src/HOL/Probability/Lebesgue_Measure.thy
changeset 62343 24106dc44def
parent 61973 0c7e865fa7cb
child 62390 842917225d56
equal deleted inserted replaced
62342:1cf129590be8 62343:24106dc44def
   534 proof -
   534 proof -
   535   have "A \<subseteq> (\<Union>i. {from_nat_into A i})" using from_nat_into_surj assms by force
   535   have "A \<subseteq> (\<Union>i. {from_nat_into A i})" using from_nat_into_surj assms by force
   536   moreover have "emeasure lborel (\<Union>i. {from_nat_into A i}) = 0"
   536   moreover have "emeasure lborel (\<Union>i. {from_nat_into A i}) = 0"
   537     by (rule emeasure_UN_eq_0) auto
   537     by (rule emeasure_UN_eq_0) auto
   538   ultimately have "emeasure lborel A \<le> 0" using emeasure_mono
   538   ultimately have "emeasure lborel A \<le> 0" using emeasure_mono
   539     by (metis assms bot.extremum_unique emeasure_empty image_eq_UN range_from_nat_into sets.empty_sets)
   539     by (smt UN_E emeasure_empty equalityI from_nat_into order_refl singletonD subsetI)
   540   thus ?thesis by (auto simp add: emeasure_le_0_iff)
   540   thus ?thesis by (auto simp add: emeasure_le_0_iff)
   541 qed
   541 qed
   542 
   542 
   543 lemma countable_imp_null_set_lborel: "countable A \<Longrightarrow> A \<in> null_sets lborel"
   543 lemma countable_imp_null_set_lborel: "countable A \<Longrightarrow> A \<in> null_sets lborel"
   544   by (simp add: null_sets_def emeasure_lborel_countable sets.countable)
   544   by (simp add: null_sets_def emeasure_lborel_countable sets.countable)