1.1 --- a/src/HOL/Multivariate_Analysis/Topology_Euclidean_Space.thy Wed Aug 17 18:05:31 2011 +0200
1.2 +++ b/src/HOL/Multivariate_Analysis/Topology_Euclidean_Space.thy Wed Aug 17 09:59:10 2011 -0700
1.3 @@ -4882,56 +4882,28 @@
1.4
1.5 (* Moved interval_open_subset_closed a bit upwards *)
1.6
1.7 -lemma open_interval_lemma: fixes x :: "real" shows
1.8 - "a < x \<Longrightarrow> x < b ==> (\<exists>d>0. \<forall>x'. abs(x' - x) < d --> a < x' \<and> x' < b)"
1.9 - by(rule_tac x="min (x - a) (b - x)" in exI, auto)
1.10 -
1.11 -lemma open_interval[intro]: fixes a :: "'a::ordered_euclidean_space" shows "open {a<..<b}"
1.12 +lemma open_interval[intro]:
1.13 + fixes a b :: "'a::ordered_euclidean_space" shows "open {a<..<b}"
1.14 proof-
1.15 - { fix x assume x:"x\<in>{a<..<b}"
1.16 - { fix i assume "i<DIM('a)"
1.17 - hence "\<exists>d>0. \<forall>x'. abs (x' - (x$$i)) < d \<longrightarrow> a$$i < x' \<and> x' < b$$i"
1.18 - using x[unfolded mem_interval, THEN spec[where x=i]]
1.19 - using open_interval_lemma[of "a$$i" "x$$i" "b$$i"] by auto }
1.20 - hence "\<forall>i\<in>{..<DIM('a)}. \<exists>d>0. \<forall>x'. abs (x' - (x$$i)) < d \<longrightarrow> a$$i < x' \<and> x' < b$$i" by auto
1.21 - from bchoice[OF this] guess d .. note d=this
1.22 - let ?d = "Min (d ` {..<DIM('a)})"
1.23 - have **:"finite (d ` {..<DIM('a)})" "d ` {..<DIM('a)} \<noteq> {}" by auto
1.24 - have "?d>0" using Min_gr_iff[OF **] using d by auto
1.25 - moreover
1.26 - { fix x' assume as:"dist x' x < ?d"
1.27 - { fix i assume i:"i<DIM('a)"
1.28 - hence "\<bar>x'$$i - x $$ i\<bar> < d i"
1.29 - using norm_bound_component_lt[OF as[unfolded dist_norm], of i]
1.30 - unfolding euclidean_simps Min_gr_iff[OF **] by auto
1.31 - hence "a $$ i < x' $$ i" "x' $$ i < b $$ i" using i and d[THEN bspec[where x=i]] by auto }
1.32 - hence "a < x' \<and> x' < b" apply(subst(2) eucl_less,subst(1) eucl_less) by auto }
1.33 - ultimately have "\<exists>e>0. \<forall>x'. dist x' x < e \<longrightarrow> x' \<in> {a<..<b}" by auto
1.34 - }
1.35 - thus ?thesis unfolding open_dist using open_interval_lemma by auto
1.36 -qed
1.37 -
1.38 -lemma closed_interval[intro]: fixes a :: "'a::ordered_euclidean_space" shows "closed {a .. b}"
1.39 + have "open (\<Inter>i<DIM('a). (\<lambda>x. x$$i) -` {a$$i<..<b$$i})"
1.40 + by (intro open_INT finite_lessThan ballI continuous_open_vimage allI
1.41 + linear_continuous_at bounded_linear_euclidean_component
1.42 + open_real_greaterThanLessThan)
1.43 + also have "(\<Inter>i<DIM('a). (\<lambda>x. x$$i) -` {a$$i<..<b$$i}) = {a<..<b}"
1.44 + by (auto simp add: eucl_less [where 'a='a])
1.45 + finally show "open {a<..<b}" .
1.46 +qed
1.47 +
1.48 +lemma closed_interval[intro]:
1.49 + fixes a b :: "'a::ordered_euclidean_space" shows "closed {a .. b}"
1.50 proof-
1.51 - { fix x i assume i:"i<DIM('a)"
1.52 - assume as:"\<forall>e>0. \<exists>x'\<in>{a..b}. x' \<noteq> x \<and> dist x' x < e"(* and xab:"a$$i > x$$i \<or> b$$i < x$$i"*)
1.53 - { assume xa:"a$$i > x$$i"
1.54 - with as obtain y where y:"y\<in>{a..b}" "y \<noteq> x" "dist y x < a$$i - x$$i" by(erule_tac x="a$$i - x$$i" in allE)auto
1.55 - hence False unfolding mem_interval and dist_norm
1.56 - using component_le_norm[of "y-x" i, unfolded euclidean_simps] and xa using i
1.57 - by(auto elim!: allE[where x=i])
1.58 - } hence "a$$i \<le> x$$i" by(rule ccontr)auto
1.59 - moreover
1.60 - { assume xb:"b$$i < x$$i"
1.61 - with as obtain y where y:"y\<in>{a..b}" "y \<noteq> x" "dist y x < x$$i - b$$i"
1.62 - by(erule_tac x="x$$i - b$$i" in allE)auto
1.63 - hence False unfolding mem_interval and dist_norm
1.64 - using component_le_norm[of "y-x" i, unfolded euclidean_simps] and xb using i
1.65 - by(auto elim!: allE[where x=i])
1.66 - } hence "x$$i \<le> b$$i" by(rule ccontr)auto
1.67 - ultimately
1.68 - have "a $$ i \<le> x $$ i \<and> x $$ i \<le> b $$ i" by auto }
1.69 - thus ?thesis unfolding closed_limpt islimpt_approachable mem_interval by auto
1.70 + have "closed (\<Inter>i<DIM('a). (\<lambda>x. x$$i) -` {a$$i .. b$$i})"
1.71 + by (intro closed_INT ballI continuous_closed_vimage allI
1.72 + linear_continuous_at bounded_linear_euclidean_component
1.73 + closed_real_atLeastAtMost)
1.74 + also have "(\<Inter>i<DIM('a). (\<lambda>x. x$$i) -` {a$$i .. b$$i}) = {a .. b}"
1.75 + by (auto simp add: eucl_le [where 'a='a])
1.76 + finally show "closed {a .. b}" .
1.77 qed
1.78
1.79 lemma interior_closed_interval[intro]: fixes a :: "'a::ordered_euclidean_space" shows