src/HOL/Probability/Finite_Product_Measure.thy
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(*  Title:      HOL/Probability/Finite_Product_Measure.thy
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    Author:     Johannes Hölzl, TU München
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*)
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header {*Finite product measures*}
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theory Finite_Product_Measure
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imports Binary_Product_Measure
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begin
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lemma Pi_iff: "f \<in> Pi I X \<longleftrightarrow> (\<forall>i\<in>I. f i \<in> X i)"
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  unfolding Pi_def by auto
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abbreviation
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  "Pi\<^isub>E A B \<equiv> Pi A B \<inter> extensional A"
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syntax
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  "_PiE"  :: "[pttrn, 'a set, 'b set] => ('a => 'b) set"  ("(3PIE _:_./ _)" 10)
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syntax (xsymbols)
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  "_PiE" :: "[pttrn, 'a set, 'b set] => ('a => 'b) set"  ("(3\<Pi>\<^isub>E _\<in>_./ _)"   10)
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syntax (HTML output)
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  "_PiE" :: "[pttrn, 'a set, 'b set] => ('a => 'b) set"  ("(3\<Pi>\<^isub>E _\<in>_./ _)"   10)
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translations
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  "PIE x:A. B" == "CONST Pi\<^isub>E A (%x. B)"
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abbreviation
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  funcset_extensional :: "['a set, 'b set] => ('a => 'b) set"
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    (infixr "->\<^isub>E" 60) where
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  "A ->\<^isub>E B \<equiv> Pi\<^isub>E A (%_. B)"
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notation (xsymbols)
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  funcset_extensional  (infixr "\<rightarrow>\<^isub>E" 60)
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lemma extensional_empty[simp]: "extensional {} = {\<lambda>x. undefined}"
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  by safe (auto simp add: extensional_def fun_eq_iff)
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lemma extensional_insert[intro, simp]:
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  assumes "a \<in> extensional (insert i I)"
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  shows "a(i := b) \<in> extensional (insert i I)"
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  using assms unfolding extensional_def by auto
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lemma extensional_Int[simp]:
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  "extensional I \<inter> extensional I' = extensional (I \<inter> I')"
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  unfolding extensional_def by auto
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definition
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  "merge I x J y = (\<lambda>i. if i \<in> I then x i else if i \<in> J then y i else undefined)"
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lemma merge_apply[simp]:
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  "I \<inter> J = {} \<Longrightarrow> i \<in> I \<Longrightarrow> merge I x J y i = x i"
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  "I \<inter> J = {} \<Longrightarrow> i \<in> J \<Longrightarrow> merge I x J y i = y i"
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  "J \<inter> I = {} \<Longrightarrow> i \<in> I \<Longrightarrow> merge I x J y i = x i"
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  "J \<inter> I = {} \<Longrightarrow> i \<in> J \<Longrightarrow> merge I x J y i = y i"
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  "i \<notin> I \<Longrightarrow> i \<notin> J \<Longrightarrow> merge I x J y i = undefined"
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  unfolding merge_def by auto
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lemma merge_commute:
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  "I \<inter> J = {} \<Longrightarrow> merge I x J y = merge J y I x"
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  by (auto simp: merge_def intro!: ext)
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lemma Pi_cancel_merge_range[simp]:
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  "I \<inter> J = {} \<Longrightarrow> x \<in> Pi I (merge I A J B) \<longleftrightarrow> x \<in> Pi I A"
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  "I \<inter> J = {} \<Longrightarrow> x \<in> Pi I (merge J B I A) \<longleftrightarrow> x \<in> Pi I A"
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  "J \<inter> I = {} \<Longrightarrow> x \<in> Pi I (merge I A J B) \<longleftrightarrow> x \<in> Pi I A"
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  "J \<inter> I = {} \<Longrightarrow> x \<in> Pi I (merge J B I A) \<longleftrightarrow> x \<in> Pi I A"
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  by (auto simp: Pi_def)
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lemma Pi_cancel_merge[simp]:
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  "I \<inter> J = {} \<Longrightarrow> merge I x J y \<in> Pi I B \<longleftrightarrow> x \<in> Pi I B"
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  "J \<inter> I = {} \<Longrightarrow> merge I x J y \<in> Pi I B \<longleftrightarrow> x \<in> Pi I B"
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  "I \<inter> J = {} \<Longrightarrow> merge I x J y \<in> Pi J B \<longleftrightarrow> y \<in> Pi J B"
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  "J \<inter> I = {} \<Longrightarrow> merge I x J y \<in> Pi J B \<longleftrightarrow> y \<in> Pi J B"
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  by (auto simp: Pi_def)
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lemma extensional_merge[simp]: "merge I x J y \<in> extensional (I \<union> J)"
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  by (auto simp: extensional_def)
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lemma restrict_Pi_cancel: "restrict x I \<in> Pi I A \<longleftrightarrow> x \<in> Pi I A"
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  by (auto simp: restrict_def Pi_def)
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lemma restrict_merge[simp]:
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  "I \<inter> J = {} \<Longrightarrow> restrict (merge I x J y) I = restrict x I"
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  "I \<inter> J = {} \<Longrightarrow> restrict (merge I x J y) J = restrict y J"
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  "J \<inter> I = {} \<Longrightarrow> restrict (merge I x J y) I = restrict x I"
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  "J \<inter> I = {} \<Longrightarrow> restrict (merge I x J y) J = restrict y J"
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  by (auto simp: restrict_def intro!: ext)
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lemma extensional_insert_undefined[intro, simp]:
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  assumes "a \<in> extensional (insert i I)"
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  shows "a(i := undefined) \<in> extensional I"
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  using assms unfolding extensional_def by auto
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lemma extensional_insert_cancel[intro, simp]:
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  assumes "a \<in> extensional I"
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  shows "a \<in> extensional (insert i I)"
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  using assms unfolding extensional_def by auto
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lemma merge_singleton[simp]: "i \<notin> I \<Longrightarrow> merge I x {i} y = restrict (x(i := y i)) (insert i I)"
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  unfolding merge_def by (auto simp: fun_eq_iff)
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lemma Pi_Int: "Pi I E \<inter> Pi I F = (\<Pi> i\<in>I. E i \<inter> F i)"
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  by auto
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lemma PiE_Int: "(Pi\<^isub>E I A) \<inter> (Pi\<^isub>E I B) = Pi\<^isub>E I (\<lambda>x. A x \<inter> B x)"
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  by auto
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lemma Pi_cancel_fupd_range[simp]: "i \<notin> I \<Longrightarrow> x \<in> Pi I (B(i := b)) \<longleftrightarrow> x \<in> Pi I B"
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  by (auto simp: Pi_def)
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lemma Pi_split_insert_domain[simp]: "x \<in> Pi (insert i I) X \<longleftrightarrow> x \<in> Pi I X \<and> x i \<in> X i"
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  by (auto simp: Pi_def)
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lemma Pi_split_domain[simp]: "x \<in> Pi (I \<union> J) X \<longleftrightarrow> x \<in> Pi I X \<and> x \<in> Pi J X"
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  by (auto simp: Pi_def)
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lemma Pi_cancel_fupd[simp]: "i \<notin> I \<Longrightarrow> x(i := a) \<in> Pi I B \<longleftrightarrow> x \<in> Pi I B"
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  by (auto simp: Pi_def)
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lemma restrict_vimage:
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  assumes "I \<inter> J = {}"
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  shows "(\<lambda>x. (restrict x I, restrict x J)) -` (Pi\<^isub>E I E \<times> Pi\<^isub>E J F) = Pi (I \<union> J) (merge I E J F)"
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  using assms by (auto simp: restrict_Pi_cancel)
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lemma merge_vimage:
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  assumes "I \<inter> J = {}"
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  shows "(\<lambda>(x,y). merge I x J y) -` Pi\<^isub>E (I \<union> J) E = Pi I E \<times> Pi J E"
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  using assms by (auto simp: restrict_Pi_cancel)
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lemma restrict_fupd[simp]: "i \<notin> I \<Longrightarrow> restrict (f (i := x)) I = restrict f I"
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  by (auto simp: restrict_def intro!: ext)
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lemma merge_restrict[simp]:
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  "merge I (restrict x I) J y = merge I x J y"
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diff changeset
   137
  "merge I x J (restrict y J) = merge I x J y"
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diff changeset
   138
  unfolding merge_def by (auto intro!: ext)
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diff changeset
   139
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   140
lemma merge_x_x_eq_restrict[simp]:
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diff changeset
   141
  "merge I x J x = restrict x (I \<union> J)"
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diff changeset
   142
  unfolding merge_def by (auto intro!: ext)
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parents: 41026
diff changeset
   143
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   144
lemma Pi_fupd_iff: "i \<in> I \<Longrightarrow> f \<in> Pi I (B(i := A)) \<longleftrightarrow> f \<in> Pi (I - {i}) B \<and> f i \<in> A"
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diff changeset
   145
  apply auto
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diff changeset
   146
  apply (drule_tac x=x in Pi_mem)
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diff changeset
   147
  apply (simp_all split: split_if_asm)
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diff changeset
   148
  apply (drule_tac x=i in Pi_mem)
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diff changeset
   149
  apply (auto dest!: Pi_mem)
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diff changeset
   150
  done
c335d880ff82 cleanup bijectivity btw. product spaces and pairs
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diff changeset
   151
c335d880ff82 cleanup bijectivity btw. product spaces and pairs
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   152
lemma Pi_UN:
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diff changeset
   153
  fixes A :: "nat \<Rightarrow> 'i \<Rightarrow> 'a set"
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diff changeset
   154
  assumes "finite I" and mono: "\<And>i n m. i \<in> I \<Longrightarrow> n \<le> m \<Longrightarrow> A n i \<subseteq> A m i"
c335d880ff82 cleanup bijectivity btw. product spaces and pairs
hoelzl
parents: 41026
diff changeset
   155
  shows "(\<Union>n. Pi I (A n)) = (\<Pi> i\<in>I. \<Union>n. A n i)"
c335d880ff82 cleanup bijectivity btw. product spaces and pairs
hoelzl
parents: 41026
diff changeset
   156
proof (intro set_eqI iffI)
c335d880ff82 cleanup bijectivity btw. product spaces and pairs
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parents: 41026
diff changeset
   157
  fix f assume "f \<in> (\<Pi> i\<in>I. \<Union>n. A n i)"
c335d880ff82 cleanup bijectivity btw. product spaces and pairs
hoelzl
parents: 41026
diff changeset
   158
  then have "\<forall>i\<in>I. \<exists>n. f i \<in> A n i" by auto
c335d880ff82 cleanup bijectivity btw. product spaces and pairs
hoelzl
parents: 41026
diff changeset
   159
  from bchoice[OF this] obtain n where n: "\<And>i. i \<in> I \<Longrightarrow> f i \<in> (A (n i) i)" by auto
c335d880ff82 cleanup bijectivity btw. product spaces and pairs
hoelzl
parents: 41026
diff changeset
   160
  obtain k where k: "\<And>i. i \<in> I \<Longrightarrow> n i \<le> k"
c335d880ff82 cleanup bijectivity btw. product spaces and pairs
hoelzl
parents: 41026
diff changeset
   161
    using `finite I` finite_nat_set_iff_bounded_le[of "n`I"] by auto
c335d880ff82 cleanup bijectivity btw. product spaces and pairs
hoelzl
parents: 41026
diff changeset
   162
  have "f \<in> Pi I (A k)"
c335d880ff82 cleanup bijectivity btw. product spaces and pairs
hoelzl
parents: 41026
diff changeset
   163
  proof (intro Pi_I)
c335d880ff82 cleanup bijectivity btw. product spaces and pairs
hoelzl
parents: 41026
diff changeset
   164
    fix i assume "i \<in> I"
c335d880ff82 cleanup bijectivity btw. product spaces and pairs
hoelzl
parents: 41026
diff changeset
   165
    from mono[OF this, of "n i" k] k[OF this] n[OF this]
c335d880ff82 cleanup bijectivity btw. product spaces and pairs
hoelzl
parents: 41026
diff changeset
   166
    show "f i \<in> A k i" by auto
c335d880ff82 cleanup bijectivity btw. product spaces and pairs
hoelzl
parents: 41026
diff changeset
   167
  qed
c335d880ff82 cleanup bijectivity btw. product spaces and pairs
hoelzl
parents: 41026
diff changeset
   168
  then show "f \<in> (\<Union>n. Pi I (A n))" by auto
c335d880ff82 cleanup bijectivity btw. product spaces and pairs
hoelzl
parents: 41026
diff changeset
   169
qed auto
c335d880ff82 cleanup bijectivity btw. product spaces and pairs
hoelzl
parents: 41026
diff changeset
   170
c335d880ff82 cleanup bijectivity btw. product spaces and pairs
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diff changeset
   171
lemma PiE_cong:
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diff changeset
   172
  assumes "\<And>i. i\<in>I \<Longrightarrow> A i = B i"
c335d880ff82 cleanup bijectivity btw. product spaces and pairs
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parents: 41026
diff changeset
   173
  shows "Pi\<^isub>E I A = Pi\<^isub>E I B"
c335d880ff82 cleanup bijectivity btw. product spaces and pairs
hoelzl
parents: 41026
diff changeset
   174
  using assms by (auto intro!: Pi_cong)
c335d880ff82 cleanup bijectivity btw. product spaces and pairs
hoelzl
parents: 41026
diff changeset
   175
c335d880ff82 cleanup bijectivity btw. product spaces and pairs
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diff changeset
   176
lemma restrict_upd[simp]:
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diff changeset
   177
  "i \<notin> I \<Longrightarrow> (restrict f I)(i := y) = restrict (f(i := y)) (insert i I)"
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diff changeset
   178
  by (auto simp: fun_eq_iff)
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diff changeset
   179
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
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   180
lemma Pi_eq_subset:
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
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diff changeset
   181
  assumes ne: "\<And>i. i \<in> I \<Longrightarrow> F i \<noteq> {}" "\<And>i. i \<in> I \<Longrightarrow> F' i \<noteq> {}"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
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   182
  assumes eq: "Pi\<^isub>E I F = Pi\<^isub>E I F'" and "i \<in> I"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   183
  shows "F i \<subseteq> F' i"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
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diff changeset
   184
proof
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
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diff changeset
   185
  fix x assume "x \<in> F i"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   186
  with ne have "\<forall>j. \<exists>y. ((j \<in> I \<longrightarrow> y \<in> F j \<and> (i = j \<longrightarrow> x = y)) \<and> (j \<notin> I \<longrightarrow> y = undefined))" by auto
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   187
  from choice[OF this] guess f .. note f = this
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   188
  then have "f \<in> Pi\<^isub>E I F" by (auto simp: extensional_def)
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   189
  then have "f \<in> Pi\<^isub>E I F'" using assms by simp
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   190
  then show "x \<in> F' i" using f `i \<in> I` by auto
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   191
qed
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   192
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
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diff changeset
   193
lemma Pi_eq_iff_not_empty:
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
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parents: 41661
diff changeset
   194
  assumes ne: "\<And>i. i \<in> I \<Longrightarrow> F i \<noteq> {}" "\<And>i. i \<in> I \<Longrightarrow> F' i \<noteq> {}"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   195
  shows "Pi\<^isub>E I F = Pi\<^isub>E I F' \<longleftrightarrow> (\<forall>i\<in>I. F i = F' i)"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   196
proof (intro iffI ballI)
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   197
  fix i assume eq: "Pi\<^isub>E I F = Pi\<^isub>E I F'" and i: "i \<in> I"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   198
  show "F i = F' i"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   199
    using Pi_eq_subset[of I F F', OF ne eq i]
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   200
    using Pi_eq_subset[of I F' F, OF ne(2,1) eq[symmetric] i]
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
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diff changeset
   201
    by auto
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   202
qed auto
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   203
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
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diff changeset
   204
lemma Pi_eq_empty_iff:
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
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parents: 41661
diff changeset
   205
  "Pi\<^isub>E I F = {} \<longleftrightarrow> (\<exists>i\<in>I. F i = {})"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
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diff changeset
   206
proof
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   207
  assume "Pi\<^isub>E I F = {}"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   208
  show "\<exists>i\<in>I. F i = {}"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   209
  proof (rule ccontr)
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   210
    assume "\<not> ?thesis"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   211
    then have "\<forall>i. \<exists>y. (i \<in> I \<longrightarrow> y \<in> F i) \<and> (i \<notin> I \<longrightarrow> y = undefined)" by auto
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   212
    from choice[OF this] guess f ..
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   213
    then have "f \<in> Pi\<^isub>E I F" by (auto simp: extensional_def)
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   214
    with `Pi\<^isub>E I F = {}` show False by auto
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   215
  qed
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   216
qed auto
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   217
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
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diff changeset
   218
lemma Pi_eq_iff:
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
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parents: 41661
diff changeset
   219
  "Pi\<^isub>E I F = Pi\<^isub>E I F' \<longleftrightarrow> (\<forall>i\<in>I. F i = F' i) \<or> ((\<exists>i\<in>I. F i = {}) \<and> (\<exists>i\<in>I. F' i = {}))"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   220
proof (intro iffI disjCI)
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   221
  assume eq[simp]: "Pi\<^isub>E I F = Pi\<^isub>E I F'"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   222
  assume "\<not> ((\<exists>i\<in>I. F i = {}) \<and> (\<exists>i\<in>I. F' i = {}))"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   223
  then have "(\<forall>i\<in>I. F i \<noteq> {}) \<and> (\<forall>i\<in>I. F' i \<noteq> {})"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   224
    using Pi_eq_empty_iff[of I F] Pi_eq_empty_iff[of I F'] by auto
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   225
  with Pi_eq_iff_not_empty[of I F F'] show "\<forall>i\<in>I. F i = F' i" by auto
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   226
next
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   227
  assume "(\<forall>i\<in>I. F i = F' i) \<or> (\<exists>i\<in>I. F i = {}) \<and> (\<exists>i\<in>I. F' i = {})"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   228
  then show "Pi\<^isub>E I F = Pi\<^isub>E I F'"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   229
    using Pi_eq_empty_iff[of I F] Pi_eq_empty_iff[of I F'] by auto
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   230
qed
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   231
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
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diff changeset
   232
section "Finite product spaces"
de0b30e6c2d2 Support product spaces on sigma finite measures.
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diff changeset
   233
de0b30e6c2d2 Support product spaces on sigma finite measures.
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diff changeset
   234
section "Products"
de0b30e6c2d2 Support product spaces on sigma finite measures.
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diff changeset
   235
de0b30e6c2d2 Support product spaces on sigma finite measures.
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diff changeset
   236
locale product_sigma_algebra =
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
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diff changeset
   237
  fixes M :: "'i \<Rightarrow> ('a, 'b) measure_space_scheme"
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
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diff changeset
   238
  assumes sigma_algebras: "\<And>i. sigma_algebra (M i)"
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   239
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
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diff changeset
   240
locale finite_product_sigma_algebra = product_sigma_algebra M
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   241
  for M :: "'i \<Rightarrow> ('a, 'b) measure_space_scheme" +
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   242
  fixes I :: "'i set"
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   243
  assumes finite_index: "finite I"
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   244
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
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diff changeset
   245
definition
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   246
  "product_algebra_generator I M = \<lparr> space = (\<Pi>\<^isub>E i \<in> I. space (M i)),
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   247
    sets = Pi\<^isub>E I ` (\<Pi> i \<in> I. sets (M i)),
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   248
    measure = \<lambda>A. (\<Prod>i\<in>I. measure (M i) ((SOME F. A = Pi\<^isub>E I F) i)) \<rparr>"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   249
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   250
definition product_algebra_def:
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   251
  "Pi\<^isub>M I M = sigma (product_algebra_generator I M)
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   252
    \<lparr> measure := (SOME \<mu>. sigma_finite_measure (sigma (product_algebra_generator I M) \<lparr> measure := \<mu> \<rparr>) \<and>
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   253
      (\<forall>A\<in>\<Pi> i\<in>I. sets (M i). \<mu> (Pi\<^isub>E I A) = (\<Prod>i\<in>I. measure (M i) (A i))))\<rparr>"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   254
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   255
syntax
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   256
  "_PiM"  :: "[pttrn, 'i set, ('a, 'b) measure_space_scheme] =>
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
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   257
              ('i => 'a, 'b) measure_space_scheme"  ("(3PIM _:_./ _)" 10)
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diff changeset
   258
de0b30e6c2d2 Support product spaces on sigma finite measures.
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diff changeset
   259
syntax (xsymbols)
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
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diff changeset
   260
  "_PiM" :: "[pttrn, 'i set, ('a, 'b) measure_space_scheme] =>
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   261
             ('i => 'a, 'b) measure_space_scheme"  ("(3\<Pi>\<^isub>M _\<in>_./ _)"   10)
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
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diff changeset
   262
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   263
syntax (HTML output)
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   264
  "_PiM" :: "[pttrn, 'i set, ('a, 'b) measure_space_scheme] =>
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   265
             ('i => 'a, 'b) measure_space_scheme"  ("(3\<Pi>\<^isub>M _\<in>_./ _)"   10)
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   266
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   267
translations
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
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diff changeset
   268
  "PIM x:I. M" == "CONST Pi\<^isub>M I (%x. M)"
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
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parents: 39098
diff changeset
   269
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
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diff changeset
   270
abbreviation (in finite_product_sigma_algebra) "G \<equiv> product_algebra_generator I M"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
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diff changeset
   271
abbreviation (in finite_product_sigma_algebra) "P \<equiv> Pi\<^isub>M I M"
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
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diff changeset
   272
de0b30e6c2d2 Support product spaces on sigma finite measures.
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diff changeset
   273
sublocale product_sigma_algebra \<subseteq> M: sigma_algebra "M i" for i by (rule sigma_algebras)
de0b30e6c2d2 Support product spaces on sigma finite measures.
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parents: 39098
diff changeset
   274
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
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parents: 41661
diff changeset
   275
lemma sigma_into_space:
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
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diff changeset
   276
  assumes "sets M \<subseteq> Pow (space M)"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   277
  shows "sets (sigma M) \<subseteq> Pow (space M)"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   278
  using sigma_sets_into_sp[OF assms] unfolding sigma_def by auto
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   279
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   280
lemma (in product_sigma_algebra) product_algebra_generator_into_space:
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   281
  "sets (product_algebra_generator I M) \<subseteq> Pow (space (product_algebra_generator I M))"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   282
  using M.sets_into_space unfolding product_algebra_generator_def
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   283
  by auto blast
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   284
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   285
lemma (in product_sigma_algebra) product_algebra_into_space:
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   286
  "sets (Pi\<^isub>M I M) \<subseteq> Pow (space (Pi\<^isub>M I M))"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   287
  using product_algebra_generator_into_space
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   288
  by (auto intro!: sigma_into_space simp add: product_algebra_def)
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   289
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   290
lemma (in product_sigma_algebra) sigma_algebra_product_algebra: "sigma_algebra (Pi\<^isub>M I M)"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   291
  using product_algebra_generator_into_space unfolding product_algebra_def
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   292
  by (rule sigma_algebra.sigma_algebra_cong[OF sigma_algebra_sigma]) simp_all
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   293
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   294
sublocale finite_product_sigma_algebra \<subseteq> sigma_algebra P
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   295
  using sigma_algebra_product_algebra .
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   296
41095
c335d880ff82 cleanup bijectivity btw. product spaces and pairs
hoelzl
parents: 41026
diff changeset
   297
lemma product_algebraE:
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   298
  assumes "A \<in> sets (product_algebra_generator I M)"
41095
c335d880ff82 cleanup bijectivity btw. product spaces and pairs
hoelzl
parents: 41026
diff changeset
   299
  obtains E where "A = Pi\<^isub>E I E" "E \<in> (\<Pi> i\<in>I. sets (M i))"
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   300
  using assms unfolding product_algebra_generator_def by auto
41095
c335d880ff82 cleanup bijectivity btw. product spaces and pairs
hoelzl
parents: 41026
diff changeset
   301
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   302
lemma product_algebra_generatorI[intro]:
41095
c335d880ff82 cleanup bijectivity btw. product spaces and pairs
hoelzl
parents: 41026
diff changeset
   303
  assumes "E \<in> (\<Pi> i\<in>I. sets (M i))"
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   304
  shows "Pi\<^isub>E I E \<in> sets (product_algebra_generator I M)"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   305
  using assms unfolding product_algebra_generator_def by auto
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   306
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   307
lemma space_product_algebra_generator[simp]:
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   308
  "space (product_algebra_generator I M) = Pi\<^isub>E I (\<lambda>i. space (M i))"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   309
  unfolding product_algebra_generator_def by simp
41095
c335d880ff82 cleanup bijectivity btw. product spaces and pairs
hoelzl
parents: 41026
diff changeset
   310
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
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diff changeset
   311
lemma space_product_algebra[simp]:
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   312
  "space (Pi\<^isub>M I M) = (\<Pi>\<^isub>E i\<in>I. space (M i))"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   313
  unfolding product_algebra_def product_algebra_generator_def by simp
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   314
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   315
lemma sets_product_algebra:
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   316
  "sets (Pi\<^isub>M I M) = sets (sigma (product_algebra_generator I M))"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   317
  unfolding product_algebra_def sigma_def by simp
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   318
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   319
lemma product_algebra_generator_sets_into_space:
41095
c335d880ff82 cleanup bijectivity btw. product spaces and pairs
hoelzl
parents: 41026
diff changeset
   320
  assumes "\<And>i. i\<in>I \<Longrightarrow> sets (M i) \<subseteq> Pow (space (M i))"
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   321
  shows "sets (product_algebra_generator I M) \<subseteq> Pow (space (product_algebra_generator I M))"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   322
  using assms by (auto simp: product_algebra_generator_def) blast
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   323
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   324
lemma (in finite_product_sigma_algebra) in_P[simp, intro]:
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   325
  "\<lbrakk> \<And>i. i \<in> I \<Longrightarrow> A i \<in> sets (M i) \<rbrakk> \<Longrightarrow> Pi\<^isub>E I A \<in> sets P"
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   326
  by (auto simp: sets_product_algebra)
41026
bea75746dc9d folding on arbitrary Lebesgue integrable functions
hoelzl
parents: 41023
diff changeset
   327
42988
d8f3fc934ff6 add lemma indep_distribution_eq_measure
hoelzl
parents: 42950
diff changeset
   328
lemma Int_stable_product_algebra_generator:
d8f3fc934ff6 add lemma indep_distribution_eq_measure
hoelzl
parents: 42950
diff changeset
   329
  "(\<And>i. i \<in> I \<Longrightarrow> Int_stable (M i)) \<Longrightarrow> Int_stable (product_algebra_generator I M)"
d8f3fc934ff6 add lemma indep_distribution_eq_measure
hoelzl
parents: 42950
diff changeset
   330
  by (auto simp add: product_algebra_generator_def Int_stable_def PiE_Int Pi_iff)
d8f3fc934ff6 add lemma indep_distribution_eq_measure
hoelzl
parents: 42950
diff changeset
   331
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   332
section "Generating set generates also product algebra"
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   333
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   334
lemma sigma_product_algebra_sigma_eq:
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   335
  assumes "finite I"
41981
cdf7693bbe08 reworked Probability theory: measures are not type restricted to positive extended reals
hoelzl
parents: 41831
diff changeset
   336
  assumes mono: "\<And>i. i \<in> I \<Longrightarrow> incseq (S i)"
cdf7693bbe08 reworked Probability theory: measures are not type restricted to positive extended reals
hoelzl
parents: 41831
diff changeset
   337
  assumes union: "\<And>i. i \<in> I \<Longrightarrow> (\<Union>j. S i j) = space (E i)"
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   338
  assumes sets_into: "\<And>i. i \<in> I \<Longrightarrow> range (S i) \<subseteq> sets (E i)"
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   339
  and E: "\<And>i. sets (E i) \<subseteq> Pow (space (E i))"
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   340
  shows "sets (\<Pi>\<^isub>M i\<in>I. sigma (E i)) = sets (\<Pi>\<^isub>M i\<in>I. E i)"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   341
    (is "sets ?S = sets ?E")
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   342
proof cases
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   343
  assume "I = {}" then show ?thesis
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   344
    by (simp add: product_algebra_def product_algebra_generator_def)
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   345
next
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   346
  assume "I \<noteq> {}"
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   347
  interpret E: sigma_algebra "sigma (E i)" for i
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   348
    using E by (rule sigma_algebra_sigma)
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   349
  have into_space[intro]: "\<And>i x A. A \<in> sets (E i) \<Longrightarrow> x i \<in> A \<Longrightarrow> x i \<in> space (E i)"
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   350
    using E by auto
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   351
  interpret G: sigma_algebra ?E
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   352
    unfolding product_algebra_def product_algebra_generator_def using E
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   353
    by (intro sigma_algebra.sigma_algebra_cong[OF sigma_algebra_sigma]) (auto dest: Pi_mem)
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   354
  { fix A i assume "i \<in> I" and A: "A \<in> sets (E i)"
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   355
    then have "(\<lambda>x. x i) -` A \<inter> space ?E = (\<Pi>\<^isub>E j\<in>I. if j = i then A else \<Union>n. S j n) \<inter> space ?E"
41981
cdf7693bbe08 reworked Probability theory: measures are not type restricted to positive extended reals
hoelzl
parents: 41831
diff changeset
   356
      using mono union unfolding incseq_Suc_iff space_product_algebra
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   357
      by (auto dest: Pi_mem)
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   358
    also have "\<dots> = (\<Union>n. (\<Pi>\<^isub>E j\<in>I. if j = i then A else S j n))"
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   359
      unfolding space_product_algebra
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   360
      apply simp
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   361
      apply (subst Pi_UN[OF `finite I`])
41981
cdf7693bbe08 reworked Probability theory: measures are not type restricted to positive extended reals
hoelzl
parents: 41831
diff changeset
   362
      using mono[THEN incseqD] apply simp
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   363
      apply (simp add: PiE_Int)
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   364
      apply (intro PiE_cong)
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   365
      using A sets_into by (auto intro!: into_space)
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   366
    also have "\<dots> \<in> sets ?E"
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   367
      using sets_into `A \<in> sets (E i)`
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   368
      unfolding sets_product_algebra sets_sigma
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   369
      by (intro sigma_sets.Union)
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   370
         (auto simp: image_subset_iff intro!: sigma_sets.Basic)
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   371
    finally have "(\<lambda>x. x i) -` A \<inter> space ?E \<in> sets ?E" . }
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   372
  then have proj:
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   373
    "\<And>i. i\<in>I \<Longrightarrow> (\<lambda>x. x i) \<in> measurable ?E (sigma (E i))"
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   374
    using E by (subst G.measurable_iff_sigma)
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   375
               (auto simp: sets_product_algebra sets_sigma)
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   376
  { fix A assume A: "\<And>i. i \<in> I \<Longrightarrow> A i \<in> sets (sigma (E i))"
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   377
    with proj have basic: "\<And>i. i \<in> I \<Longrightarrow> (\<lambda>x. x i) -` (A i) \<inter> space ?E \<in> sets ?E"
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   378
      unfolding measurable_def by simp
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   379
    have "Pi\<^isub>E I A = (\<Inter>i\<in>I. (\<lambda>x. x i) -` (A i) \<inter> space ?E)"
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   380
      using A E.sets_into_space `I \<noteq> {}` unfolding product_algebra_def by auto blast
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   381
    then have "Pi\<^isub>E I A \<in> sets ?E"
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   382
      using G.finite_INT[OF `finite I` `I \<noteq> {}` basic, of "\<lambda>i. i"] by simp }
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   383
  then have "sigma_sets (space ?E) (sets (product_algebra_generator I (\<lambda>i. sigma (E i)))) \<subseteq> sets ?E"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   384
    by (intro G.sigma_sets_subset) (auto simp add: product_algebra_generator_def)
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   385
  then have subset: "sets ?S \<subseteq> sets ?E"
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   386
    by (simp add: sets_sigma sets_product_algebra)
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   387
  show "sets ?S = sets ?E"
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   388
  proof (intro set_eqI iffI)
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   389
    fix A assume "A \<in> sets ?E" then show "A \<in> sets ?S"
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   390
      unfolding sets_sigma sets_product_algebra
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   391
    proof induct
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   392
      case (Basic A) then show ?case
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   393
        by (auto simp: sets_sigma product_algebra_generator_def intro: sigma_sets.Basic)
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   394
    qed (auto intro: sigma_sets.intros simp: product_algebra_generator_def)
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   395
  next
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   396
    fix A assume "A \<in> sets ?S" then show "A \<in> sets ?E" using subset by auto
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   397
  qed
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   398
qed
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   399
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   400
lemma product_algebraI[intro]:
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   401
    "E \<in> (\<Pi> i\<in>I. sets (M i)) \<Longrightarrow> Pi\<^isub>E I E \<in> sets (Pi\<^isub>M I M)"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   402
  using assms unfolding product_algebra_def by (auto intro: product_algebra_generatorI)
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   403
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   404
lemma (in product_sigma_algebra) measurable_component_update:
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   405
  assumes "x \<in> space (Pi\<^isub>M I M)" and "i \<notin> I"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   406
  shows "(\<lambda>v. x(i := v)) \<in> measurable (M i) (Pi\<^isub>M (insert i I) M)" (is "?f \<in> _")
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   407
  unfolding product_algebra_def apply simp
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   408
proof (intro measurable_sigma)
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   409
  let ?G = "product_algebra_generator (insert i I) M"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   410
  show "sets ?G \<subseteq> Pow (space ?G)" using product_algebra_generator_into_space .
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   411
  show "?f \<in> space (M i) \<rightarrow> space ?G"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   412
    using M.sets_into_space assms by auto
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   413
  fix A assume "A \<in> sets ?G"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   414
  from product_algebraE[OF this] guess E . note E = this
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   415
  then have "?f -` A \<inter> space (M i) = E i \<or> ?f -` A \<inter> space (M i) = {}"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   416
    using M.sets_into_space assms by auto
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   417
  then show "?f -` A \<inter> space (M i) \<in> sets (M i)"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   418
    using E by (auto intro!: product_algebraI)
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   419
qed
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   420
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   421
lemma (in product_sigma_algebra) measurable_add_dim:
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   422
  assumes "i \<notin> I"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   423
  shows "(\<lambda>(f, y). f(i := y)) \<in> measurable (Pi\<^isub>M I M \<Otimes>\<^isub>M M i) (Pi\<^isub>M (insert i I) M)"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   424
proof -
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   425
  let ?f = "(\<lambda>(f, y). f(i := y))" and ?G = "product_algebra_generator (insert i I) M"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   426
  interpret Ii: pair_sigma_algebra "Pi\<^isub>M I M" "M i"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   427
    unfolding pair_sigma_algebra_def
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   428
    by (intro sigma_algebra_product_algebra sigma_algebras conjI)
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   429
  have "?f \<in> measurable Ii.P (sigma ?G)"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   430
  proof (rule Ii.measurable_sigma)
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   431
    show "sets ?G \<subseteq> Pow (space ?G)"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   432
      using product_algebra_generator_into_space .
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   433
    show "?f \<in> space (Pi\<^isub>M I M \<Otimes>\<^isub>M M i) \<rightarrow> space ?G"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   434
      by (auto simp: space_pair_measure)
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   435
  next
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   436
    fix A assume "A \<in> sets ?G"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   437
    then obtain F where "A = Pi\<^isub>E (insert i I) F"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   438
      and F: "\<And>j. j \<in> I \<Longrightarrow> F j \<in> sets (M j)" "F i \<in> sets (M i)"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   439
      by (auto elim!: product_algebraE)
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   440
    then have "?f -` A \<inter> space (Pi\<^isub>M I M \<Otimes>\<^isub>M M i) = Pi\<^isub>E I F \<times> (F i)"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   441
      using sets_into_space `i \<notin> I`
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   442
      by (auto simp add: space_pair_measure) blast+
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   443
    then show "?f -` A \<inter> space (Pi\<^isub>M I M \<Otimes>\<^isub>M M i) \<in> sets (Pi\<^isub>M I M \<Otimes>\<^isub>M M i)"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   444
      using F by (auto intro!: pair_measureI)
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   445
  qed
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   446
  then show ?thesis
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   447
    by (simp add: product_algebra_def)
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   448
qed
41095
c335d880ff82 cleanup bijectivity btw. product spaces and pairs
hoelzl
parents: 41026
diff changeset
   449
c335d880ff82 cleanup bijectivity btw. product spaces and pairs
hoelzl
parents: 41026
diff changeset
   450
lemma (in product_sigma_algebra) measurable_merge:
c335d880ff82 cleanup bijectivity btw. product spaces and pairs
hoelzl
parents: 41026
diff changeset
   451
  assumes [simp]: "I \<inter> J = {}"
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   452
  shows "(\<lambda>(x, y). merge I x J y) \<in> measurable (Pi\<^isub>M I M \<Otimes>\<^isub>M Pi\<^isub>M J M) (Pi\<^isub>M (I \<union> J) M)"
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   453
proof -
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   454
  let ?I = "Pi\<^isub>M I M" and ?J = "Pi\<^isub>M J M"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   455
  interpret P: sigma_algebra "?I \<Otimes>\<^isub>M ?J"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   456
    by (intro sigma_algebra_pair_measure product_algebra_into_space)
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   457
  let ?f = "\<lambda>(x, y). merge I x J y"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   458
  let ?G = "product_algebra_generator (I \<union> J) M"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   459
  have "?f \<in> measurable (?I \<Otimes>\<^isub>M ?J) (sigma ?G)"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   460
  proof (rule P.measurable_sigma)
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   461
    fix A assume "A \<in> sets ?G"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   462
    from product_algebraE[OF this]
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   463
    obtain E where E: "A = Pi\<^isub>E (I \<union> J) E" "E \<in> (\<Pi> i\<in>I \<union> J. sets (M i))" .
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   464
    then have *: "?f -` A \<inter> space (?I \<Otimes>\<^isub>M ?J) = Pi\<^isub>E I E \<times> Pi\<^isub>E J E"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   465
      using sets_into_space `I \<inter> J = {}`
41981
cdf7693bbe08 reworked Probability theory: measures are not type restricted to positive extended reals
hoelzl
parents: 41831
diff changeset
   466
      by (auto simp add: space_pair_measure) fast+
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   467
    then show "?f -` A \<inter> space (?I \<Otimes>\<^isub>M ?J) \<in> sets (?I \<Otimes>\<^isub>M ?J)"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   468
      using E unfolding * by (auto intro!: pair_measureI in_sigma product_algebra_generatorI
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   469
        simp: product_algebra_def)
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   470
  qed (insert product_algebra_generator_into_space, auto simp: space_pair_measure)
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   471
  then show "?f \<in> measurable (?I \<Otimes>\<^isub>M ?J) (Pi\<^isub>M (I \<union> J) M)"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   472
    unfolding product_algebra_def[of "I \<union> J"] by simp
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   473
qed
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   474
41095
c335d880ff82 cleanup bijectivity btw. product spaces and pairs
hoelzl
parents: 41026
diff changeset
   475
lemma (in product_sigma_algebra) measurable_component_singleton:
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   476
  assumes "i \<in> I" shows "(\<lambda>x. x i) \<in> measurable (Pi\<^isub>M I M) (M i)"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   477
proof (unfold measurable_def, intro CollectI conjI ballI)
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   478
  fix A assume "A \<in> sets (M i)"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   479
  then have "(\<lambda>x. x i) -` A \<inter> space (Pi\<^isub>M I M) = (\<Pi>\<^isub>E j\<in>I. if i = j then A else space (M j))"
44890
22f665a2e91c new fastforce replacing fastsimp - less confusing name
nipkow
parents: 43920
diff changeset
   480
    using M.sets_into_space `i \<in> I` by (fastforce dest: Pi_mem split: split_if_asm)
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   481
  then show "(\<lambda>x. x i) -` A \<inter> space (Pi\<^isub>M I M) \<in> sets (Pi\<^isub>M I M)"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   482
    using `A \<in> sets (M i)` by (auto intro!: product_algebraI)
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   483
qed (insert `i \<in> I`, auto)
41661
baf1964bc468 use pre-image measure, instead of image
hoelzl
parents: 41659
diff changeset
   484
42988
d8f3fc934ff6 add lemma indep_distribution_eq_measure
hoelzl
parents: 42950
diff changeset
   485
lemma (in sigma_algebra) measurable_restrict:
d8f3fc934ff6 add lemma indep_distribution_eq_measure
hoelzl
parents: 42950
diff changeset
   486
  assumes I: "finite I"
d8f3fc934ff6 add lemma indep_distribution_eq_measure
hoelzl
parents: 42950
diff changeset
   487
  assumes "\<And>i. i \<in> I \<Longrightarrow> sets (N i) \<subseteq> Pow (space (N i))"
d8f3fc934ff6 add lemma indep_distribution_eq_measure
hoelzl
parents: 42950
diff changeset
   488
  assumes X: "\<And>i. i \<in> I \<Longrightarrow> X i \<in> measurable M (N i)"
d8f3fc934ff6 add lemma indep_distribution_eq_measure
hoelzl
parents: 42950
diff changeset
   489
  shows "(\<lambda>x. \<lambda>i\<in>I. X i x) \<in> measurable M (Pi\<^isub>M I N)"
d8f3fc934ff6 add lemma indep_distribution_eq_measure
hoelzl
parents: 42950
diff changeset
   490
  unfolding product_algebra_def
d8f3fc934ff6 add lemma indep_distribution_eq_measure
hoelzl
parents: 42950
diff changeset
   491
proof (simp, rule measurable_sigma)
d8f3fc934ff6 add lemma indep_distribution_eq_measure
hoelzl
parents: 42950
diff changeset
   492
  show "sets (product_algebra_generator I N) \<subseteq> Pow (space (product_algebra_generator I N))"
d8f3fc934ff6 add lemma indep_distribution_eq_measure
hoelzl
parents: 42950
diff changeset
   493
    by (rule product_algebra_generator_sets_into_space) fact
d8f3fc934ff6 add lemma indep_distribution_eq_measure
hoelzl
parents: 42950
diff changeset
   494
  show "(\<lambda>x. \<lambda>i\<in>I. X i x) \<in> space M \<rightarrow> space (product_algebra_generator I N)"
d8f3fc934ff6 add lemma indep_distribution_eq_measure
hoelzl
parents: 42950
diff changeset
   495
    using X by (auto simp: measurable_def)
d8f3fc934ff6 add lemma indep_distribution_eq_measure
hoelzl
parents: 42950
diff changeset
   496
  fix E assume "E \<in> sets (product_algebra_generator I N)"
d8f3fc934ff6 add lemma indep_distribution_eq_measure
hoelzl
parents: 42950
diff changeset
   497
  then obtain F where "E = Pi\<^isub>E I F" and F: "\<And>i. i \<in> I \<Longrightarrow> F i \<in> sets (N i)"
d8f3fc934ff6 add lemma indep_distribution_eq_measure
hoelzl
parents: 42950
diff changeset
   498
    by (auto simp: product_algebra_generator_def)
d8f3fc934ff6 add lemma indep_distribution_eq_measure
hoelzl
parents: 42950
diff changeset
   499
  then have "(\<lambda>x. \<lambda>i\<in>I. X i x) -` E \<inter> space M = (\<Inter>i\<in>I. X i -` F i \<inter> space M) \<inter> space M"
d8f3fc934ff6 add lemma indep_distribution_eq_measure
hoelzl
parents: 42950
diff changeset
   500
    by (auto simp: Pi_iff)
d8f3fc934ff6 add lemma indep_distribution_eq_measure
hoelzl
parents: 42950
diff changeset
   501
  also have "\<dots> \<in> sets M"
d8f3fc934ff6 add lemma indep_distribution_eq_measure
hoelzl
parents: 42950
diff changeset
   502
  proof cases
d8f3fc934ff6 add lemma indep_distribution_eq_measure
hoelzl
parents: 42950
diff changeset
   503
    assume "I = {}" then show ?thesis by simp
d8f3fc934ff6 add lemma indep_distribution_eq_measure
hoelzl
parents: 42950
diff changeset
   504
  next
d8f3fc934ff6 add lemma indep_distribution_eq_measure
hoelzl
parents: 42950
diff changeset
   505
    assume "I \<noteq> {}" with X F I show ?thesis
d8f3fc934ff6 add lemma indep_distribution_eq_measure
hoelzl
parents: 42950
diff changeset
   506
      by (intro finite_INT measurable_sets Int) auto
d8f3fc934ff6 add lemma indep_distribution_eq_measure
hoelzl
parents: 42950
diff changeset
   507
  qed
d8f3fc934ff6 add lemma indep_distribution_eq_measure
hoelzl
parents: 42950
diff changeset
   508
  finally show "(\<lambda>x. \<lambda>i\<in>I. X i x) -` E \<inter> space M \<in> sets M" .
d8f3fc934ff6 add lemma indep_distribution_eq_measure
hoelzl
parents: 42950
diff changeset
   509
qed
d8f3fc934ff6 add lemma indep_distribution_eq_measure
hoelzl
parents: 42950
diff changeset
   510
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   511
locale product_sigma_finite =
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   512
  fixes M :: "'i \<Rightarrow> ('a,'b) measure_space_scheme"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   513
  assumes sigma_finite_measures: "\<And>i. sigma_finite_measure (M i)"
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   514
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   515
locale finite_product_sigma_finite = product_sigma_finite M
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   516
  for M :: "'i \<Rightarrow> ('a,'b) measure_space_scheme" +
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   517
  fixes I :: "'i set" assumes finite_index'[intro]: "finite I"
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   518
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   519
sublocale product_sigma_finite \<subseteq> M: sigma_finite_measure "M i" for i
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   520
  by (rule sigma_finite_measures)
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   521
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   522
sublocale product_sigma_finite \<subseteq> product_sigma_algebra
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   523
  by default
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   524
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   525
sublocale finite_product_sigma_finite \<subseteq> finite_product_sigma_algebra
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   526
  by default (fact finite_index')
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   527
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   528
lemma (in finite_product_sigma_finite) product_algebra_generator_measure:
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   529
  assumes "Pi\<^isub>E I F \<in> sets G"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   530
  shows "measure G (Pi\<^isub>E I F) = (\<Prod>i\<in>I. M.\<mu> i (F i))"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   531
proof cases
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   532
  assume ne: "\<forall>i\<in>I. F i \<noteq> {}"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   533
  have "\<forall>i\<in>I. (SOME F'. Pi\<^isub>E I F = Pi\<^isub>E I F') i = F i"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   534
    by (rule someI2[where P="\<lambda>F'. Pi\<^isub>E I F = Pi\<^isub>E I F'"])
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   535
       (insert ne, auto simp: Pi_eq_iff)
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   536
  then show ?thesis
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   537
    unfolding product_algebra_generator_def by simp
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   538
next
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   539
  assume empty: "\<not> (\<forall>j\<in>I. F j \<noteq> {})"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   540
  then have "(\<Prod>j\<in>I. M.\<mu> j (F j)) = 0"
43920
cedb5cb948fd Rename extreal => ereal
hoelzl
parents: 42988
diff changeset
   541
    by (auto simp: setprod_ereal_0 intro!: bexI)
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   542
  moreover
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   543
  have "\<exists>j\<in>I. (SOME F'. Pi\<^isub>E I F = Pi\<^isub>E I F') j = {}"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   544
    by (rule someI2[where P="\<lambda>F'. Pi\<^isub>E I F = Pi\<^isub>E I F'"])
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   545
       (insert empty, auto simp: Pi_eq_empty_iff[symmetric])
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   546
  then have "(\<Prod>j\<in>I. M.\<mu> j ((SOME F'. Pi\<^isub>E I F = Pi\<^isub>E I F') j)) = 0"
43920
cedb5cb948fd Rename extreal => ereal
hoelzl
parents: 42988
diff changeset
   547
    by (auto simp: setprod_ereal_0 intro!: bexI)
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   548
  ultimately show ?thesis
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   549
    unfolding product_algebra_generator_def by simp
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   550
qed
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   551
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   552
lemma (in finite_product_sigma_finite) sigma_finite_pairs:
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   553
  "\<exists>F::'i \<Rightarrow> nat \<Rightarrow> 'a set.
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   554
    (\<forall>i\<in>I. range (F i) \<subseteq> sets (M i)) \<and>
41981
cdf7693bbe08 reworked Probability theory: measures are not type restricted to positive extended reals
hoelzl
parents: 41831
diff changeset
   555
    (\<forall>k. \<forall>i\<in>I. \<mu> i (F i k) \<noteq> \<infinity>) \<and> incseq (\<lambda>k. \<Pi>\<^isub>E i\<in>I. F i k) \<and>
cdf7693bbe08 reworked Probability theory: measures are not type restricted to positive extended reals
hoelzl
parents: 41831
diff changeset
   556
    (\<Union>k. \<Pi>\<^isub>E i\<in>I. F i k) = space G"
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   557
proof -
41981
cdf7693bbe08 reworked Probability theory: measures are not type restricted to positive extended reals
hoelzl
parents: 41831
diff changeset
   558
  have "\<forall>i::'i. \<exists>F::nat \<Rightarrow> 'a set. range F \<subseteq> sets (M i) \<and> incseq F \<and> (\<Union>i. F i) = space (M i) \<and> (\<forall>k. \<mu> i (F k) \<noteq> \<infinity>)"
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   559
    using M.sigma_finite_up by simp
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   560
  from choice[OF this] guess F :: "'i \<Rightarrow> nat \<Rightarrow> 'a set" ..
41981
cdf7693bbe08 reworked Probability theory: measures are not type restricted to positive extended reals
hoelzl
parents: 41831
diff changeset
   561
  then have F: "\<And>i. range (F i) \<subseteq> sets (M i)" "\<And>i. incseq (F i)" "\<And>i. (\<Union>j. F i j) = space (M i)" "\<And>i k. \<mu> i (F i k) \<noteq> \<infinity>"
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   562
    by auto
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   563
  let ?F = "\<lambda>k. \<Pi>\<^isub>E i\<in>I. F i k"
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   564
  note space_product_algebra[simp]
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   565
  show ?thesis
41981
cdf7693bbe08 reworked Probability theory: measures are not type restricted to positive extended reals
hoelzl
parents: 41831
diff changeset
   566
  proof (intro exI[of _ F] conjI allI incseq_SucI set_eqI iffI ballI)
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   567
    fix i show "range (F i) \<subseteq> sets (M i)" by fact
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   568
  next
41981
cdf7693bbe08 reworked Probability theory: measures are not type restricted to positive extended reals
hoelzl
parents: 41831
diff changeset
   569
    fix i k show "\<mu> i (F i k) \<noteq> \<infinity>" by fact
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   570
  next
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   571
    fix A assume "A \<in> (\<Union>i. ?F i)" then show "A \<in> space G"
41831
91a2b435dd7a use measure_preserving in ..._vimage lemmas
hoelzl
parents: 41706
diff changeset
   572
      using `\<And>i. range (F i) \<subseteq> sets (M i)` M.sets_into_space
91a2b435dd7a use measure_preserving in ..._vimage lemmas
hoelzl
parents: 41706
diff changeset
   573
      by (force simp: image_subset_iff)
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   574
  next
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   575
    fix f assume "f \<in> space G"
41981
cdf7693bbe08 reworked Probability theory: measures are not type restricted to positive extended reals
hoelzl
parents: 41831
diff changeset
   576
    with Pi_UN[OF finite_index, of "\<lambda>k i. F i k"] F
cdf7693bbe08 reworked Probability theory: measures are not type restricted to positive extended reals
hoelzl
parents: 41831
diff changeset
   577
    show "f \<in> (\<Union>i. ?F i)" by (auto simp: incseq_def)
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   578
  next
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   579
    fix i show "?F i \<subseteq> ?F (Suc i)"
41981
cdf7693bbe08 reworked Probability theory: measures are not type restricted to positive extended reals
hoelzl
parents: 41831
diff changeset
   580
      using `\<And>i. incseq (F i)`[THEN incseq_SucD] by auto
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   581
  qed
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   582
qed
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   583
41831
91a2b435dd7a use measure_preserving in ..._vimage lemmas
hoelzl
parents: 41706
diff changeset
   584
lemma sets_pair_cancel_measure[simp]:
91a2b435dd7a use measure_preserving in ..._vimage lemmas
hoelzl
parents: 41706
diff changeset
   585
  "sets (M1\<lparr>measure := m1\<rparr> \<Otimes>\<^isub>M M2) = sets (M1 \<Otimes>\<^isub>M M2)"
91a2b435dd7a use measure_preserving in ..._vimage lemmas
hoelzl
parents: 41706
diff changeset
   586
  "sets (M1 \<Otimes>\<^isub>M M2\<lparr>measure := m2\<rparr>) = sets (M1 \<Otimes>\<^isub>M M2)"
91a2b435dd7a use measure_preserving in ..._vimage lemmas
hoelzl
parents: 41706
diff changeset
   587
  unfolding pair_measure_def pair_measure_generator_def sets_sigma
91a2b435dd7a use measure_preserving in ..._vimage lemmas
hoelzl
parents: 41706
diff changeset
   588
  by simp_all
91a2b435dd7a use measure_preserving in ..._vimage lemmas
hoelzl
parents: 41706
diff changeset
   589
91a2b435dd7a use measure_preserving in ..._vimage lemmas
hoelzl
parents: 41706
diff changeset
   590
lemma measurable_pair_cancel_measure[simp]:
91a2b435dd7a use measure_preserving in ..._vimage lemmas
hoelzl
parents: 41706
diff changeset
   591
  "measurable (M1\<lparr>measure := m1\<rparr> \<Otimes>\<^isub>M M2) M = measurable (M1 \<Otimes>\<^isub>M M2) M"
91a2b435dd7a use measure_preserving in ..._vimage lemmas
hoelzl
parents: 41706
diff changeset
   592
  "measurable (M1 \<Otimes>\<^isub>M M2\<lparr>measure := m2\<rparr>) M = measurable (M1 \<Otimes>\<^isub>M M2) M"
91a2b435dd7a use measure_preserving in ..._vimage lemmas
hoelzl
parents: 41706
diff changeset
   593
  "measurable M (M1\<lparr>measure := m3\<rparr> \<Otimes>\<^isub>M M2) = measurable M (M1 \<Otimes>\<^isub>M M2)"
91a2b435dd7a use measure_preserving in ..._vimage lemmas
hoelzl
parents: 41706
diff changeset
   594
  "measurable M (M1 \<Otimes>\<^isub>M M2\<lparr>measure := m4\<rparr>) = measurable M (M1 \<Otimes>\<^isub>M M2)"
91a2b435dd7a use measure_preserving in ..._vimage lemmas
hoelzl
parents: 41706
diff changeset
   595
  unfolding measurable_def by (auto simp add: space_pair_measure)
91a2b435dd7a use measure_preserving in ..._vimage lemmas
hoelzl
parents: 41706
diff changeset
   596
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   597
lemma (in product_sigma_finite) product_measure_exists:
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   598
  assumes "finite I"
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   599
  shows "\<exists>\<nu>. sigma_finite_measure (sigma (product_algebra_generator I M) \<lparr> measure := \<nu> \<rparr>) \<and>
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   600
    (\<forall>A\<in>\<Pi> i\<in>I. sets (M i). \<nu> (Pi\<^isub>E I A) = (\<Prod>i\<in>I. M.\<mu> i (A i)))"
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   601
using `finite I` proof induct
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   602
  case empty
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   603
  interpret finite_product_sigma_finite M "{}" by default simp
43920
cedb5cb948fd Rename extreal => ereal
hoelzl
parents: 42988
diff changeset
   604
  let ?\<nu> = "(\<lambda>A. if A = {} then 0 else 1) :: 'd set \<Rightarrow> ereal"
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   605
  show ?case
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   606
  proof (intro exI conjI ballI)
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   607
    have "sigma_algebra (sigma G \<lparr>measure := ?\<nu>\<rparr>)"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   608
      by (rule sigma_algebra_cong) (simp_all add: product_algebra_def)
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   609
    then have "measure_space (sigma G\<lparr>measure := ?\<nu>\<rparr>)"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   610
      by (rule finite_additivity_sufficient)
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   611
         (simp_all add: positive_def additive_def sets_sigma
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   612
                        product_algebra_generator_def image_constant)
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   613
    then show "sigma_finite_measure (sigma G\<lparr>measure := ?\<nu>\<rparr>)"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   614
      by (auto intro!: exI[of _ "\<lambda>i. {\<lambda>_. undefined}"]
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   615
               simp: sigma_finite_measure_def sigma_finite_measure_axioms_def
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   616
                     product_algebra_generator_def)
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   617
  qed auto
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   618
next
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   619
  case (insert i I)
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   620
  interpret finite_product_sigma_finite M I by default fact
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   621
  have "finite (insert i I)" using `finite I` by auto
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   622
  interpret I': finite_product_sigma_finite M "insert i I" by default fact
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   623
  from insert obtain \<nu> where
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   624
    prod: "\<And>A. A \<in> (\<Pi> i\<in>I. sets (M i)) \<Longrightarrow> \<nu> (Pi\<^isub>E I A) = (\<Prod>i\<in>I. M.\<mu> i (A i))" and
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   625
    "sigma_finite_measure (sigma G\<lparr> measure := \<nu> \<rparr>)" by auto
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   626
  then interpret I: sigma_finite_measure "P\<lparr> measure := \<nu>\<rparr>" unfolding product_algebra_def by simp
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   627
  interpret P: pair_sigma_finite "P\<lparr> measure := \<nu>\<rparr>" "M i" ..
41661
baf1964bc468 use pre-image measure, instead of image
hoelzl
parents: 41659
diff changeset
   628
  let ?h = "(\<lambda>(f, y). f(i := y))"
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   629
  let ?\<nu> = "\<lambda>A. P.\<mu> (?h -` A \<inter> space P.P)"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   630
  have I': "sigma_algebra (I'.P\<lparr> measure := ?\<nu> \<rparr>)"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   631
    by (rule I'.sigma_algebra_cong) simp_all
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   632
  interpret I'': measure_space "I'.P\<lparr> measure := ?\<nu> \<rparr>"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   633
    using measurable_add_dim[OF `i \<notin> I`]
41831
91a2b435dd7a use measure_preserving in ..._vimage lemmas
hoelzl
parents: 41706
diff changeset
   634
    by (intro P.measure_space_vimage[OF I']) (auto simp add: measure_preserving_def)
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   635
  show ?case
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   636
  proof (intro exI[of _ ?\<nu>] conjI ballI)
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   637
    let "?m A" = "measure (Pi\<^isub>M I M\<lparr>measure := \<nu>\<rparr> \<Otimes>\<^isub>M M i) (?h -` A \<inter> space P.P)"
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   638
    { fix A assume A: "A \<in> (\<Pi> i\<in>insert i I. sets (M i))"
41661
baf1964bc468 use pre-image measure, instead of image
hoelzl
parents: 41659
diff changeset
   639
      then have *: "?h -` Pi\<^isub>E (insert i I) A \<inter> space P.P = Pi\<^isub>E I A \<times> A i"
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   640
        using `i \<notin> I` M.sets_into_space by (auto simp: space_pair_measure space_product_algebra) blast
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   641
      show "?m (Pi\<^isub>E (insert i I) A) = (\<Prod>i\<in>insert i I. M.\<mu> i (A i))"
41661
baf1964bc468 use pre-image measure, instead of image
hoelzl
parents: 41659
diff changeset
   642
        unfolding * using A
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   643
        apply (subst P.pair_measure_times)
44890
22f665a2e91c new fastforce replacing fastsimp - less confusing name
nipkow
parents: 43920
diff changeset
   644
        using A apply fastforce
22f665a2e91c new fastforce replacing fastsimp - less confusing name
nipkow
parents: 43920
diff changeset
   645
        using A apply fastforce
41661
baf1964bc468 use pre-image measure, instead of image
hoelzl
parents: 41659
diff changeset
   646
        using `i \<notin> I` `finite I` prod[of A] A by (auto simp: ac_simps) }
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   647
    note product = this
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   648
    have *: "sigma I'.G\<lparr> measure := ?\<nu> \<rparr> = I'.P\<lparr> measure := ?\<nu> \<rparr>"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   649
      by (simp add: product_algebra_def)
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   650
    show "sigma_finite_measure (sigma I'.G\<lparr> measure := ?\<nu> \<rparr>)"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   651
    proof (unfold *, default, simp)
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   652
      from I'.sigma_finite_pairs guess F :: "'i \<Rightarrow> nat \<Rightarrow> 'a set" ..
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   653
      then have F: "\<And>j. j \<in> insert i I \<Longrightarrow> range (F j) \<subseteq> sets (M j)"
41981
cdf7693bbe08 reworked Probability theory: measures are not type restricted to positive extended reals
hoelzl
parents: 41831
diff changeset
   654
        "incseq (\<lambda>k. \<Pi>\<^isub>E j \<in> insert i I. F j k)"
cdf7693bbe08 reworked Probability theory: measures are not type restricted to positive extended reals
hoelzl
parents: 41831
diff changeset
   655
        "(\<Union>k. \<Pi>\<^isub>E j \<in> insert i I. F j k) = space I'.G"
cdf7693bbe08 reworked Probability theory: measures are not type restricted to positive extended reals
hoelzl
parents: 41831
diff changeset
   656
        "\<And>k. \<And>j. j \<in> insert i I \<Longrightarrow> \<mu> j (F j k) \<noteq> \<infinity>"
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   657
        by blast+
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   658
      let "?F k" = "\<Pi>\<^isub>E j \<in> insert i I. F j k"
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   659
      show "\<exists>F::nat \<Rightarrow> ('i \<Rightarrow> 'a) set. range F \<subseteq> sets I'.P \<and>
41981
cdf7693bbe08 reworked Probability theory: measures are not type restricted to positive extended reals
hoelzl
parents: 41831
diff changeset
   660
          (\<Union>i. F i) = (\<Pi>\<^isub>E i\<in>insert i I. space (M i)) \<and> (\<forall>i. ?m (F i) \<noteq> \<infinity>)"
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   661
      proof (intro exI[of _ ?F] conjI allI)
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   662
        show "range ?F \<subseteq> sets I'.P" using F(1) by auto
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   663
      next
41981
cdf7693bbe08 reworked Probability theory: measures are not type restricted to positive extended reals
hoelzl
parents: 41831
diff changeset
   664
        from F(3) show "(\<Union>i. ?F i) = (\<Pi>\<^isub>E i\<in>insert i I. space (M i))" by simp
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   665
      next
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   666
        fix j
41981
cdf7693bbe08 reworked Probability theory: measures are not type restricted to positive extended reals
hoelzl
parents: 41831
diff changeset
   667
        have "\<And>k. k \<in> insert i I \<Longrightarrow> 0 \<le> measure (M k) (F k j)"
cdf7693bbe08 reworked Probability theory: measures are not type restricted to positive extended reals
hoelzl
parents: 41831
diff changeset
   668
          using F(1) by auto
cdf7693bbe08 reworked Probability theory: measures are not type restricted to positive extended reals
hoelzl
parents: 41831
diff changeset
   669
        with F `finite I` setprod_PInf[of "insert i I", OF this] show "?\<nu> (?F j) \<noteq> \<infinity>"
cdf7693bbe08 reworked Probability theory: measures are not type restricted to positive extended reals
hoelzl
parents: 41831
diff changeset
   670
          by (subst product) auto
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   671
      qed
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   672
    qed
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   673
  qed
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   674
qed
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   675
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   676
sublocale finite_product_sigma_finite \<subseteq> sigma_finite_measure P
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   677
  unfolding product_algebra_def
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   678
  using product_measure_exists[OF finite_index]
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   679
  by (rule someI2_ex) auto
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   680
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   681
lemma (in finite_product_sigma_finite) measure_times:
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   682
  assumes "\<And>i. i \<in> I \<Longrightarrow> A i \<in> sets (M i)"
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   683
  shows "\<mu> (Pi\<^isub>E I A) = (\<Prod>i\<in>I. M.\<mu> i (A i))"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   684
  unfolding product_algebra_def
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   685
  using product_measure_exists[OF finite_index]
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   686
  proof (rule someI2_ex, elim conjE)
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   687
    fix \<nu> assume *: "\<forall>A\<in>\<Pi> i\<in>I. sets (M i). \<nu> (Pi\<^isub>E I A) = (\<Prod>i\<in>I. M.\<mu> i (A i))"
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   688
    have "Pi\<^isub>E I A = Pi\<^isub>E I (\<lambda>i\<in>I. A i)" by (auto dest: Pi_mem)
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   689
    then have "\<nu> (Pi\<^isub>E I A) = \<nu> (Pi\<^isub>E I (\<lambda>i\<in>I. A i))" by simp
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   690
    also have "\<dots> = (\<Prod>i\<in>I. M.\<mu> i ((\<lambda>i\<in>I. A i) i))" using assms * by auto
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   691
    finally show "measure (sigma G\<lparr>measure := \<nu>\<rparr>) (Pi\<^isub>E I A) = (\<Prod>i\<in>I. M.\<mu> i (A i))"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   692
      by (simp add: sigma_def)
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   693
  qed
41096
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   694
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   695
lemma (in product_sigma_finite) product_measure_empty[simp]:
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   696
  "measure (Pi\<^isub>M {} M) {\<lambda>x. undefined} = 1"
41096
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   697
proof -
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   698
  interpret finite_product_sigma_finite M "{}" by default auto
41096
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   699
  from measure_times[of "\<lambda>x. {}"] show ?thesis by simp
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   700
qed
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   701
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   702
lemma (in finite_product_sigma_algebra) P_empty:
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   703
  assumes "I = {}"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   704
  shows "space P = {\<lambda>k. undefined}" "sets P = { {}, {\<lambda>k. undefined} }"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   705
  unfolding product_algebra_def product_algebra_generator_def `I = {}`
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   706
  by (simp_all add: sigma_def image_constant)
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   707
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   708
lemma (in product_sigma_finite) positive_integral_empty:
41981
cdf7693bbe08 reworked Probability theory: measures are not type restricted to positive extended reals
hoelzl
parents: 41831
diff changeset
   709
  assumes pos: "0 \<le> f (\<lambda>k. undefined)"
cdf7693bbe08 reworked Probability theory: measures are not type restricted to positive extended reals
hoelzl
parents: 41831
diff changeset
   710
  shows "integral\<^isup>P (Pi\<^isub>M {} M) f = f (\<lambda>k. undefined)"
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   711
proof -
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   712
  interpret finite_product_sigma_finite M "{}" by default (fact finite.emptyI)
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   713
  have "\<And>A. measure (Pi\<^isub>M {} M) (Pi\<^isub>E {} A) = 1"
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   714
    using assms by (subst measure_times) auto
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   715
  then show ?thesis
40873
1ef85f4e7097 Shorter definition for positive_integral.
hoelzl
parents: 40872
diff changeset
   716
    unfolding positive_integral_def simple_function_def simple_integral_def_raw
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   717
  proof (simp add: P_empty, intro antisym)
41981
cdf7693bbe08 reworked Probability theory: measures are not type restricted to positive extended reals
hoelzl
parents: 41831
diff changeset
   718
    show "f (\<lambda>k. undefined) \<le> (SUP f:{g. g \<le> max 0 \<circ> f}. f (\<lambda>k. undefined))"
44928
7ef6505bde7f renamed Complete_Lattices lemmas, removed legacy names
hoelzl
parents: 44890
diff changeset
   719
      by (intro SUP_upper) (auto simp: le_fun_def split: split_max)
41981
cdf7693bbe08 reworked Probability theory: measures are not type restricted to positive extended reals
hoelzl
parents: 41831
diff changeset
   720
    show "(SUP f:{g. g \<le> max 0 \<circ> f}. f (\<lambda>k. undefined)) \<le> f (\<lambda>k. undefined)" using pos
44928
7ef6505bde7f renamed Complete_Lattices lemmas, removed legacy names
hoelzl
parents: 44890
diff changeset
   721
      by (intro SUP_least) (auto simp: le_fun_def simp: max_def split: split_if_asm)
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   722
  qed
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   723
qed
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   724
41026
bea75746dc9d folding on arbitrary Lebesgue integrable functions
hoelzl
parents: 41023
diff changeset
   725
lemma (in product_sigma_finite) measure_fold:
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   726
  assumes IJ[simp]: "I \<inter> J = {}" and fin: "finite I" "finite J"
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   727
  assumes A: "A \<in> sets (Pi\<^isub>M (I \<union> J) M)"
41706
a207a858d1f6 prefer p2e before e2p; use measure_unique_Int_stable_vimage;
hoelzl
parents: 41705
diff changeset
   728
  shows "measure (Pi\<^isub>M (I \<union> J) M) A =
a207a858d1f6 prefer p2e before e2p; use measure_unique_Int_stable_vimage;
hoelzl
parents: 41705
diff changeset
   729
    measure (Pi\<^isub>M I M \<Otimes>\<^isub>M Pi\<^isub>M J M) ((\<lambda>(x,y). merge I x J y) -` A \<inter> space (Pi\<^isub>M I M \<Otimes>\<^isub>M Pi\<^isub>M J M))"
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   730
proof -
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   731
  interpret I: finite_product_sigma_finite M I by default fact
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   732
  interpret J: finite_product_sigma_finite M J by default fact
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   733
  have "finite (I \<union> J)" using fin by auto
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   734
  interpret IJ: finite_product_sigma_finite M "I \<union> J" by default fact
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   735
  interpret P: pair_sigma_finite I.P J.P by default
41661
baf1964bc468 use pre-image measure, instead of image
hoelzl
parents: 41659
diff changeset
   736
  let ?g = "\<lambda>(x,y). merge I x J y"
baf1964bc468 use pre-image measure, instead of image
hoelzl
parents: 41659
diff changeset
   737
  let "?X S" = "?g -` S \<inter> space P.P"
baf1964bc468 use pre-image measure, instead of image
hoelzl
parents: 41659
diff changeset
   738
  from IJ.sigma_finite_pairs obtain F where
baf1964bc468 use pre-image measure, instead of image
hoelzl
parents: 41659
diff changeset
   739
    F: "\<And>i. i\<in> I \<union> J \<Longrightarrow> range (F i) \<subseteq> sets (M i)"
41981
cdf7693bbe08 reworked Probability theory: measures are not type restricted to positive extended reals
hoelzl
parents: 41831
diff changeset
   740
       "incseq (\<lambda>k. \<Pi>\<^isub>E i\<in>I \<union> J. F i k)"
cdf7693bbe08 reworked Probability theory: measures are not type restricted to positive extended reals
hoelzl
parents: 41831
diff changeset
   741
       "(\<Union>k. \<Pi>\<^isub>E i\<in>I \<union> J. F i k) = space IJ.G"
cdf7693bbe08 reworked Probability theory: measures are not type restricted to positive extended reals
hoelzl
parents: 41831
diff changeset
   742
       "\<And>k. \<forall>i\<in>I\<union>J. \<mu> i (F i k) \<noteq> \<infinity>"
41661
baf1964bc468 use pre-image measure, instead of image
hoelzl
parents: 41659
diff changeset
   743
    by auto
baf1964bc468 use pre-image measure, instead of image
hoelzl
parents: 41659
diff changeset
   744
  let ?F = "\<lambda>k. \<Pi>\<^isub>E i\<in>I \<union> J. F i k"
41706
a207a858d1f6 prefer p2e before e2p; use measure_unique_Int_stable_vimage;
hoelzl
parents: 41705
diff changeset
   745
  show "IJ.\<mu> A = P.\<mu> (?X A)"
a207a858d1f6 prefer p2e before e2p; use measure_unique_Int_stable_vimage;
hoelzl
parents: 41705
diff changeset
   746
  proof (rule measure_unique_Int_stable_vimage)
a207a858d1f6 prefer p2e before e2p; use measure_unique_Int_stable_vimage;
hoelzl
parents: 41705
diff changeset
   747
    show "measure_space IJ.P" "measure_space P.P" by default
a207a858d1f6 prefer p2e before e2p; use measure_unique_Int_stable_vimage;
hoelzl
parents: 41705
diff changeset
   748
    show "sets (sigma IJ.G) = sets IJ.P" "space IJ.G = space IJ.P" "A \<in> sets (sigma IJ.G)"
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   749
      using A unfolding product_algebra_def by auto
41706
a207a858d1f6 prefer p2e before e2p; use measure_unique_Int_stable_vimage;
hoelzl
parents: 41705
diff changeset
   750
  next
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   751
    show "Int_stable IJ.G"
42988
d8f3fc934ff6 add lemma indep_distribution_eq_measure
hoelzl
parents: 42950
diff changeset
   752
      by (rule Int_stable_product_algebra_generator)
d8f3fc934ff6 add lemma indep_distribution_eq_measure
hoelzl
parents: 42950
diff changeset
   753
         (auto simp: Int_stable_def)
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   754
    show "range ?F \<subseteq> sets IJ.G" using F
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   755
      by (simp add: image_subset_iff product_algebra_def
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   756
                    product_algebra_generator_def)
41981
cdf7693bbe08 reworked Probability theory: measures are not type restricted to positive extended reals
hoelzl
parents: 41831
diff changeset
   757
    show "incseq ?F" "(\<Union>i. ?F i) = space IJ.G " by fact+
cdf7693bbe08 reworked Probability theory: measures are not type restricted to positive extended reals
hoelzl
parents: 41831
diff changeset
   758
  next
cdf7693bbe08 reworked Probability theory: measures are not type restricted to positive extended reals
hoelzl
parents: 41831
diff changeset
   759
    fix k
cdf7693bbe08 reworked Probability theory: measures are not type restricted to positive extended reals
hoelzl
parents: 41831
diff changeset
   760
    have "\<And>j. j \<in> I \<union> J \<Longrightarrow> 0 \<le> measure (M j) (F j k)"
cdf7693bbe08 reworked Probability theory: measures are not type restricted to positive extended reals
hoelzl
parents: 41831
diff changeset
   761
      using F(1) by auto
cdf7693bbe08 reworked Probability theory: measures are not type restricted to positive extended reals
hoelzl
parents: 41831
diff changeset
   762
    with F `finite I` setprod_PInf[of "I \<union> J", OF this]
cdf7693bbe08 reworked Probability theory: measures are not type restricted to positive extended reals
hoelzl
parents: 41831
diff changeset
   763
    show "IJ.\<mu> (?F k) \<noteq> \<infinity>" by (subst IJ.measure_times) auto
41661
baf1964bc468 use pre-image measure, instead of image
hoelzl
parents: 41659
diff changeset
   764
  next
baf1964bc468 use pre-image measure, instead of image
hoelzl
parents: 41659
diff changeset
   765
    fix A assume "A \<in> sets IJ.G"
41706
a207a858d1f6 prefer p2e before e2p; use measure_unique_Int_stable_vimage;
hoelzl
parents: 41705
diff changeset
   766
    then obtain F where A: "A = Pi\<^isub>E (I \<union> J) F"
41661
baf1964bc468 use pre-image measure, instead of image
hoelzl
parents: 41659
diff changeset
   767
      and F: "\<And>i. i \<in> I \<union> J \<Longrightarrow> F i \<in> sets (M i)"
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   768
      by (auto simp: product_algebra_generator_def)
41706
a207a858d1f6 prefer p2e before e2p; use measure_unique_Int_stable_vimage;
hoelzl
parents: 41705
diff changeset
   769
    then have X: "?X A = (Pi\<^isub>E I F \<times> Pi\<^isub>E J F)"
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   770
      using sets_into_space by (auto simp: space_pair_measure) blast+
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   771
    then have "P.\<mu> (?X A) = (\<Prod>i\<in>I. \<mu> i (F i)) * (\<Prod>i\<in>J. \<mu> i (F i))"
41661
baf1964bc468 use pre-image measure, instead of image
hoelzl
parents: 41659
diff changeset
   772
      using `finite J` `finite I` F
baf1964bc468 use pre-image measure, instead of image
hoelzl
parents: 41659
diff changeset
   773
      by (simp add: P.pair_measure_times I.measure_times J.measure_times)
baf1964bc468 use pre-image measure, instead of image
hoelzl
parents: 41659
diff changeset
   774
    also have "\<dots> = (\<Prod>i\<in>I \<union> J. \<mu> i (F i))"
baf1964bc468 use pre-image measure, instead of image
hoelzl
parents: 41659
diff changeset
   775
      using `finite J` `finite I` `I \<inter> J = {}`  by (simp add: setprod_Un_one)
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   776
    also have "\<dots> = IJ.\<mu> A"
41661
baf1964bc468 use pre-image measure, instead of image
hoelzl
parents: 41659
diff changeset
   777
      using `finite J` `finite I` F unfolding A
baf1964bc468 use pre-image measure, instead of image
hoelzl
parents: 41659
diff changeset
   778
      by (intro IJ.measure_times[symmetric]) auto
41706
a207a858d1f6 prefer p2e before e2p; use measure_unique_Int_stable_vimage;
hoelzl
parents: 41705
diff changeset
   779
    finally show "IJ.\<mu> A = P.\<mu> (?X A)" by (rule sym)
41981
cdf7693bbe08 reworked Probability theory: measures are not type restricted to positive extended reals
hoelzl
parents: 41831
diff changeset
   780
  qed (rule measurable_merge[OF IJ])
41661
baf1964bc468 use pre-image measure, instead of image
hoelzl
parents: 41659
diff changeset
   781
qed
41026
bea75746dc9d folding on arbitrary Lebesgue integrable functions
hoelzl
parents: 41023
diff changeset
   782
41831
91a2b435dd7a use measure_preserving in ..._vimage lemmas
hoelzl
parents: 41706
diff changeset
   783
lemma (in product_sigma_finite) measure_preserving_merge:
91a2b435dd7a use measure_preserving in ..._vimage lemmas
hoelzl
parents: 41706
diff changeset
   784
  assumes IJ: "I \<inter> J = {}" and "finite I" "finite J"
91a2b435dd7a use measure_preserving in ..._vimage lemmas
hoelzl
parents: 41706
diff changeset
   785
  shows "(\<lambda>(x,y). merge I x J y) \<in> measure_preserving (Pi\<^isub>M I M \<Otimes>\<^isub>M Pi\<^isub>M J M) (Pi\<^isub>M (I \<union> J) M)"
91a2b435dd7a use measure_preserving in ..._vimage lemmas
hoelzl
parents: 41706
diff changeset
   786
  by (intro measure_preservingI measurable_merge[OF IJ] measure_fold[symmetric] assms)
91a2b435dd7a use measure_preserving in ..._vimage lemmas
hoelzl
parents: 41706
diff changeset
   787
41026
bea75746dc9d folding on arbitrary Lebesgue integrable functions
hoelzl
parents: 41023
diff changeset
   788
lemma (in product_sigma_finite) product_positive_integral_fold:
41831
91a2b435dd7a use measure_preserving in ..._vimage lemmas
hoelzl
parents: 41706
diff changeset
   789
  assumes IJ[simp]: "I \<inter> J = {}" "finite I" "finite J"
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   790
  and f: "f \<in> borel_measurable (Pi\<^isub>M (I \<union> J) M)"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   791
  shows "integral\<^isup>P (Pi\<^isub>M (I \<union> J) M) f =
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   792
    (\<integral>\<^isup>+ x. (\<integral>\<^isup>+ y. f (merge I x J y) \<partial>(Pi\<^isub>M J M)) \<partial>(Pi\<^isub>M I M))"
41026
bea75746dc9d folding on arbitrary Lebesgue integrable functions
hoelzl
parents: 41023
diff changeset
   793
proof -
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   794
  interpret I: finite_product_sigma_finite M I by default fact
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   795
  interpret J: finite_product_sigma_finite M J by default fact
41831
91a2b435dd7a use measure_preserving in ..._vimage lemmas
hoelzl
parents: 41706
diff changeset
   796
  interpret P: pair_sigma_finite "Pi\<^isub>M I M" "Pi\<^isub>M J M" by default
91a2b435dd7a use measure_preserving in ..._vimage lemmas
hoelzl
parents: 41706
diff changeset
   797
  interpret IJ: finite_product_sigma_finite M "I \<union> J" by default simp
41026
bea75746dc9d folding on arbitrary Lebesgue integrable functions
hoelzl
parents: 41023
diff changeset
   798
  have P_borel: "(\<lambda>x. f (case x of (x, y) \<Rightarrow> merge I x J y)) \<in> borel_measurable P.P"
41831
91a2b435dd7a use measure_preserving in ..._vimage lemmas
hoelzl
parents: 41706
diff changeset
   799
    using measurable_comp[OF measurable_merge[OF IJ(1)] f] by (simp add: comp_def)
41661
baf1964bc468 use pre-image measure, instead of image
hoelzl
parents: 41659
diff changeset
   800
  show ?thesis
41026
bea75746dc9d folding on arbitrary Lebesgue integrable functions
hoelzl
parents: 41023
diff changeset
   801
    unfolding P.positive_integral_fst_measurable[OF P_borel, simplified]
41661
baf1964bc468 use pre-image measure, instead of image
hoelzl
parents: 41659
diff changeset
   802
  proof (rule P.positive_integral_vimage)
baf1964bc468 use pre-image measure, instead of image
hoelzl
parents: 41659
diff changeset
   803
    show "sigma_algebra IJ.P" by default
41831
91a2b435dd7a use measure_preserving in ..._vimage lemmas
hoelzl
parents: 41706
diff changeset
   804
    show "(\<lambda>(x, y). merge I x J y) \<in> measure_preserving P.P IJ.P"
91a2b435dd7a use measure_preserving in ..._vimage lemmas
hoelzl
parents: 41706
diff changeset
   805
      using IJ by (rule measure_preserving_merge)
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   806
    show "f \<in> borel_measurable IJ.P" using f by simp
41661
baf1964bc468 use pre-image measure, instead of image
hoelzl
parents: 41659
diff changeset
   807
  qed
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   808
qed
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   809
41831
91a2b435dd7a use measure_preserving in ..._vimage lemmas
hoelzl
parents: 41706
diff changeset
   810
lemma (in product_sigma_finite) measure_preserving_component_singelton:
91a2b435dd7a use measure_preserving in ..._vimage lemmas
hoelzl
parents: 41706
diff changeset
   811
  "(\<lambda>x. x i) \<in> measure_preserving (Pi\<^isub>M {i} M) (M i)"
91a2b435dd7a use measure_preserving in ..._vimage lemmas
hoelzl
parents: 41706
diff changeset
   812
proof (intro measure_preservingI measurable_component_singleton)
91a2b435dd7a use measure_preserving in ..._vimage lemmas
hoelzl
parents: 41706
diff changeset
   813
  interpret I: finite_product_sigma_finite M "{i}" by default simp
91a2b435dd7a use measure_preserving in ..._vimage lemmas
hoelzl
parents: 41706
diff changeset
   814
  fix A let ?P = "(\<lambda>x. x i) -` A \<inter> space I.P"
91a2b435dd7a use measure_preserving in ..._vimage lemmas
hoelzl
parents: 41706
diff changeset
   815
  assume A: "A \<in> sets (M i)"
91a2b435dd7a use measure_preserving in ..._vimage lemmas
hoelzl
parents: 41706
diff changeset
   816
  then have *: "?P = {i} \<rightarrow>\<^isub>E A" using sets_into_space by auto
91a2b435dd7a use measure_preserving in ..._vimage lemmas
hoelzl
parents: 41706
diff changeset
   817
  show "I.\<mu> ?P = M.\<mu> i A" unfolding *
91a2b435dd7a use measure_preserving in ..._vimage lemmas
hoelzl
parents: 41706
diff changeset
   818
    using A I.measure_times[of "\<lambda>_. A"] by auto
91a2b435dd7a use measure_preserving in ..._vimage lemmas
hoelzl
parents: 41706
diff changeset
   819
qed auto
91a2b435dd7a use measure_preserving in ..._vimage lemmas
hoelzl
parents: 41706
diff changeset
   820
41026
bea75746dc9d folding on arbitrary Lebesgue integrable functions
hoelzl
parents: 41023
diff changeset
   821
lemma (in product_sigma_finite) product_positive_integral_singleton:
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   822
  assumes f: "f \<in> borel_measurable (M i)"
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   823
  shows "integral\<^isup>P (Pi\<^isub>M {i} M) (\<lambda>x. f (x i)) = integral\<^isup>P (M i) f"
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   824
proof -
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   825
  interpret I: finite_product_sigma_finite M "{i}" by default simp
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   826
  show ?thesis
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   827
  proof (rule I.positive_integral_vimage[symmetric])
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   828
    show "sigma_algebra (M i)" by (rule sigma_algebras)
41831
91a2b435dd7a use measure_preserving in ..._vimage lemmas
hoelzl
parents: 41706
diff changeset
   829
    show "(\<lambda>x. x i) \<in> measure_preserving (Pi\<^isub>M {i} M) (M i)"
91a2b435dd7a use measure_preserving in ..._vimage lemmas
hoelzl
parents: 41706
diff changeset
   830
      by (rule measure_preserving_component_singelton)
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   831
    show "f \<in> borel_measurable (M i)" by fact
41661
baf1964bc468 use pre-image measure, instead of image
hoelzl
parents: 41659
diff changeset
   832
  qed
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   833
qed
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
   834
41096
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   835
lemma (in product_sigma_finite) product_positive_integral_insert:
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   836
  assumes [simp]: "finite I" "i \<notin> I"
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   837
    and f: "f \<in> borel_measurable (Pi\<^isub>M (insert i I) M)"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   838
  shows "integral\<^isup>P (Pi\<^isub>M (insert i I) M) f = (\<integral>\<^isup>+ x. (\<integral>\<^isup>+ y. f (x(i := y)) \<partial>(M i)) \<partial>(Pi\<^isub>M I M))"
41096
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   839
proof -
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   840
  interpret I: finite_product_sigma_finite M I by default auto
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   841
  interpret i: finite_product_sigma_finite M "{i}" by default auto
41096
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   842
  interpret P: pair_sigma_algebra I.P i.P ..
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   843
  have IJ: "I \<inter> {i} = {}" and insert: "I \<union> {i} = insert i I"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   844
    using f by auto
41096
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   845
  show ?thesis
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   846
    unfolding product_positive_integral_fold[OF IJ, unfolded insert, simplified, OF f]
41096
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   847
  proof (rule I.positive_integral_cong, subst product_positive_integral_singleton)
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   848
    fix x assume x: "x \<in> space I.P"
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   849
    let "?f y" = "f (restrict (x(i := y)) (insert i I))"
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   850
    have f'_eq: "\<And>y. ?f y = f (x(i := y))"
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   851
      using x by (auto intro!: arg_cong[where f=f] simp: fun_eq_iff extensional_def)
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   852
    show "?f \<in> borel_measurable (M i)" unfolding f'_eq
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   853
      using measurable_comp[OF measurable_component_update f] x `i \<notin> I`
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   854
      by (simp add: comp_def)
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   855
    show "integral\<^isup>P (M i) ?f = \<integral>\<^isup>+ y. f (x(i:=y)) \<partial>M i"
41096
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   856
      unfolding f'_eq by simp
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   857
  qed
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   858
qed
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   859
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   860
lemma (in product_sigma_finite) product_positive_integral_setprod:
43920
cedb5cb948fd Rename extreal => ereal
hoelzl
parents: 42988
diff changeset
   861
  fixes f :: "'i \<Rightarrow> 'a \<Rightarrow> ereal"
41096
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   862
  assumes "finite I" and borel: "\<And>i. i \<in> I \<Longrightarrow> f i \<in> borel_measurable (M i)"
41981
cdf7693bbe08 reworked Probability theory: measures are not type restricted to positive extended reals
hoelzl
parents: 41831
diff changeset
   863
  and pos: "\<And>i x. i \<in> I \<Longrightarrow> 0 \<le> f i x"
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   864
  shows "(\<integral>\<^isup>+ x. (\<Prod>i\<in>I. f i (x i)) \<partial>Pi\<^isub>M I M) = (\<Prod>i\<in>I. integral\<^isup>P (M i) (f i))"
41096
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   865
using assms proof induct
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   866
  case empty
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   867
  interpret finite_product_sigma_finite M "{}" by default auto
41096
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   868
  then show ?case by simp
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   869
next
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   870
  case (insert i I)
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   871
  note `finite I`[intro, simp]
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   872
  interpret I: finite_product_sigma_finite M I by default auto
41096
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   873
  have *: "\<And>x y. (\<Prod>j\<in>I. f j (if j = i then y else x j)) = (\<Prod>j\<in>I. f j (x j))"
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   874
    using insert by (auto intro!: setprod_cong)
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   875
  have prod: "\<And>J. J \<subseteq> insert i I \<Longrightarrow> (\<lambda>x. (\<Prod>i\<in>J. f i (x i))) \<in> borel_measurable (Pi\<^isub>M J M)"
41096
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   876
    using sets_into_space insert
43920
cedb5cb948fd Rename extreal => ereal
hoelzl
parents: 42988
diff changeset
   877
    by (intro sigma_algebra.borel_measurable_ereal_setprod sigma_algebra_product_algebra
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   878
              measurable_comp[OF measurable_component_singleton, unfolded comp_def])
41096
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   879
       auto
41981
cdf7693bbe08 reworked Probability theory: measures are not type restricted to positive extended reals
hoelzl
parents: 41831
diff changeset
   880
  then show ?case
cdf7693bbe08 reworked Probability theory: measures are not type restricted to positive extended reals
hoelzl
parents: 41831
diff changeset
   881
    apply (simp add: product_positive_integral_insert[OF insert(1,2) prod])
43920
cedb5cb948fd Rename extreal => ereal
hoelzl
parents: 42988
diff changeset
   882
    apply (simp add: insert * pos borel setprod_ereal_pos M.positive_integral_multc)
41981
cdf7693bbe08 reworked Probability theory: measures are not type restricted to positive extended reals
hoelzl
parents: 41831
diff changeset
   883
    apply (subst I.positive_integral_cmult)
43920
cedb5cb948fd Rename extreal => ereal
hoelzl
parents: 42988
diff changeset
   884
    apply (auto simp add: pos borel insert setprod_ereal_pos positive_integral_positive)
41981
cdf7693bbe08 reworked Probability theory: measures are not type restricted to positive extended reals
hoelzl
parents: 41831
diff changeset
   885
    done
41096
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   886
qed
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   887
41026
bea75746dc9d folding on arbitrary Lebesgue integrable functions
hoelzl
parents: 41023
diff changeset
   888
lemma (in product_sigma_finite) product_integral_singleton:
bea75746dc9d folding on arbitrary Lebesgue integrable functions
hoelzl
parents: 41023
diff changeset
   889
  assumes f: "f \<in> borel_measurable (M i)"
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   890
  shows "(\<integral>x. f (x i) \<partial>Pi\<^isub>M {i} M) = integral\<^isup>L (M i) f"
41026
bea75746dc9d folding on arbitrary Lebesgue integrable functions
hoelzl
parents: 41023
diff changeset
   891
proof -
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   892
  interpret I: finite_product_sigma_finite M "{i}" by default simp
43920
cedb5cb948fd Rename extreal => ereal
hoelzl
parents: 42988
diff changeset
   893
  have *: "(\<lambda>x. ereal (f x)) \<in> borel_measurable (M i)"
cedb5cb948fd Rename extreal => ereal
hoelzl
parents: 42988
diff changeset
   894
    "(\<lambda>x. ereal (- f x)) \<in> borel_measurable (M i)"
41026
bea75746dc9d folding on arbitrary Lebesgue integrable functions
hoelzl
parents: 41023
diff changeset
   895
    using assms by auto
bea75746dc9d folding on arbitrary Lebesgue integrable functions
hoelzl
parents: 41023
diff changeset
   896
  show ?thesis
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   897
    unfolding lebesgue_integral_def *[THEN product_positive_integral_singleton] ..
41026
bea75746dc9d folding on arbitrary Lebesgue integrable functions
hoelzl
parents: 41023
diff changeset
   898
qed
bea75746dc9d folding on arbitrary Lebesgue integrable functions
hoelzl
parents: 41023
diff changeset
   899
bea75746dc9d folding on arbitrary Lebesgue integrable functions
hoelzl
parents: 41023
diff changeset
   900
lemma (in product_sigma_finite) product_integral_fold:
bea75746dc9d folding on arbitrary Lebesgue integrable functions
hoelzl
parents: 41023
diff changeset
   901
  assumes IJ[simp]: "I \<inter> J = {}" and fin: "finite I" "finite J"
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   902
  and f: "integrable (Pi\<^isub>M (I \<union> J) M) f"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   903
  shows "integral\<^isup>L (Pi\<^isub>M (I \<union> J) M) f = (\<integral>x. (\<integral>y. f (merge I x J y) \<partial>Pi\<^isub>M J M) \<partial>Pi\<^isub>M I M)"
41026
bea75746dc9d folding on arbitrary Lebesgue integrable functions
hoelzl
parents: 41023
diff changeset
   904
proof -
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   905
  interpret I: finite_product_sigma_finite M I by default fact
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   906
  interpret J: finite_product_sigma_finite M J by default fact
41026
bea75746dc9d folding on arbitrary Lebesgue integrable functions
hoelzl
parents: 41023
diff changeset
   907
  have "finite (I \<union> J)" using fin by auto
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   908
  interpret IJ: finite_product_sigma_finite M "I \<union> J" by default fact
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   909
  interpret P: pair_sigma_finite I.P J.P by default
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   910
  let ?M = "\<lambda>(x, y). merge I x J y"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   911
  let ?f = "\<lambda>x. f (?M x)"
41026
bea75746dc9d folding on arbitrary Lebesgue integrable functions
hoelzl
parents: 41023
diff changeset
   912
  show ?thesis
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   913
  proof (subst P.integrable_fst_measurable(2)[of ?f, simplified])
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   914
    have 1: "sigma_algebra IJ.P" by default
41831
91a2b435dd7a use measure_preserving in ..._vimage lemmas
hoelzl
parents: 41706
diff changeset
   915
    have 2: "?M \<in> measure_preserving P.P IJ.P" using measure_preserving_merge[OF assms(1,2,3)] .
91a2b435dd7a use measure_preserving in ..._vimage lemmas
hoelzl
parents: 41706
diff changeset
   916
    have 3: "integrable (Pi\<^isub>M (I \<union> J) M) f" by fact
91a2b435dd7a use measure_preserving in ..._vimage lemmas
hoelzl
parents: 41706
diff changeset
   917
    then have 4: "f \<in> borel_measurable (Pi\<^isub>M (I \<union> J) M)"
91a2b435dd7a use measure_preserving in ..._vimage lemmas
hoelzl
parents: 41706
diff changeset
   918
      by (simp add: integrable_def)
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   919
    show "integrable P.P ?f"
41831
91a2b435dd7a use measure_preserving in ..._vimage lemmas
hoelzl
parents: 41706
diff changeset
   920
      by (rule P.integrable_vimage[where f=f, OF 1 2 3])
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   921
    show "integral\<^isup>L IJ.P f = integral\<^isup>L P.P ?f"
41831
91a2b435dd7a use measure_preserving in ..._vimage lemmas
hoelzl
parents: 41706
diff changeset
   922
      by (rule P.integral_vimage[where f=f, OF 1 2 4])
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   923
  qed
41026
bea75746dc9d folding on arbitrary Lebesgue integrable functions
hoelzl
parents: 41023
diff changeset
   924
qed
bea75746dc9d folding on arbitrary Lebesgue integrable functions
hoelzl
parents: 41023
diff changeset
   925
41096
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   926
lemma (in product_sigma_finite) product_integral_insert:
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   927
  assumes [simp]: "finite I" "i \<notin> I"
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   928
    and f: "integrable (Pi\<^isub>M (insert i I) M) f"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   929
  shows "integral\<^isup>L (Pi\<^isub>M (insert i I) M) f = (\<integral>x. (\<integral>y. f (x(i:=y)) \<partial>M i) \<partial>Pi\<^isub>M I M)"
41096
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   930
proof -
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   931
  interpret I: finite_product_sigma_finite M I by default auto
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   932
  interpret I': finite_product_sigma_finite M "insert i I" by default auto
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   933
  interpret i: finite_product_sigma_finite M "{i}" by default auto
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   934
  interpret P: pair_sigma_finite I.P i.P ..
41096
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   935
  have IJ: "I \<inter> {i} = {}" by auto
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   936
  show ?thesis
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   937
    unfolding product_integral_fold[OF IJ, simplified, OF f]
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   938
  proof (rule I.integral_cong, subst product_integral_singleton)
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   939
    fix x assume x: "x \<in> space I.P"
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   940
    let "?f y" = "f (restrict (x(i := y)) (insert i I))"
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   941
    have f'_eq: "\<And>y. ?f y = f (x(i := y))"
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   942
      using x by (auto intro!: arg_cong[where f=f] simp: fun_eq_iff extensional_def)
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   943
    have f: "f \<in> borel_measurable I'.P" using f unfolding integrable_def by auto
41096
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   944
    show "?f \<in> borel_measurable (M i)"
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   945
      unfolding measurable_cong[OF f'_eq]
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   946
      using measurable_comp[OF measurable_component_update f] x `i \<notin> I`
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   947
      by (simp add: comp_def)
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   948
    show "integral\<^isup>L (M i) ?f = integral\<^isup>L (M i) (\<lambda>y. f (x(i := y)))"
41096
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   949
      unfolding f'_eq by simp
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   950
  qed
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   951
qed
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   952
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   953
lemma (in product_sigma_finite) product_integrable_setprod:
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   954
  fixes f :: "'i \<Rightarrow> 'a \<Rightarrow> real"
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   955
  assumes [simp]: "finite I" and integrable: "\<And>i. i \<in> I \<Longrightarrow> integrable (M i) (f i)"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   956
  shows "integrable (Pi\<^isub>M I M) (\<lambda>x. (\<Prod>i\<in>I. f i (x i)))" (is "integrable _ ?f")
41096
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   957
proof -
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   958
  interpret finite_product_sigma_finite M I by default fact
41096
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   959
  have f: "\<And>i. i \<in> I \<Longrightarrow> f i \<in> borel_measurable (M i)"
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   960
    using integrable unfolding integrable_def by auto
41096
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   961
  then have borel: "?f \<in> borel_measurable P"
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   962
    using measurable_comp[OF measurable_component_singleton f]
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   963
    by (auto intro!: borel_measurable_setprod simp: comp_def)
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   964
  moreover have "integrable (Pi\<^isub>M I M) (\<lambda>x. \<bar>\<Prod>i\<in>I. f i (x i)\<bar>)"
41096
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   965
  proof (unfold integrable_def, intro conjI)
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   966
    show "(\<lambda>x. abs (?f x)) \<in> borel_measurable P"
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   967
      using borel by auto
43920
cedb5cb948fd Rename extreal => ereal
hoelzl
parents: 42988
diff changeset
   968
    have "(\<integral>\<^isup>+x. ereal (abs (?f x)) \<partial>P) = (\<integral>\<^isup>+x. (\<Prod>i\<in>I. ereal (abs (f i (x i)))) \<partial>P)"
cedb5cb948fd Rename extreal => ereal
hoelzl
parents: 42988
diff changeset
   969
      by (simp add: setprod_ereal abs_setprod)
cedb5cb948fd Rename extreal => ereal
hoelzl
parents: 42988
diff changeset
   970
    also have "\<dots> = (\<Prod>i\<in>I. (\<integral>\<^isup>+x. ereal (abs (f i x)) \<partial>M i))"
41096
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   971
      using f by (subst product_positive_integral_setprod) auto
41981
cdf7693bbe08 reworked Probability theory: measures are not type restricted to positive extended reals
hoelzl
parents: 41831
diff changeset
   972
    also have "\<dots> < \<infinity>"
41096
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   973
      using integrable[THEN M.integrable_abs]
41981
cdf7693bbe08 reworked Probability theory: measures are not type restricted to positive extended reals
hoelzl
parents: 41831
diff changeset
   974
      by (simp add: setprod_PInf integrable_def M.positive_integral_positive)
43920
cedb5cb948fd Rename extreal => ereal
hoelzl
parents: 42988
diff changeset
   975
    finally show "(\<integral>\<^isup>+x. ereal (abs (?f x)) \<partial>P) \<noteq> \<infinity>" by auto
cedb5cb948fd Rename extreal => ereal
hoelzl
parents: 42988
diff changeset
   976
    have "(\<integral>\<^isup>+x. ereal (- abs (?f x)) \<partial>P) = (\<integral>\<^isup>+x. 0 \<partial>P)"
41981
cdf7693bbe08 reworked Probability theory: measures are not type restricted to positive extended reals
hoelzl
parents: 41831
diff changeset
   977
      by (intro positive_integral_cong_pos) auto
43920
cedb5cb948fd Rename extreal => ereal
hoelzl
parents: 42988
diff changeset
   978
    then show "(\<integral>\<^isup>+x. ereal (- abs (?f x)) \<partial>P) \<noteq> \<infinity>" by simp
41096
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   979
  qed
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   980
  ultimately show ?thesis
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   981
    by (rule integrable_abs_iff[THEN iffD1])
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   982
qed
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   983
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   984
lemma (in product_sigma_finite) product_integral_setprod:
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   985
  fixes f :: "'i \<Rightarrow> 'a \<Rightarrow> real"
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   986
  assumes "finite I" "I \<noteq> {}" and integrable: "\<And>i. i \<in> I \<Longrightarrow> integrable (M i) (f i)"
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   987
  shows "(\<integral>x. (\<Prod>i\<in>I. f i (x i)) \<partial>Pi\<^isub>M I M) = (\<Prod>i\<in>I. integral\<^isup>L (M i) (f i))"
41096
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   988
using assms proof (induct rule: finite_ne_induct)
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   989
  case (singleton i)
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   990
  then show ?case by (simp add: product_integral_singleton integrable_def)
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   991
next
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   992
  case (insert i I)
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   993
  then have iI: "finite (insert i I)" by auto
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   994
  then have prod: "\<And>J. J \<subseteq> insert i I \<Longrightarrow>
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   995
    integrable (Pi\<^isub>M J M) (\<lambda>x. (\<Prod>i\<in>J. f i (x i)))"
41096
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   996
    by (intro product_integrable_setprod insert(5)) (auto intro: finite_subset)
41689
3e39b0e730d6 the measure valuation is again part of the measure_space type, instead of an explicit parameter to the locale;
hoelzl
parents: 41661
diff changeset
   997
  interpret I: finite_product_sigma_finite M I by default fact
41096
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   998
  have *: "\<And>x y. (\<Prod>j\<in>I. f j (if j = i then y else x j)) = (\<Prod>j\<in>I. f j (x j))"
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
   999
    using `i \<notin> I` by (auto intro!: setprod_cong)
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
  1000
  show ?case
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
  1001
    unfolding product_integral_insert[OF insert(1,3) prod[OF subset_refl]]
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
  1002
    by (simp add: * insert integral_multc I.integral_cmult[OF prod] subset_insertI)
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
  1003
qed
843c40bbc379 integral over setprod
hoelzl
parents: 41095
diff changeset
  1004
40859
de0b30e6c2d2 Support product spaces on sigma finite measures.
hoelzl
parents: 39098
diff changeset
  1005
end