src/HOL/Analysis/Measure_Space.thy
changeset 69597 ff784d5a5bfb
parent 69566 c41954ee87cf
child 69661 a03a63b81f44
equal deleted inserted replaced
69596:c8a2755bf220 69597:ff784d5a5bfb
    53     unfolding indicator_def
    53     unfolding indicator_def
    54     by (simp add: if_distrib sum.If_cases[OF \<open>finite P\<close>])
    54     by (simp add: if_distrib sum.If_cases[OF \<open>finite P\<close>])
    55 qed
    55 qed
    56 
    56 
    57 text \<open>
    57 text \<open>
    58   The type for emeasure spaces is already defined in @{theory "HOL-Analysis.Sigma_Algebra"}, as it
    58   The type for emeasure spaces is already defined in \<^theory>\<open>HOL-Analysis.Sigma_Algebra\<close>, as it
    59   is also used to represent sigma algebras (with an arbitrary emeasure).
    59   is also used to represent sigma algebras (with an arbitrary emeasure).
    60 \<close>
    60 \<close>
    61 
    61 
    62 subsection%unimportant "Extend binary sets"
    62 subsection%unimportant "Extend binary sets"
    63 
    63 
    89 lemma suminf_binaryset_eq:
    89 lemma suminf_binaryset_eq:
    90   fixes f :: "'a set \<Rightarrow> 'b::{comm_monoid_add, t2_space}"
    90   fixes f :: "'a set \<Rightarrow> 'b::{comm_monoid_add, t2_space}"
    91   shows "f {} = 0 \<Longrightarrow> (\<Sum>n. f (binaryset A B n)) = f A + f B"
    91   shows "f {} = 0 \<Longrightarrow> (\<Sum>n. f (binaryset A B n)) = f A + f B"
    92   by (metis binaryset_sums sums_unique)
    92   by (metis binaryset_sums sums_unique)
    93 
    93 
    94 subsection%unimportant \<open>Properties of a premeasure @{term \<mu>}\<close>
    94 subsection%unimportant \<open>Properties of a premeasure \<^term>\<open>\<mu>\<close>\<close>
    95 
    95 
    96 text \<open>
    96 text \<open>
    97   The definitions for @{const positive} and @{const countably_additive} should be here, by they are
    97   The definitions for \<^const>\<open>positive\<close> and \<^const>\<open>countably_additive\<close> should be here, by they are
    98   necessary to define @{typ "'a measure"} in @{theory "HOL-Analysis.Sigma_Algebra"}.
    98   necessary to define \<^typ>\<open>'a measure\<close> in \<^theory>\<open>HOL-Analysis.Sigma_Algebra\<close>.
    99 \<close>
    99 \<close>
   100 
   100 
   101 definition subadditive where
   101 definition subadditive where
   102   "subadditive M f \<longleftrightarrow> (\<forall>x\<in>M. \<forall>y\<in>M. x \<inter> y = {} \<longrightarrow> f (x \<union> y) \<le> f x + f y)"
   102   "subadditive M f \<longleftrightarrow> (\<forall>x\<in>M. \<forall>y\<in>M. x \<inter> y = {} \<longrightarrow> f (x \<union> y) \<le> f x + f y)"
   103 
   103 
   440   shows "countably_additive M f"
   440   shows "countably_additive M f"
   441   using countably_additive_iff_continuous_from_below[OF f]
   441   using countably_additive_iff_continuous_from_below[OF f]
   442   using empty_continuous_imp_continuous_from_below[OF f fin] cont
   442   using empty_continuous_imp_continuous_from_below[OF f fin] cont
   443   by blast
   443   by blast
   444 
   444 
   445 subsection%unimportant \<open>Properties of @{const emeasure}\<close>
   445 subsection%unimportant \<open>Properties of \<^const>\<open>emeasure\<close>\<close>
   446 
   446 
   447 lemma emeasure_positive: "positive (sets M) (emeasure M)"
   447 lemma emeasure_positive: "positive (sets M) (emeasure M)"
   448   by (cases M) (auto simp: sets_def emeasure_def Abs_measure_inverse measure_space_def)
   448   by (cases M) (auto simp: sets_def emeasure_def Abs_measure_inverse measure_space_def)
   449 
   449 
   450 lemma emeasure_empty[simp, intro]: "emeasure M {} = 0"
   450 lemma emeasure_empty[simp, intro]: "emeasure M {} = 0"
  1383   have "B i \<in> sets M" "B i \<subseteq> W" "emeasure M (B i) < \<infinity>" "emeasure M (B i) > C"
  1383   have "B i \<in> sets M" "B i \<subseteq> W" "emeasure M (B i) < \<infinity>" "emeasure M (B i) > C"
  1384     using B_meas b c d by auto
  1384     using B_meas b c d by auto
  1385   then show ?thesis using that by blast
  1385   then show ?thesis using that by blast
  1386 qed
  1386 qed
  1387 
  1387 
  1388 subsection \<open>Measure space induced by distribution of @{const measurable}-functions\<close>
  1388 subsection \<open>Measure space induced by distribution of \<^const>\<open>measurable\<close>-functions\<close>
  1389 
  1389 
  1390 definition%important distr :: "'a measure \<Rightarrow> 'b measure \<Rightarrow> ('a \<Rightarrow> 'b) \<Rightarrow> 'b measure" where
  1390 definition%important distr :: "'a measure \<Rightarrow> 'b measure \<Rightarrow> ('a \<Rightarrow> 'b) \<Rightarrow> 'b measure" where
  1391 "distr M N f =
  1391 "distr M N f =
  1392   measure_of (space N) (sets N) (\<lambda>A. emeasure M (f -` A \<inter> space M))"
  1392   measure_of (space N) (sets N) (\<lambda>A. emeasure M (f -` A \<inter> space M))"
  1393 
  1393 
  2069     then have "eventually (\<lambda>n. x \<notin> A n) sequentially" using eventually_sequentially by auto
  2069     then have "eventually (\<lambda>n. x \<notin> A n) sequentially" using eventually_sequentially by auto
  2070   }
  2070   }
  2071   ultimately show ?thesis by auto
  2071   ultimately show ?thesis by auto
  2072 qed
  2072 qed
  2073 
  2073 
  2074 subsection \<open>Measure spaces with @{term "emeasure M (space M) < \<infinity>"}\<close>
  2074 subsection \<open>Measure spaces with \<^term>\<open>emeasure M (space M) < \<infinity>\<close>\<close>
  2075 
  2075 
  2076 locale%important finite_measure = sigma_finite_measure M for M +
  2076 locale%important finite_measure = sigma_finite_measure M for M +
  2077   assumes finite_emeasure_space: "emeasure M (space M) \<noteq> top"
  2077   assumes finite_emeasure_space: "emeasure M (space M) \<noteq> top"
  2078 
  2078 
  2079 lemma finite_measureI[Pure.intro!]:
  2079 lemma finite_measureI[Pure.intro!]:
  2828     apply auto
  2828     apply auto
  2829     done
  2829     done
  2830 qed
  2830 qed
  2831 
  2831 
  2832 text%important \<open>
  2832 text%important \<open>
  2833   Define a lexicographical order on @{type measure}, in the order space, sets and measure. The parts
  2833   Define a lexicographical order on \<^type>\<open>measure\<close>, in the order space, sets and measure. The parts
  2834   of the lexicographical order are point-wise ordered.
  2834   of the lexicographical order are point-wise ordered.
  2835 \<close>
  2835 \<close>
  2836 
  2836 
  2837 instantiation measure :: (type) order_bot
  2837 instantiation measure :: (type) order_bot
  2838 begin
  2838 begin