrow> M - {#x#} = M"
```
```   195   by (auto simp add: multiset_eq_iff)
```
```   196
```
```   197 lemma diff_single_eq_union:
```
```   198   "x \<in># M \<Longrightarrow> M - {#x#} = N \<longleftrightarrow> M = N + {#x#}"
```
```   199   by auto
```
```   200
```
```   201 lemma union_single_eq_diff:
```
```   202   "M + {#x#} = N \<Longrightarrow> M = N - {#x#}"
```
```   203   by (auto dest: sym)
```
```   204
```
```   205 lemma union_single_eq_member:
```
```   206   "M + {#x#} = N \<Longrightarrow> x \<in># N"
```
```   207   by auto
```
```   208
```
```   209 lemma union_is_single:
```
```   210   "M + N = {#a#} \<longleftrightarrow> M = {#a#} \<and> N={#} \<or> M = {#} \<and> N = {#a#}" (is "?lhs = ?rhs")
```
```   211 proof
```
```   212   assume ?rhs then show ?lhs by auto
```
```   213 next
```
```   214   assume ?lhs then show ?rhs
```
```   215     by (simp add: multiset_eq_iff split:if_splits) (metis add_is_1)
```
```   216 qed
```
```   217
```
```   218 lemma single_is_union:
```
```   219   "{#a#} = M + N \<longleftrightarrow> {#a#} = M \<and> N = {#} \<or> M = {#} \<and> {#a#} = N"
```
```   220   by (auto simp add: eq_commute [of "{#a#}" "M + N"] union_is_single)
```
```   221
```
```   222 lemma add_eq_conv_diff:
```
```   223   "M + {#a#} = N + {#b#} \<longleftrightarrow> M = N \<and> a = b \<or> M = N - {#a#} + {#b#} \<and> N = M - {#b#} + {#a#}"  (is "?lhs = ?rhs")
```
```   224 (* shorter: by (simp add: multiset_eq_iff) fastforce *)
```
```   225 proof
```
```   226   assume ?rhs then show ?lhs
```
```   227   by (auto simp add: add_assoc add_commute [of "{#b#}"])
```
```   228     (drule sym, simp add: add_assoc [symmetric])
```
```   229 next
```
```   230   assume ?lhs
```
```   231   show ?rhs
```
```   232   proof (cases "a = b")
```
```   233     case True with `?lhs` show ?thesis by simp
```
```   234   next
```
```   235     case False
```
```   236     from `?lhs` have "a \<in># N + {#b#}" by (rule union_single_eq_member)
```
```   237     with False have "a \<in># N" by auto
```
```   238     moreover from `?lhs` have "M = N + {#b#} - {#a#}" by (rule union_single_eq_diff)
```
```   239     moreover note False
```
```   240     ultimately show ?thesis by (auto simp add: diff_right_commute [of _ "{#a#}"] diff_union_swap)
```
```   241   qed
```
```   242 qed
```
```   243
```
```   244 lemma insert_noteq_member:
```
```   245   assumes BC: "B + {#b#} = C + {#c#}"
```
```   246    and bnotc: "b \<noteq> c"
```
```   247   shows "c \<in># B"
```
```   248 proof -
```
```   249   have "c \<in># C + {#c#}" by simp
```
```   250   have nc: "\<not> c \<in># {#b#}" using bnotc by simp
```
```   251   then have "c \<in># B + {#b#}" using BC by simp
```
```   252   then show "c \<in># B" using nc by simp
```
```   253 qed
```
```   254
```
```   255 lemma add_eq_conv_ex:
```
```   256   "(M + {#a#} = N + {#b#}) =
```
```   257     (M = N \<and> a = b \<or> (\<exists>K. M = K + {#b#} \<and> N = K + {#a#}))"
```
```   258   by (auto simp add: add_eq_conv_diff)
```
```   259
```
```   260
```
```   261 subsubsection {* Pointwise ordering induced by count *}
```
```   262
```
```   263 instantiation multiset :: (type) ordered_ab_semigroup_add_imp_le
```
```   264 begin
```
```   265
```
```   266 lift_definition less_eq_multiset :: "'a multiset \<Rightarrow> 'a multiset \<Rightarrow> bool" is "\<lambda> A B. (\<forall>a. A a \<le> B a)"
```
```   267 by simp
```
```   268 lemmas mset_le_def = less_eq_multiset_def
```
```   269
```
```   270 definition less_multiset :: "'a multiset \<Rightarrow> 'a multiset \<Rightarrow> bool" where
```
```   271   mset_less_def: "(A::'a multiset) < B \<longleftrightarrow> A \<le> B \<and> A \<noteq> B"
```
```   272
```
```   273 instance
```
```   274   by default (auto simp add: mset_le_def mset_less_def multiset_eq_iff intro: order_trans antisym)
```
```   275
```
```   276 end
```
```   277
```
```   278 lemma mset_less_eqI:
```
```   279   "(\<And>x. count A x \<le> count B x) \<Longrightarrow> A \<le> B"
```
```   280   by (simp add: mset_le_def)
```
```   281
```
```   282 lemma mset_le_exists_conv:
```
```   283   "(A::'a multiset) \<le> B \<longleftrightarrow> (\<exists>C. B = A + C)"
```
```   284 apply (unfold mset_le_def, rule iffI, rule_tac x = "B - A" in exI)
```
```   285 apply (auto intro: multiset_eq_iff [THEN iffD2])
```
```   286 done
```
```   287
```
```   288 lemma mset_le_mono_add_right_cancel [simp]:
```
```   289   "(A::'a multiset) + C \<le> B + C \<longleftrightarrow> A \<le> B"
```
```   290   by (fact add_le_cancel_right)
```
```   291
```
```   292 lemma mset_le_mono_add_left_cancel [simp]:
```
```   293   "C + (A::'a multiset) \<le> C + B \<longleftrightarrow> A \<le> B"
```
```   294   by (fact add_le_cancel_left)
```
```   295
```
```   296 lemma mset_le_mono_add:
```
```   297   "(A::'a multiset) \<le> B \<Longrightarrow> C \<le> D \<Longrightarrow> A + C \<le> B + D"
```
```   298   by (fact add_mono)
```
```   299
```
```   300 lemma mset_le_add_left [simp]:
```
```   301   "(A::'a multiset) \<le> A + B"
```
```   302   unfolding mset_le_def by auto
```
```   303
```
```   304 lemma mset_le_add_right [simp]:
```
```   305   "B \<le> (A::'a multiset) + B"
```
```   306   unfolding mset_le_def by auto
```
```   307
```
```   308 lemma mset_le_single:
```
```   309   "a :# B \<Longrightarrow> {#a#} \<le> B"
```
```   310   by (simp add: mset_le_def)
```
```   311
```
```   312 lemma multiset_diff_union_assoc:
```
```   313   "C \<le> B \<Longrightarrow> (A::'a multiset) + B - C = A + (B - C)"
```
```   314   by (simp add: multiset_eq_iff mset_le_def)
```
```   315
```
```   316 lemma mset_le_multiset_union_diff_commute:
```
```   317   "B \<le> A \<Longrightarrow> (A::'a multiset) - B + C = A + C - B"
```
```   318 by (simp add: multiset_eq_iff mset_le_def)
```
```   319
```
```   320 lemma diff_le_self[simp]: "(M::'a multiset) - N \<le> M"
```
```   321 by(simp add: mset_le_def)
```
```   322
```
```   323 lemma mset_lessD: "A < B \<Longrightarrow> x \<in># A \<Longrightarrow> x \<in># B"
```
```   324 apply (clarsimp simp: mset_le_def mset_less_def)
```
```   325 apply (erule_tac x=x in allE)
```
```   326 apply auto
```
```   327 done
```
```   328
```
```   329 lemma mset_leD: "A \<le> B \<Longrightarrow> x \<in># A \<Longrightarrow> x \<in># B"
```
```   330 apply (clarsimp simp: mset_le_def mset_less_def)
```
```   331 apply (erule_tac x = x in allE)
```
```   332 apply auto
```
```   333 done
```
```   334
```
```   335 lemma mset_less_insertD: "(A + {#x#} < B) \<Longrightarrow> (x \<in># B \<and> A < B)"
```
```   336 apply (rule conjI)
```
```   337  apply (simp add: mset_lessD)
```
```   338 apply (clarsimp simp: mset_le_def mset_less_def)
```
```   339 apply safe
```
```   340  apply (erule_tac x = a in allE)
```
```   341  apply (auto split: split_if_asm)
```
```   342 done
```
```   343
```
```   344 lemma mset_le_insertD: "(A + {#x#} \<le> B) \<Longrightarrow> (x \<in># B \<and> A \<le> B)"
```
```   345 apply (rule conjI)
```
```   346  apply (simp add: mset_leD)
```
```   347 apply (force simp: mset_le_def mset_less_def split: split_if_asm)
```
```   348 done
```
```   349
```
```   350 lemma mset_less_of_empty[simp]: "A < {#} \<longleftrightarrow> False"
```
```   351   by (auto simp add: mset_less_def mset_le_def multiset_eq_iff)
```
```   352
```
```   353 lemma multi_psub_of_add_self[simp]: "A < A + {#x#}"
```
```   354   by (auto simp: mset_le_def mset_less_def)
```
```   355
```
```   356 lemma multi_psub_self[simp]: "(A::'a multiset) < A = False"
```
```   357   by simp
```
```   358
```
```   359 lemma mset_less_add_bothsides:
```
```   360   "T + {#x#} < S + {#x#} \<Longrightarrow> T < S"
```
```   361   by (fact add_less_imp_less_right)
```
```   362
```
```   363 lemma mset_less_empty_nonempty:
```
```   364   "{#} < S \<longleftrightarrow> S \<noteq> {#}"
```
```   365   by (auto simp: mset_le_def mset_less_def)
```
```   366
```
```   367 lemma mset_less_diff_self:
```
```   368   "c \<in># B \<Longrightarrow> B - {#c#} < B"
```
```   369   by (auto simp: mset_le_def mset_less_def multiset_eq_iff)
```
```   370
```
```   371
```
```   372 subsubsection {* Intersection *}
```
```   373
```
```   374 instantiation multiset :: (type) semilattice_inf
```
```   375 begin
```
```   376
```
```   377 definition inf_multiset :: "'a multiset \<Rightarrow> 'a multiset \<Rightarrow> 'a multiset" where
```
```   378   multiset_inter_def: "inf_multiset A B = A - (A - B)"
```
```   379
```
```   380 instance
```
```   381 proof -
```
```   382   have aux: "\<And>m n q :: nat. m \<le> n \<Longrightarrow> m \<le> q \<Longrightarrow> m \<le> n - (n - q)" by arith
```
```   383   show "OFCLASS('a multiset, semilattice_inf_class)"
```
```   384     by default (auto simp add: multiset_inter_def mset_le_def aux)
```
```   385 qed
```
```   386
```
```   387 end
```
```   388
```
```   389 abbreviation multiset_inter :: "'a multiset \<Rightarrow> 'a multiset \<Rightarrow> 'a multiset" (infixl "#\<inter>" 70) where
```
```   390   "multiset_inter \<equiv> inf"
```
```   391
```
```   392 lemma multiset_inter_count [simp]:
```
```   393   "count (A #\<inter> B) x = min (count A x) (count B x)"
```
```   394   by (simp add: multiset_inter_def)
```
```   395
```
```   396 lemma multiset_inter_single: "a \<noteq> b \<Longrightarrow> {#a#} #\<inter> {#b#} = {#}"
```
```   397   by (rule multiset_eqI) auto
```
```   398
```
```   399 lemma multiset_union_diff_commute:
```
```   400   assumes "B #\<inter> C = {#}"
```
```   401   shows "A + B - C = A - C + B"
```
```   402 proof (rule multiset_eqI)
```
```   403   fix x
```
```   404   from assms have "min (count B x) (count C x) = 0"
```
```   405     by (auto simp add: multiset_eq_iff)
```
```   406   then have "count B x = 0 \<or> count C x = 0"
```
```   407     by auto
```
```   408   then show "count (A + B - C) x = count (A - C + B) x"
```
```   409     by auto
```
```   410 qed
```
```   411
```
```   412
```
```   413 subsubsection {* Filter (with comprehension syntax) *}
```
```   414
```
```   415 text {* Multiset comprehension *}
```
```   416
```
```   417 lift_definition filter :: "('a \<Rightarrow> bool) \<Rightarrow> 'a multiset \<Rightarrow> 'a multiset" is "\<lambda>P M. \<lambda>x. if P x then M x else 0"
```
```   418 by (rule filter_preserves_multiset)
```
```   419
```
```   420 hide_const (open) filter
```
```   421
```
```   422 lemma count_filter [simp]:
```
```   423   "count (Multiset.filter P M) a = (if P a then count M a else 0)"
```
```   424   by (simp add: filter.rep_eq)
```
```   425
```
```   426 lemma filter_empty [simp]:
```
```   427   "Multiset.filter P {#} = {#}"
```
```   428   by (rule multiset_eqI) simp
```
```   429
```
```   430 lemma filter_single [simp]:
```
```   431   "Multiset.filter P {#x#} = (if P x then {#x#} else {#})"
```
```   432   by (rule multiset_eqI) simp
```
```   433
```
```   434 lemma filter_union [simp]:
```
```   435   "Multiset.filter P (M + N) = Multiset.filter P M + Multiset.filter P N"
```
```   436   by (rule multiset_eqI) simp
```
```   437
```
```   438 lemma filter_diff [simp]:
```
```   439   "Multiset.filter P (M - N) = Multiset.filter P M - Multiset.filter P N"
```
```   440   by (rule multiset_eqI) simp
```
```   441
```
```   442 lemma filter_inter [simp]:
```
```   443   "Multiset.filter P (M #\<inter> N) = Multiset.filter P M #\<inter> Multiset.filter P N"
```
```   444   by (rule multiset_eqI) simp
```
```   445
```
```   446 syntax
```
```   447   "_MCollect" :: "pttrn \<Rightarrow> 'a multiset \<Rightarrow> bool \<Rightarrow> 'a multiset"    ("(1{# _ :# _./ _#})")
```
```   448 syntax (xsymbol)
```
```   449   "_MCollect" :: "pttrn \<Rightarrow> 'a multiset \<Rightarrow> bool \<Rightarrow> 'a multiset"    ("(1{# _ \<in># _./ _#})")
```
```   450 translations
```
```   451   "{#x \<in># M. P#}" == "CONST Multiset.filter (\<lambda>x. P) M"
```
```   452
```
```   453
```
```   454 subsubsection {* Set of elements *}
```
```   455
```
```   456 definition set_of :: "'a multiset => 'a set" where
```
```   457   "set_of M = {x. x :# M}"
```
```   458
```
```   459 lemma set_of_empty [simp]: "set_of {#} = {}"
```
```   460 by (simp add: set_of_def)
```
```   461
```
```   462 lemma set_of_single [simp]: "set_of {#b#} = {b}"
```
```   463 by (simp add: set_of_def)
```
```   464
```
```   465 lemma set_of_union [simp]: "set_of (M + N) = set_of M \<union> set_of N"
```
```   466 by (auto simp add: set_of_def)
```
```   467
```
```   468 lemma set_of_eq_empty_iff [simp]: "(set_of M = {}) = (M = {#})"
```
```   469 by (auto simp add: set_of_def multiset_eq_iff)
```
```   470
```
```   471 lemma mem_set_of_iff [simp]: "(x \<in> set_of M) = (x :# M)"
```
```   472 by (auto simp add: set_of_def)
```
```   473
```
```   474 lemma set_of_filter [simp]: "set_of {# x:#M. P x #} = set_of M \<inter> {x. P x}"
```
```   475 by (auto simp add: set_of_def)
```
```   476
```
```   477 lemma finite_set_of [iff]: "finite (set_of M)"
```
```   478   using count [of M] by (simp add: multiset_def set_of_def)
```
```   479
```
```   480 lemma finite_Collect_mem [iff]: "finite {x. x :# M}"
```
```   481   unfolding set_of_def[symmetric] by simp
```
```   482
```
```   483 subsubsection {* Size *}
```
```   484
```
```   485 instantiation multiset :: (type) size
```
```   486 begin
```
```   487
```
```   488 definition size_def:
```
```   489   "size M = setsum (count M) (set_of M)"
```
```   490
```
```   491 instance ..
```
```   492
```
```   493 end
```
```   494
```
```   495 lemma size_empty [simp]: "size {#} = 0"
```
```   496 by (simp add: size_def)
```
```   497
```
```   498 lemma size_single [simp]: "size {#b#} = 1"
```
```   499 by (simp add: size_def)
```
```   500
```
```   501 lemma setsum_count_Int:
```
```   502   "finite A ==> setsum (count N) (A \<inter> set_of N) = setsum (count N) A"
```
```   503 apply (induct rule: finite_induct)
```
```   504  apply simp
```
```   505 apply (simp add: Int_insert_left set_of_def)
```
```   506 done
```
```   507
```
```   508 lemma size_union [simp]: "size (M + N::'a multiset) = size M + size N"
```
```   509 apply (unfold size_def)
```
```   510 apply (subgoal_tac "count (M + N) = (\<lambda>a. count M a + count N a)")
```
```   511  prefer 2
```
```   512  apply (rule ext, simp)
```
```   513 apply (simp (no_asm_simp) add: setsum_Un_nat setsum_addf setsum_count_Int)
```
```   514 apply (subst Int_commute)
```
```   515 apply (simp (no_asm_simp) add: setsum_count_Int)
```
```   516 done
```
```   517
```
```   518 lemma size_eq_0_iff_empty [iff]: "(size M = 0) = (M = {#})"
```
```   519 by (auto simp add: size_def multiset_eq_iff)
```
```   520
```
```   521 lemma nonempty_has_size: "(S \<noteq> {#}) = (0 < size S)"
```
```   522 by (metis gr0I gr_implies_not0 size_empty size_eq_0_iff_empty)
```
```   523
```
```   524 lemma size_eq_Suc_imp_elem: "size M = Suc n ==> \<exists>a. a :# M"
```
```   525 apply (unfold size_def)
```
```   526 apply (drule setsum_SucD)
```
```   527 apply auto
```
```   528 done
```
```   529
```
```   530 lemma size_eq_Suc_imp_eq_union:
```
```   531   assumes "size M = Suc n"
```
```   532   shows "\<exists>a N. M = N + {#a#}"
```
```   533 proof -
```
```   534   from assms obtain a where "a \<in># M"
```
```   535     by (erule size_eq_Suc_imp_elem [THEN exE])
```
```   536   then have "M = M - {#a#} + {#a#}" by simp
```
```   537   then show ?thesis by blast
```
```   538 qed
```
```   539
```
```   540
```
```   541 subsection {* Induction and case splits *}
```
```   542
```
```   543 theorem multiset_induct [case_names empty add, induct type: multiset]:
```
```   544   assumes empty: "P {#}"
```
```   545   assumes add: "\<And>M x. P M \<Longrightarrow> P (M + {#x#})"
```
```   546   shows "P M"
```
```   547 proof (induct n \<equiv> "size M" arbitrary: M)
```
```   548   case 0 thus "P M" by (simp add: empty)
```
```   549 next
```
```   550   case (Suc k)
```
```   551   obtain N x where "M = N + {#x#}"
```
```   552     using `Suc k = size M` [symmetric]
```
```   553     using size_eq_Suc_imp_eq_union by fast
```
```   554   with Suc add show "P M" by simp
```
```   555 qed
```
```   556
```
```   557 lemma multi_nonempty_split: "M \<noteq> {#} \<Longrightarrow> \<exists>A a. M = A + {#a#}"
```
```   558 by (induct M) auto
```
```   559
```
```   560 lemma multiset_cases [cases type, case_names empty add]:
```
```   561 assumes em:  "M = {#} \<Longrightarrow> P"
```
```   562 assumes add: "\<And>N x. M = N + {#x#} \<Longrightarrow> P"
```
```   563 shows "P"
```
```   564 using assms by (induct M) simp_all
```
```   565
```
```   566 lemma multi_member_split: "x \<in># M \<Longrightarrow> \<exists>A. M = A + {#x#}"
```
```   567 by (rule_tac x="M - {#x#}" in exI, simp)
```
```   568
```
```   569 lemma multi_drop_mem_not_eq: "c \<in># B \<Longrightarrow> B - {#c#} \<noteq> B"
```
```   570 by (cases "B = {#}") (auto dest: multi_member_split)
```
```   571
```
```   572 lemma multiset_partition: "M = {# x:#M. P x #} + {# x:#M. \<not> P x #}"
```
```   573 apply (subst multiset_eq_iff)
```
```   574 apply auto
```
```   575 done
```
```   576
```
```   577 lemma mset_less_size: "(A::'a multiset) < B \<Longrightarrow> size A < size B"
```
```   578 proof (induct A arbitrary: B)
```
```   579   case (empty M)
```
```   580   then have "M \<noteq> {#}" by (simp add: mset_less_empty_nonempty)
```
```   581   then obtain M' x where "M = M' + {#x#}"
```
```   582     by (blast dest: multi_nonempty_split)
```
```   583   then show ?case by simp
```
```   584 next
```
```   585   case (add S x T)
```
```   586   have IH: "\<And>B. S < B \<Longrightarrow> size S < size B" by fact
```
```   587   have SxsubT: "S + {#x#} < T" by fact
```
```   588   then have "x \<in># T" and "S < T" by (auto dest: mset_less_insertD)
```
```   589   then obtain T' where T: "T = T' + {#x#}"
```
```   590     by (blast dest: multi_member_split)
```
```   591   then have "S < T'" using SxsubT
```
```   592     by (blast intro: mset_less_add_bothsides)
```
```   593   then have "size S < size T'" using IH by simp
```
```   594   then show ?case using T by simp
```
```   595 qed
```
```   596
```
```   597
```
```   598 subsubsection {* Strong induction and subset induction for multisets *}
```
```   599
```
```   600 text {* Well-foundedness of proper subset operator: *}
```
```   601
```
```   602 text {* proper multiset subset *}
```
```   603
```
```   604 definition
```
```   605   mset_less_rel :: "('a multiset * 'a multiset) set" where
```
```   606   "mset_less_rel = {(A,B). A < B}"
```
```   607
```
```   608 lemma multiset_add_sub_el_shuffle:
```
```   609   assumes "c \<in># B" and "b \<noteq> c"
```
```   610   shows "B - {#c#} + {#b#} = B + {#b#} - {#c#}"
```
```   611 proof -
```
```   612   from `c \<in># B` obtain A where B: "B = A + {#c#}"
```
```   613     by (blast dest: multi_member_split)
```
```   614   have "A + {#b#} = A + {#b#} + {#c#} - {#c#}" by simp
```
```   615   then have "A + {#b#} = A + {#c#} + {#b#} - {#c#}"
```
```   616     by (simp add: add_ac)
```
```   617   then show ?thesis using B by simp
```
```   618 qed
```
```   619
```
```   620 lemma wf_mset_less_rel: "wf mset_less_rel"
```
```   621 apply (unfold mset_less_rel_def)
```
```   622 apply (rule wf_measure [THEN wf_subset, where f1=size])
```
```   623 apply (clarsimp simp: measure_def inv_image_def mset_less_size)
```
```   624 done
```
```   625
```
```   626 text {* The induction rules: *}
```
```   627
```
```   628 lemma full_multiset_induct [case_names less]:
```
```   629 assumes ih: "\<And>B. \<forall>(A::'a multiset). A < B \<longrightarrow> P A \<Longrightarrow> P B"
```
```   630 shows "P B"
```
```   631 apply (rule wf_mset_less_rel [THEN wf_induct])
```
```   632 apply (rule ih, auto simp: mset_less_rel_def)
```
```   633 done
```
```   634
```
```   635 lemma multi_subset_induct [consumes 2, case_names empty add]:
```
```   636 assumes "F \<le> A"
```
```   637   and empty: "P {#}"
```
```   638   and insert: "\<And>a F. a \<in># A \<Longrightarrow> P F \<Longrightarrow> P (F + {#a#})"
```
```   639 shows "P F"
```
```   640 proof -
```
```   641   from `F \<le> A`
```
```   642   show ?thesis
```
```   643   proof (induct F)
```
```   644     show "P {#}" by fact
```
```   645   next
```
```   646     fix x F
```
```   647     assume P: "F \<le> A \<Longrightarrow> P F" and i: "F + {#x#} \<le> A"
```
```   648     show "P (F + {#x#})"
```
```   649     proof (rule insert)
```
```   650       from i show "x \<in># A" by (auto dest: mset_le_insertD)
```
```   651       from i have "F \<le> A" by (auto dest: mset_le_insertD)
```
```   652       with P show "P F" .
```
```   653     qed
```
```   654   qed
```
```   655 qed
```
```   656
```
```   657
```
```   658 subsection {* The fold combinator *}
```
```   659
```
```   660 text {*
```
```   661   The intended behaviour is
```
```   662   @{text "fold_mset f z {#x\<^isub>1, ..., x\<^isub>n#} = f x\<^isub>1 (\<dots> (f x\<^isub>n z)\<dots>)"}
```
```   663   if @{text f} is associative-commutative.
```
```   664 *}
```
```   665
```
```   666 text {*
```
```   667   The graph of @{text "fold_mset"}, @{text "z"}: the start element,
```
```   668   @{text "f"}: folding function, @{text "A"}: the multiset, @{text
```
```   669   "y"}: the result.
```
```   670 *}
```
```   671 inductive
```
```   672   fold_msetG :: "('a \<Rightarrow> 'b \<Rightarrow> 'b) \<Rightarrow> 'b \<Rightarrow> 'a multiset \<Rightarrow> 'b \<Rightarrow> bool"
```
```   673   for f :: "'a \<Rightarrow> 'b \<Rightarrow> 'b"
```
```   674   and z :: 'b
```
```   675 where
```
```   676   emptyI [intro]:  "fold_msetG f z {#} z"
```
```   677 | insertI [intro]: "fold_msetG f z A y \<Longrightarrow> fold_msetG f z (A + {#x#}) (f x y)"
```
```   678
```
```   679 inductive_cases empty_fold_msetGE [elim!]: "fold_msetG f z {#} x"
```
```   680 inductive_cases insert_fold_msetGE: "fold_msetG f z (A + {#}) y"
```
```   681
```
```   682 definition
```
```   683   fold_mset :: "('a \<Rightarrow> 'b \<Rightarrow> 'b) \<Rightarrow> 'b \<Rightarrow> 'a multiset \<Rightarrow> 'b" where
```
```   684   "fold_mset f z A = (THE x. fold_msetG f z A x)"
```
```   685
```
```   686 lemma Diff1_fold_msetG:
```
```   687   "fold_msetG f z (A - {#x#}) y \<Longrightarrow> x \<in># A \<Longrightarrow> fold_msetG f z A (f x y)"
```
```   688 apply (frule_tac x = x in fold_msetG.insertI)
```
```   689 apply auto
```
```   690 done
```
```   691
```
```   692 lemma fold_msetG_nonempty: "\<exists>x. fold_msetG f z A x"
```
```   693 apply (induct A)
```
```   694  apply blast
```
```   695 apply clarsimp
```
```   696 apply (drule_tac x = x in fold_msetG.insertI)
```
```   697 apply auto
```
```   698 done
```
```   699
```
```   700 lemma fold_mset_empty[simp]: "fold_mset f z {#} = z"
```
```   701 unfolding fold_mset_def by blast
```
```   702
```
```   703 context comp_fun_commute
```
```   704 begin
```
```   705
```
```   706 lemma fold_msetG_insertE_aux:
```
```   707   "fold_msetG f z A y \<Longrightarrow> a \<in># A \<Longrightarrow> \<exists>y'. y = f a y' \<and> fold_msetG f z (A - {#a#}) y'"
```
```   708 proof (induct set: fold_msetG)
```
```   709   case (insertI A y x) show ?case
```
```   710   proof (cases "x = a")
```
```   711     assume "x = a" with insertI show ?case by auto
```
```   712   next
```
```   713     assume "x \<noteq> a"
```
```   714     then obtain y' where y: "y = f a y'" and y': "fold_msetG f z (A - {#a#}) y'"
```
```   715       using insertI by auto
```
```   716     have "f x y = f a (f x y')"
```
```   717       unfolding y by (rule fun_left_comm)
```
```   718     moreover have "fold_msetG f z (A + {#x#} - {#a#}) (f x y')"
```
```   719       using y' and `x \<noteq> a`
```
```   720       by (simp add: diff_union_swap [symmetric] fold_msetG.insertI)
```
```   721     ultimately show ?case by fast
```
```   722   qed
```
```   723 qed simp
```
```   724
```
```   725 lemma fold_msetG_insertE:
```
```   726   assumes "fold_msetG f z (A + {#x#}) v"
```
```   727   obtains y where "v = f x y" and "fold_msetG f z A y"
```
```   728 using assms by (auto dest: fold_msetG_insertE_aux [where a=x])
```
```   729
```
```   730 lemma fold_msetG_determ:
```
```   731   "fold_msetG f z A x \<Longrightarrow> fold_msetG f z A y \<Longrightarrow> y = x"
```
```   732 proof (induct arbitrary: y set: fold_msetG)
```
```   733   case (insertI A y x v)
```
```   734   from `fold_msetG f z (A + {#x#}) v`
```
```   735   obtain y' where "v = f x y'" and "fold_msetG f z A y'"
```
```   736     by (rule fold_msetG_insertE)
```
```   737   from `fold_msetG f z A y'` have "y' = y" by (rule insertI)
```
```   738   with `v = f x y'` show "v = f x y" by simp
```
```   739 qed fast
```
```   740
```
```   741 lemma fold_mset_equality: "fold_msetG f z A y \<Longrightarrow> fold_mset f z A = y"
```
```   742 unfolding fold_mset_def by (blast intro: fold_msetG_determ)
```
```   743
```
```   744 lemma fold_msetG_fold_mset: "fold_msetG f z A (fold_mset f z A)"
```
```   745 proof -
```
```   746   from fold_msetG_nonempty fold_msetG_determ
```
```   747   have "\<exists>!x. fold_msetG f z A x" by (rule ex_ex1I)
```
```   748   then show ?thesis unfolding fold_mset_def by (rule theI')
```
```   749 qed
```
```   750
```
```   751 lemma fold_mset_insert:
```
```   752   "fold_mset f z (A + {#x#}) = f x (fold_mset f z A)"
```
```   753 by (intro fold_mset_equality fold_msetG.insertI fold_msetG_fold_mset)
```
```   754
```
```   755 lemma fold_mset_commute: "f x (fold_mset f z A) = fold_mset f (f x z) A"
```
```   756 by (induct A) (auto simp: fold_mset_insert fun_left_comm [of x])
```
```   757
```
```   758 lemma fold_mset_single [simp]: "fold_mset f z {#x#} = f x z"
```
```   759 using fold_mset_insert [of z "{#}"] by simp
```
```   760
```
```   761 lemma fold_mset_union [simp]:
```
```   762   "fold_mset f z (A+B) = fold_mset f (fold_mset f z A) B"
```
```   763 proof (induct A)
```
```   764   case empty then show ?case by simp
```
```   765 next
```
```   766   case (add A x)
```
```   767   have "A + {#x#} + B = (A+B) + {#x#}" by (simp add: add_ac)
```
```   768   then have "fold_mset f z (A + {#x#} + B) = f x (fold_mset f z (A + B))"
```
```   769     by (simp add: fold_mset_insert)
```
```   770   also have "\<dots> = fold_mset f (fold_mset f z (A + {#x#})) B"
```
```   771     by (simp add: fold_mset_commute[of x,symmetric] add fold_mset_insert)
```
```   772   finally show ?case .
```
```   773 qed
```
```   774
```
```   775 lemma fold_mset_fusion:
```
```   776   assumes "comp_fun_commute g"
```
```   777   shows "(\<And>x y. h (g x y) = f x (h y)) \<Longrightarrow> h (fold_mset g w A) = fold_mset f (h w) A" (is "PROP ?P")
```
```   778 proof -
```
```   779   interpret comp_fun_commute g by (fact assms)
```
```   780   show "PROP ?P" by (induct A) auto
```
```   781 qed
```
```   782
```
```   783 lemma fold_mset_rec:
```
```   784   assumes "a \<in># A"
```
```   785   shows "fold_mset f z A = f a (fold_mset f z (A - {#a#}))"
```
```   786 proof -
```
```   787   from assms obtain A' where "A = A' + {#a#}"
```
```   788     by (blast dest: multi_member_split)
```
```   789   then show ?thesis by simp
```
```   790 qed
```
```   791
```
```   792 end
```
```   793
```
```   794 text {*
```
```   795   A note on code generation: When defining some function containing a
```
```   796   subterm @{term"fold_mset F"}, code generation is not automatic. When
```
```   797   interpreting locale @{text left_commutative} with @{text F}, the
```
```   798   would be code thms for @{const fold_mset} become thms like
```
```   799   @{term"fold_mset F z {#} = z"} where @{text F} is not a pattern but
```
```   800   contains defined symbols, i.e.\ is not a code thm. Hence a separate
```
```   801   constant with its own code thms needs to be introduced for @{text
```
```   802   F}. See the image operator below.
```
```   803 *}
```
```   804
```
```   805
```
```   806 subsection {* Image *}
```
```   807
```
```   808 definition image_mset :: "('a \<Rightarrow> 'b) \<Rightarrow> 'a multiset \<Rightarrow> 'b multiset" where
```
```   809   "image_mset f = fold_mset (op + o single o f) {#}"
```
```   810
```
```   811 interpretation image_fun_commute: comp_fun_commute "op + o single o f" for f
```
```   812 proof qed (simp add: add_ac fun_eq_iff)
```
```   813
```
```   814 lemma image_mset_empty [simp]: "image_mset f {#} = {#}"
```
```   815 by (simp add: image_mset_def)
```
```   816
```
```   817 lemma image_mset_single [simp]: "image_mset f {#x#} = {#f x#}"
```
```   818 by (simp add: image_mset_def)
```
```   819
```
```   820 lemma image_mset_insert:
```
```   821   "image_mset f (M + {#a#}) = image_mset f M + {#f a#}"
```
```   822 by (simp add: image_mset_def add_ac)
```
```   823
```
```   824 lemma image_mset_union [simp]:
```
```   825   "image_mset f (M+N) = image_mset f M + image_mset f N"
```
```   826 apply (induct N)
```
```   827  apply simp
```
```   828 apply (simp add: add_assoc [symmetric] image_mset_insert)
```
```   829 done
```
```   830
```
```   831 lemma set_of_image_mset [simp]: "set_of (image_mset f M) = image f (set_of M)"
```
```   832 by (induct M) simp_all
```
```   833
```
```   834 lemma size_image_mset [simp]: "size (image_mset f M) = size M"
```
```   835 by (induct M) simp_all
```
```   836
```
```   837 lemma image_mset_is_empty_iff [simp]: "image_mset f M = {#} \<longleftrightarrow> M = {#}"
```
```   838 by (cases M) auto
```
```   839
```
```   840 syntax
```
```   841   "_comprehension1_mset" :: "'a \<Rightarrow> 'b \<Rightarrow> 'b multiset \<Rightarrow> 'a multiset"
```
```   842       ("({#_/. _ :# _#})")
```
```   843 translations
```
```   844   "{#e. x:#M#}" == "CONST image_mset (%x. e) M"
```
```   845
```
```   846 syntax
```
```   847   "_comprehension2_mset" :: "'a \<Rightarrow> 'b \<Rightarrow> 'b multiset \<Rightarrow> bool \<Rightarrow> 'a multiset"
```
```   848       ("({#_/ | _ :# _./ _#})")
```
```   849 translations
```
```   850   "{#e | x:#M. P#}" => "{#e. x :# {# x:#M. P#}#}"
```
```   851
```
```   852 text {*
```
```   853   This allows to write not just filters like @{term "{#x:#M. x<c#}"}
```
```   854   but also images like @{term "{#x+x. x:#M #}"} and @{term [source]
```
```   855   "{#x+x|x:#M. x<c#}"}, where the latter is currently displayed as
```
```   856   @{term "{#x+x|x:#M. x<c#}"}.
```
```   857 *}
```
```   858
```
```   859 enriched_type image_mset: image_mset
```
```   860 proof -
```
```   861   fix f g show "image_mset f \<circ> image_mset g = image_mset (f \<circ> g)"
```
```   862   proof
```
```   863     fix A
```
```   864     show "(image_mset f \<circ> image_mset g) A = image_mset (f \<circ> g) A"
```
```   865       by (induct A) simp_all
```
```   866   qed
```
```   867   show "image_mset id = id"
```
```   868   proof
```
```   869     fix A
```
```   870     show "image_mset id A = id A"
```
```   871       by (induct A) simp_all
```
```   872   qed
```
```   873 qed
```
```   874
```
```   875 declare image_mset.identity [simp]
```
```   876
```
```   877
```
```   878 subsection {* Alternative representations *}
```
```   879
```
```   880 subsubsection {* Lists *}
```
```   881
```
```   882 primrec multiset_of :: "'a list \<Rightarrow> 'a multiset" where
```
```   883   "multiset_of [] = {#}" |
```
```   884   "multiset_of (a # x) = multiset_of x + {# a #}"
```
```   885
```
```   886 lemma in_multiset_in_set:
```
```   887   "x \<in># multiset_of xs \<longleftrightarrow> x \<in> set xs"
```
```   888   by (induct xs) simp_all
```
```   889
```
```   890 lemma count_multiset_of:
```
```   891   "count (multiset_of xs) x = length (filter (\<lambda>y. x = y) xs)"
```
```   892   by (induct xs) simp_all
```
```   893
```
```   894 lemma multiset_of_zero_iff[simp]: "(multiset_of x = {#}) = (x = [])"
```
```   895 by (induct x) auto
```
```   896
```
```   897 lemma multiset_of_zero_iff_right[simp]: "({#} = multiset_of x) = (x = [])"
```
```   898 by (induct x) auto
```
```   899
```
```   900 lemma set_of_multiset_of[simp]: "set_of (multiset_of x) = set x"
```
```   901 by (induct x) auto
```
```   902
```
```   903 lemma mem_set_multiset_eq: "x \<in> set xs = (x :# multiset_of xs)"
```
```   904 by (induct xs) auto
```
```   905
```
```   906 lemma size_multiset_of [simp]: "size (multiset_of xs) = length xs"
```
```   907   by (induct xs) simp_all
```
```   908
```
```   909 lemma multiset_of_append [simp]:
```
```   910   "multiset_of (xs @ ys) = multiset_of xs + multiset_of ys"
```
```   911   by (induct xs arbitrary: ys) (auto simp: add_ac)
```
```   912
```
```   913 lemma multiset_of_filter:
```
```   914   "multiset_of (filter P xs) = {#x :# multiset_of xs. P x #}"
```
```   915   by (induct xs) simp_all
```
```   916
```
```   917 lemma multiset_of_rev [simp]:
```
```   918   "multiset_of (rev xs) = multiset_of xs"
```
```   919   by (induct xs) simp_all
```
```   920
```
```   921 lemma surj_multiset_of: "surj multiset_of"
```
```   922 apply (unfold surj_def)
```
```   923 apply (rule allI)
```
```   924 apply (rule_tac M = y in multiset_induct)
```
```   925  apply auto
```
```   926 apply (rule_tac x = "x # xa" in exI)
```
```   927 apply auto
```
```   928 done
```
```   929
```
```   930 lemma set_count_greater_0: "set x = {a. count (multiset_of x) a > 0}"
```
```   931 by (induct x) auto
```
```   932
```
```   933 lemma distinct_count_atmost_1:
```
```   934   "distinct x = (! a. count (multiset_of x) a = (if a \<in> set x then 1 else 0))"
```
```   935 apply (induct x, simp, rule iffI, simp_all)
```
```   936 apply (rule conjI)
```
```   937 apply (simp_all add: set_of_multiset_of [THEN sym] del: set_of_multiset_of)
```
```   938 apply (erule_tac x = a in allE, simp, clarify)
```
```   939 apply (erule_tac x = aa in allE, simp)
```
```   940 done
```
```   941
```
```   942 lemma multiset_of_eq_setD:
```
```   943   "multiset_of xs = multiset_of ys \<Longrightarrow> set xs = set ys"
```
```   944 by (rule) (auto simp add:multiset_eq_iff set_count_greater_0)
```
```   945
```
```   946 lemma set_eq_iff_multiset_of_eq_distinct:
```
```   947   "distinct x \<Longrightarrow> distinct y \<Longrightarrow>
```
```   948     (set x = set y) = (multiset_of x = multiset_of y)"
```
```   949 by (auto simp: multiset_eq_iff distinct_count_atmost_1)
```
```   950
```
```   951 lemma set_eq_iff_multiset_of_remdups_eq:
```
```   952    "(set x = set y) = (multiset_of (remdups x) = multiset_of (remdups y))"
```
```   953 apply (rule iffI)
```
```   954 apply (simp add: set_eq_iff_multiset_of_eq_distinct[THEN iffD1])
```
```   955 apply (drule distinct_remdups [THEN distinct_remdups
```
```   956       [THEN set_eq_iff_multiset_of_eq_distinct [THEN iffD2]]])
```
```   957 apply simp
```
```   958 done
```
```   959
```
```   960 lemma multiset_of_compl_union [simp]:
```
```   961   "multiset_of [x\<leftarrow>xs. P x] + multiset_of [x\<leftarrow>xs. \<not>P x] = multiset_of xs"
```
```   962   by (induct xs) (auto simp: add_ac)
```
```   963
```
```   964 lemma count_multiset_of_length_filter:
```
```   965   "count (multiset_of xs) x = length (filter (\<lambda>y. x = y) xs)"
```
```   966   by (induct xs) auto
```
```   967
```
```   968 lemma nth_mem_multiset_of: "i < length ls \<Longrightarrow> (ls ! i) :# multiset_of ls"
```
```   969 apply (induct ls arbitrary: i)
```
```   970  apply simp
```
```   971 apply (case_tac i)
```
```   972  apply auto
```
```   973 done
```
```   974
```
```   975 lemma multiset_of_remove1[simp]:
```
```   976   "multiset_of (remove1 a xs) = multiset_of xs - {#a#}"
```
```   977 by (induct xs) (auto simp add: multiset_eq_iff)
```
```   978
```
```   979 lemma multiset_of_eq_length:
```
```   980   assumes "multiset_of xs = multiset_of ys"
```
```   981   shows "length xs = length ys"
```
```   982   using assms by (metis size_multiset_of)
```
```   983
```
```   984 lemma multiset_of_eq_length_filter:
```
```   985   assumes "multiset_of xs = multiset_of ys"
```
```   986   shows "length (filter (\<lambda>x. z = x) xs) = length (filter (\<lambda>y. z = y) ys)"
```
```   987   using assms by (metis count_multiset_of)
```
```   988
```
```   989 lemma fold_multiset_equiv:
```
```   990   assumes f: "\<And>x y. x \<in> set xs \<Longrightarrow> y \<in> set xs \<Longrightarrow> f x \<circ> f y = f y \<circ> f x"
```
```   991     and equiv: "multiset_of xs = multiset_of ys"
```
```   992   shows "fold f xs = fold f ys"
```
```   993 using f equiv [symmetric]
```
```   994 proof (induct xs arbitrary: ys)
```
```   995   case Nil then show ?case by simp
```
```   996 next
```
```   997   case (Cons x xs)
```
```   998   then have *: "set ys = set (x # xs)" by (blast dest: multiset_of_eq_setD)
```
```   999   have "\<And>x y. x \<in> set ys \<Longrightarrow> y \<in> set ys \<Longrightarrow> f x \<circ> f y = f y \<circ> f x"
```
```  1000     by (rule Cons.prems(1)) (simp_all add: *)
```
```  1001   moreover from * have "x \<in> set ys" by simp
```
```  1002   ultimately have "fold f ys = fold f (remove1 x ys) \<circ> f x" by (fact fold_remove1_split)
```
```  1003   moreover from Cons.prems have "fold f xs = fold f (remove1 x ys)" by (auto intro: Cons.hyps)
```
```  1004   ultimately show ?case by simp
```
```  1005 qed
```
```  1006
```
```  1007 context linorder
```
```  1008 begin
```
```  1009
```
```  1010 lemma multiset_of_insort [simp]:
```
```  1011   "multiset_of (insort_key k x xs) = {#x#} + multiset_of xs"
```
```  1012   by (induct xs) (simp_all add: ac_simps)
```
```  1013
```
```  1014 lemma multiset_of_sort [simp]:
```
```  1015   "multiset_of (sort_key k xs) = multiset_of xs"
```
```  1016   by (induct xs) (simp_all add: ac_simps)
```
```  1017
```
```  1018 text {*
```
```  1019   This lemma shows which properties suffice to show that a function
```
```  1020   @{text "f"} with @{text "f xs = ys"} behaves like sort.
```
```  1021 *}
```
```  1022
```
```  1023 lemma properties_for_sort_key:
```
```  1024   assumes "multiset_of ys = multiset_of xs"
```
```  1025   and "\<And>k. k \<in> set ys \<Longrightarrow> filter (\<lambda>x. f k = f x) ys = filter (\<lambda>x. f k = f x) xs"
```
```  1026   and "sorted (map f ys)"
```
```  1027   shows "sort_key f xs = ys"
```
```  1028 using assms
```
```  1029 proof (induct xs arbitrary: ys)
```
```  1030   case Nil then show ?case by simp
```
```  1031 next
```
```  1032   case (Cons x xs)
```
```  1033   from Cons.prems(2) have
```
```  1034     "\<forall>k \<in> set ys. filter (\<lambda>x. f k = f x) (remove1 x ys) = filter (\<lambda>x. f k = f x) xs"
```
```  1035     by (simp add: filter_remove1)
```
```  1036   with Cons.prems have "sort_key f xs = remove1 x ys"
```
```  1037     by (auto intro!: Cons.hyps simp add: sorted_map_remove1)
```
```  1038   moreover from Cons.prems have "x \<in> set ys"
```
```  1039     by (auto simp add: mem_set_multiset_eq intro!: ccontr)
```
```  1040   ultimately show ?case using Cons.prems by (simp add: insort_key_remove1)
```
```  1041 qed
```
```  1042
```
```  1043 lemma properties_for_sort:
```
```  1044   assumes multiset: "multiset_of ys = multiset_of xs"
```
```  1045   and "sorted ys"
```
```  1046   shows "sort xs = ys"
```
```  1047 proof (rule properties_for_sort_key)
```
```  1048   from multiset show "multiset_of ys = multiset_of xs" .
```
```  1049   from `sorted ys` show "sorted (map (\<lambda>x. x) ys)" by simp
```
```  1050   from multiset have "\<And>k. length (filter (\<lambda>y. k = y) ys) = length (filter (\<lambda>x. k = x) xs)"
```
```  1051     by (rule multiset_of_eq_length_filter)
```
```  1052   then have "\<And>k. replicate (length (filter (\<lambda>y. k = y) ys)) k = replicate (length (filter (\<lambda>x. k = x) xs)) k"
```
```  1053     by simp
```
```  1054   then show "\<And>k. k \<in> set ys \<Longrightarrow> filter (\<lambda>y. k = y) ys = filter (\<lambda>x. k = x) xs"
```
```  1055     by (simp add: replicate_length_filter)
```
```  1056 qed
```
```  1057
```
```  1058 lemma sort_key_by_quicksort:
```
```  1059   "sort_key f xs = sort_key f [x\<leftarrow>xs. f x < f (xs ! (length xs div 2))]
```
```  1060     @ [x\<leftarrow>xs. f x = f (xs ! (length xs div 2))]
```
```  1061     @ sort_key f [x\<leftarrow>xs. f x > f (xs ! (length xs div 2))]" (is "sort_key f ?lhs = ?rhs")
```
```  1062 proof (rule properties_for_sort_key)
```
```  1063   show "multiset_of ?rhs = multiset_of ?lhs"
```
```  1064     by (rule multiset_eqI) (auto simp add: multiset_of_filter)
```
```  1065 next
```
```  1066   show "sorted (map f ?rhs)"
```
```  1067     by (auto simp add: sorted_append intro: sorted_map_same)
```
```  1068 next
```
```  1069   fix l
```
```  1070   assume "l \<in> set ?rhs"
```
```  1071   let ?pivot = "f (xs ! (length xs div 2))"
```
```  1072   have *: "\<And>x. f l = f x \<longleftrightarrow> f x = f l" by auto
```
```  1073   have "[x \<leftarrow> sort_key f xs . f x = f l] = [x \<leftarrow> xs. f x = f l]"
```
```  1074     unfolding filter_sort by (rule properties_for_sort_key) (auto intro: sorted_map_same)
```
```  1075   with * have **: "[x \<leftarrow> sort_key f xs . f l = f x] = [x \<leftarrow> xs. f l = f x]" by simp
```
```  1076   have "\<And>x P. P (f x) ?pivot \<and> f l = f x \<longleftrightarrow> P (f l) ?pivot \<and> f l = f x" by auto
```
```  1077   then have "\<And>P. [x \<leftarrow> sort_key f xs . P (f x) ?pivot \<and> f l = f x] =
```
```  1078     [x \<leftarrow> sort_key f xs. P (f l) ?pivot \<and> f l = f x]" by simp
```
```  1079   note *** = this [of "op <"] this [of "op >"] this [of "op ="]
```
```  1080   show "[x \<leftarrow> ?rhs. f l = f x] = [x \<leftarrow> ?lhs. f l = f x]"
```
```  1081   proof (cases "f l" ?pivot rule: linorder_cases)
```
```  1082     case less
```
```  1083     then have "f l \<noteq> ?pivot" and "\<not> f l > ?pivot" by auto
```
```  1084     with less show ?thesis
```
```  1085       by (simp add: filter_sort [symmetric] ** ***)
```
```  1086   next
```
```  1087     case equal then show ?thesis
```
```  1088       by (simp add: * less_le)
```
```  1089   next
```
```  1090     case greater
```
```  1091     then have "f l \<noteq> ?pivot" and "\<not> f l < ?pivot" by auto
```
```  1092     with greater show ?thesis
```
```  1093       by (simp add: filter_sort [symmetric] ** ***)
```
```  1094   qed
```
```  1095 qed
```
```  1096
```
```  1097 lemma sort_by_quicksort:
```
```  1098   "sort xs = sort [x\<leftarrow>xs. x < xs ! (length xs div 2)]
```
```  1099     @ [x\<leftarrow>xs. x = xs ! (length xs div 2)]
```
```  1100     @ sort [x\<leftarrow>xs. x > xs ! (length xs div 2)]" (is "sort ?lhs = ?rhs")
```
```  1101   using sort_key_by_quicksort [of "\<lambda>x. x", symmetric] by simp
```
```  1102
```
```  1103 text {* A stable parametrized quicksort *}
```
```  1104
```
```  1105 definition part :: "('b \<Rightarrow> 'a) \<Rightarrow> 'a \<Rightarrow> 'b list \<Rightarrow> 'b list \<times> 'b list \<times> 'b list" where
```
```  1106   "part f pivot xs = ([x \<leftarrow> xs. f x < pivot], [x \<leftarrow> xs. f x = pivot], [x \<leftarrow> xs. pivot < f x])"
```
```  1107
```
```  1108 lemma part_code [code]:
```
```  1109   "part f pivot [] = ([], [], [])"
```
```  1110   "part f pivot (x # xs) = (let (lts, eqs, gts) = part f pivot xs; x' = f x in
```
```  1111      if x' < pivot then (x # lts, eqs, gts)
```
```  1112      else if x' > pivot then (lts, eqs, x # gts)
```
```  1113      else (lts, x # eqs, gts))"
```
```  1114   by (auto simp add: part_def Let_def split_def)
```
```  1115
```
```  1116 lemma sort_key_by_quicksort_code [code]:
```
```  1117   "sort_key f xs = (case xs of [] \<Rightarrow> []
```
```  1118     | [x] \<Rightarrow> xs
```
```  1119     | [x, y] \<Rightarrow> (if f x \<le> f y then xs else [y, x])
```
```  1120     | _ \<Rightarrow> (let (lts, eqs, gts) = part f (f (xs ! (length xs div 2))) xs
```
```  1121        in sort_key f lts @ eqs @ sort_key f gts))"
```
```  1122 proof (cases xs)
```
```  1123   case Nil then show ?thesis by simp
```
```  1124 next
```
```  1125   case (Cons _ ys) note hyps = Cons show ?thesis
```
```  1126   proof (cases ys)
```
```  1127     case Nil with hyps show ?thesis by simp
```
```  1128   next
```
```  1129     case (Cons _ zs) note hyps = hyps Cons show ?thesis
```
```  1130     proof (cases zs)
```
```  1131       case Nil with hyps show ?thesis by auto
```
```  1132     next
```
```  1133       case Cons
```
```  1134       from sort_key_by_quicksort [of f xs]
```
```  1135       have "sort_key f xs = (let (lts, eqs, gts) = part f (f (xs ! (length xs div 2))) xs
```
```  1136         in sort_key f lts @ eqs @ sort_key f gts)"
```
```  1137       by (simp only: split_def Let_def part_def fst_conv snd_conv)
```
```  1138       with hyps Cons show ?thesis by (simp only: list.cases)
```
```  1139     qed
```
```  1140   qed
```
```  1141 qed
```
```  1142
```
```  1143 end
```
```  1144
```
```  1145 hide_const (open) part
```
```  1146
```
```  1147 lemma multiset_of_remdups_le: "multiset_of (remdups xs) \<le> multiset_of xs"
```
```  1148   by (induct xs) (auto intro: order_trans)
```
```  1149
```
```  1150 lemma multiset_of_update:
```
```  1151   "i < length ls \<Longrightarrow> multiset_of (ls[i := v]) = multiset_of ls - {#ls ! i#} + {#v#}"
```
```  1152 proof (induct ls arbitrary: i)
```
```  1153   case Nil then show ?case by simp
```
```  1154 next
```
```  1155   case (Cons x xs)
```
```  1156   show ?case
```
```  1157   proof (cases i)
```
```  1158     case 0 then show ?thesis by simp
```
```  1159   next
```
```  1160     case (Suc i')
```
```  1161     with Cons show ?thesis
```
```  1162       apply simp
```
```  1163       apply (subst add_assoc)
```
```  1164       apply (subst add_commute [of "{#v#}" "{#x#}"])
```
```  1165       apply (subst add_assoc [symmetric])
```
```  1166       apply simp
```
```  1167       apply (rule mset_le_multiset_union_diff_commute)
```
```  1168       apply (simp add: mset_le_single nth_mem_multiset_of)
```
```  1169       done
```
```  1170   qed
```
```  1171 qed
```
```  1172
```
```  1173 lemma multiset_of_swap:
```
```  1174   "i < length ls \<Longrightarrow> j < length ls \<Longrightarrow>
```
```  1175     multiset_of (ls[j := ls ! i, i := ls ! j]) = multiset_of ls"
```
```  1176   by (cases "i = j") (simp_all add: multiset_of_update nth_mem_multiset_of)
```
```  1177
```
```  1178
```
```  1179 subsubsection {* Association lists -- including code generation *}
```
```  1180
```
```  1181 text {* Preliminaries *}
```
```  1182
```
```  1183 text {* Raw operations on lists *}
```
```  1184
```
```  1185 definition join_raw :: "('key \<Rightarrow> 'val \<times> 'val \<Rightarrow> 'val) \<Rightarrow> ('key \<times> 'val) list \<Rightarrow> ('key \<times> 'val) list \<Rightarrow> ('key \<times> 'val) list"
```
```  1186 where
```
```  1187   "join_raw f xs ys = foldr (\<lambda>(k, v). map_default k v (%v'. f k (v', v))) ys xs"
```
```  1188
```
```  1189 lemma join_raw_Nil [simp]:
```
```  1190   "join_raw f xs [] = xs"
```
```  1191 by (simp add: join_raw_def)
```
```  1192
```
```  1193 lemma join_raw_Cons [simp]:
```
```  1194   "join_raw f xs ((k, v) # ys) = map_default k v (%v'. f k (v', v)) (join_raw f xs ys)"
```
```  1195 by (simp add: join_raw_def)
```
```  1196
```
```  1197 lemma map_of_join_raw:
```
```  1198   assumes "distinct (map fst ys)"
```
```  1199   shows "map_of (join_raw f xs ys) x = (case map_of xs x of None => map_of ys x | Some v =>
```
```  1200     (case map_of ys x of None => Some v | Some v' => Some (f x (v, v'))))"
```
```  1201 using assms
```
```  1202 apply (induct ys)
```
```  1203 apply (auto simp add: map_of_map_default split: option.split)
```
```  1204 apply (metis map_of_eq_None_iff option.simps(2) weak_map_of_SomeI)
```
```  1205 by (metis Some_eq_map_of_iff map_of_eq_None_iff option.simps(2))
```
```  1206
```
```  1207 lemma distinct_join_raw:
```
```  1208   assumes "distinct (map fst xs)"
```
```  1209   shows "distinct (map fst (join_raw f xs ys))"
```
```  1210 using assms
```
```  1211 proof (induct ys)
```
```  1212   case (Cons y ys)
```
```  1213   thus ?case by (cases y) (simp add: distinct_map_default)
```
```  1214 qed auto
```
```  1215
```
```  1216 definition
```
```  1217   "subtract_entries_raw xs ys = foldr (%(k, v). AList.map_entry k (%v'. v' - v)) ys xs"
```
```  1218
```
```  1219 lemma map_of_subtract_entries_raw:
```
```  1220   assumes "distinct (map fst ys)"
```
```  1221   shows "map_of (subtract_entries_raw xs ys) x = (case map_of xs x of None => None | Some v =>
```
```  1222     (case map_of ys x of None => Some v | Some v' => Some (v - v')))"
```
```  1223 using assms unfolding subtract_entries_raw_def
```
```  1224 apply (induct ys)
```
```  1225 apply auto
```
```  1226 apply (simp split: option.split)
```
```  1227 apply (simp add: map_of_map_entry)
```
```  1228 apply (auto split: option.split)
```
```  1229 apply (metis map_of_eq_None_iff option.simps(3) option.simps(4))
```
```  1230 by (metis map_of_eq_None_iff option.simps(4) option.simps(5))
```
```  1231
```
```  1232 lemma distinct_subtract_entries_raw:
```
```  1233   assumes "distinct (map fst xs)"
```
```  1234   shows "distinct (map fst (subtract_entries_raw xs ys))"
```
```  1235 using assms
```
```  1236 unfolding subtract_entries_raw_def by (induct ys) (auto simp add: distinct_map_entry)
```
```  1237
```
```  1238 text {* Operations on alists with distinct keys *}
```
```  1239
```
```  1240 lift_definition join :: "('a \<Rightarrow> 'b \<times> 'b \<Rightarrow> 'b) \<Rightarrow> ('a, 'b) alist \<Rightarrow> ('a, 'b) alist \<Rightarrow> ('a, 'b) alist"
```
```  1241 is join_raw
```
```  1242 by (simp add: distinct_join_raw)
```
```  1243
```
```  1244 lift_definition subtract_entries :: "('a, ('b :: minus)) alist \<Rightarrow> ('a, 'b) alist \<Rightarrow> ('a, 'b) alist"
```
```  1245 is subtract_entries_raw
```
```  1246 by (simp add: distinct_subtract_entries_raw)
```
```  1247
```
```  1248 text {* Implementing multisets by means of association lists *}
```
```  1249
```
```  1250 definition count_of :: "('a \<times> nat) list \<Rightarrow> 'a \<Rightarrow> nat" where
```
```  1251   "count_of xs x = (case map_of xs x of None \<Rightarrow> 0 | Some n \<Rightarrow> n)"
```
```  1252
```
```  1253 lemma count_of_multiset:
```
```  1254   "count_of xs \<in> multiset"
```
```  1255 proof -
```
```  1256   let ?A = "{x::'a. 0 < (case map_of xs x of None \<Rightarrow> 0\<Colon>nat | Some (n\<Colon>nat) \<Rightarrow> n)}"
```
```  1257   have "?A \<subseteq> dom (map_of xs)"
```
```  1258   proof
```
```  1259     fix x
```
```  1260     assume "x \<in> ?A"
```
```  1261     then have "0 < (case map_of xs x of None \<Rightarrow> 0\<Colon>nat | Some (n\<Colon>nat) \<Rightarrow> n)" by simp
```
```  1262     then have "map_of xs x \<noteq> None" by (cases "map_of xs x") auto
```
```  1263     then show "x \<in> dom (map_of xs)" by auto
```
```  1264   qed
```
```  1265   with finite_dom_map_of [of xs] have "finite ?A"
```
```  1266     by (auto intro: finite_subset)
```
```  1267   then show ?thesis
```
```  1268     by (simp add: count_of_def fun_eq_iff multiset_def)
```
```  1269 qed
```
```  1270
```
```  1271 lemma count_simps [simp]:
```
```  1272   "count_of [] = (\<lambda>_. 0)"
```
```  1273   "count_of ((x, n) # xs) = (\<lambda>y. if x = y then n else count_of xs y)"
```
```  1274   by (simp_all add: count_of_def fun_eq_iff)
```
```  1275
```
```  1276 lemma count_of_empty:
```
```  1277   "x \<notin> fst ` set xs \<Longrightarrow> count_of xs x = 0"
```
```  1278   by (induct xs) (simp_all add: count_of_def)
```
```  1279
```
```  1280 lemma count_of_filter:
```
```  1281   "count_of (List.filter (P \<circ> fst) xs) x = (if P x then count_of xs x else 0)"
```
```  1282   by (induct xs) auto
```
```  1283
```
```  1284 lemma count_of_map_default [simp]:
```
```  1285   "count_of (map_default x b (%x. x + b) xs) y = (if x = y then count_of xs x + b else count_of xs y)"
```
```  1286 unfolding count_of_def by (simp add: map_of_map_default split: option.split)
```
```  1287
```
```  1288 lemma count_of_join_raw:
```
```  1289   "distinct (map fst ys) ==> count_of xs x + count_of ys x = count_of (join_raw (%x (x, y). x + y) xs ys) x"
```
```  1290 unfolding count_of_def by (simp add: map_of_join_raw split: option.split)
```
```  1291
```
```  1292 lemma count_of_subtract_entries_raw:
```
```  1293   "distinct (map fst ys) ==> count_of xs x - count_of ys x = count_of (subtract_entries_raw xs ys) x"
```
```  1294 unfolding count_of_def by (simp add: map_of_subtract_entries_raw split: option.split)
```
```  1295
```
```  1296 text {* Code equations for multiset operations *}
```
```  1297
```
```  1298 definition Bag :: "('a, nat) alist \<Rightarrow> 'a multiset" where
```
```  1299   "Bag xs = Abs_multiset (count_of (DAList.impl_of xs))"
```
```  1300
```
```  1301 code_datatype Bag
```
```  1302
```
```  1303 lemma count_Bag [simp, code]:
```
```  1304   "count (Bag xs) = count_of (DAList.impl_of xs)"
```
```  1305   by (simp add: Bag_def count_of_multiset Abs_multiset_inverse)
```
```  1306
```
```  1307 lemma Mempty_Bag [code]:
```
```  1308   "{#} = Bag (DAList.empty)"
```
```  1309   by (simp add: multiset_eq_iff alist.Alist_inverse DAList.empty_def)
```
```  1310
```
```  1311 lemma single_Bag [code]:
```
```  1312   "{#x#} = Bag (DAList.update x 1 DAList.empty)"
```
```  1313   by (simp add: multiset_eq_iff alist.Alist_inverse update.rep_eq empty.rep_eq)
```
```  1314
```
```  1315 lemma union_Bag [code]:
```
```  1316   "Bag xs + Bag ys = Bag (join (\<lambda>x (n1, n2). n1 + n2) xs ys)"
```
```  1317 by (rule multiset_eqI) (simp add: count_of_join_raw alist.Alist_inverse distinct_join_raw join_def)
```
```  1318
```
```  1319 lemma minus_Bag [code]:
```
```  1320   "Bag xs - Bag ys = Bag (subtract_entries xs ys)"
```
```  1321 by (rule multiset_eqI)
```
```  1322   (simp add: count_of_subtract_entries_raw alist.Alist_inverse distinct_subtract_entries_raw subtract_entries_def)
```
```  1323
```
```  1324 lemma filter_Bag [code]:
```
```  1325   "Multiset.filter P (Bag xs) = Bag (DAList.filter (P \<circ> fst) xs)"
```
```  1326 by (rule multiset_eqI) (simp add: count_of_filter DAList.filter.rep_eq)
```
```  1327
```
```  1328 lemma mset_less_eq_Bag [code]:
```
```  1329   "Bag xs \<le> A \<longleftrightarrow> (\<forall>(x, n) \<in> set (DAList.impl_of xs). count_of (DAList.impl_of xs) x \<le> count A x)"
```
```  1330     (is "?lhs \<longleftrightarrow> ?rhs")
```
```  1331 proof
```
```  1332   assume ?lhs then show ?rhs
```
```  1333     by (auto simp add: mset_le_def)
```
```  1334 next
```
```  1335   assume ?rhs
```
```  1336   show ?lhs
```
```  1337   proof (rule mset_less_eqI)
```
```  1338     fix x
```
```  1339     from `?rhs` have "count_of (DAList.impl_of xs) x \<le> count A x"
```
```  1340       by (cases "x \<in> fst ` set (DAList.impl_of xs)") (auto simp add: count_of_empty)
```
```  1341     then show "count (Bag xs) x \<le> count A x"
```
```  1342       by (simp add: mset_le_def)
```
```  1343   qed
```
```  1344 qed
```
```  1345
```
```  1346 instantiation multiset :: (equal) equal
```
```  1347 begin
```
```  1348
```
```  1349 definition
```
```  1350   [code]: "HOL.equal A B \<longleftrightarrow> (A::'a multiset) \<le> B \<and> B \<le> A"
```
```  1351
```
```  1352 instance
```
```  1353   by default (simp add: equal_multiset_def eq_iff)
```
```  1354
```
```  1355 end
```
```  1356
```
```  1357 text {* Quickcheck generators *}
```
```  1358
```
```  1359 definition (in term_syntax)
```
```  1360   bagify :: "('a\<Colon>typerep, nat) alist \<times> (unit \<Rightarrow> Code_Evaluation.term)
```
```  1361     \<Rightarrow> 'a multiset \<times> (unit \<Rightarrow> Code_Evaluation.term)" where
```
```  1362   [code_unfold]: "bagify xs = Code_Evaluation.valtermify Bag {\<cdot>} xs"
```
```  1363
```
```  1364 notation fcomp (infixl "\<circ>>" 60)
```
```  1365 notation scomp (infixl "\<circ>\<rightarrow>" 60)
```
```  1366
```
```  1367 instantiation multiset :: (random) random
```
```  1368 begin
```
```  1369
```
```  1370 definition
```
```  1371   "Quickcheck.random i = Quickcheck.random i \<circ>\<rightarrow> (\<lambda>xs. Pair (bagify xs))"
```
```  1372
```
```  1373 instance ..
```
```  1374
```
```  1375 end
```
```  1376
```
```  1377 no_notation fcomp (infixl "\<circ>>" 60)
```
```  1378 no_notation scomp (infixl "\<circ>\<rightarrow>" 60)
```
```  1379
```
```  1380 instantiation multiset :: (exhaustive) exhaustive
```
```  1381 begin
```
```  1382
```
```  1383 definition exhaustive_multiset :: "('a multiset => (bool * term list) option) => code_numeral => (bool * term list) option"
```
```  1384 where
```
```  1385   "exhaustive_multiset f i = Quickcheck_Exhaustive.exhaustive (%xs. f (Bag xs)) i"
```
```  1386
```
```  1387 instance ..
```
```  1388
```
```  1389 end
```
```  1390
```
```  1391 instantiation multiset :: (full_exhaustive) full_exhaustive
```
```  1392 begin
```
```  1393
```
```  1394 definition full_exhaustive_multiset :: "('a multiset * (unit => term) => (bool * term list) option) => code_numeral => (bool * term list) option"
```
```  1395 where
```
```  1396   "full_exhaustive_multiset f i = Quickcheck_Exhaustive.full_exhaustive (%xs. f (bagify xs)) i"
```
```  1397
```
```  1398 instance ..
```
```  1399
```
```  1400 end
```
```  1401
```
```  1402 hide_const (open) bagify
```
```  1403
```
```  1404
```
```  1405 subsection {* The multiset order *}
```
```  1406
```
```  1407 subsubsection {* Well-foundedness *}
```
```  1408
```
```  1409 definition mult1 :: "('a \<times> 'a) set => ('a multiset \<times> 'a multiset) set" where
```
```  1410   "mult1 r = {(N, M). \<exists>a M0 K. M = M0 + {#a#} \<and> N = M0 + K \<and>
```
```  1411       (\<forall>b. b :# K --> (b, a) \<in> r)}"
```
```  1412
```
```  1413 definition mult :: "('a \<times> 'a) set => ('a multiset \<times> 'a multiset) set" where
```
```  1414   "mult r = (mult1 r)\<^sup>+"
```
```  1415
```
```  1416 lemma not_less_empty [iff]: "(M, {#}) \<notin> mult1 r"
```
```  1417 by (simp add: mult1_def)
```
```  1418
```
```  1419 lemma less_add: "(N, M0 + {#a#}) \<in> mult1 r ==>
```
```  1420     (\<exists>M. (M, M0) \<in> mult1 r \<and> N = M + {#a#}) \<or>
```
```  1421     (\<exists>K. (\<forall>b. b :# K --> (b, a) \<in> r) \<and> N = M0 + K)"
```
```  1422   (is "_ \<Longrightarrow> ?case1 (mult1 r) \<or> ?case2")
```
```  1423 proof (unfold mult1_def)
```
```  1424   let ?r = "\<lambda>K a. \<forall>b. b :# K --> (b, a) \<in> r"
```
```  1425   let ?R = "\<lambda>N M. \<exists>a M0 K. M = M0 + {#a#} \<and> N = M0 + K \<and> ?r K a"
```
```  1426   let ?case1 = "?case1 {(N, M). ?R N M}"
```
```  1427
```
```  1428   assume "(N, M0 + {#a#}) \<in> {(N, M). ?R N M}"
```
```  1429   then have "\<exists>a' M0' K.
```
```  1430       M0 + {#a#} = M0' + {#a'#} \<and> N = M0' + K \<and> ?r K a'" by simp
```
```  1431   then show "?case1 \<or> ?case2"
```
```  1432   proof (elim exE conjE)
```
```  1433     fix a' M0' K
```
```  1434     assume N: "N = M0' + K" and r: "?r K a'"
```
```  1435     assume "M0 + {#a#} = M0' + {#a'#}"
```
```  1436     then have "M0 = M0' \<and> a = a' \<or>
```
```  1437         (\<exists>K'. M0 = K' + {#a'#} \<and> M0' = K' + {#a#})"
```
```  1438       by (simp only: add_eq_conv_ex)
```
```  1439     then show ?thesis
```
```  1440     proof (elim disjE conjE exE)
```
```  1441       assume "M0 = M0'" "a = a'"
```
```  1442       with N r have "?r K a \<and> N = M0 + K" by simp
```
```  1443       then have ?case2 .. then show ?thesis ..
```
```  1444     next
```
```  1445       fix K'
```
```  1446       assume "M0' = K' + {#a#}"
```
```  1447       with N have n: "N = K' + K + {#a#}" by (simp add: add_ac)
```
```  1448
```
```  1449       assume "M0 = K' + {#a'#}"
```
```  1450       with r have "?R (K' + K) M0" by blast
```
```  1451       with n have ?case1 by simp then show ?thesis ..
```
```  1452     qed
```
```  1453   qed
```
```  1454 qed
```
```  1455
```
```  1456 lemma all_accessible: "wf r ==> \<forall>M. M \<in> acc (mult1 r)"
```
```  1457 proof
```
```  1458   let ?R = "mult1 r"
```
```  1459   let ?W = "acc ?R"
```
```  1460   {
```
```  1461     fix M M0 a
```
```  1462     assume M0: "M0 \<in> ?W"
```
```  1463       and wf_hyp: "!!b. (b, a) \<in> r ==> (\<forall>M \<in> ?W. M + {#b#} \<in> ?W)"
```
```  1464       and acc_hyp: "\<forall>M. (M, M0) \<in> ?R --> M + {#a#} \<in> ?W"
```
```  1465     have "M0 + {#a#} \<in> ?W"
```
```  1466     proof (rule accI [of "M0 + {#a#}"])
```
```  1467       fix N
```
```  1468       assume "(N, M0 + {#a#}) \<in> ?R"
```
```  1469       then have "((\<exists>M. (M, M0) \<in> ?R \<and> N = M + {#a#}) \<or>
```
```  1470           (\<exists>K. (\<forall>b. b :# K --> (b, a) \<in> r) \<and> N = M0 + K))"
```
```  1471         by (rule less_add)
```
```  1472       then show "N \<in> ?W"
```
```  1473       proof (elim exE disjE conjE)
```
```  1474         fix M assume "(M, M0) \<in> ?R" and N: "N = M + {#a#}"
```
```  1475         from acc_hyp have "(M, M0) \<in> ?R --> M + {#a#} \<in> ?W" ..
```
```  1476         from this and `(M, M0) \<in> ?R` have "M + {#a#} \<in> ?W" ..
```
```  1477         then show "N \<in> ?W" by (simp only: N)
```
```  1478       next
```
```  1479         fix K
```
```  1480         assume N: "N = M0 + K"
```
```  1481         assume "\<forall>b. b :# K --> (b, a) \<in> r"
```
```  1482         then have "M0 + K \<in> ?W"
```
```  1483         proof (induct K)
```
```  1484           case empty
```
```  1485           from M0 show "M0 + {#} \<in> ?W" by simp
```
```  1486         next
```
```  1487           case (add K x)
```
```  1488           from add.prems have "(x, a) \<in> r" by simp
```
```  1489           with wf_hyp have "\<forall>M \<in> ?W. M + {#x#} \<in> ?W" by blast
```
```  1490           moreover from add have "M0 + K \<in> ?W" by simp
```
```  1491           ultimately have "(M0 + K) + {#x#} \<in> ?W" ..
```
```  1492           then show "M0 + (K + {#x#}) \<in> ?W" by (simp only: add_assoc)
```
```  1493         qed
```
```  1494         then show "N \<in> ?W" by (simp only: N)
```
```  1495       qed
```
```  1496     qed
```
```  1497   } note tedious_reasoning = this
```
```  1498
```
```  1499   assume wf: "wf r"
```
```  1500   fix M
```
```  1501   show "M \<in> ?W"
```
```  1502   proof (induct M)
```
```  1503     show "{#} \<in> ?W"
```
```  1504     proof (rule accI)
```
```  1505       fix b assume "(b, {#}) \<in> ?R"
```
```  1506       with not_less_empty show "b \<in> ?W" by contradiction
```
```  1507     qed
```
```  1508
```
```  1509     fix M a assume "M \<in> ?W"
```
```  1510     from wf have "\<forall>M \<in> ?W. M + {#a#} \<in> ?W"
```
```  1511     proof induct
```
```  1512       fix a
```
```  1513       assume r: "!!b. (b, a) \<in> r ==> (\<forall>M \<in> ?W. M + {#b#} \<in> ?W)"
```
```  1514       show "\<forall>M \<in> ?W. M + {#a#} \<in> ?W"
```
```  1515       proof
```
```  1516         fix M assume "M \<in> ?W"
```
```  1517         then show "M + {#a#} \<in> ?W"
```
```  1518           by (rule acc_induct) (rule tedious_reasoning [OF _ r])
```
```  1519       qed
```
```  1520     qed
```
```  1521     from this and `M \<in> ?W` show "M + {#a#} \<in> ?W" ..
```
```  1522   qed
```
```  1523 qed
```
```  1524
```
```  1525 theorem wf_mult1: "wf r ==> wf (mult1 r)"
```
```  1526 by (rule acc_wfI) (rule all_accessible)
```
```  1527
```
```  1528 theorem wf_mult: "wf r ==> wf (mult r)"
```
```  1529 unfolding mult_def by (rule wf_trancl) (rule wf_mult1)
```
```  1530
```
```  1531
```
```  1532 subsubsection {* Closure-free presentation *}
```
```  1533
```
```  1534 text {* One direction. *}
```
```  1535
```
```  1536 lemma mult_implies_one_step:
```
```  1537   "trans r ==> (M, N) \<in> mult r ==>
```
```  1538     \<exists>I J K. N = I + J \<and> M = I + K \<and> J \<noteq> {#} \<and>
```
```  1539     (\<forall>k \<in> set_of K. \<exists>j \<in> set_of J. (k, j) \<in> r)"
```
```  1540 apply (unfold mult_def mult1_def set_of_def)
```
```  1541 apply (erule converse_trancl_induct, clarify)
```
```  1542  apply (rule_tac x = M0 in exI, simp, clarify)
```
```  1543 apply (case_tac "a :# K")
```
```  1544  apply (rule_tac x = I in exI)
```
```  1545  apply (simp (no_asm))
```
```  1546  apply (rule_tac x = "(K - {#a#}) + Ka" in exI)
```
```  1547  apply (simp (no_asm_simp) add: add_assoc [symmetric])
```
```  1548  apply (drule_tac f = "\<lambda>M. M - {#a#}" in arg_cong)
```
```  1549  apply (simp add: diff_union_single_conv)
```
```  1550  apply (simp (no_asm_use) add: trans_def)
```
```  1551  apply blast
```
```  1552 apply (subgoal_tac "a :# I")
```
```  1553  apply (rule_tac x = "I - {#a#}" in exI)
```
```  1554  apply (rule_tac x = "J + {#a#}" in exI)
```
```  1555  apply (rule_tac x = "K + Ka" in exI)
```
```  1556  apply (rule conjI)
```
```  1557   apply (simp add: multiset_eq_iff split: nat_diff_split)
```
```  1558  apply (rule conjI)
```
```  1559   apply (drule_tac f = "\<lambda>M. M - {#a#}" in arg_cong, simp)
```
```  1560   apply (simp add: multiset_eq_iff split: nat_diff_split)
```
```  1561  apply (simp (no_asm_use) add: trans_def)
```
```  1562  apply blast
```
```  1563 apply (subgoal_tac "a :# (M0 + {#a#})")
```
```  1564  apply simp
```
```  1565 apply (simp (no_asm))
```
```  1566 done
```
```  1567
```
```  1568 lemma one_step_implies_mult_aux:
```
```  1569   "trans r ==>
```
```  1570     \<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))
```
```  1571       --> (I + K, I + J) \<in> mult r"
```
```  1572 apply (induct_tac n, auto)
```
```  1573 apply (frule size_eq_Suc_imp_eq_union, clarify)
```
```  1574 apply (rename_tac "J'", simp)
```
```  1575 apply (erule notE, auto)
```
```  1576 apply (case_tac "J' = {#}")
```
```  1577  apply (simp add: mult_def)
```
```  1578  apply (rule r_into_trancl)
```
```  1579  apply (simp add: mult1_def set_of_def, blast)
```
```  1580 txt {* Now we know @{term "J' \<noteq> {#}"}. *}
```
```  1581 apply (cut_tac M = K and P = "\<lambda>x. (x, a) \<in> r" in multiset_partition)
```
```  1582 apply (erule_tac P = "\<forall>k \<in> set_of K. ?P k" in rev_mp)
```
```  1583 apply (erule ssubst)
```
```  1584 apply (simp add: Ball_def, auto)
```
```  1585 apply (subgoal_tac
```
```  1586   "((I + {# x :# K. (x, a) \<in> r #}) + {# x :# K. (x, a) \<notin> r #},
```
```  1587     (I + {# x :# K. (x, a) \<in> r #}) + J') \<in> mult r")
```
```  1588  prefer 2
```
```  1589  apply force
```
```  1590 apply (simp (no_asm_use) add: add_assoc [symmetric] mult_def)
```
```  1591 apply (erule trancl_trans)
```
```  1592 apply (rule r_into_trancl)
```
```  1593 apply (simp add: mult1_def set_of_def)
```
```  1594 apply (rule_tac x = a in exI)
```
```  1595 apply (rule_tac x = "I + J'" in exI)
```
```  1596 apply (simp add: add_ac)
```
```  1597 done
```
```  1598
```
```  1599 lemma one_step_implies_mult:
```
```  1600   "trans r ==> J \<noteq> {#} ==> \<forall>k \<in> set_of K. \<exists>j \<in> set_of J. (k, j) \<in> r
```
```  1601     ==> (I + K, I + J) \<in> mult r"
```
```  1602 using one_step_implies_mult_aux by blast
```
```  1603
```
```  1604
```
```  1605 subsubsection {* Partial-order properties *}
```
```  1606
```
```  1607 definition less_multiset :: "'a\<Colon>order multiset \<Rightarrow> 'a multiset \<Rightarrow> bool" (infix "<#" 50) where
```
```  1608   "M' <# M \<longleftrightarrow> (M', M) \<in> mult {(x', x). x' < x}"
```
```  1609
```
```  1610 definition le_multiset :: "'a\<Colon>order multiset \<Rightarrow> 'a multiset \<Rightarrow> bool" (infix "<=#" 50) where
```
```  1611   "M' <=# M \<longleftrightarrow> M' <# M \<or> M' = M"
```
```  1612
```
```  1613 notation (xsymbols) less_multiset (infix "\<subset>#" 50)
```
```  1614 notation (xsymbols) le_multiset (infix "\<subseteq>#" 50)
```
```  1615
```
```  1616 interpretation multiset_order: order le_multiset less_multiset
```
```  1617 proof -
```
```  1618   have irrefl: "\<And>M :: 'a multiset. \<not> M \<subset># M"
```
```  1619   proof
```
```  1620     fix M :: "'a multiset"
```
```  1621     assume "M \<subset># M"
```
```  1622     then have MM: "(M, M) \<in> mult {(x, y). x < y}" by (simp add: less_multiset_def)
```
```  1623     have "trans {(x'::'a, x). x' < x}"
```
```  1624       by (rule transI) simp
```
```  1625     moreover note MM
```
```  1626     ultimately have "\<exists>I J K. M = I + J \<and> M = I + K
```
```  1627       \<and> J \<noteq> {#} \<and> (\<forall>k\<in>set_of K. \<exists>j\<in>set_of J. (k, j) \<in> {(x, y). x < y})"
```
```  1628       by (rule mult_implies_one_step)
```
```  1629     then obtain I J K where "M = I + J" and "M = I + K"
```
```  1630       and "J \<noteq> {#}" and "(\<forall>k\<in>set_of K. \<exists>j\<in>set_of J. (k, j) \<in> {(x, y). x < y})" by blast
```
```  1631     then have aux1: "K \<noteq> {#}" and aux2: "\<forall>k\<in>set_of K. \<exists>j\<in>set_of K. k < j" by auto
```
```  1632     have "finite (set_of K)" by simp
```
```  1633     moreover note aux2
```
```  1634     ultimately have "set_of K = {}"
```
```  1635       by (induct rule: finite_induct) (auto intro: order_less_trans)
```
```  1636     with aux1 show False by simp
```
```  1637   qed
```
```  1638   have trans: "\<And>K M N :: 'a multiset. K \<subset># M \<Longrightarrow> M \<subset># N \<Longrightarrow> K \<subset># N"
```
```  1639     unfolding less_multiset_def mult_def by (blast intro: trancl_trans)
```
```  1640   show "class.order (le_multiset :: 'a multiset \<Rightarrow> _) less_multiset"
```
```  1641     by default (auto simp add: le_multiset_def irrefl dest: trans)
```
```  1642 qed
```
```  1643
```
```  1644 lemma mult_less_irrefl [elim!]: "M \<subset># (M::'a::order multiset) ==> R"
```
```  1645   by simp
```
```  1646
```
```  1647
```
```  1648 subsubsection {* Monotonicity of multiset union *}
```
```  1649
```
```  1650 lemma mult1_union: "(B, D) \<in> mult1 r ==> (C + B, C + D) \<in> mult1 r"
```
```  1651 apply (unfold mult1_def)
```
```  1652 apply auto
```
```  1653 apply (rule_tac x = a in exI)
```
```  1654 apply (rule_tac x = "C + M0" in exI)
```
```  1655 apply (simp add: add_assoc)
```
```  1656 done
```
```  1657
```
```  1658 lemma union_less_mono2: "B \<subset># D ==> C + B \<subset># C + (D::'a::order multiset)"
```
```  1659 apply (unfold less_multiset_def mult_def)
```
```  1660 apply (erule trancl_induct)
```
```  1661  apply (blast intro: mult1_union)
```
```  1662 apply (blast intro: mult1_union trancl_trans)
```
```  1663 done
```
```  1664
```
```  1665 lemma union_less_mono1: "B \<subset># D ==> B + C \<subset># D + (C::'a::order multiset)"
```
```  1666 apply (subst add_commute [of B C])
```
```  1667 apply (subst add_commute [of D C])
```
```  1668 apply (erule union_less_mono2)
```
```  1669 done
```
```  1670
```
```  1671 lemma union_less_mono:
```
```  1672   "A \<subset># C ==> B \<subset># D ==> A + B \<subset># C + (D::'a::order multiset)"
```
```  1673   by (blast intro!: union_less_mono1 union_less_mono2 multiset_order.less_trans)
```
```  1674
```
```  1675 interpretation multiset_order: ordered_ab_semigroup_add plus le_multiset less_multiset
```
```  1676 proof
```
```  1677 qed (auto simp add: le_multiset_def intro: union_less_mono2)
```
```  1678
```
```  1679
```
```  1680 subsection {* Termination proofs with multiset orders *}
```
```  1681
```
```  1682 lemma multi_member_skip: "x \<in># XS \<Longrightarrow> x \<in># {# y #} + XS"
```
```  1683   and multi_member_this: "x \<in># {# x #} + XS"
```
```  1684   and multi_member_last: "x \<in># {# x #}"
```
```  1685   by auto
```
```  1686
```
```  1687 definition "ms_strict = mult pair_less"
```
```  1688 definition "ms_weak = ms_strict \<union> Id"
```
```  1689
```
```  1690 lemma ms_reduction_pair: "reduction_pair (ms_strict, ms_weak)"
```
```  1691 unfolding reduction_pair_def ms_strict_def ms_weak_def pair_less_def
```
```  1692 by (auto intro: wf_mult1 wf_trancl simp: mult_def)
```
```  1693
```
```  1694 lemma smsI:
```
```  1695   "(set_of A, set_of B) \<in> max_strict \<Longrightarrow> (Z + A, Z + B) \<in> ms_strict"
```
```  1696   unfolding ms_strict_def
```
```  1697 by (rule one_step_implies_mult) (auto simp add: max_strict_def pair_less_def elim!:max_ext.cases)
```
```  1698
```
```  1699 lemma wmsI:
```
```  1700   "(set_of A, set_of B) \<in> max_strict \<or> A = {#} \<and> B = {#}
```
```  1701   \<Longrightarrow> (Z + A, Z + B) \<in> ms_weak"
```
```  1702 unfolding ms_weak_def ms_strict_def
```
```  1703 by (auto simp add: pair_less_def max_strict_def elim!:max_ext.cases intro: one_step_implies_mult)
```
```  1704
```
```  1705 inductive pw_leq
```
```  1706 where
```
```  1707   pw_leq_empty: "pw_leq {#} {#}"
```
```  1708 | pw_leq_step:  "\<lbrakk>(x,y) \<in> pair_leq; pw_leq X Y \<rbrakk> \<Longrightarrow> pw_leq ({#x#} + X) ({#y#} + Y)"
```
```  1709
```
```  1710 lemma pw_leq_lstep:
```
```  1711   "(x, y) \<in> pair_leq \<Longrightarrow> pw_leq {#x#} {#y#}"
```
```  1712 by (drule pw_leq_step) (rule pw_leq_empty, simp)
```
```  1713
```
```  1714 lemma pw_leq_split:
```
```  1715   assumes "pw_leq X Y"
```
```  1716   shows "\<exists>A B Z. X = A + Z \<and> Y = B + Z \<and> ((set_of A, set_of B) \<in> max_strict \<or> (B = {#} \<and> A = {#}))"
```
```  1717   using assms
```
```  1718 proof (induct)
```
```  1719   case pw_leq_empty thus ?case by auto
```
```  1720 next
```
```  1721   case (pw_leq_step x y X Y)
```
```  1722   then obtain A B Z where
```
```  1723     [simp]: "X = A + Z" "Y = B + Z"
```
```  1724       and 1[simp]: "(set_of A, set_of B) \<in> max_strict \<or> (B = {#} \<and> A = {#})"
```
```  1725     by auto
```
```  1726   from pw_leq_step have "x = y \<or> (x, y) \<in> pair_less"
```
```  1727     unfolding pair_leq_def by auto
```
```  1728   thus ?case
```
```  1729   proof
```
```  1730     assume [simp]: "x = y"
```
```  1731     have
```
```  1732       "{#x#} + X = A + ({#y#}+Z)
```
```  1733       \<and> {#y#} + Y = B + ({#y#}+Z)
```
```  1734       \<and> ((set_of A, set_of B) \<in> max_strict \<or> (B = {#} \<and> A = {#}))"
```
```  1735       by (auto simp: add_ac)
```
```  1736     thus ?case by (intro exI)
```
```  1737   next
```
```  1738     assume A: "(x, y) \<in> pair_less"
```
```  1739     let ?A' = "{#x#} + A" and ?B' = "{#y#} + B"
```
```  1740     have "{#x#} + X = ?A' + Z"
```
```  1741       "{#y#} + Y = ?B' + Z"
```
```  1742       by (auto simp add: add_ac)
```
```  1743     moreover have
```
```  1744       "(set_of ?A', set_of ?B') \<in> max_strict"
```
```  1745       using 1 A unfolding max_strict_def
```
```  1746       by (auto elim!: max_ext.cases)
```
```  1747     ultimately show ?thesis by blast
```
```  1748   qed
```
```  1749 qed
```
```  1750
```
```  1751 lemma
```
```  1752   assumes pwleq: "pw_leq Z Z'"
```
```  1753   shows ms_strictI: "(set_of A, set_of B) \<in> max_strict \<Longrightarrow> (Z + A, Z' + B) \<in> ms_strict"
```
```  1754   and   ms_weakI1:  "(set_of A, set_of B) \<in> max_strict \<Longrightarrow> (Z + A, Z' + B) \<in> ms_weak"
```
```  1755   and   ms_weakI2:  "(Z + {#}, Z' + {#}) \<in> ms_weak"
```
```  1756 proof -
```
```  1757   from pw_leq_split[OF pwleq]
```
```  1758   obtain A' B' Z''
```
```  1759     where [simp]: "Z = A' + Z''" "Z' = B' + Z''"
```
```  1760     and mx_or_empty: "(set_of A', set_of B') \<in> max_strict \<or> (A' = {#} \<and> B' = {#})"
```
```  1761     by blast
```
```  1762   {
```
```  1763     assume max: "(set_of A, set_of B) \<in> max_strict"
```
```  1764     from mx_or_empty
```
```  1765     have "(Z'' + (A + A'), Z'' + (B + B')) \<in> ms_strict"
```
```  1766     proof
```
```  1767       assume max': "(set_of A', set_of B') \<in> max_strict"
```
```  1768       with max have "(set_of (A + A'), set_of (B + B')) \<in> max_strict"
```
```  1769         by (auto simp: max_strict_def intro: max_ext_additive)
```
```  1770       thus ?thesis by (rule smsI)
```
```  1771     next
```
```  1772       assume [simp]: "A' = {#} \<and> B' = {#}"
```
```  1773       show ?thesis by (rule smsI) (auto intro: max)
```
```  1774     qed
```
```  1775     thus "(Z + A, Z' + B) \<in> ms_strict" by (simp add:add_ac)
```
```  1776     thus "(Z + A, Z' + B) \<in> ms_weak" by (simp add: ms_weak_def)
```
```  1777   }
```
```  1778   from mx_or_empty
```
```  1779   have "(Z'' + A', Z'' + B') \<in> ms_weak" by (rule wmsI)
```
```  1780   thus "(Z + {#}, Z' + {#}) \<in> ms_weak" by (simp add:add_ac)
```
```  1781 qed
```
```  1782
```
```  1783 lemma empty_neutral: "{#} + x = x" "x + {#} = x"
```
```  1784 and nonempty_plus: "{# x #} + rs \<noteq> {#}"
```
```  1785 and nonempty_single: "{# x #} \<noteq> {#}"
```
```  1786 by auto
```
```  1787
```
```  1788 setup {*
```
```  1789 let
```
```  1790   fun msetT T = Type (@{type_name multiset}, [T]);
```
```  1791
```
```  1792   fun mk_mset T [] = Const (@{const_abbrev Mempty}, msetT T)
```
```  1793     | mk_mset T [x] = Const (@{const_name single}, T --> msetT T) \$ x
```
```  1794     | mk_mset T (x :: xs) =
```
```  1795           Const (@{const_name plus}, msetT T --> msetT T --> msetT T) \$
```
```  1796                 mk_mset T [x] \$ mk_mset T xs
```
```  1797
```
```  1798   fun mset_member_tac m i =
```
```  1799       (if m <= 0 then
```
```  1800            rtac @{thm multi_member_this} i ORELSE rtac @{thm multi_member_last} i
```
```  1801        else
```
```  1802            rtac @{thm multi_member_skip} i THEN mset_member_tac (m - 1) i)
```
```  1803
```
```  1804   val mset_nonempty_tac =
```
```  1805       rtac @{thm nonempty_plus} ORELSE' rtac @{thm nonempty_single}
```
```  1806
```
```  1807   val regroup_munion_conv =
```
```  1808       Function_Lib.regroup_conv @{const_abbrev Mempty} @{const_name plus}
```
```  1809         (map (fn t => t RS eq_reflection) (@{thms add_ac} @ @{thms empty_neutral}))
```
```  1810
```
```  1811   fun unfold_pwleq_tac i =
```
```  1812     (rtac @{thm pw_leq_step} i THEN (fn st => unfold_pwleq_tac (i + 1) st))
```
```  1813       ORELSE (rtac @{thm pw_leq_lstep} i)
```
```  1814       ORELSE (rtac @{thm pw_leq_empty} i)
```
```  1815
```
```  1816   val set_of_simps = [@{thm set_of_empty}, @{thm set_of_single}, @{thm set_of_union},
```
```  1817                       @{thm Un_insert_left}, @{thm Un_empty_left}]
```
```  1818 in
```
```  1819   ScnpReconstruct.multiset_setup (ScnpReconstruct.Multiset
```
```  1820   {
```
```  1821     msetT=msetT, mk_mset=mk_mset, mset_regroup_conv=regroup_munion_conv,
```
```  1822     mset_member_tac=mset_member_tac, mset_nonempty_tac=mset_nonempty_tac,
```
```  1823     mset_pwleq_tac=unfold_pwleq_tac, set_of_simps=set_of_simps,
```
```  1824     smsI'= @{thm ms_strictI}, wmsI2''= @{thm ms_weakI2}, wmsI1= @{thm ms_weakI1},
```
```  1825     reduction_pair= @{thm ms_reduction_pair}
```
```  1826   })
```
```  1827 end
```
```  1828 *}
```
```  1829
```
```  1830
```
```  1831 subsection {* Legacy theorem bindings *}
```
```  1832
```
```  1833 lemmas multi_count_eq = multiset_eq_iff [symmetric]
```
```  1834
```
```  1835 lemma union_commute: "M + N = N + (M::'a multiset)"
```
```  1836   by (fact add_commute)
```
```  1837
```
```  1838 lemma union_assoc: "(M + N) + K = M + (N + (K::'a multiset))"
```
```  1839   by (fact add_assoc)
```
```  1840
```
```  1841 lemma union_lcomm: "M + (N + K) = N + (M + (K::'a multiset))"
```
```  1842   by (fact add_left_commute)
```
```  1843
```
```  1844 lemmas union_ac = union_assoc union_commute union_lcomm
```
```  1845
```
```  1846 lemma union_right_cancel: "M + K = N + K \<longleftrightarrow> M = (N::'a multiset)"
```
```  1847   by (fact add_right_cancel)
```
```  1848
```
```  1849 lemma union_left_cancel: "K + M = K + N \<longleftrightarrow> M = (N::'a multiset)"
```
```  1850   by (fact add_left_cancel)
```
```  1851
```
```  1852 lemma multi_union_self_other_eq: "(A::'a multiset) + X = A + Y \<Longrightarrow> X = Y"
```
```  1853   by (fact add_imp_eq)
```
```  1854
```
```  1855 lemma mset_less_trans: "(M::'a multiset) < K \<Longrightarrow> K < N \<Longrightarrow> M < N"
```
```  1856   by (fact order_less_trans)
```
```  1857
```
```  1858 lemma multiset_inter_commute: "A #\<inter> B = B #\<inter> A"
```
```  1859   by (fact inf.commute)
```
```  1860
```
```  1861 lemma multiset_inter_assoc: "A #\<inter> (B #\<inter> C) = A #\<inter> B #\<inter> C"
```
```  1862   by (fact inf.assoc [symmetric])
```
```  1863
```
```  1864 lemma multiset_inter_left_commute: "A #\<inter> (B #\<inter> C) = B #\<inter> (A #\<inter> C)"
```
```  1865   by (fact inf.left_commute)
```
```  1866
```
```  1867 lemmas multiset_inter_ac =
```
```  1868   multiset_inter_commute
```
```  1869   multiset_inter_assoc
```
```  1870   multiset_inter_left_commute
```
```  1871
```
```  1872 lemma mult_less_not_refl:
```
```  1873   "\<not> M \<subset># (M::'a::order multiset)"
```
```  1874   by (fact multiset_order.less_irrefl)
```
```  1875
```
```  1876 lemma mult_less_trans:
```
```  1877   "K \<subset># M ==> M \<subset># N ==> K \<subset># (N::'a::order multiset)"
```
```  1878   by (fact multiset_order.less_trans)
```
```  1879
```
```  1880 lemma mult_less_not_sym:
```
```  1881   "M \<subset># N ==> \<not> N \<subset># (M::'a::order multiset)"
```
```  1882   by (fact multiset_order.less_not_sym)
```
```  1883
```
```  1884 lemma mult_less_asym:
```
```  1885   "M \<subset># N ==> (\<not> P ==> N \<subset># (M::'a::order multiset)) ==> P"
```
```  1886   by (fact multiset_order.less_asym)
```
```  1887
```
```  1888 ML {*
```
```  1889 fun multiset_postproc _ maybe_name all_values (T as Type (_, [elem_T]))
```
```  1890                       (Const _ \$ t') =
```
```  1891     let
```
```  1892       val (maybe_opt, ps) =
```
```  1893         Nitpick_Model.dest_plain_fun t' ||> op ~~
```
```  1894         ||> map (apsnd (snd o HOLogic.dest_number))
```
```  1895       fun elems_for t =
```
```  1896         case AList.lookup (op =) ps t of
```
```  1897           SOME n => replicate n t
```
```  1898         | NONE => [Const (maybe_name, elem_T --> elem_T) \$ t]
```
```  1899     in
```
```  1900       case maps elems_for (all_values elem_T) @
```
```  1901            (if maybe_opt then [Const (Nitpick_Model.unrep (), elem_T)]
```
```  1902             else []) of
```
```  1903         [] => Const (@{const_name zero_class.zero}, T)
```
```  1904       | ts => foldl1 (fn (t1, t2) =>
```
```  1905                          Const (@{const_name plus_class.plus}, T --> T --> T)
```
```  1906                          \$ t1 \$ t2)
```
```  1907                      (map (curry (op \$) (Const (@{const_name single},
```
```  1908                                                 elem_T --> T))) ts)
```
```  1909     end
```
```  1910   | multiset_postproc _ _ _ _ t = t
```
```  1911 *}
```
```  1912
```
```  1913 declaration {*
```
```  1914 Nitpick_Model.register_term_postprocessor @{typ "'a multiset"}
```
```  1915     multiset_postproc
```
```  1916 *}
```
```  1917
```
```  1918 end
```
```  1919
```