src/HOL/Topological_Spaces.thy
changeset 60150 bd773c47ad0b
parent 60040 1fa1023b13b9
child 60172 423273355b55
equal deleted inserted replaced
60149:9b0825a00b1a 60150:bd773c47ad0b
  1476 lemma continuous_on_subset: "continuous_on s f \<Longrightarrow> t \<subseteq> s \<Longrightarrow> continuous_on t f"
  1476 lemma continuous_on_subset: "continuous_on s f \<Longrightarrow> t \<subseteq> s \<Longrightarrow> continuous_on t f"
  1477   unfolding continuous_on_def by (metis subset_eq tendsto_within_subset)
  1477   unfolding continuous_on_def by (metis subset_eq tendsto_within_subset)
  1478 
  1478 
  1479 lemma continuous_at_imp_continuous_on: "\<forall>x\<in>s. isCont f x \<Longrightarrow> continuous_on s f"
  1479 lemma continuous_at_imp_continuous_on: "\<forall>x\<in>s. isCont f x \<Longrightarrow> continuous_on s f"
  1480   by (auto intro: continuous_at_within simp: continuous_on_eq_continuous_within)
  1480   by (auto intro: continuous_at_within simp: continuous_on_eq_continuous_within)
  1481 
       
  1482 lemma isContI_continuous: "continuous (at x within UNIV) f \<Longrightarrow> isCont f x"
       
  1483   by simp
       
  1484 
       
  1485 lemma isCont_ident[continuous_intros, simp]: "isCont (\<lambda>x. x) a"
       
  1486   using continuous_ident by (rule isContI_continuous)
       
  1487 
       
  1488 lemmas isCont_const = continuous_const
       
  1489 
  1481 
  1490 lemma isCont_o2: "isCont f a \<Longrightarrow> isCont g (f a) \<Longrightarrow> isCont (\<lambda>x. g (f x)) a"
  1482 lemma isCont_o2: "isCont f a \<Longrightarrow> isCont g (f a) \<Longrightarrow> isCont (\<lambda>x. g (f x)) a"
  1491   unfolding isCont_def by (rule tendsto_compose)
  1483   unfolding isCont_def by (rule tendsto_compose)
  1492 
  1484 
  1493 lemma isCont_o[continuous_intros]: "isCont f a \<Longrightarrow> isCont g (f a) \<Longrightarrow> isCont (g \<circ> f) a"
  1485 lemma isCont_o[continuous_intros]: "isCont f a \<Longrightarrow> isCont g (f a) \<Longrightarrow> isCont (g \<circ> f) a"