src/HOL/Topological_Spaces.thy
author hoelzl
Fri, 22 Mar 2013 10:41:42 +0100
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(*  Title:      HOL/Basic_Topology.thy
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    Author:     Brian Huffman
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    Author:     Johannes Hölzl
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*)
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header {* Topological Spaces *}
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theory Topological_Spaces
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imports Main
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begin
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subsection {* Topological space *}
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class "open" =
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  fixes "open" :: "'a set \<Rightarrow> bool"
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class topological_space = "open" +
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  assumes open_UNIV [simp, intro]: "open UNIV"
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  assumes open_Int [intro]: "open S \<Longrightarrow> open T \<Longrightarrow> open (S \<inter> T)"
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  assumes open_Union [intro]: "\<forall>S\<in>K. open S \<Longrightarrow> open (\<Union> K)"
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begin
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definition
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  closed :: "'a set \<Rightarrow> bool" where
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  "closed S \<longleftrightarrow> open (- S)"
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lemma open_empty [intro, simp]: "open {}"
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  using open_Union [of "{}"] by simp
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lemma open_Un [intro]: "open S \<Longrightarrow> open T \<Longrightarrow> open (S \<union> T)"
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  using open_Union [of "{S, T}"] by simp
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lemma open_UN [intro]: "\<forall>x\<in>A. open (B x) \<Longrightarrow> open (\<Union>x\<in>A. B x)"
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  unfolding SUP_def by (rule open_Union) auto
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lemma open_Inter [intro]: "finite S \<Longrightarrow> \<forall>T\<in>S. open T \<Longrightarrow> open (\<Inter>S)"
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  by (induct set: finite) auto
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lemma open_INT [intro]: "finite A \<Longrightarrow> \<forall>x\<in>A. open (B x) \<Longrightarrow> open (\<Inter>x\<in>A. B x)"
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  unfolding INF_def by (rule open_Inter) auto
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lemma closed_empty [intro, simp]:  "closed {}"
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  unfolding closed_def by simp
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lemma closed_Un [intro]: "closed S \<Longrightarrow> closed T \<Longrightarrow> closed (S \<union> T)"
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  unfolding closed_def by auto
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lemma closed_UNIV [intro, simp]: "closed UNIV"
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  unfolding closed_def by simp
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lemma closed_Int [intro]: "closed S \<Longrightarrow> closed T \<Longrightarrow> closed (S \<inter> T)"
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  unfolding closed_def by auto
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lemma closed_INT [intro]: "\<forall>x\<in>A. closed (B x) \<Longrightarrow> closed (\<Inter>x\<in>A. B x)"
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  unfolding closed_def by auto
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lemma closed_Inter [intro]: "\<forall>S\<in>K. closed S \<Longrightarrow> closed (\<Inter> K)"
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  unfolding closed_def uminus_Inf by auto
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lemma closed_Union [intro]: "finite S \<Longrightarrow> \<forall>T\<in>S. closed T \<Longrightarrow> closed (\<Union>S)"
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  by (induct set: finite) auto
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lemma closed_UN [intro]: "finite A \<Longrightarrow> \<forall>x\<in>A. closed (B x) \<Longrightarrow> closed (\<Union>x\<in>A. B x)"
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  unfolding SUP_def by (rule closed_Union) auto
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lemma open_closed: "open S \<longleftrightarrow> closed (- S)"
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  unfolding closed_def by simp
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lemma closed_open: "closed S \<longleftrightarrow> open (- S)"
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  unfolding closed_def by simp
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lemma open_Diff [intro]: "open S \<Longrightarrow> closed T \<Longrightarrow> open (S - T)"
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  unfolding closed_open Diff_eq by (rule open_Int)
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lemma closed_Diff [intro]: "closed S \<Longrightarrow> open T \<Longrightarrow> closed (S - T)"
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  unfolding open_closed Diff_eq by (rule closed_Int)
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lemma open_Compl [intro]: "closed S \<Longrightarrow> open (- S)"
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  unfolding closed_open .
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lemma closed_Compl [intro]: "open S \<Longrightarrow> closed (- S)"
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  unfolding open_closed .
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end
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subsection{* Hausdorff and other separation properties *}
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class t0_space = topological_space +
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  assumes t0_space: "x \<noteq> y \<Longrightarrow> \<exists>U. open U \<and> \<not> (x \<in> U \<longleftrightarrow> y \<in> U)"
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class t1_space = topological_space +
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  assumes t1_space: "x \<noteq> y \<Longrightarrow> \<exists>U. open U \<and> x \<in> U \<and> y \<notin> U"
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instance t1_space \<subseteq> t0_space
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proof qed (fast dest: t1_space)
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lemma separation_t1:
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  fixes x y :: "'a::t1_space"
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  shows "x \<noteq> y \<longleftrightarrow> (\<exists>U. open U \<and> x \<in> U \<and> y \<notin> U)"
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  using t1_space[of x y] by blast
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lemma closed_singleton:
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  fixes a :: "'a::t1_space"
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  shows "closed {a}"
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proof -
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  let ?T = "\<Union>{S. open S \<and> a \<notin> S}"
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  have "open ?T" by (simp add: open_Union)
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  also have "?T = - {a}"
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    by (simp add: set_eq_iff separation_t1, auto)
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  finally show "closed {a}" unfolding closed_def .
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qed
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lemma closed_insert [simp]:
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  fixes a :: "'a::t1_space"
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  assumes "closed S" shows "closed (insert a S)"
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proof -
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  from closed_singleton assms
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  have "closed ({a} \<union> S)" by (rule closed_Un)
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  thus "closed (insert a S)" by simp
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qed
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lemma finite_imp_closed:
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  fixes S :: "'a::t1_space set"
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  shows "finite S \<Longrightarrow> closed S"
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by (induct set: finite, simp_all)
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text {* T2 spaces are also known as Hausdorff spaces. *}
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class t2_space = topological_space +
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  assumes hausdorff: "x \<noteq> y \<Longrightarrow> \<exists>U V. open U \<and> open V \<and> x \<in> U \<and> y \<in> V \<and> U \<inter> V = {}"
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instance t2_space \<subseteq> t1_space
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proof qed (fast dest: hausdorff)
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lemma separation_t2:
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  fixes x y :: "'a::t2_space"
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  shows "x \<noteq> y \<longleftrightarrow> (\<exists>U V. open U \<and> open V \<and> x \<in> U \<and> y \<in> V \<and> U \<inter> V = {})"
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  using hausdorff[of x y] by blast
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lemma separation_t0:
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  fixes x y :: "'a::t0_space"
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  shows "x \<noteq> y \<longleftrightarrow> (\<exists>U. open U \<and> ~(x\<in>U \<longleftrightarrow> y\<in>U))"
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  using t0_space[of x y] by blast
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text {* A perfect space is a topological space with no isolated points. *}
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class perfect_space = topological_space +
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  assumes not_open_singleton: "\<not> open {x}"
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subsection {* Generators for toplogies *}
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inductive generate_topology for S where
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  UNIV: "generate_topology S UNIV"
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| Int: "generate_topology S a \<Longrightarrow> generate_topology S b \<Longrightarrow> generate_topology S (a \<inter> b)"
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| UN: "(\<And>k. k \<in> K \<Longrightarrow> generate_topology S k) \<Longrightarrow> generate_topology S (\<Union>K)"
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| Basis: "s \<in> S \<Longrightarrow> generate_topology S s"
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hide_fact (open) UNIV Int UN Basis 
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lemma generate_topology_Union: 
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  "(\<And>k. k \<in> I \<Longrightarrow> generate_topology S (K k)) \<Longrightarrow> generate_topology S (\<Union>k\<in>I. K k)"
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  unfolding SUP_def by (intro generate_topology.UN) auto
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lemma topological_space_generate_topology:
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  "class.topological_space (generate_topology S)"
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  by default (auto intro: generate_topology.intros)
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subsection {* Order topologies *}
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class order_topology = order + "open" +
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  assumes open_generated_order: "open = generate_topology (range (\<lambda>a. {..< a}) \<union> range (\<lambda>a. {a <..}))"
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begin
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subclass topological_space
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  unfolding open_generated_order
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  by (rule topological_space_generate_topology)
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lemma open_greaterThan [simp]: "open {a <..}"
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  unfolding open_generated_order by (auto intro: generate_topology.Basis)
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lemma open_lessThan [simp]: "open {..< a}"
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  unfolding open_generated_order by (auto intro: generate_topology.Basis)
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lemma open_greaterThanLessThan [simp]: "open {a <..< b}"
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   unfolding greaterThanLessThan_eq by (simp add: open_Int)
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cad22a3cc09c move topological_space to its own theory
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end
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class linorder_topology = linorder + order_topology
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lemma closed_atMost [simp]: "closed {.. a::'a::linorder_topology}"
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  by (simp add: closed_open)
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cad22a3cc09c move topological_space to its own theory
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lemma closed_atLeast [simp]: "closed {a::'a::linorder_topology ..}"
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  by (simp add: closed_open)
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lemma closed_atLeastAtMost [simp]: "closed {a::'a::linorder_topology .. b}"
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proof -
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  have "{a .. b} = {a ..} \<inter> {.. b}"
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    by auto
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  then show ?thesis
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    by (simp add: closed_Int)
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qed
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cad22a3cc09c move topological_space to its own theory
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lemma (in linorder) less_separate:
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  assumes "x < y"
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  shows "\<exists>a b. x \<in> {..< a} \<and> y \<in> {b <..} \<and> {..< a} \<inter> {b <..} = {}"
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proof cases
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  assume "\<exists>z. x < z \<and> z < y"
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  then guess z ..
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  then have "x \<in> {..< z} \<and> y \<in> {z <..} \<and> {z <..} \<inter> {..< z} = {}"
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    by auto
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  then show ?thesis by blast
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next
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  assume "\<not> (\<exists>z. x < z \<and> z < y)"
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  with `x < y` have "x \<in> {..< y} \<and> y \<in> {x <..} \<and> {x <..} \<inter> {..< y} = {}"
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    by auto
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  then show ?thesis by blast
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qed
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cad22a3cc09c move topological_space to its own theory
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instance linorder_topology \<subseteq> t2_space
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proof
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  fix x y :: 'a
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  from less_separate[of x y] less_separate[of y x]
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  show "x \<noteq> y \<Longrightarrow> \<exists>U V. open U \<and> open V \<and> x \<in> U \<and> y \<in> V \<and> U \<inter> V = {}"
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    by (elim neqE) (metis open_lessThan open_greaterThan Int_commute)+
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qed
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cad22a3cc09c move topological_space to its own theory
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lemma open_right:
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  fixes S :: "'a :: {no_top, linorder_topology} set"
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  assumes "open S" "x \<in> S" shows "\<exists>b>x. {x ..< b} \<subseteq> S"
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  using assms unfolding open_generated_order
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proof induction
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  case (Int A B)
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  then obtain a b where "a > x" "{x ..< a} \<subseteq> A"  "b > x" "{x ..< b} \<subseteq> B" by auto
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  then show ?case by (auto intro!: exI[of _ "min a b"])
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next
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  case (Basis S)
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  moreover from gt_ex[of x] guess b ..
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  ultimately show ?case by (fastforce intro: exI[of _ b])
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qed (fastforce intro: gt_ex)+
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cad22a3cc09c move topological_space to its own theory
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lemma open_left:
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  fixes S :: "'a :: {no_bot, linorder_topology} set"
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  assumes "open S" "x \<in> S" shows "\<exists>b<x. {b <.. x} \<subseteq> S"
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  using assms unfolding open_generated_order
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proof induction
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  case (Int A B)
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  then obtain a b where "a < x" "{a <.. x} \<subseteq> A"  "b < x" "{b <.. x} \<subseteq> B" by auto
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  then show ?case by (auto intro!: exI[of _ "max a b"])
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next
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  case (Basis S)
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  moreover from lt_ex[of x] guess b ..
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  ultimately show ?case by (fastforce intro: exI[of _ b])
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next
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  case UN then show ?case by blast
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qed (fastforce intro: lt_ex)
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cad22a3cc09c move topological_space to its own theory
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subsection {* Filters *}
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text {*
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  This definition also allows non-proper filters.
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*}
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locale is_filter =
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  fixes F :: "('a \<Rightarrow> bool) \<Rightarrow> bool"
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  assumes True: "F (\<lambda>x. True)"
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  assumes conj: "F (\<lambda>x. P x) \<Longrightarrow> F (\<lambda>x. Q x) \<Longrightarrow> F (\<lambda>x. P x \<and> Q x)"
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  assumes mono: "\<forall>x. P x \<longrightarrow> Q x \<Longrightarrow> F (\<lambda>x. P x) \<Longrightarrow> F (\<lambda>x. Q x)"
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typedef 'a filter = "{F :: ('a \<Rightarrow> bool) \<Rightarrow> bool. is_filter F}"
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proof
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  show "(\<lambda>x. True) \<in> ?filter" by (auto intro: is_filter.intro)
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qed
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cad22a3cc09c move topological_space to its own theory
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lemma is_filter_Rep_filter: "is_filter (Rep_filter F)"
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  using Rep_filter [of F] by simp
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cad22a3cc09c move topological_space to its own theory
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lemma Abs_filter_inverse':
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  assumes "is_filter F" shows "Rep_filter (Abs_filter F) = F"
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  using assms by (simp add: Abs_filter_inverse)
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cad22a3cc09c move topological_space to its own theory
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cad22a3cc09c move topological_space to its own theory
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subsubsection {* Eventually *}
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cad22a3cc09c move topological_space to its own theory
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definition eventually :: "('a \<Rightarrow> bool) \<Rightarrow> 'a filter \<Rightarrow> bool"
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  where "eventually P F \<longleftrightarrow> Rep_filter F P"
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cad22a3cc09c move topological_space to its own theory
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lemma eventually_Abs_filter:
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  assumes "is_filter F" shows "eventually P (Abs_filter F) = F P"
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  unfolding eventually_def using assms by (simp add: Abs_filter_inverse)
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cad22a3cc09c move topological_space to its own theory
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lemma filter_eq_iff:
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  shows "F = F' \<longleftrightarrow> (\<forall>P. eventually P F = eventually P F')"
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  unfolding Rep_filter_inject [symmetric] fun_eq_iff eventually_def ..
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cad22a3cc09c move topological_space to its own theory
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lemma eventually_True [simp]: "eventually (\<lambda>x. True) F"
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  unfolding eventually_def
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  by (rule is_filter.True [OF is_filter_Rep_filter])
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cad22a3cc09c move topological_space to its own theory
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lemma always_eventually: "\<forall>x. P x \<Longrightarrow> eventually P F"
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proof -
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  assume "\<forall>x. P x" hence "P = (\<lambda>x. True)" by (simp add: ext)
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  thus "eventually P F" by simp
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qed
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cad22a3cc09c move topological_space to its own theory
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lemma eventually_mono:
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  "(\<forall>x. P x \<longrightarrow> Q x) \<Longrightarrow> eventually P F \<Longrightarrow> eventually Q F"
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  unfolding eventually_def
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  by (rule is_filter.mono [OF is_filter_Rep_filter])
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cad22a3cc09c move topological_space to its own theory
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lemma eventually_conj:
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  assumes P: "eventually (\<lambda>x. P x) F"
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  assumes Q: "eventually (\<lambda>x. Q x) F"
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  shows "eventually (\<lambda>x. P x \<and> Q x) F"
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   317
  using assms unfolding eventually_def
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   318
  by (rule is_filter.conj [OF is_filter_Rep_filter])
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cad22a3cc09c move topological_space to its own theory
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lemma eventually_Ball_finite:
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  assumes "finite A" and "\<forall>y\<in>A. eventually (\<lambda>x. P x y) net"
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   322
  shows "eventually (\<lambda>x. \<forall>y\<in>A. P x y) net"
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   323
using assms by (induct set: finite, simp, simp add: eventually_conj)
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cad22a3cc09c move topological_space to its own theory
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lemma eventually_all_finite:
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  fixes P :: "'a \<Rightarrow> 'b::finite \<Rightarrow> bool"
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  assumes "\<And>y. eventually (\<lambda>x. P x y) net"
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diff changeset
   328
  shows "eventually (\<lambda>x. \<forall>y. P x y) net"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   329
using eventually_Ball_finite [of UNIV P] assms by simp
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   330
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   331
lemma eventually_mp:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   332
  assumes "eventually (\<lambda>x. P x \<longrightarrow> Q x) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   333
  assumes "eventually (\<lambda>x. P x) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   334
  shows "eventually (\<lambda>x. Q x) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   335
proof (rule eventually_mono)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   336
  show "\<forall>x. (P x \<longrightarrow> Q x) \<and> P x \<longrightarrow> Q x" by simp
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   337
  show "eventually (\<lambda>x. (P x \<longrightarrow> Q x) \<and> P x) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   338
    using assms by (rule eventually_conj)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   339
qed
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   340
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   341
lemma eventually_rev_mp:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   342
  assumes "eventually (\<lambda>x. P x) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   343
  assumes "eventually (\<lambda>x. P x \<longrightarrow> Q x) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   344
  shows "eventually (\<lambda>x. Q x) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   345
using assms(2) assms(1) by (rule eventually_mp)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   346
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   347
lemma eventually_conj_iff:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   348
  "eventually (\<lambda>x. P x \<and> Q x) F \<longleftrightarrow> eventually P F \<and> eventually Q F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   349
  by (auto intro: eventually_conj elim: eventually_rev_mp)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   350
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   351
lemma eventually_elim1:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   352
  assumes "eventually (\<lambda>i. P i) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   353
  assumes "\<And>i. P i \<Longrightarrow> Q i"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   354
  shows "eventually (\<lambda>i. Q i) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   355
  using assms by (auto elim!: eventually_rev_mp)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   356
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   357
lemma eventually_elim2:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   358
  assumes "eventually (\<lambda>i. P i) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   359
  assumes "eventually (\<lambda>i. Q i) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   360
  assumes "\<And>i. P i \<Longrightarrow> Q i \<Longrightarrow> R i"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   361
  shows "eventually (\<lambda>i. R i) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   362
  using assms by (auto elim!: eventually_rev_mp)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   363
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   364
lemma eventually_subst:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   365
  assumes "eventually (\<lambda>n. P n = Q n) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   366
  shows "eventually P F = eventually Q F" (is "?L = ?R")
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   367
proof -
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   368
  from assms have "eventually (\<lambda>x. P x \<longrightarrow> Q x) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   369
      and "eventually (\<lambda>x. Q x \<longrightarrow> P x) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   370
    by (auto elim: eventually_elim1)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   371
  then show ?thesis by (auto elim: eventually_elim2)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   372
qed
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   373
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   374
ML {*
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   375
  fun eventually_elim_tac ctxt thms thm =
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   376
    let
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   377
      val thy = Proof_Context.theory_of ctxt
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   378
      val mp_thms = thms RL [@{thm eventually_rev_mp}]
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   379
      val raw_elim_thm =
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   380
        (@{thm allI} RS @{thm always_eventually})
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   381
        |> fold (fn thm1 => fn thm2 => thm2 RS thm1) mp_thms
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   382
        |> fold (fn _ => fn thm => @{thm impI} RS thm) thms
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   383
      val cases_prop = prop_of (raw_elim_thm RS thm)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   384
      val cases = (Rule_Cases.make_common (thy, cases_prop) [(("elim", []), [])])
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   385
    in
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   386
      CASES cases (rtac raw_elim_thm 1) thm
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   387
    end
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   388
*}
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   389
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   390
method_setup eventually_elim = {*
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   391
  Scan.succeed (fn ctxt => METHOD_CASES (eventually_elim_tac ctxt))
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   392
*} "elimination of eventually quantifiers"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   393
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   394
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   395
subsubsection {* Finer-than relation *}
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   396
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   397
text {* @{term "F \<le> F'"} means that filter @{term F} is finer than
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   398
filter @{term F'}. *}
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   399
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   400
instantiation filter :: (type) complete_lattice
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   401
begin
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   402
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   403
definition le_filter_def:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   404
  "F \<le> F' \<longleftrightarrow> (\<forall>P. eventually P F' \<longrightarrow> eventually P F)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   405
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   406
definition
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   407
  "(F :: 'a filter) < F' \<longleftrightarrow> F \<le> F' \<and> \<not> F' \<le> F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   408
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   409
definition
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   410
  "top = Abs_filter (\<lambda>P. \<forall>x. P x)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   411
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   412
definition
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   413
  "bot = Abs_filter (\<lambda>P. True)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   414
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   415
definition
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   416
  "sup F F' = Abs_filter (\<lambda>P. eventually P F \<and> eventually P F')"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   417
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   418
definition
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   419
  "inf F F' = Abs_filter
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   420
      (\<lambda>P. \<exists>Q R. eventually Q F \<and> eventually R F' \<and> (\<forall>x. Q x \<and> R x \<longrightarrow> P x))"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   421
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   422
definition
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   423
  "Sup S = Abs_filter (\<lambda>P. \<forall>F\<in>S. eventually P F)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   424
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   425
definition
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   426
  "Inf S = Sup {F::'a filter. \<forall>F'\<in>S. F \<le> F'}"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   427
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   428
lemma eventually_top [simp]: "eventually P top \<longleftrightarrow> (\<forall>x. P x)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   429
  unfolding top_filter_def
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   430
  by (rule eventually_Abs_filter, rule is_filter.intro, auto)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   431
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   432
lemma eventually_bot [simp]: "eventually P bot"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   433
  unfolding bot_filter_def
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   434
  by (subst eventually_Abs_filter, rule is_filter.intro, auto)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   435
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   436
lemma eventually_sup:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   437
  "eventually P (sup F F') \<longleftrightarrow> eventually P F \<and> eventually P F'"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   438
  unfolding sup_filter_def
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   439
  by (rule eventually_Abs_filter, rule is_filter.intro)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   440
     (auto elim!: eventually_rev_mp)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   441
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   442
lemma eventually_inf:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   443
  "eventually P (inf F F') \<longleftrightarrow>
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   444
   (\<exists>Q R. eventually Q F \<and> eventually R F' \<and> (\<forall>x. Q x \<and> R x \<longrightarrow> P x))"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   445
  unfolding inf_filter_def
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   446
  apply (rule eventually_Abs_filter, rule is_filter.intro)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   447
  apply (fast intro: eventually_True)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   448
  apply clarify
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   449
  apply (intro exI conjI)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   450
  apply (erule (1) eventually_conj)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   451
  apply (erule (1) eventually_conj)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   452
  apply simp
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   453
  apply auto
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   454
  done
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   455
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   456
lemma eventually_Sup:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   457
  "eventually P (Sup S) \<longleftrightarrow> (\<forall>F\<in>S. eventually P F)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   458
  unfolding Sup_filter_def
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   459
  apply (rule eventually_Abs_filter, rule is_filter.intro)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   460
  apply (auto intro: eventually_conj elim!: eventually_rev_mp)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   461
  done
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   462
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   463
instance proof
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   464
  fix F F' F'' :: "'a filter" and S :: "'a filter set"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   465
  { show "F < F' \<longleftrightarrow> F \<le> F' \<and> \<not> F' \<le> F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   466
    by (rule less_filter_def) }
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   467
  { show "F \<le> F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   468
    unfolding le_filter_def by simp }
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   469
  { assume "F \<le> F'" and "F' \<le> F''" thus "F \<le> F''"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   470
    unfolding le_filter_def by simp }
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   471
  { assume "F \<le> F'" and "F' \<le> F" thus "F = F'"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   472
    unfolding le_filter_def filter_eq_iff by fast }
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   473
  { show "F \<le> top"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   474
    unfolding le_filter_def eventually_top by (simp add: always_eventually) }
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   475
  { show "bot \<le> F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   476
    unfolding le_filter_def by simp }
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   477
  { show "F \<le> sup F F'" and "F' \<le> sup F F'"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   478
    unfolding le_filter_def eventually_sup by simp_all }
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   479
  { assume "F \<le> F''" and "F' \<le> F''" thus "sup F F' \<le> F''"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   480
    unfolding le_filter_def eventually_sup by simp }
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   481
  { show "inf F F' \<le> F" and "inf F F' \<le> F'"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   482
    unfolding le_filter_def eventually_inf by (auto intro: eventually_True) }
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   483
  { assume "F \<le> F'" and "F \<le> F''" thus "F \<le> inf F' F''"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   484
    unfolding le_filter_def eventually_inf
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   485
    by (auto elim!: eventually_mono intro: eventually_conj) }
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   486
  { assume "F \<in> S" thus "F \<le> Sup S"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   487
    unfolding le_filter_def eventually_Sup by simp }
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   488
  { assume "\<And>F. F \<in> S \<Longrightarrow> F \<le> F'" thus "Sup S \<le> F'"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   489
    unfolding le_filter_def eventually_Sup by simp }
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   490
  { assume "F'' \<in> S" thus "Inf S \<le> F''"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   491
    unfolding le_filter_def Inf_filter_def eventually_Sup Ball_def by simp }
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   492
  { assume "\<And>F'. F' \<in> S \<Longrightarrow> F \<le> F'" thus "F \<le> Inf S"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   493
    unfolding le_filter_def Inf_filter_def eventually_Sup Ball_def by simp }
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   494
qed
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   495
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   496
end
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   497
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   498
lemma filter_leD:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   499
  "F \<le> F' \<Longrightarrow> eventually P F' \<Longrightarrow> eventually P F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   500
  unfolding le_filter_def by simp
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   501
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   502
lemma filter_leI:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   503
  "(\<And>P. eventually P F' \<Longrightarrow> eventually P F) \<Longrightarrow> F \<le> F'"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   504
  unfolding le_filter_def by simp
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   505
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   506
lemma eventually_False:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   507
  "eventually (\<lambda>x. False) F \<longleftrightarrow> F = bot"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   508
  unfolding filter_eq_iff by (auto elim: eventually_rev_mp)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   509
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   510
abbreviation (input) trivial_limit :: "'a filter \<Rightarrow> bool"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   511
  where "trivial_limit F \<equiv> F = bot"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   512
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   513
lemma trivial_limit_def: "trivial_limit F \<longleftrightarrow> eventually (\<lambda>x. False) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   514
  by (rule eventually_False [symmetric])
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   515
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   516
lemma eventually_const: "\<not> trivial_limit net \<Longrightarrow> eventually (\<lambda>x. P) net \<longleftrightarrow> P"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   517
  by (cases P) (simp_all add: eventually_False)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   518
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   519
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   520
subsubsection {* Map function for filters *}
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   521
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   522
definition filtermap :: "('a \<Rightarrow> 'b) \<Rightarrow> 'a filter \<Rightarrow> 'b filter"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   523
  where "filtermap f F = Abs_filter (\<lambda>P. eventually (\<lambda>x. P (f x)) F)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   524
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   525
lemma eventually_filtermap:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   526
  "eventually P (filtermap f F) = eventually (\<lambda>x. P (f x)) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   527
  unfolding filtermap_def
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   528
  apply (rule eventually_Abs_filter)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   529
  apply (rule is_filter.intro)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   530
  apply (auto elim!: eventually_rev_mp)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   531
  done
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   532
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   533
lemma filtermap_ident: "filtermap (\<lambda>x. x) F = F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   534
  by (simp add: filter_eq_iff eventually_filtermap)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   535
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   536
lemma filtermap_filtermap:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   537
  "filtermap f (filtermap g F) = filtermap (\<lambda>x. f (g x)) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   538
  by (simp add: filter_eq_iff eventually_filtermap)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   539
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   540
lemma filtermap_mono: "F \<le> F' \<Longrightarrow> filtermap f F \<le> filtermap f F'"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   541
  unfolding le_filter_def eventually_filtermap by simp
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   542
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   543
lemma filtermap_bot [simp]: "filtermap f bot = bot"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   544
  by (simp add: filter_eq_iff eventually_filtermap)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   545
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   546
lemma filtermap_sup: "filtermap f (sup F1 F2) = sup (filtermap f F1) (filtermap f F2)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   547
  by (auto simp: filter_eq_iff eventually_filtermap eventually_sup)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   548
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   549
subsubsection {* Order filters *}
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   550
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   551
definition at_top :: "('a::order) filter"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   552
  where "at_top = Abs_filter (\<lambda>P. \<exists>k. \<forall>n\<ge>k. P n)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   553
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   554
lemma eventually_at_top_linorder: "eventually P at_top \<longleftrightarrow> (\<exists>N::'a::linorder. \<forall>n\<ge>N. P n)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   555
  unfolding at_top_def
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   556
proof (rule eventually_Abs_filter, rule is_filter.intro)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   557
  fix P Q :: "'a \<Rightarrow> bool"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   558
  assume "\<exists>i. \<forall>n\<ge>i. P n" and "\<exists>j. \<forall>n\<ge>j. Q n"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   559
  then obtain i j where "\<forall>n\<ge>i. P n" and "\<forall>n\<ge>j. Q n" by auto
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   560
  then have "\<forall>n\<ge>max i j. P n \<and> Q n" by simp
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   561
  then show "\<exists>k. \<forall>n\<ge>k. P n \<and> Q n" ..
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   562
qed auto
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   563
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   564
lemma eventually_ge_at_top:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   565
  "eventually (\<lambda>x. (c::_::linorder) \<le> x) at_top"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   566
  unfolding eventually_at_top_linorder by auto
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   567
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   568
lemma eventually_at_top_dense: "eventually P at_top \<longleftrightarrow> (\<exists>N::'a::dense_linorder. \<forall>n>N. P n)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   569
  unfolding eventually_at_top_linorder
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   570
proof safe
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   571
  fix N assume "\<forall>n\<ge>N. P n" then show "\<exists>N. \<forall>n>N. P n" by (auto intro!: exI[of _ N])
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   572
next
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   573
  fix N assume "\<forall>n>N. P n"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   574
  moreover from gt_ex[of N] guess y ..
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   575
  ultimately show "\<exists>N. \<forall>n\<ge>N. P n" by (auto intro!: exI[of _ y])
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   576
qed
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   577
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   578
lemma eventually_gt_at_top:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   579
  "eventually (\<lambda>x. (c::_::dense_linorder) < x) at_top"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   580
  unfolding eventually_at_top_dense by auto
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   581
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   582
definition at_bot :: "('a::order) filter"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   583
  where "at_bot = Abs_filter (\<lambda>P. \<exists>k. \<forall>n\<le>k. P n)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   584
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   585
lemma eventually_at_bot_linorder:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   586
  fixes P :: "'a::linorder \<Rightarrow> bool" shows "eventually P at_bot \<longleftrightarrow> (\<exists>N. \<forall>n\<le>N. P n)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   587
  unfolding at_bot_def
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   588
proof (rule eventually_Abs_filter, rule is_filter.intro)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   589
  fix P Q :: "'a \<Rightarrow> bool"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   590
  assume "\<exists>i. \<forall>n\<le>i. P n" and "\<exists>j. \<forall>n\<le>j. Q n"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   591
  then obtain i j where "\<forall>n\<le>i. P n" and "\<forall>n\<le>j. Q n" by auto
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   592
  then have "\<forall>n\<le>min i j. P n \<and> Q n" by simp
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   593
  then show "\<exists>k. \<forall>n\<le>k. P n \<and> Q n" ..
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   594
qed auto
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   595
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   596
lemma eventually_le_at_bot:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   597
  "eventually (\<lambda>x. x \<le> (c::_::linorder)) at_bot"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   598
  unfolding eventually_at_bot_linorder by auto
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   599
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   600
lemma eventually_at_bot_dense:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   601
  fixes P :: "'a::dense_linorder \<Rightarrow> bool" shows "eventually P at_bot \<longleftrightarrow> (\<exists>N. \<forall>n<N. P n)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   602
  unfolding eventually_at_bot_linorder
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   603
proof safe
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   604
  fix N assume "\<forall>n\<le>N. P n" then show "\<exists>N. \<forall>n<N. P n" by (auto intro!: exI[of _ N])
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   605
next
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   606
  fix N assume "\<forall>n<N. P n" 
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   607
  moreover from lt_ex[of N] guess y ..
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   608
  ultimately show "\<exists>N. \<forall>n\<le>N. P n" by (auto intro!: exI[of _ y])
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   609
qed
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   610
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   611
lemma eventually_gt_at_bot:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   612
  "eventually (\<lambda>x. x < (c::_::dense_linorder)) at_bot"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   613
  unfolding eventually_at_bot_dense by auto
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   614
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   615
subsection {* Sequentially *}
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   616
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   617
abbreviation sequentially :: "nat filter"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   618
  where "sequentially == at_top"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   619
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   620
lemma sequentially_def: "sequentially = Abs_filter (\<lambda>P. \<exists>k. \<forall>n\<ge>k. P n)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   621
  unfolding at_top_def by simp
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   622
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   623
lemma eventually_sequentially:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   624
  "eventually P sequentially \<longleftrightarrow> (\<exists>N. \<forall>n\<ge>N. P n)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   625
  by (rule eventually_at_top_linorder)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   626
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   627
lemma sequentially_bot [simp, intro]: "sequentially \<noteq> bot"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   628
  unfolding filter_eq_iff eventually_sequentially by auto
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   629
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   630
lemmas trivial_limit_sequentially = sequentially_bot
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   631
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   632
lemma eventually_False_sequentially [simp]:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   633
  "\<not> eventually (\<lambda>n. False) sequentially"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   634
  by (simp add: eventually_False)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   635
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   636
lemma le_sequentially:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   637
  "F \<le> sequentially \<longleftrightarrow> (\<forall>N. eventually (\<lambda>n. N \<le> n) F)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   638
  unfolding le_filter_def eventually_sequentially
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   639
  by (safe, fast, drule_tac x=N in spec, auto elim: eventually_rev_mp)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   640
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   641
lemma eventually_sequentiallyI:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   642
  assumes "\<And>x. c \<le> x \<Longrightarrow> P x"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   643
  shows "eventually P sequentially"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   644
using assms by (auto simp: eventually_sequentially)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   645
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   646
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   647
subsubsection {* Standard filters *}
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   648
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   649
definition within :: "'a filter \<Rightarrow> 'a set \<Rightarrow> 'a filter" (infixr "within" 70)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   650
  where "F within S = Abs_filter (\<lambda>P. eventually (\<lambda>x. x \<in> S \<longrightarrow> P x) F)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   651
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   652
lemma eventually_within:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   653
  "eventually P (F within S) = eventually (\<lambda>x. x \<in> S \<longrightarrow> P x) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   654
  unfolding within_def
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   655
  by (rule eventually_Abs_filter, rule is_filter.intro)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   656
     (auto elim!: eventually_rev_mp)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   657
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   658
lemma within_UNIV [simp]: "F within UNIV = F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   659
  unfolding filter_eq_iff eventually_within by simp
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   660
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   661
lemma within_empty [simp]: "F within {} = bot"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   662
  unfolding filter_eq_iff eventually_within by simp
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   663
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   664
lemma within_within_eq: "(F within S) within T = F within (S \<inter> T)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   665
  by (auto simp: filter_eq_iff eventually_within elim: eventually_elim1)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   666
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   667
lemma within_le: "F within S \<le> F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   668
  unfolding le_filter_def eventually_within by (auto elim: eventually_elim1)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   669
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   670
lemma le_withinI: "F \<le> F' \<Longrightarrow> eventually (\<lambda>x. x \<in> S) F \<Longrightarrow> F \<le> F' within S"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   671
  unfolding le_filter_def eventually_within by (auto elim: eventually_elim2)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   672
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   673
lemma le_within_iff: "eventually (\<lambda>x. x \<in> S) F \<Longrightarrow> F \<le> F' within S \<longleftrightarrow> F \<le> F'"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   674
  by (blast intro: within_le le_withinI order_trans)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   675
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   676
subsubsection {* Topological filters *}
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   677
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   678
definition (in topological_space) nhds :: "'a \<Rightarrow> 'a filter"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   679
  where "nhds a = Abs_filter (\<lambda>P. \<exists>S. open S \<and> a \<in> S \<and> (\<forall>x\<in>S. P x))"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   680
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   681
definition (in topological_space) at :: "'a \<Rightarrow> 'a filter"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   682
  where "at a = nhds a within - {a}"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   683
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   684
abbreviation at_right :: "'a\<Colon>{topological_space, order} \<Rightarrow> 'a filter" where
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   685
  "at_right x \<equiv> at x within {x <..}"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   686
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   687
abbreviation at_left :: "'a\<Colon>{topological_space, order} \<Rightarrow> 'a filter" where
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   688
  "at_left x \<equiv> at x within {..< x}"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   689
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   690
lemma eventually_nhds:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   691
  "eventually P (nhds a) \<longleftrightarrow> (\<exists>S. open S \<and> a \<in> S \<and> (\<forall>x\<in>S. P x))"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   692
  unfolding nhds_def
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   693
proof (rule eventually_Abs_filter, rule is_filter.intro)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   694
  have "open (UNIV :: 'a :: topological_space set) \<and> a \<in> UNIV \<and> (\<forall>x\<in>UNIV. True)" by simp
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   695
  thus "\<exists>S. open S \<and> a \<in> S \<and> (\<forall>x\<in>S. True)" ..
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   696
next
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   697
  fix P Q
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   698
  assume "\<exists>S. open S \<and> a \<in> S \<and> (\<forall>x\<in>S. P x)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   699
     and "\<exists>T. open T \<and> a \<in> T \<and> (\<forall>x\<in>T. Q x)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   700
  then obtain S T where
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   701
    "open S \<and> a \<in> S \<and> (\<forall>x\<in>S. P x)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   702
    "open T \<and> a \<in> T \<and> (\<forall>x\<in>T. Q x)" by auto
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   703
  hence "open (S \<inter> T) \<and> a \<in> S \<inter> T \<and> (\<forall>x\<in>(S \<inter> T). P x \<and> Q x)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   704
    by (simp add: open_Int)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   705
  thus "\<exists>S. open S \<and> a \<in> S \<and> (\<forall>x\<in>S. P x \<and> Q x)" ..
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   706
qed auto
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   707
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   708
lemma nhds_neq_bot [simp]: "nhds a \<noteq> bot"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   709
  unfolding trivial_limit_def eventually_nhds by simp
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   710
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   711
lemma eventually_at_topological:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   712
  "eventually P (at a) \<longleftrightarrow> (\<exists>S. open S \<and> a \<in> S \<and> (\<forall>x\<in>S. x \<noteq> a \<longrightarrow> P x))"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   713
unfolding at_def eventually_within eventually_nhds by simp
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   714
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   715
lemma at_eq_bot_iff: "at a = bot \<longleftrightarrow> open {a}"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   716
  unfolding trivial_limit_def eventually_at_topological
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   717
  by (safe, case_tac "S = {a}", simp, fast, fast)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   718
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   719
lemma at_neq_bot [simp]: "at (a::'a::perfect_space) \<noteq> bot"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   720
  by (simp add: at_eq_bot_iff not_open_singleton)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   721
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   722
lemma eventually_at_right:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   723
  fixes x :: "'a :: {no_top, linorder_topology}"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   724
  shows "eventually P (at_right x) \<longleftrightarrow> (\<exists>b. x < b \<and> (\<forall>z. x < z \<and> z < b \<longrightarrow> P z))"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   725
  unfolding eventually_nhds eventually_within at_def
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   726
proof safe
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   727
  fix S assume "open S" "x \<in> S"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   728
  note open_right[OF this]
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   729
  moreover assume "\<forall>s\<in>S. s \<in> - {x} \<longrightarrow> s \<in> {x<..} \<longrightarrow> P s"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   730
  ultimately show "\<exists>b>x. \<forall>z. x < z \<and> z < b \<longrightarrow> P z"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   731
    by (auto simp: subset_eq Ball_def)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   732
next
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   733
  fix b assume "x < b" "\<forall>z. x < z \<and> z < b \<longrightarrow> P z"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   734
  then show "\<exists>S. open S \<and> x \<in> S \<and> (\<forall>xa\<in>S. xa \<in> - {x} \<longrightarrow> xa \<in> {x<..} \<longrightarrow> P xa)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   735
    by (intro exI[of _ "{..< b}"]) auto
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   736
qed
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   737
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   738
lemma eventually_at_left:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   739
  fixes x :: "'a :: {no_bot, linorder_topology}"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   740
  shows "eventually P (at_left x) \<longleftrightarrow> (\<exists>b. x > b \<and> (\<forall>z. b < z \<and> z < x \<longrightarrow> P z))"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   741
  unfolding eventually_nhds eventually_within at_def
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   742
proof safe
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   743
  fix S assume "open S" "x \<in> S"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   744
  note open_left[OF this]
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   745
  moreover assume "\<forall>s\<in>S. s \<in> - {x} \<longrightarrow> s \<in> {..<x} \<longrightarrow> P s"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   746
  ultimately show "\<exists>b<x. \<forall>z. b < z \<and> z < x \<longrightarrow> P z"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   747
    by (auto simp: subset_eq Ball_def)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   748
next
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   749
  fix b assume "b < x" "\<forall>z. b < z \<and> z < x \<longrightarrow> P z"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   750
  then show "\<exists>S. open S \<and> x \<in> S \<and> (\<forall>xa\<in>S. xa \<in> - {x} \<longrightarrow> xa \<in> {..<x} \<longrightarrow> P xa)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   751
    by (intro exI[of _ "{b <..}"]) auto
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   752
qed
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   753
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   754
lemma trivial_limit_at_left_real [simp]:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   755
  "\<not> trivial_limit (at_left (x::'a::{no_bot, dense_linorder, linorder_topology}))"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   756
  unfolding trivial_limit_def eventually_at_left by (auto dest: dense)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   757
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   758
lemma trivial_limit_at_right_real [simp]:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   759
  "\<not> trivial_limit (at_right (x::'a::{no_top, dense_linorder, linorder_topology}))"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   760
  unfolding trivial_limit_def eventually_at_right by (auto dest: dense)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   761
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   762
lemma at_within_eq: "at x within T = nhds x within (T - {x})"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   763
  unfolding at_def within_within_eq by (simp add: ac_simps Diff_eq)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   764
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   765
lemma at_eq_sup_left_right: "at (x::'a::linorder_topology) = sup (at_left x) (at_right x)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   766
  by (auto simp: eventually_within at_def filter_eq_iff eventually_sup 
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   767
           elim: eventually_elim2 eventually_elim1)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   768
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   769
lemma eventually_at_split:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   770
  "eventually P (at (x::'a::linorder_topology)) \<longleftrightarrow> eventually P (at_left x) \<and> eventually P (at_right x)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   771
  by (subst at_eq_sup_left_right) (simp add: eventually_sup)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   772
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   773
subsection {* Limits *}
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   774
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   775
definition filterlim :: "('a \<Rightarrow> 'b) \<Rightarrow> 'b filter \<Rightarrow> 'a filter \<Rightarrow> bool" where
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   776
  "filterlim f F2 F1 \<longleftrightarrow> filtermap f F1 \<le> F2"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   777
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   778
syntax
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   779
  "_LIM" :: "pttrns \<Rightarrow> 'a \<Rightarrow> 'b \<Rightarrow> 'a \<Rightarrow> bool" ("(3LIM (_)/ (_)./ (_) :> (_))" [1000, 10, 0, 10] 10)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   780
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   781
translations
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   782
  "LIM x F1. f :> F2"   == "CONST filterlim (%x. f) F2 F1"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   783
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   784
lemma filterlim_iff:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   785
  "(LIM x F1. f x :> F2) \<longleftrightarrow> (\<forall>P. eventually P F2 \<longrightarrow> eventually (\<lambda>x. P (f x)) F1)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   786
  unfolding filterlim_def le_filter_def eventually_filtermap ..
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   787
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   788
lemma filterlim_compose:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   789
  "filterlim g F3 F2 \<Longrightarrow> filterlim f F2 F1 \<Longrightarrow> filterlim (\<lambda>x. g (f x)) F3 F1"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   790
  unfolding filterlim_def filtermap_filtermap[symmetric] by (metis filtermap_mono order_trans)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   791
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   792
lemma filterlim_mono:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   793
  "filterlim f F2 F1 \<Longrightarrow> F2 \<le> F2' \<Longrightarrow> F1' \<le> F1 \<Longrightarrow> filterlim f F2' F1'"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   794
  unfolding filterlim_def by (metis filtermap_mono order_trans)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   795
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   796
lemma filterlim_ident: "LIM x F. x :> F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   797
  by (simp add: filterlim_def filtermap_ident)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   798
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   799
lemma filterlim_cong:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   800
  "F1 = F1' \<Longrightarrow> F2 = F2' \<Longrightarrow> eventually (\<lambda>x. f x = g x) F2 \<Longrightarrow> filterlim f F1 F2 = filterlim g F1' F2'"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   801
  by (auto simp: filterlim_def le_filter_def eventually_filtermap elim: eventually_elim2)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   802
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   803
lemma filterlim_within:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   804
  "(LIM x F1. f x :> F2 within S) \<longleftrightarrow> (eventually (\<lambda>x. f x \<in> S) F1 \<and> (LIM x F1. f x :> F2))"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   805
  unfolding filterlim_def
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   806
proof safe
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   807
  assume "filtermap f F1 \<le> F2 within S" then show "eventually (\<lambda>x. f x \<in> S) F1"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   808
    by (auto simp: le_filter_def eventually_filtermap eventually_within elim!: allE[of _ "\<lambda>x. x \<in> S"])
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   809
qed (auto intro: within_le order_trans simp: le_within_iff eventually_filtermap)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   810
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   811
lemma filterlim_filtermap: "filterlim f F1 (filtermap g F2) = filterlim (\<lambda>x. f (g x)) F1 F2"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   812
  unfolding filterlim_def filtermap_filtermap ..
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   813
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   814
lemma filterlim_sup:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   815
  "filterlim f F F1 \<Longrightarrow> filterlim f F F2 \<Longrightarrow> filterlim f F (sup F1 F2)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   816
  unfolding filterlim_def filtermap_sup by auto
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   817
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   818
lemma filterlim_Suc: "filterlim Suc sequentially sequentially"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   819
  by (simp add: filterlim_iff eventually_sequentially) (metis le_Suc_eq)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   820
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   821
subsubsection {* Tendsto *}
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   822
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   823
abbreviation (in topological_space)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   824
  tendsto :: "('b \<Rightarrow> 'a) \<Rightarrow> 'a \<Rightarrow> 'b filter \<Rightarrow> bool" (infixr "--->" 55) where
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   825
  "(f ---> l) F \<equiv> filterlim f (nhds l) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   826
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   827
lemma tendsto_eq_rhs: "(f ---> x) F \<Longrightarrow> x = y \<Longrightarrow> (f ---> y) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   828
  by simp
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   829
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   830
ML {*
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   831
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   832
structure Tendsto_Intros = Named_Thms
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   833
(
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   834
  val name = @{binding tendsto_intros}
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   835
  val description = "introduction rules for tendsto"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   836
)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   837
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   838
*}
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   839
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   840
setup {*
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   841
  Tendsto_Intros.setup #>
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   842
  Global_Theory.add_thms_dynamic (@{binding tendsto_eq_intros},
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   843
    map (fn thm => @{thm tendsto_eq_rhs} OF [thm]) o Tendsto_Intros.get o Context.proof_of);
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   844
*}
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   845
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   846
lemma tendsto_def: "(f ---> l) F \<longleftrightarrow> (\<forall>S. open S \<longrightarrow> l \<in> S \<longrightarrow> eventually (\<lambda>x. f x \<in> S) F)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   847
  unfolding filterlim_def
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   848
proof safe
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   849
  fix S assume "open S" "l \<in> S" "filtermap f F \<le> nhds l"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   850
  then show "eventually (\<lambda>x. f x \<in> S) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   851
    unfolding eventually_nhds eventually_filtermap le_filter_def
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   852
    by (auto elim!: allE[of _ "\<lambda>x. x \<in> S"] eventually_rev_mp)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   853
qed (auto elim!: eventually_rev_mp simp: eventually_nhds eventually_filtermap le_filter_def)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   854
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   855
lemma filterlim_at:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   856
  "(LIM x F. f x :> at b) \<longleftrightarrow> (eventually (\<lambda>x. f x \<noteq> b) F \<and> (f ---> b) F)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   857
  by (simp add: at_def filterlim_within)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   858
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   859
lemma tendsto_mono: "F \<le> F' \<Longrightarrow> (f ---> l) F' \<Longrightarrow> (f ---> l) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   860
  unfolding tendsto_def le_filter_def by fast
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   861
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   862
lemma topological_tendstoI:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   863
  "(\<And>S. open S \<Longrightarrow> l \<in> S \<Longrightarrow> eventually (\<lambda>x. f x \<in> S) F)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   864
    \<Longrightarrow> (f ---> l) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   865
  unfolding tendsto_def by auto
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   866
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   867
lemma topological_tendstoD:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   868
  "(f ---> l) F \<Longrightarrow> open S \<Longrightarrow> l \<in> S \<Longrightarrow> eventually (\<lambda>x. f x \<in> S) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   869
  unfolding tendsto_def by auto
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   870
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   871
lemma order_tendstoI:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   872
  fixes y :: "_ :: order_topology"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   873
  assumes "\<And>a. a < y \<Longrightarrow> eventually (\<lambda>x. a < f x) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   874
  assumes "\<And>a. y < a \<Longrightarrow> eventually (\<lambda>x. f x < a) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   875
  shows "(f ---> y) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   876
proof (rule topological_tendstoI)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   877
  fix S assume "open S" "y \<in> S"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   878
  then show "eventually (\<lambda>x. f x \<in> S) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   879
    unfolding open_generated_order
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   880
  proof induct
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   881
    case (UN K)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   882
    then obtain k where "y \<in> k" "k \<in> K" by auto
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   883
    with UN(2)[of k] show ?case
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   884
      by (auto elim: eventually_elim1)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   885
  qed (insert assms, auto elim: eventually_elim2)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   886
qed
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   887
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   888
lemma order_tendstoD:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   889
  fixes y :: "_ :: order_topology"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   890
  assumes y: "(f ---> y) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   891
  shows "a < y \<Longrightarrow> eventually (\<lambda>x. a < f x) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   892
    and "y < a \<Longrightarrow> eventually (\<lambda>x. f x < a) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   893
  using topological_tendstoD[OF y, of "{..< a}"] topological_tendstoD[OF y, of "{a <..}"] by auto
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   894
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   895
lemma order_tendsto_iff: 
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   896
  fixes f :: "_ \<Rightarrow> 'a :: order_topology"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   897
  shows "(f ---> x) F \<longleftrightarrow>(\<forall>l<x. eventually (\<lambda>x. l < f x) F) \<and> (\<forall>u>x. eventually (\<lambda>x. f x < u) F)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   898
  by (metis order_tendstoI order_tendstoD)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   899
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   900
lemma tendsto_bot [simp]: "(f ---> a) bot"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   901
  unfolding tendsto_def by simp
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   902
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   903
lemma tendsto_ident_at [tendsto_intros]: "((\<lambda>x. x) ---> a) (at a)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   904
  unfolding tendsto_def eventually_at_topological by auto
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   905
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   906
lemma tendsto_ident_at_within [tendsto_intros]:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   907
  "((\<lambda>x. x) ---> a) (at a within S)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   908
  unfolding tendsto_def eventually_within eventually_at_topological by auto
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   909
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   910
lemma tendsto_const [tendsto_intros]: "((\<lambda>x. k) ---> k) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   911
  by (simp add: tendsto_def)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   912
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   913
lemma tendsto_unique:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   914
  fixes f :: "'a \<Rightarrow> 'b::t2_space"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   915
  assumes "\<not> trivial_limit F" and "(f ---> a) F" and "(f ---> b) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   916
  shows "a = b"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   917
proof (rule ccontr)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   918
  assume "a \<noteq> b"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   919
  obtain U V where "open U" "open V" "a \<in> U" "b \<in> V" "U \<inter> V = {}"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   920
    using hausdorff [OF `a \<noteq> b`] by fast
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   921
  have "eventually (\<lambda>x. f x \<in> U) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   922
    using `(f ---> a) F` `open U` `a \<in> U` by (rule topological_tendstoD)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   923
  moreover
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   924
  have "eventually (\<lambda>x. f x \<in> V) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   925
    using `(f ---> b) F` `open V` `b \<in> V` by (rule topological_tendstoD)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   926
  ultimately
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   927
  have "eventually (\<lambda>x. False) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   928
  proof eventually_elim
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   929
    case (elim x)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   930
    hence "f x \<in> U \<inter> V" by simp
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   931
    with `U \<inter> V = {}` show ?case by simp
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   932
  qed
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   933
  with `\<not> trivial_limit F` show "False"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   934
    by (simp add: trivial_limit_def)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   935
qed
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   936
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   937
lemma tendsto_const_iff:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   938
  fixes a b :: "'a::t2_space"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   939
  assumes "\<not> trivial_limit F" shows "((\<lambda>x. a) ---> b) F \<longleftrightarrow> a = b"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   940
  by (safe intro!: tendsto_const tendsto_unique [OF assms tendsto_const])
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   941
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   942
lemma increasing_tendsto:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   943
  fixes f :: "_ \<Rightarrow> 'a::order_topology"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   944
  assumes bdd: "eventually (\<lambda>n. f n \<le> l) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   945
      and en: "\<And>x. x < l \<Longrightarrow> eventually (\<lambda>n. x < f n) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   946
  shows "(f ---> l) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   947
  using assms by (intro order_tendstoI) (auto elim!: eventually_elim1)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   948
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   949
lemma decreasing_tendsto:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   950
  fixes f :: "_ \<Rightarrow> 'a::order_topology"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   951
  assumes bdd: "eventually (\<lambda>n. l \<le> f n) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   952
      and en: "\<And>x. l < x \<Longrightarrow> eventually (\<lambda>n. f n < x) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   953
  shows "(f ---> l) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   954
  using assms by (intro order_tendstoI) (auto elim!: eventually_elim1)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   955
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   956
lemma tendsto_sandwich:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   957
  fixes f g h :: "'a \<Rightarrow> 'b::order_topology"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   958
  assumes ev: "eventually (\<lambda>n. f n \<le> g n) net" "eventually (\<lambda>n. g n \<le> h n) net"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   959
  assumes lim: "(f ---> c) net" "(h ---> c) net"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   960
  shows "(g ---> c) net"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   961
proof (rule order_tendstoI)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   962
  fix a show "a < c \<Longrightarrow> eventually (\<lambda>x. a < g x) net"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   963
    using order_tendstoD[OF lim(1), of a] ev by (auto elim: eventually_elim2)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   964
next
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   965
  fix a show "c < a \<Longrightarrow> eventually (\<lambda>x. g x < a) net"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   966
    using order_tendstoD[OF lim(2), of a] ev by (auto elim: eventually_elim2)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   967
qed
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   968
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   969
lemma tendsto_le:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   970
  fixes f g :: "'a \<Rightarrow> 'b::linorder_topology"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   971
  assumes F: "\<not> trivial_limit F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   972
  assumes x: "(f ---> x) F" and y: "(g ---> y) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   973
  assumes ev: "eventually (\<lambda>x. g x \<le> f x) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   974
  shows "y \<le> x"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   975
proof (rule ccontr)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   976
  assume "\<not> y \<le> x"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   977
  with less_separate[of x y] obtain a b where xy: "x < a" "b < y" "{..<a} \<inter> {b<..} = {}"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   978
    by (auto simp: not_le)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   979
  then have "eventually (\<lambda>x. f x < a) F" "eventually (\<lambda>x. b < g x) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   980
    using x y by (auto intro: order_tendstoD)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   981
  with ev have "eventually (\<lambda>x. False) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   982
    by eventually_elim (insert xy, fastforce)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   983
  with F show False
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   984
    by (simp add: eventually_False)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   985
qed
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   986
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   987
lemma tendsto_le_const:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   988
  fixes f :: "'a \<Rightarrow> 'b::linorder_topology"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   989
  assumes F: "\<not> trivial_limit F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   990
  assumes x: "(f ---> x) F" and a: "eventually (\<lambda>x. a \<le> f x) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   991
  shows "a \<le> x"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   992
  using F x tendsto_const a by (rule tendsto_le)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   993
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   994
subsection {* Limits to @{const at_top} and @{const at_bot} *}
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   995
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   996
lemma filterlim_at_top:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   997
  fixes f :: "'a \<Rightarrow> ('b::linorder)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   998
  shows "(LIM x F. f x :> at_top) \<longleftrightarrow> (\<forall>Z. eventually (\<lambda>x. Z \<le> f x) F)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
   999
  by (auto simp: filterlim_iff eventually_at_top_linorder elim!: eventually_elim1)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1000
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1001
lemma filterlim_at_top_dense:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1002
  fixes f :: "'a \<Rightarrow> ('b::dense_linorder)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1003
  shows "(LIM x F. f x :> at_top) \<longleftrightarrow> (\<forall>Z. eventually (\<lambda>x. Z < f x) F)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1004
  by (metis eventually_elim1[of _ F] eventually_gt_at_top order_less_imp_le
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1005
            filterlim_at_top[of f F] filterlim_iff[of f at_top F])
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1006
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1007
lemma filterlim_at_top_ge:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1008
  fixes f :: "'a \<Rightarrow> ('b::linorder)" and c :: "'b"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1009
  shows "(LIM x F. f x :> at_top) \<longleftrightarrow> (\<forall>Z\<ge>c. eventually (\<lambda>x. Z \<le> f x) F)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1010
  unfolding filterlim_at_top
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1011
proof safe
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1012
  fix Z assume *: "\<forall>Z\<ge>c. eventually (\<lambda>x. Z \<le> f x) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1013
  with *[THEN spec, of "max Z c"] show "eventually (\<lambda>x. Z \<le> f x) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1014
    by (auto elim!: eventually_elim1)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1015
qed simp
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1016
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1017
lemma filterlim_at_top_at_top:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1018
  fixes f :: "'a::linorder \<Rightarrow> 'b::linorder"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1019
  assumes mono: "\<And>x y. Q x \<Longrightarrow> Q y \<Longrightarrow> x \<le> y \<Longrightarrow> f x \<le> f y"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1020
  assumes bij: "\<And>x. P x \<Longrightarrow> f (g x) = x" "\<And>x. P x \<Longrightarrow> Q (g x)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1021
  assumes Q: "eventually Q at_top"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1022
  assumes P: "eventually P at_top"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1023
  shows "filterlim f at_top at_top"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1024
proof -
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1025
  from P obtain x where x: "\<And>y. x \<le> y \<Longrightarrow> P y"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1026
    unfolding eventually_at_top_linorder by auto
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1027
  show ?thesis
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1028
  proof (intro filterlim_at_top_ge[THEN iffD2] allI impI)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1029
    fix z assume "x \<le> z"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1030
    with x have "P z" by auto
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1031
    have "eventually (\<lambda>x. g z \<le> x) at_top"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1032
      by (rule eventually_ge_at_top)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1033
    with Q show "eventually (\<lambda>x. z \<le> f x) at_top"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1034
      by eventually_elim (metis mono bij `P z`)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1035
  qed
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1036
qed
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1037
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1038
lemma filterlim_at_top_gt:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1039
  fixes f :: "'a \<Rightarrow> ('b::dense_linorder)" and c :: "'b"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1040
  shows "(LIM x F. f x :> at_top) \<longleftrightarrow> (\<forall>Z>c. eventually (\<lambda>x. Z \<le> f x) F)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1041
  by (metis filterlim_at_top order_less_le_trans gt_ex filterlim_at_top_ge)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1042
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1043
lemma filterlim_at_bot: 
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1044
  fixes f :: "'a \<Rightarrow> ('b::linorder)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1045
  shows "(LIM x F. f x :> at_bot) \<longleftrightarrow> (\<forall>Z. eventually (\<lambda>x. f x \<le> Z) F)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1046
  by (auto simp: filterlim_iff eventually_at_bot_linorder elim!: eventually_elim1)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1047
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1048
lemma filterlim_at_bot_le:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1049
  fixes f :: "'a \<Rightarrow> ('b::linorder)" and c :: "'b"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1050
  shows "(LIM x F. f x :> at_bot) \<longleftrightarrow> (\<forall>Z\<le>c. eventually (\<lambda>x. Z \<ge> f x) F)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1051
  unfolding filterlim_at_bot
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1052
proof safe
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1053
  fix Z assume *: "\<forall>Z\<le>c. eventually (\<lambda>x. Z \<ge> f x) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1054
  with *[THEN spec, of "min Z c"] show "eventually (\<lambda>x. Z \<ge> f x) F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1055
    by (auto elim!: eventually_elim1)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1056
qed simp
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1057
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1058
lemma filterlim_at_bot_lt:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1059
  fixes f :: "'a \<Rightarrow> ('b::dense_linorder)" and c :: "'b"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1060
  shows "(LIM x F. f x :> at_bot) \<longleftrightarrow> (\<forall>Z<c. eventually (\<lambda>x. Z \<ge> f x) F)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1061
  by (metis filterlim_at_bot filterlim_at_bot_le lt_ex order_le_less_trans)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1062
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1063
lemma filterlim_at_bot_at_right:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1064
  fixes f :: "'a::{no_top, linorder_topology} \<Rightarrow> 'b::linorder"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1065
  assumes mono: "\<And>x y. Q x \<Longrightarrow> Q y \<Longrightarrow> x \<le> y \<Longrightarrow> f x \<le> f y"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1066
  assumes bij: "\<And>x. P x \<Longrightarrow> f (g x) = x" "\<And>x. P x \<Longrightarrow> Q (g x)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1067
  assumes Q: "eventually Q (at_right a)" and bound: "\<And>b. Q b \<Longrightarrow> a < b"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1068
  assumes P: "eventually P at_bot"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1069
  shows "filterlim f at_bot (at_right a)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1070
proof -
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1071
  from P obtain x where x: "\<And>y. y \<le> x \<Longrightarrow> P y"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1072
    unfolding eventually_at_bot_linorder by auto
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1073
  show ?thesis
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1074
  proof (intro filterlim_at_bot_le[THEN iffD2] allI impI)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1075
    fix z assume "z \<le> x"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1076
    with x have "P z" by auto
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1077
    have "eventually (\<lambda>x. x \<le> g z) (at_right a)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1078
      using bound[OF bij(2)[OF `P z`]]
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1079
      unfolding eventually_at_right by (auto intro!: exI[of _ "g z"])
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1080
    with Q show "eventually (\<lambda>x. f x \<le> z) (at_right a)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1081
      by eventually_elim (metis bij `P z` mono)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1082
  qed
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1083
qed
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1084
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1085
lemma filterlim_at_top_at_left:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1086
  fixes f :: "'a::{no_bot, linorder_topology} \<Rightarrow> 'b::linorder"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1087
  assumes mono: "\<And>x y. Q x \<Longrightarrow> Q y \<Longrightarrow> x \<le> y \<Longrightarrow> f x \<le> f y"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1088
  assumes bij: "\<And>x. P x \<Longrightarrow> f (g x) = x" "\<And>x. P x \<Longrightarrow> Q (g x)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1089
  assumes Q: "eventually Q (at_left a)" and bound: "\<And>b. Q b \<Longrightarrow> b < a"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1090
  assumes P: "eventually P at_top"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1091
  shows "filterlim f at_top (at_left a)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1092
proof -
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1093
  from P obtain x where x: "\<And>y. x \<le> y \<Longrightarrow> P y"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1094
    unfolding eventually_at_top_linorder by auto
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1095
  show ?thesis
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1096
  proof (intro filterlim_at_top_ge[THEN iffD2] allI impI)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1097
    fix z assume "x \<le> z"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1098
    with x have "P z" by auto
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1099
    have "eventually (\<lambda>x. g z \<le> x) (at_left a)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1100
      using bound[OF bij(2)[OF `P z`]]
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1101
      unfolding eventually_at_left by (auto intro!: exI[of _ "g z"])
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1102
    with Q show "eventually (\<lambda>x. z \<le> f x) (at_left a)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1103
      by eventually_elim (metis bij `P z` mono)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1104
  qed
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1105
qed
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1106
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1107
lemma filterlim_split_at:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1108
  "filterlim f F (at_left x) \<Longrightarrow> filterlim f F (at_right x) \<Longrightarrow> filterlim f F (at (x::'a::linorder_topology))"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1109
  by (subst at_eq_sup_left_right) (rule filterlim_sup)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1110
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1111
lemma filterlim_at_split:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1112
  "filterlim f F (at (x::'a::linorder_topology)) \<longleftrightarrow> filterlim f F (at_left x) \<and> filterlim f F (at_right x)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1113
  by (subst at_eq_sup_left_right) (simp add: filterlim_def filtermap_sup)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1114
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1115
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1116
subsection {* Limits on sequences *}
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1117
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1118
abbreviation (in topological_space)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1119
  LIMSEQ :: "[nat \<Rightarrow> 'a, 'a] \<Rightarrow> bool"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1120
    ("((_)/ ----> (_))" [60, 60] 60) where
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1121
  "X ----> L \<equiv> (X ---> L) sequentially"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1122
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1123
definition
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1124
  lim :: "(nat \<Rightarrow> 'a::t2_space) \<Rightarrow> 'a" where
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1125
    --{*Standard definition of limit using choice operator*}
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1126
  "lim X = (THE L. X ----> L)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1127
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1128
definition (in topological_space) convergent :: "(nat \<Rightarrow> 'a) \<Rightarrow> bool" where
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1129
  "convergent X = (\<exists>L. X ----> L)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1130
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1131
subsubsection {* Monotone sequences and subsequences *}
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1132
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1133
definition
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1134
  monoseq :: "(nat \<Rightarrow> 'a::order) \<Rightarrow> bool" where
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1135
    --{*Definition of monotonicity.
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1136
        The use of disjunction here complicates proofs considerably.
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1137
        One alternative is to add a Boolean argument to indicate the direction.
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1138
        Another is to develop the notions of increasing and decreasing first.*}
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1139
  "monoseq X = ((\<forall>m. \<forall>n\<ge>m. X m \<le> X n) | (\<forall>m. \<forall>n\<ge>m. X n \<le> X m))"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1140
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1141
definition
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1142
  incseq :: "(nat \<Rightarrow> 'a::order) \<Rightarrow> bool" where
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1143
    --{*Increasing sequence*}
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1144
  "incseq X \<longleftrightarrow> (\<forall>m. \<forall>n\<ge>m. X m \<le> X n)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1145
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1146
definition
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1147
  decseq :: "(nat \<Rightarrow> 'a::order) \<Rightarrow> bool" where
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1148
    --{*Decreasing sequence*}
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1149
  "decseq X \<longleftrightarrow> (\<forall>m. \<forall>n\<ge>m. X n \<le> X m)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1150
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1151
definition
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1152
  subseq :: "(nat \<Rightarrow> nat) \<Rightarrow> bool" where
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1153
    --{*Definition of subsequence*}
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1154
  "subseq f \<longleftrightarrow> (\<forall>m. \<forall>n>m. f m < f n)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1155
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1156
lemma incseq_mono: "mono f \<longleftrightarrow> incseq f"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1157
  unfolding mono_def incseq_def by auto
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1158
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1159
lemma incseq_SucI:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1160
  "(\<And>n. X n \<le> X (Suc n)) \<Longrightarrow> incseq X"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1161
  using lift_Suc_mono_le[of X]
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1162
  by (auto simp: incseq_def)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1163
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1164
lemma incseqD: "\<And>i j. incseq f \<Longrightarrow> i \<le> j \<Longrightarrow> f i \<le> f j"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1165
  by (auto simp: incseq_def)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1166
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1167
lemma incseq_SucD: "incseq A \<Longrightarrow> A i \<le> A (Suc i)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1168
  using incseqD[of A i "Suc i"] by auto
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1169
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1170
lemma incseq_Suc_iff: "incseq f \<longleftrightarrow> (\<forall>n. f n \<le> f (Suc n))"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1171
  by (auto intro: incseq_SucI dest: incseq_SucD)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1172
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1173
lemma incseq_const[simp, intro]: "incseq (\<lambda>x. k)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1174
  unfolding incseq_def by auto
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1175
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1176
lemma decseq_SucI:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1177
  "(\<And>n. X (Suc n) \<le> X n) \<Longrightarrow> decseq X"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1178
  using order.lift_Suc_mono_le[OF dual_order, of X]
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1179
  by (auto simp: decseq_def)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1180
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1181
lemma decseqD: "\<And>i j. decseq f \<Longrightarrow> i \<le> j \<Longrightarrow> f j \<le> f i"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1182
  by (auto simp: decseq_def)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1183
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1184
lemma decseq_SucD: "decseq A \<Longrightarrow> A (Suc i) \<le> A i"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1185
  using decseqD[of A i "Suc i"] by auto
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1186
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1187
lemma decseq_Suc_iff: "decseq f \<longleftrightarrow> (\<forall>n. f (Suc n) \<le> f n)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1188
  by (auto intro: decseq_SucI dest: decseq_SucD)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1189
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1190
lemma decseq_const[simp, intro]: "decseq (\<lambda>x. k)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1191
  unfolding decseq_def by auto
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1192
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1193
lemma monoseq_iff: "monoseq X \<longleftrightarrow> incseq X \<or> decseq X"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1194
  unfolding monoseq_def incseq_def decseq_def ..
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1195
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1196
lemma monoseq_Suc:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1197
  "monoseq X \<longleftrightarrow> (\<forall>n. X n \<le> X (Suc n)) \<or> (\<forall>n. X (Suc n) \<le> X n)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1198
  unfolding monoseq_iff incseq_Suc_iff decseq_Suc_iff ..
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1199
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1200
lemma monoI1: "\<forall>m. \<forall> n \<ge> m. X m \<le> X n ==> monoseq X"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1201
by (simp add: monoseq_def)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1202
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1203
lemma monoI2: "\<forall>m. \<forall> n \<ge> m. X n \<le> X m ==> monoseq X"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1204
by (simp add: monoseq_def)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1205
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1206
lemma mono_SucI1: "\<forall>n. X n \<le> X (Suc n) ==> monoseq X"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1207
by (simp add: monoseq_Suc)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1208
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1209
lemma mono_SucI2: "\<forall>n. X (Suc n) \<le> X n ==> monoseq X"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1210
by (simp add: monoseq_Suc)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1211
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1212
lemma monoseq_minus:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1213
  fixes a :: "nat \<Rightarrow> 'a::ordered_ab_group_add"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1214
  assumes "monoseq a"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1215
  shows "monoseq (\<lambda> n. - a n)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1216
proof (cases "\<forall> m. \<forall> n \<ge> m. a m \<le> a n")
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1217
  case True
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1218
  hence "\<forall> m. \<forall> n \<ge> m. - a n \<le> - a m" by auto
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1219
  thus ?thesis by (rule monoI2)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1220
next
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1221
  case False
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1222
  hence "\<forall> m. \<forall> n \<ge> m. - a m \<le> - a n" using `monoseq a`[unfolded monoseq_def] by auto
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1223
  thus ?thesis by (rule monoI1)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1224
qed
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1225
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1226
text{*Subsequence (alternative definition, (e.g. Hoskins)*}
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1227
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1228
lemma subseq_Suc_iff: "subseq f = (\<forall>n. (f n) < (f (Suc n)))"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1229
apply (simp add: subseq_def)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1230
apply (auto dest!: less_imp_Suc_add)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1231
apply (induct_tac k)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1232
apply (auto intro: less_trans)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1233
done
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1234
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1235
text{* for any sequence, there is a monotonic subsequence *}
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1236
lemma seq_monosub:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1237
  fixes s :: "nat => 'a::linorder"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1238
  shows "\<exists>f. subseq f \<and> monoseq (\<lambda> n. (s (f n)))"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1239
proof cases
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1240
  let "?P p n" = "p > n \<and> (\<forall>m\<ge>p. s m \<le> s p)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1241
  assume *: "\<forall>n. \<exists>p. ?P p n"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1242
  def f \<equiv> "nat_rec (SOME p. ?P p 0) (\<lambda>_ n. SOME p. ?P p n)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1243
  have f_0: "f 0 = (SOME p. ?P p 0)" unfolding f_def by simp
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1244
  have f_Suc: "\<And>i. f (Suc i) = (SOME p. ?P p (f i))" unfolding f_def nat_rec_Suc ..
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1245
  have P_0: "?P (f 0) 0" unfolding f_0 using *[rule_format] by (rule someI2_ex) auto
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1246
  have P_Suc: "\<And>i. ?P (f (Suc i)) (f i)" unfolding f_Suc using *[rule_format] by (rule someI2_ex) auto
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1247
  then have "subseq f" unfolding subseq_Suc_iff by auto
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1248
  moreover have "monoseq (\<lambda>n. s (f n))" unfolding monoseq_Suc
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1249
  proof (intro disjI2 allI)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1250
    fix n show "s (f (Suc n)) \<le> s (f n)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1251
    proof (cases n)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1252
      case 0 with P_Suc[of 0] P_0 show ?thesis by auto
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1253
    next
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1254
      case (Suc m)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1255
      from P_Suc[of n] Suc have "f (Suc m) \<le> f (Suc (Suc m))" by simp
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1256
      with P_Suc Suc show ?thesis by simp
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1257
    qed
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1258
  qed
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1259
  ultimately show ?thesis by auto
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1260
next
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1261
  let "?P p m" = "m < p \<and> s m < s p"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1262
  assume "\<not> (\<forall>n. \<exists>p>n. (\<forall>m\<ge>p. s m \<le> s p))"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1263
  then obtain N where N: "\<And>p. p > N \<Longrightarrow> \<exists>m>p. s p < s m" by (force simp: not_le le_less)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1264
  def f \<equiv> "nat_rec (SOME p. ?P p (Suc N)) (\<lambda>_ n. SOME p. ?P p n)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1265
  have f_0: "f 0 = (SOME p. ?P p (Suc N))" unfolding f_def by simp
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1266
  have f_Suc: "\<And>i. f (Suc i) = (SOME p. ?P p (f i))" unfolding f_def nat_rec_Suc ..
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1267
  have P_0: "?P (f 0) (Suc N)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1268
    unfolding f_0 some_eq_ex[of "\<lambda>p. ?P p (Suc N)"] using N[of "Suc N"] by auto
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1269
  { fix i have "N < f i \<Longrightarrow> ?P (f (Suc i)) (f i)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1270
      unfolding f_Suc some_eq_ex[of "\<lambda>p. ?P p (f i)"] using N[of "f i"] . }
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1271
  note P' = this
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1272
  { fix i have "N < f i \<and> ?P (f (Suc i)) (f i)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1273
      by (induct i) (insert P_0 P', auto) }
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1274
  then have "subseq f" "monoseq (\<lambda>x. s (f x))"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1275
    unfolding subseq_Suc_iff monoseq_Suc by (auto simp: not_le intro: less_imp_le)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1276
  then show ?thesis by auto
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1277
qed
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1278
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1279
lemma seq_suble: assumes sf: "subseq f" shows "n \<le> f n"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1280
proof(induct n)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1281
  case 0 thus ?case by simp
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1282
next
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1283
  case (Suc n)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1284
  from sf[unfolded subseq_Suc_iff, rule_format, of n] Suc.hyps
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1285
  have "n < f (Suc n)" by arith
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1286
  thus ?case by arith
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1287
qed
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1288
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1289
lemma eventually_subseq:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1290
  "subseq r \<Longrightarrow> eventually P sequentially \<Longrightarrow> eventually (\<lambda>n. P (r n)) sequentially"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1291
  unfolding eventually_sequentially by (metis seq_suble le_trans)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1292
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1293
lemma filterlim_subseq: "subseq f \<Longrightarrow> filterlim f sequentially sequentially"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1294
  unfolding filterlim_iff by (metis eventually_subseq)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1295
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1296
lemma subseq_o: "subseq r \<Longrightarrow> subseq s \<Longrightarrow> subseq (r \<circ> s)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1297
  unfolding subseq_def by simp
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1298
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1299
lemma subseq_mono: assumes "subseq r" "m < n" shows "r m < r n"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1300
  using assms by (auto simp: subseq_def)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1301
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1302
lemma incseq_imp_monoseq:  "incseq X \<Longrightarrow> monoseq X"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1303
  by (simp add: incseq_def monoseq_def)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1304
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1305
lemma decseq_imp_monoseq:  "decseq X \<Longrightarrow> monoseq X"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1306
  by (simp add: decseq_def monoseq_def)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1307
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1308
lemma decseq_eq_incseq:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1309
  fixes X :: "nat \<Rightarrow> 'a::ordered_ab_group_add" shows "decseq X = incseq (\<lambda>n. - X n)" 
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1310
  by (simp add: decseq_def incseq_def)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1311
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1312
lemma INT_decseq_offset:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1313
  assumes "decseq F"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1314
  shows "(\<Inter>i. F i) = (\<Inter>i\<in>{n..}. F i)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1315
proof safe
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1316
  fix x i assume x: "x \<in> (\<Inter>i\<in>{n..}. F i)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1317
  show "x \<in> F i"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1318
  proof cases
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1319
    from x have "x \<in> F n" by auto
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1320
    also assume "i \<le> n" with `decseq F` have "F n \<subseteq> F i"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1321
      unfolding decseq_def by simp
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1322
    finally show ?thesis .
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1323
  qed (insert x, simp)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1324
qed auto
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1325
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1326
lemma LIMSEQ_const_iff:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1327
  fixes k l :: "'a::t2_space"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1328
  shows "(\<lambda>n. k) ----> l \<longleftrightarrow> k = l"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1329
  using trivial_limit_sequentially by (rule tendsto_const_iff)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1330
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1331
lemma LIMSEQ_SUP:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1332
  "incseq X \<Longrightarrow> X ----> (SUP i. X i :: 'a :: {complete_linorder, linorder_topology})"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1333
  by (intro increasing_tendsto)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1334
     (auto simp: SUP_upper less_SUP_iff incseq_def eventually_sequentially intro: less_le_trans)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1335
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1336
lemma LIMSEQ_INF:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1337
  "decseq X \<Longrightarrow> X ----> (INF i. X i :: 'a :: {complete_linorder, linorder_topology})"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1338
  by (intro decreasing_tendsto)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1339
     (auto simp: INF_lower INF_less_iff decseq_def eventually_sequentially intro: le_less_trans)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1340
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1341
lemma LIMSEQ_ignore_initial_segment:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1342
  "f ----> a \<Longrightarrow> (\<lambda>n. f (n + k)) ----> a"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1343
apply (rule topological_tendstoI)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1344
apply (drule (2) topological_tendstoD)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1345
apply (simp only: eventually_sequentially)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1346
apply (erule exE, rename_tac N)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1347
apply (rule_tac x=N in exI)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1348
apply simp
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1349
done
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1350
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1351
lemma LIMSEQ_offset:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1352
  "(\<lambda>n. f (n + k)) ----> a \<Longrightarrow> f ----> a"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1353
apply (rule topological_tendstoI)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1354
apply (drule (2) topological_tendstoD)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1355
apply (simp only: eventually_sequentially)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1356
apply (erule exE, rename_tac N)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1357
apply (rule_tac x="N + k" in exI)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1358
apply clarify
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1359
apply (drule_tac x="n - k" in spec)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1360
apply (simp add: le_diff_conv2)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1361
done
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1362
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1363
lemma LIMSEQ_Suc: "f ----> l \<Longrightarrow> (\<lambda>n. f (Suc n)) ----> l"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1364
by (drule_tac k="Suc 0" in LIMSEQ_ignore_initial_segment, simp)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1365
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1366
lemma LIMSEQ_imp_Suc: "(\<lambda>n. f (Suc n)) ----> l \<Longrightarrow> f ----> l"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1367
by (rule_tac k="Suc 0" in LIMSEQ_offset, simp)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1368
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1369
lemma LIMSEQ_Suc_iff: "(\<lambda>n. f (Suc n)) ----> l = f ----> l"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1370
by (blast intro: LIMSEQ_imp_Suc LIMSEQ_Suc)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1371
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1372
lemma LIMSEQ_unique:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1373
  fixes a b :: "'a::t2_space"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1374
  shows "\<lbrakk>X ----> a; X ----> b\<rbrakk> \<Longrightarrow> a = b"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1375
  using trivial_limit_sequentially by (rule tendsto_unique)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1376
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1377
lemma LIMSEQ_le_const:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1378
  "\<lbrakk>X ----> (x::'a::linorder_topology); \<exists>N. \<forall>n\<ge>N. a \<le> X n\<rbrakk> \<Longrightarrow> a \<le> x"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1379
  using tendsto_le_const[of sequentially X x a] by (simp add: eventually_sequentially)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1380
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1381
lemma LIMSEQ_le:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1382
  "\<lbrakk>X ----> x; Y ----> y; \<exists>N. \<forall>n\<ge>N. X n \<le> Y n\<rbrakk> \<Longrightarrow> x \<le> (y::'a::linorder_topology)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1383
  using tendsto_le[of sequentially Y y X x] by (simp add: eventually_sequentially)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1384
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1385
lemma LIMSEQ_le_const2:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1386
  "\<lbrakk>X ----> (x::'a::linorder_topology); \<exists>N. \<forall>n\<ge>N. X n \<le> a\<rbrakk> \<Longrightarrow> x \<le> a"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1387
  by (rule LIMSEQ_le[of X x "\<lambda>n. a"]) (auto simp: tendsto_const)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1388
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1389
lemma convergentD: "convergent X ==> \<exists>L. (X ----> L)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1390
by (simp add: convergent_def)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1391
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1392
lemma convergentI: "(X ----> L) ==> convergent X"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1393
by (auto simp add: convergent_def)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1394
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1395
lemma convergent_LIMSEQ_iff: "convergent X = (X ----> lim X)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1396
by (auto intro: theI LIMSEQ_unique simp add: convergent_def lim_def)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1397
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1398
lemma convergent_const: "convergent (\<lambda>n. c)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1399
  by (rule convergentI, rule tendsto_const)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1400
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1401
lemma monoseq_le:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1402
  "monoseq a \<Longrightarrow> a ----> (x::'a::linorder_topology) \<Longrightarrow>
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1403
    ((\<forall> n. a n \<le> x) \<and> (\<forall>m. \<forall>n\<ge>m. a m \<le> a n)) \<or> ((\<forall> n. x \<le> a n) \<and> (\<forall>m. \<forall>n\<ge>m. a n \<le> a m))"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1404
  by (metis LIMSEQ_le_const LIMSEQ_le_const2 decseq_def incseq_def monoseq_iff)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1405
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1406
lemma LIMSEQ_subseq_LIMSEQ:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1407
  "\<lbrakk> X ----> L; subseq f \<rbrakk> \<Longrightarrow> (X o f) ----> L"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1408
  unfolding comp_def by (rule filterlim_compose[of X, OF _ filterlim_subseq])
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1409
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1410
lemma convergent_subseq_convergent:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1411
  "\<lbrakk>convergent X; subseq f\<rbrakk> \<Longrightarrow> convergent (X o f)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1412
  unfolding convergent_def by (auto intro: LIMSEQ_subseq_LIMSEQ)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1413
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1414
lemma limI: "X ----> L ==> lim X = L"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1415
apply (simp add: lim_def)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1416
apply (blast intro: LIMSEQ_unique)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1417
done
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1418
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1419
lemma lim_le: "convergent f \<Longrightarrow> (\<And>n. f n \<le> (x::'a::linorder_topology)) \<Longrightarrow> lim f \<le> x"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1420
  using LIMSEQ_le_const2[of f "lim f" x] by (simp add: convergent_LIMSEQ_iff)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1421
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1422
subsubsection{*Increasing and Decreasing Series*}
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1423
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1424
lemma incseq_le: "incseq X \<Longrightarrow> X ----> L \<Longrightarrow> X n \<le> (L::'a::linorder_topology)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1425
  by (metis incseq_def LIMSEQ_le_const)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1426
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1427
lemma decseq_le: "decseq X \<Longrightarrow> X ----> L \<Longrightarrow> (L::'a::linorder_topology) \<le> X n"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1428
  by (metis decseq_def LIMSEQ_le_const2)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1429
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1430
subsection {* Function limit at a point *}
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1431
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1432
abbreviation
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1433
  LIM :: "('a::topological_space \<Rightarrow> 'b::topological_space) \<Rightarrow> 'a \<Rightarrow> 'b \<Rightarrow> bool"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1434
        ("((_)/ -- (_)/ --> (_))" [60, 0, 60] 60) where
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1435
  "f -- a --> L \<equiv> (f ---> L) (at a)"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1436
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1437
lemma LIM_const_not_eq[tendsto_intros]:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1438
  fixes a :: "'a::perfect_space"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1439
  fixes k L :: "'b::t2_space"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1440
  shows "k \<noteq> L \<Longrightarrow> \<not> (\<lambda>x. k) -- a --> L"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1441
  by (simp add: tendsto_const_iff)
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1442
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1443
lemmas LIM_not_zero = LIM_const_not_eq [where L = 0]
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1444
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1445
lemma LIM_const_eq:
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1446
  fixes a :: "'a::perfect_space"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1447
  fixes k L :: "'b::t2_space"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1448
  shows "(\<lambda>x. k) -- a --> L \<Longrightarrow> k = L"
cad22a3cc09c move topological_space to its own theory
hoelzl
parents:
diff changeset
  1449