src/HOL/Analysis/Elementary_Topology.thy
changeset 69768 7e4966eaf781
parent 69748 7aafd0472661
child 70044 da5857dbcbb9
equal deleted inserted replaced
69767:d10fafeb93c0 69768:7e4966eaf781
  2493   fixes a :: "'a :: real_normed_vector"
  2493   fixes a :: "'a :: real_normed_vector"
  2494   shows "homeomorphism ((+) a ` S) S ((+) (- a)) ((+) a)"
  2494   shows "homeomorphism ((+) a ` S) S ((+) (- a)) ((+) a)"
  2495 unfolding homeomorphism_def by (auto simp: algebra_simps continuous_intros)
  2495 unfolding homeomorphism_def by (auto simp: algebra_simps continuous_intros)
  2496 
  2496 
  2497 lemma homeomorphism_ident: "homeomorphism T T (\<lambda>a. a) (\<lambda>a. a)"
  2497 lemma homeomorphism_ident: "homeomorphism T T (\<lambda>a. a) (\<lambda>a. a)"
  2498   by (rule homeomorphismI) (auto simp: continuous_on_id)
  2498   by (rule homeomorphismI) auto
  2499 
  2499 
  2500 lemma homeomorphism_compose:
  2500 lemma homeomorphism_compose:
  2501   assumes "homeomorphism S T f g" "homeomorphism T U h k"
  2501   assumes "homeomorphism S T f g" "homeomorphism T U h k"
  2502     shows "homeomorphism S U (h o f) (g o k)"
  2502     shows "homeomorphism S U (h o f) (g o k)"
  2503   using assms
  2503   using assms
  2504   unfolding homeomorphism_def
  2504   unfolding homeomorphism_def
  2505   by (intro conjI ballI continuous_on_compose) (auto simp: image_comp [symmetric])
  2505   by (intro conjI ballI continuous_on_compose) (auto simp: image_iff)
       
  2506 
  2506 
  2507 
  2507 lemma homeomorphism_symD: "homeomorphism S t f g \<Longrightarrow> homeomorphism t S g f"
  2508 lemma homeomorphism_symD: "homeomorphism S t f g \<Longrightarrow> homeomorphism t S g f"
  2508   by (simp add: homeomorphism_def)
  2509   by (simp add: homeomorphism_def)
  2509 
  2510 
  2510 lemma homeomorphism_sym: "homeomorphism S t f g = homeomorphism t S g f"
  2511 lemma homeomorphism_sym: "homeomorphism S t f g = homeomorphism t S g f"