huffman@27407
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(* Title: HOL/Library/Infinite_Set.thy
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wenzelm@20809
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Author: Stephan Merz
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wenzelm@20809
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*)
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wenzelm@20809
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wenzelm@20809
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header {* Infinite Sets and Related Concepts *}
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wenzelm@20809
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wenzelm@20809
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theory Infinite_Set
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haftmann@30663
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imports Main
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wenzelm@20809
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begin
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wenzelm@20809
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wenzelm@20809
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subsection "Infinite Sets"
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wenzelm@20809
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wenzelm@20809
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text {*
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wenzelm@20809
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Some elementary facts about infinite sets, mostly by Stefan Merz.
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wenzelm@20809
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Beware! Because "infinite" merely abbreviates a negation, these
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wenzelm@20809
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lemmas may not work well with @{text "blast"}.
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wenzelm@20809
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*}
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wenzelm@20809
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wenzelm@20809
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abbreviation
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wenzelm@21404
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infinite :: "'a set \<Rightarrow> bool" where
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wenzelm@20809
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"infinite S == \<not> finite S"
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wenzelm@20809
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wenzelm@20809
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text {*
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wenzelm@20809
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Infinite sets are non-empty, and if we remove some elements from an
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wenzelm@20809
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infinite set, the result is still infinite.
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wenzelm@20809
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*}
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wenzelm@20809
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wenzelm@20809
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lemma infinite_imp_nonempty: "infinite S ==> S \<noteq> {}"
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wenzelm@20809
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by auto
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wenzelm@20809
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wenzelm@20809
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lemma infinite_remove:
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wenzelm@20809
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"infinite S \<Longrightarrow> infinite (S - {a})"
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wenzelm@20809
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by simp
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wenzelm@20809
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wenzelm@20809
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lemma Diff_infinite_finite:
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wenzelm@20809
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assumes T: "finite T" and S: "infinite S"
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wenzelm@20809
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shows "infinite (S - T)"
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wenzelm@20809
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using T
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wenzelm@20809
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proof induct
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wenzelm@20809
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from S
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wenzelm@20809
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show "infinite (S - {})" by auto
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wenzelm@20809
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next
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wenzelm@20809
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fix T x
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wenzelm@20809
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assume ih: "infinite (S - T)"
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wenzelm@20809
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have "S - (insert x T) = (S - T) - {x}"
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wenzelm@20809
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by (rule Diff_insert)
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wenzelm@20809
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with ih
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wenzelm@20809
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show "infinite (S - (insert x T))"
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wenzelm@20809
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by (simp add: infinite_remove)
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wenzelm@20809
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qed
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wenzelm@20809
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wenzelm@20809
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lemma Un_infinite: "infinite S \<Longrightarrow> infinite (S \<union> T)"
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wenzelm@20809
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by simp
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wenzelm@20809
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urbanc@35844
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lemma infinite_Un: "infinite (S \<union> T) \<longleftrightarrow> infinite S \<or> infinite T"
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urbanc@35844
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by simp
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urbanc@35844
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wenzelm@20809
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lemma infinite_super:
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wenzelm@20809
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assumes T: "S \<subseteq> T" and S: "infinite S"
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wenzelm@20809
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shows "infinite T"
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wenzelm@20809
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proof
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wenzelm@20809
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assume "finite T"
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wenzelm@20809
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with T have "finite S" by (simp add: finite_subset)
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wenzelm@20809
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with S show False by simp
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wenzelm@20809
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qed
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wenzelm@20809
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wenzelm@20809
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text {*
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wenzelm@20809
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As a concrete example, we prove that the set of natural numbers is
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wenzelm@20809
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infinite.
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wenzelm@20809
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*}
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wenzelm@20809
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wenzelm@20809
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lemma finite_nat_bounded:
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wenzelm@20809
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assumes S: "finite (S::nat set)"
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wenzelm@20809
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shows "\<exists>k. S \<subseteq> {..<k}" (is "\<exists>k. ?bounded S k")
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wenzelm@20809
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using S
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wenzelm@20809
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proof induct
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wenzelm@20809
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have "?bounded {} 0" by simp
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wenzelm@20809
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then show "\<exists>k. ?bounded {} k" ..
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wenzelm@20809
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next
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wenzelm@20809
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fix S x
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wenzelm@20809
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assume "\<exists>k. ?bounded S k"
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wenzelm@20809
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then obtain k where k: "?bounded S k" ..
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wenzelm@20809
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show "\<exists>k. ?bounded (insert x S) k"
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wenzelm@20809
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proof (cases "x < k")
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wenzelm@20809
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case True
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wenzelm@20809
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with k show ?thesis by auto
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wenzelm@20809
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next
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wenzelm@20809
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case False
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wenzelm@20809
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with k have "?bounded S (Suc x)" by auto
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wenzelm@20809
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then show ?thesis by auto
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wenzelm@20809
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qed
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wenzelm@20809
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qed
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wenzelm@20809
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wenzelm@20809
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lemma finite_nat_iff_bounded:
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wenzelm@20809
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"finite (S::nat set) = (\<exists>k. S \<subseteq> {..<k})" (is "?lhs = ?rhs")
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wenzelm@20809
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proof
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wenzelm@20809
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assume ?lhs
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wenzelm@20809
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then show ?rhs by (rule finite_nat_bounded)
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wenzelm@20809
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next
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wenzelm@20809
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assume ?rhs
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wenzelm@20809
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then obtain k where "S \<subseteq> {..<k}" ..
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wenzelm@20809
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then show "finite S"
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wenzelm@20809
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by (rule finite_subset) simp
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wenzelm@20809
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qed
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wenzelm@20809
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wenzelm@20809
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lemma finite_nat_iff_bounded_le:
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wenzelm@20809
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"finite (S::nat set) = (\<exists>k. S \<subseteq> {..k})" (is "?lhs = ?rhs")
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wenzelm@20809
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proof
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wenzelm@20809
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assume ?lhs
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wenzelm@20809
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then obtain k where "S \<subseteq> {..<k}"
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wenzelm@20809
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by (blast dest: finite_nat_bounded)
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wenzelm@20809
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then have "S \<subseteq> {..k}" by auto
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wenzelm@20809
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then show ?rhs ..
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wenzelm@20809
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next
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wenzelm@20809
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assume ?rhs
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wenzelm@20809
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then obtain k where "S \<subseteq> {..k}" ..
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wenzelm@20809
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then show "finite S"
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wenzelm@20809
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by (rule finite_subset) simp
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wenzelm@20809
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qed
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wenzelm@20809
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wenzelm@20809
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lemma infinite_nat_iff_unbounded:
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wenzelm@20809
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"infinite (S::nat set) = (\<forall>m. \<exists>n. m<n \<and> n\<in>S)"
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wenzelm@20809
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(is "?lhs = ?rhs")
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wenzelm@20809
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proof
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wenzelm@20809
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assume ?lhs
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wenzelm@20809
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show ?rhs
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wenzelm@20809
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proof (rule ccontr)
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wenzelm@20809
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assume "\<not> ?rhs"
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wenzelm@20809
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then obtain m where m: "\<forall>n. m<n \<longrightarrow> n\<notin>S" by blast
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wenzelm@20809
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then have "S \<subseteq> {..m}"
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wenzelm@20809
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by (auto simp add: sym [OF linorder_not_less])
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wenzelm@20809
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with `?lhs` show False
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wenzelm@20809
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by (simp add: finite_nat_iff_bounded_le)
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wenzelm@20809
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qed
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wenzelm@20809
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next
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wenzelm@20809
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assume ?rhs
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wenzelm@20809
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show ?lhs
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wenzelm@20809
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proof
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wenzelm@20809
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assume "finite S"
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wenzelm@20809
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then obtain m where "S \<subseteq> {..m}"
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wenzelm@20809
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by (auto simp add: finite_nat_iff_bounded_le)
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wenzelm@20809
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then have "\<forall>n. m<n \<longrightarrow> n\<notin>S" by auto
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wenzelm@20809
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with `?rhs` show False by blast
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wenzelm@20809
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qed
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wenzelm@20809
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qed
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wenzelm@20809
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wenzelm@20809
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lemma infinite_nat_iff_unbounded_le:
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wenzelm@20809
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"infinite (S::nat set) = (\<forall>m. \<exists>n. m\<le>n \<and> n\<in>S)"
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wenzelm@20809
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(is "?lhs = ?rhs")
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wenzelm@20809
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proof
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wenzelm@20809
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assume ?lhs
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wenzelm@20809
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show ?rhs
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wenzelm@20809
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proof
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wenzelm@20809
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fix m
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wenzelm@20809
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from `?lhs` obtain n where "m<n \<and> n\<in>S"
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wenzelm@20809
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by (auto simp add: infinite_nat_iff_unbounded)
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wenzelm@20809
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then have "m\<le>n \<and> n\<in>S" by simp
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wenzelm@20809
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then show "\<exists>n. m \<le> n \<and> n \<in> S" ..
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wenzelm@20809
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qed
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wenzelm@20809
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next
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wenzelm@20809
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assume ?rhs
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wenzelm@20809
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show ?lhs
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wenzelm@20809
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proof (auto simp add: infinite_nat_iff_unbounded)
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wenzelm@20809
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fix m
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wenzelm@20809
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from `?rhs` obtain n where "Suc m \<le> n \<and> n\<in>S"
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wenzelm@20809
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by blast
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wenzelm@20809
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then have "m<n \<and> n\<in>S" by simp
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wenzelm@20809
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then show "\<exists>n. m < n \<and> n \<in> S" ..
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wenzelm@20809
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qed
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wenzelm@20809
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qed
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wenzelm@20809
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wenzelm@20809
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text {*
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wenzelm@20809
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For a set of natural numbers to be infinite, it is enough to know
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wenzelm@20809
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that for any number larger than some @{text k}, there is some larger
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wenzelm@20809
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number that is an element of the set.
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wenzelm@20809
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*}
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wenzelm@20809
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wenzelm@20809
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lemma unbounded_k_infinite:
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wenzelm@20809
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assumes k: "\<forall>m. k<m \<longrightarrow> (\<exists>n. m<n \<and> n\<in>S)"
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wenzelm@20809
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shows "infinite (S::nat set)"
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wenzelm@20809
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proof -
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wenzelm@20809
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{
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wenzelm@20809
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fix m have "\<exists>n. m<n \<and> n\<in>S"
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wenzelm@20809
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proof (cases "k<m")
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wenzelm@20809
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case True
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wenzelm@20809
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with k show ?thesis by blast
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wenzelm@20809
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next
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wenzelm@20809
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case False
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wenzelm@20809
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from k obtain n where "Suc k < n \<and> n\<in>S" by auto
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wenzelm@20809
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with False have "m<n \<and> n\<in>S" by auto
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wenzelm@20809
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then show ?thesis ..
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wenzelm@20809
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qed
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wenzelm@20809
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}
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wenzelm@20809
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then show ?thesis
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wenzelm@20809
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by (auto simp add: infinite_nat_iff_unbounded)
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wenzelm@20809
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qed
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wenzelm@20809
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huffman@35056
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(* duplicates Finite_Set.infinite_UNIV_nat *)
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huffman@35056
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lemma nat_infinite: "infinite (UNIV :: nat set)"
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wenzelm@20809
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by (auto simp add: infinite_nat_iff_unbounded)
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wenzelm@20809
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huffman@35056
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lemma nat_not_finite: "finite (UNIV::nat set) \<Longrightarrow> R"
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wenzelm@20809
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by simp
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wenzelm@20809
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wenzelm@20809
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text {*
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wenzelm@20809
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Every infinite set contains a countable subset. More precisely we
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wenzelm@20809
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show that a set @{text S} is infinite if and only if there exists an
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wenzelm@20809
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injective function from the naturals into @{text S}.
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wenzelm@20809
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*}
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wenzelm@20809
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wenzelm@20809
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lemma range_inj_infinite:
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wenzelm@20809
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"inj (f::nat \<Rightarrow> 'a) \<Longrightarrow> infinite (range f)"
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wenzelm@20809
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proof
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huffman@27407
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assume "finite (range f)" and "inj f"
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wenzelm@20809
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then have "finite (UNIV::nat set)"
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huffman@27407
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by (rule finite_imageD)
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wenzelm@20809
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then show False by simp
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wenzelm@20809
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qed
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wenzelm@20809
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paulson@22226
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lemma int_infinite [simp]:
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paulson@22226
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shows "infinite (UNIV::int set)"
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paulson@22226
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proof -
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paulson@22226
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from inj_int have "infinite (range int)" by (rule range_inj_infinite)
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paulson@22226
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moreover
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paulson@22226
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have "range int \<subseteq> (UNIV::int set)" by simp
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paulson@22226
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ultimately show "infinite (UNIV::int set)" by (simp add: infinite_super)
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paulson@22226
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qed
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paulson@22226
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wenzelm@20809
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text {*
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wenzelm@20809
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The ``only if'' direction is harder because it requires the
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wenzelm@20809
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construction of a sequence of pairwise different elements of an
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wenzelm@20809
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infinite set @{text S}. The idea is to construct a sequence of
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wenzelm@20809
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non-empty and infinite subsets of @{text S} obtained by successively
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wenzelm@20809
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removing elements of @{text S}.
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wenzelm@20809
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*}
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wenzelm@20809
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wenzelm@20809
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lemma linorder_injI:
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wenzelm@20809
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assumes hyp: "!!x y. x < (y::'a::linorder) ==> f x \<noteq> f y"
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wenzelm@20809
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shows "inj f"
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wenzelm@20809
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proof (rule inj_onI)
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wenzelm@20809
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fix x y
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wenzelm@20809
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assume f_eq: "f x = f y"
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wenzelm@20809
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show "x = y"
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wenzelm@20809
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proof (rule linorder_cases)
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wenzelm@20809
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assume "x < y"
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wenzelm@20809
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with hyp have "f x \<noteq> f y" by blast
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wenzelm@20809
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with f_eq show ?thesis by simp
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wenzelm@20809
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next
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wenzelm@20809
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249 |
assume "x = y"
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wenzelm@20809
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then show ?thesis .
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wenzelm@20809
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next
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wenzelm@20809
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assume "y < x"
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wenzelm@20809
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with hyp have "f y \<noteq> f x" by blast
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wenzelm@20809
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with f_eq show ?thesis by simp
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wenzelm@20809
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qed
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wenzelm@20809
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256 |
qed
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wenzelm@20809
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257 |
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wenzelm@20809
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lemma infinite_countable_subset:
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wenzelm@20809
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assumes inf: "infinite (S::'a set)"
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wenzelm@20809
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shows "\<exists>f. inj (f::nat \<Rightarrow> 'a) \<and> range f \<subseteq> S"
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wenzelm@20809
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proof -
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wenzelm@20809
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262 |
def Sseq \<equiv> "nat_rec S (\<lambda>n T. T - {SOME e. e \<in> T})"
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wenzelm@20809
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263 |
def pick \<equiv> "\<lambda>n. (SOME e. e \<in> Sseq n)"
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wenzelm@20809
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264 |
have Sseq_inf: "\<And>n. infinite (Sseq n)"
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wenzelm@20809
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proof -
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wenzelm@20809
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fix n
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wenzelm@20809
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show "infinite (Sseq n)"
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wenzelm@20809
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proof (induct n)
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wenzelm@20809
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from inf show "infinite (Sseq 0)"
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wenzelm@20809
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by (simp add: Sseq_def)
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wenzelm@20809
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next
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wenzelm@20809
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fix n
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wenzelm@20809
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273 |
assume "infinite (Sseq n)" then show "infinite (Sseq (Suc n))"
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wenzelm@20809
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274 |
by (simp add: Sseq_def infinite_remove)
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wenzelm@20809
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qed
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wenzelm@20809
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qed
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wenzelm@20809
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277 |
have Sseq_S: "\<And>n. Sseq n \<subseteq> S"
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wenzelm@20809
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278 |
proof -
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wenzelm@20809
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279 |
fix n
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wenzelm@20809
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280 |
show "Sseq n \<subseteq> S"
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wenzelm@20809
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by (induct n) (auto simp add: Sseq_def)
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wenzelm@20809
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282 |
qed
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wenzelm@20809
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283 |
have Sseq_pick: "\<And>n. pick n \<in> Sseq n"
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wenzelm@20809
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proof -
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wenzelm@20809
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285 |
fix n
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wenzelm@20809
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286 |
show "pick n \<in> Sseq n"
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wenzelm@20809
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287 |
proof (unfold pick_def, rule someI_ex)
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wenzelm@20809
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288 |
from Sseq_inf have "infinite (Sseq n)" .
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wenzelm@20809
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289 |
then have "Sseq n \<noteq> {}" by auto
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wenzelm@20809
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290 |
then show "\<exists>x. x \<in> Sseq n" by auto
|
wenzelm@20809
|
291 |
qed
|
wenzelm@20809
|
292 |
qed
|
wenzelm@20809
|
293 |
with Sseq_S have rng: "range pick \<subseteq> S"
|
wenzelm@20809
|
294 |
by auto
|
wenzelm@20809
|
295 |
have pick_Sseq_gt: "\<And>n m. pick n \<notin> Sseq (n + Suc m)"
|
wenzelm@20809
|
296 |
proof -
|
wenzelm@20809
|
297 |
fix n m
|
wenzelm@20809
|
298 |
show "pick n \<notin> Sseq (n + Suc m)"
|
wenzelm@20809
|
299 |
by (induct m) (auto simp add: Sseq_def pick_def)
|
wenzelm@20809
|
300 |
qed
|
wenzelm@20809
|
301 |
have pick_pick: "\<And>n m. pick n \<noteq> pick (n + Suc m)"
|
wenzelm@20809
|
302 |
proof -
|
wenzelm@20809
|
303 |
fix n m
|
wenzelm@20809
|
304 |
from Sseq_pick have "pick (n + Suc m) \<in> Sseq (n + Suc m)" .
|
wenzelm@20809
|
305 |
moreover from pick_Sseq_gt
|
wenzelm@20809
|
306 |
have "pick n \<notin> Sseq (n + Suc m)" .
|
wenzelm@20809
|
307 |
ultimately show "pick n \<noteq> pick (n + Suc m)"
|
wenzelm@20809
|
308 |
by auto
|
wenzelm@20809
|
309 |
qed
|
wenzelm@20809
|
310 |
have inj: "inj pick"
|
wenzelm@20809
|
311 |
proof (rule linorder_injI)
|
wenzelm@20809
|
312 |
fix i j :: nat
|
wenzelm@20809
|
313 |
assume "i < j"
|
wenzelm@20809
|
314 |
show "pick i \<noteq> pick j"
|
wenzelm@20809
|
315 |
proof
|
wenzelm@20809
|
316 |
assume eq: "pick i = pick j"
|
wenzelm@20809
|
317 |
from `i < j` obtain k where "j = i + Suc k"
|
wenzelm@20809
|
318 |
by (auto simp add: less_iff_Suc_add)
|
wenzelm@20809
|
319 |
with pick_pick have "pick i \<noteq> pick j" by simp
|
wenzelm@20809
|
320 |
with eq show False by simp
|
wenzelm@20809
|
321 |
qed
|
wenzelm@20809
|
322 |
qed
|
wenzelm@20809
|
323 |
from rng inj show ?thesis by auto
|
wenzelm@20809
|
324 |
qed
|
wenzelm@20809
|
325 |
|
wenzelm@20809
|
326 |
lemma infinite_iff_countable_subset:
|
wenzelm@20809
|
327 |
"infinite S = (\<exists>f. inj (f::nat \<Rightarrow> 'a) \<and> range f \<subseteq> S)"
|
wenzelm@20809
|
328 |
by (auto simp add: infinite_countable_subset range_inj_infinite infinite_super)
|
wenzelm@20809
|
329 |
|
wenzelm@20809
|
330 |
text {*
|
wenzelm@20809
|
331 |
For any function with infinite domain and finite range there is some
|
wenzelm@20809
|
332 |
element that is the image of infinitely many domain elements. In
|
wenzelm@20809
|
333 |
particular, any infinite sequence of elements from a finite set
|
wenzelm@20809
|
334 |
contains some element that occurs infinitely often.
|
wenzelm@20809
|
335 |
*}
|
wenzelm@20809
|
336 |
|
wenzelm@20809
|
337 |
lemma inf_img_fin_dom:
|
wenzelm@20809
|
338 |
assumes img: "finite (f`A)" and dom: "infinite A"
|
wenzelm@20809
|
339 |
shows "\<exists>y \<in> f`A. infinite (f -` {y})"
|
wenzelm@20809
|
340 |
proof (rule ccontr)
|
wenzelm@20809
|
341 |
assume "\<not> ?thesis"
|
nipkow@41030
|
342 |
with img have "finite (UN y:f`A. f -` {y})" by blast
|
wenzelm@20809
|
343 |
moreover have "A \<subseteq> (UN y:f`A. f -` {y})" by auto
|
wenzelm@20809
|
344 |
moreover note dom
|
wenzelm@20809
|
345 |
ultimately show False by (simp add: infinite_super)
|
wenzelm@20809
|
346 |
qed
|
wenzelm@20809
|
347 |
|
wenzelm@20809
|
348 |
lemma inf_img_fin_domE:
|
wenzelm@20809
|
349 |
assumes "finite (f`A)" and "infinite A"
|
wenzelm@20809
|
350 |
obtains y where "y \<in> f`A" and "infinite (f -` {y})"
|
wenzelm@23394
|
351 |
using assms by (blast dest: inf_img_fin_dom)
|
wenzelm@20809
|
352 |
|
wenzelm@20809
|
353 |
|
wenzelm@20809
|
354 |
subsection "Infinitely Many and Almost All"
|
wenzelm@20809
|
355 |
|
wenzelm@20809
|
356 |
text {*
|
wenzelm@20809
|
357 |
We often need to reason about the existence of infinitely many
|
wenzelm@20809
|
358 |
(resp., all but finitely many) objects satisfying some predicate, so
|
wenzelm@20809
|
359 |
we introduce corresponding binders and their proof rules.
|
wenzelm@20809
|
360 |
*}
|
wenzelm@20809
|
361 |
|
wenzelm@20809
|
362 |
definition
|
berghofe@22432
|
363 |
Inf_many :: "('a \<Rightarrow> bool) \<Rightarrow> bool" (binder "INFM " 10) where
|
wenzelm@20809
|
364 |
"Inf_many P = infinite {x. P x}"
|
wenzelm@21404
|
365 |
|
wenzelm@21404
|
366 |
definition
|
wenzelm@21404
|
367 |
Alm_all :: "('a \<Rightarrow> bool) \<Rightarrow> bool" (binder "MOST " 10) where
|
berghofe@22432
|
368 |
"Alm_all P = (\<not> (INFM x. \<not> P x))"
|
wenzelm@20809
|
369 |
|
wenzelm@21210
|
370 |
notation (xsymbols)
|
wenzelm@21404
|
371 |
Inf_many (binder "\<exists>\<^sub>\<infinity>" 10) and
|
wenzelm@20809
|
372 |
Alm_all (binder "\<forall>\<^sub>\<infinity>" 10)
|
wenzelm@20809
|
373 |
|
wenzelm@21210
|
374 |
notation (HTML output)
|
wenzelm@21404
|
375 |
Inf_many (binder "\<exists>\<^sub>\<infinity>" 10) and
|
wenzelm@20809
|
376 |
Alm_all (binder "\<forall>\<^sub>\<infinity>" 10)
|
wenzelm@20809
|
377 |
|
huffman@34110
|
378 |
lemma INFM_iff_infinite: "(INFM x. P x) \<longleftrightarrow> infinite {x. P x}"
|
huffman@34110
|
379 |
unfolding Inf_many_def ..
|
wenzelm@20809
|
380 |
|
huffman@34110
|
381 |
lemma MOST_iff_cofinite: "(MOST x. P x) \<longleftrightarrow> finite {x. \<not> P x}"
|
huffman@34110
|
382 |
unfolding Alm_all_def Inf_many_def by simp
|
huffman@34110
|
383 |
|
huffman@34110
|
384 |
(* legacy name *)
|
huffman@34110
|
385 |
lemmas MOST_iff_finiteNeg = MOST_iff_cofinite
|
huffman@34110
|
386 |
|
huffman@34110
|
387 |
lemma not_INFM [simp]: "\<not> (INFM x. P x) \<longleftrightarrow> (MOST x. \<not> P x)"
|
huffman@34110
|
388 |
unfolding Alm_all_def not_not ..
|
huffman@34110
|
389 |
|
huffman@34110
|
390 |
lemma not_MOST [simp]: "\<not> (MOST x. P x) \<longleftrightarrow> (INFM x. \<not> P x)"
|
huffman@34110
|
391 |
unfolding Alm_all_def not_not ..
|
huffman@34110
|
392 |
|
huffman@34110
|
393 |
lemma INFM_const [simp]: "(INFM x::'a. P) \<longleftrightarrow> P \<and> infinite (UNIV::'a set)"
|
huffman@34110
|
394 |
unfolding Inf_many_def by simp
|
huffman@34110
|
395 |
|
huffman@34110
|
396 |
lemma MOST_const [simp]: "(MOST x::'a. P) \<longleftrightarrow> P \<or> finite (UNIV::'a set)"
|
huffman@34110
|
397 |
unfolding Alm_all_def by simp
|
huffman@34110
|
398 |
|
huffman@34110
|
399 |
lemma INFM_EX: "(\<exists>\<^sub>\<infinity>x. P x) \<Longrightarrow> (\<exists>x. P x)"
|
huffman@34110
|
400 |
by (erule contrapos_pp, simp)
|
wenzelm@20809
|
401 |
|
wenzelm@20809
|
402 |
lemma ALL_MOST: "\<forall>x. P x \<Longrightarrow> \<forall>\<^sub>\<infinity>x. P x"
|
huffman@34110
|
403 |
by simp
|
huffman@34110
|
404 |
|
huffman@34110
|
405 |
lemma INFM_E: assumes "INFM x. P x" obtains x where "P x"
|
huffman@34110
|
406 |
using INFM_EX [OF assms] by (rule exE)
|
huffman@34110
|
407 |
|
huffman@34110
|
408 |
lemma MOST_I: assumes "\<And>x. P x" shows "MOST x. P x"
|
huffman@34110
|
409 |
using assms by simp
|
wenzelm@20809
|
410 |
|
huffman@27407
|
411 |
lemma INFM_mono:
|
wenzelm@20809
|
412 |
assumes inf: "\<exists>\<^sub>\<infinity>x. P x" and q: "\<And>x. P x \<Longrightarrow> Q x"
|
wenzelm@20809
|
413 |
shows "\<exists>\<^sub>\<infinity>x. Q x"
|
wenzelm@20809
|
414 |
proof -
|
wenzelm@20809
|
415 |
from inf have "infinite {x. P x}" unfolding Inf_many_def .
|
wenzelm@20809
|
416 |
moreover from q have "{x. P x} \<subseteq> {x. Q x}" by auto
|
wenzelm@20809
|
417 |
ultimately show ?thesis
|
wenzelm@20809
|
418 |
by (simp add: Inf_many_def infinite_super)
|
wenzelm@20809
|
419 |
qed
|
wenzelm@20809
|
420 |
|
wenzelm@20809
|
421 |
lemma MOST_mono: "\<forall>\<^sub>\<infinity>x. P x \<Longrightarrow> (\<And>x. P x \<Longrightarrow> Q x) \<Longrightarrow> \<forall>\<^sub>\<infinity>x. Q x"
|
huffman@27407
|
422 |
unfolding Alm_all_def by (blast intro: INFM_mono)
|
wenzelm@20809
|
423 |
|
huffman@27407
|
424 |
lemma INFM_disj_distrib:
|
huffman@27407
|
425 |
"(\<exists>\<^sub>\<infinity>x. P x \<or> Q x) \<longleftrightarrow> (\<exists>\<^sub>\<infinity>x. P x) \<or> (\<exists>\<^sub>\<infinity>x. Q x)"
|
huffman@27407
|
426 |
unfolding Inf_many_def by (simp add: Collect_disj_eq)
|
huffman@27407
|
427 |
|
huffman@34110
|
428 |
lemma INFM_imp_distrib:
|
huffman@34110
|
429 |
"(INFM x. P x \<longrightarrow> Q x) \<longleftrightarrow> ((MOST x. P x) \<longrightarrow> (INFM x. Q x))"
|
huffman@34110
|
430 |
by (simp only: imp_conv_disj INFM_disj_distrib not_MOST)
|
huffman@34110
|
431 |
|
huffman@27407
|
432 |
lemma MOST_conj_distrib:
|
huffman@27407
|
433 |
"(\<forall>\<^sub>\<infinity>x. P x \<and> Q x) \<longleftrightarrow> (\<forall>\<^sub>\<infinity>x. P x) \<and> (\<forall>\<^sub>\<infinity>x. Q x)"
|
huffman@27407
|
434 |
unfolding Alm_all_def by (simp add: INFM_disj_distrib del: disj_not1)
|
huffman@27407
|
435 |
|
huffman@34110
|
436 |
lemma MOST_conjI:
|
huffman@34110
|
437 |
"MOST x. P x \<Longrightarrow> MOST x. Q x \<Longrightarrow> MOST x. P x \<and> Q x"
|
huffman@34110
|
438 |
by (simp add: MOST_conj_distrib)
|
huffman@34110
|
439 |
|
huffman@34111
|
440 |
lemma INFM_conjI:
|
huffman@34111
|
441 |
"INFM x. P x \<Longrightarrow> MOST x. Q x \<Longrightarrow> INFM x. P x \<and> Q x"
|
huffman@34111
|
442 |
unfolding MOST_iff_cofinite INFM_iff_infinite
|
huffman@34111
|
443 |
apply (drule (1) Diff_infinite_finite)
|
huffman@34111
|
444 |
apply (simp add: Collect_conj_eq Collect_neg_eq)
|
huffman@34111
|
445 |
done
|
huffman@34111
|
446 |
|
huffman@27407
|
447 |
lemma MOST_rev_mp:
|
huffman@27407
|
448 |
assumes "\<forall>\<^sub>\<infinity>x. P x" and "\<forall>\<^sub>\<infinity>x. P x \<longrightarrow> Q x"
|
huffman@27407
|
449 |
shows "\<forall>\<^sub>\<infinity>x. Q x"
|
huffman@27407
|
450 |
proof -
|
huffman@27407
|
451 |
have "\<forall>\<^sub>\<infinity>x. P x \<and> (P x \<longrightarrow> Q x)"
|
huffman@34110
|
452 |
using assms by (rule MOST_conjI)
|
huffman@27407
|
453 |
thus ?thesis by (rule MOST_mono) simp
|
huffman@27407
|
454 |
qed
|
huffman@27407
|
455 |
|
huffman@34110
|
456 |
lemma MOST_imp_iff:
|
huffman@34110
|
457 |
assumes "MOST x. P x"
|
huffman@34110
|
458 |
shows "(MOST x. P x \<longrightarrow> Q x) \<longleftrightarrow> (MOST x. Q x)"
|
huffman@34110
|
459 |
proof
|
huffman@34110
|
460 |
assume "MOST x. P x \<longrightarrow> Q x"
|
huffman@34110
|
461 |
with assms show "MOST x. Q x" by (rule MOST_rev_mp)
|
huffman@34110
|
462 |
next
|
huffman@34110
|
463 |
assume "MOST x. Q x"
|
huffman@34110
|
464 |
then show "MOST x. P x \<longrightarrow> Q x" by (rule MOST_mono) simp
|
huffman@34110
|
465 |
qed
|
huffman@27407
|
466 |
|
huffman@34110
|
467 |
lemma INFM_MOST_simps [simp]:
|
huffman@34110
|
468 |
"\<And>P Q. (INFM x. P x \<and> Q) \<longleftrightarrow> (INFM x. P x) \<and> Q"
|
huffman@34110
|
469 |
"\<And>P Q. (INFM x. P \<and> Q x) \<longleftrightarrow> P \<and> (INFM x. Q x)"
|
huffman@34110
|
470 |
"\<And>P Q. (MOST x. P x \<or> Q) \<longleftrightarrow> (MOST x. P x) \<or> Q"
|
huffman@34110
|
471 |
"\<And>P Q. (MOST x. P \<or> Q x) \<longleftrightarrow> P \<or> (MOST x. Q x)"
|
huffman@34110
|
472 |
"\<And>P Q. (MOST x. P x \<longrightarrow> Q) \<longleftrightarrow> ((INFM x. P x) \<longrightarrow> Q)"
|
huffman@34110
|
473 |
"\<And>P Q. (MOST x. P \<longrightarrow> Q x) \<longleftrightarrow> (P \<longrightarrow> (MOST x. Q x))"
|
huffman@34110
|
474 |
unfolding Alm_all_def Inf_many_def
|
huffman@34110
|
475 |
by (simp_all add: Collect_conj_eq)
|
huffman@27407
|
476 |
|
huffman@34110
|
477 |
text {* Properties of quantifiers with injective functions. *}
|
huffman@27407
|
478 |
|
huffman@34110
|
479 |
lemma INFM_inj:
|
huffman@34110
|
480 |
"INFM x. P (f x) \<Longrightarrow> inj f \<Longrightarrow> INFM x. P x"
|
huffman@34110
|
481 |
unfolding INFM_iff_infinite
|
huffman@34110
|
482 |
by (clarify, drule (1) finite_vimageI, simp)
|
huffman@34110
|
483 |
|
huffman@34110
|
484 |
lemma MOST_inj:
|
huffman@34110
|
485 |
"MOST x. P x \<Longrightarrow> inj f \<Longrightarrow> MOST x. P (f x)"
|
huffman@34110
|
486 |
unfolding MOST_iff_cofinite
|
huffman@34110
|
487 |
by (drule (1) finite_vimageI, simp)
|
huffman@34110
|
488 |
|
huffman@34110
|
489 |
text {* Properties of quantifiers with singletons. *}
|
huffman@34110
|
490 |
|
huffman@34110
|
491 |
lemma not_INFM_eq [simp]:
|
huffman@34110
|
492 |
"\<not> (INFM x. x = a)"
|
huffman@34110
|
493 |
"\<not> (INFM x. a = x)"
|
huffman@34110
|
494 |
unfolding INFM_iff_infinite by simp_all
|
huffman@34110
|
495 |
|
huffman@34110
|
496 |
lemma MOST_neq [simp]:
|
huffman@34110
|
497 |
"MOST x. x \<noteq> a"
|
huffman@34110
|
498 |
"MOST x. a \<noteq> x"
|
huffman@34110
|
499 |
unfolding MOST_iff_cofinite by simp_all
|
huffman@34110
|
500 |
|
huffman@34110
|
501 |
lemma INFM_neq [simp]:
|
huffman@34110
|
502 |
"(INFM x::'a. x \<noteq> a) \<longleftrightarrow> infinite (UNIV::'a set)"
|
huffman@34110
|
503 |
"(INFM x::'a. a \<noteq> x) \<longleftrightarrow> infinite (UNIV::'a set)"
|
huffman@34110
|
504 |
unfolding INFM_iff_infinite by simp_all
|
huffman@34110
|
505 |
|
huffman@34110
|
506 |
lemma MOST_eq [simp]:
|
huffman@34110
|
507 |
"(MOST x::'a. x = a) \<longleftrightarrow> finite (UNIV::'a set)"
|
huffman@34110
|
508 |
"(MOST x::'a. a = x) \<longleftrightarrow> finite (UNIV::'a set)"
|
huffman@34110
|
509 |
unfolding MOST_iff_cofinite by simp_all
|
huffman@34110
|
510 |
|
huffman@34110
|
511 |
lemma MOST_eq_imp:
|
huffman@34110
|
512 |
"MOST x. x = a \<longrightarrow> P x"
|
huffman@34110
|
513 |
"MOST x. a = x \<longrightarrow> P x"
|
huffman@34110
|
514 |
unfolding MOST_iff_cofinite by simp_all
|
huffman@34110
|
515 |
|
huffman@34110
|
516 |
text {* Properties of quantifiers over the naturals. *}
|
huffman@27407
|
517 |
|
huffman@27407
|
518 |
lemma INFM_nat: "(\<exists>\<^sub>\<infinity>n. P (n::nat)) = (\<forall>m. \<exists>n. m<n \<and> P n)"
|
wenzelm@20809
|
519 |
by (simp add: Inf_many_def infinite_nat_iff_unbounded)
|
wenzelm@20809
|
520 |
|
huffman@27407
|
521 |
lemma INFM_nat_le: "(\<exists>\<^sub>\<infinity>n. P (n::nat)) = (\<forall>m. \<exists>n. m\<le>n \<and> P n)"
|
wenzelm@20809
|
522 |
by (simp add: Inf_many_def infinite_nat_iff_unbounded_le)
|
wenzelm@20809
|
523 |
|
wenzelm@20809
|
524 |
lemma MOST_nat: "(\<forall>\<^sub>\<infinity>n. P (n::nat)) = (\<exists>m. \<forall>n. m<n \<longrightarrow> P n)"
|
huffman@27407
|
525 |
by (simp add: Alm_all_def INFM_nat)
|
wenzelm@20809
|
526 |
|
wenzelm@20809
|
527 |
lemma MOST_nat_le: "(\<forall>\<^sub>\<infinity>n. P (n::nat)) = (\<exists>m. \<forall>n. m\<le>n \<longrightarrow> P n)"
|
huffman@27407
|
528 |
by (simp add: Alm_all_def INFM_nat_le)
|
wenzelm@20809
|
529 |
|
wenzelm@20809
|
530 |
|
wenzelm@20809
|
531 |
subsection "Enumeration of an Infinite Set"
|
wenzelm@20809
|
532 |
|
wenzelm@20809
|
533 |
text {*
|
wenzelm@20809
|
534 |
The set's element type must be wellordered (e.g. the natural numbers).
|
wenzelm@20809
|
535 |
*}
|
wenzelm@20809
|
536 |
|
haftmann@34928
|
537 |
primrec (in wellorder) enumerate :: "'a set \<Rightarrow> nat \<Rightarrow> 'a" where
|
haftmann@34928
|
538 |
enumerate_0: "enumerate S 0 = (LEAST n. n \<in> S)"
|
haftmann@34928
|
539 |
| enumerate_Suc: "enumerate S (Suc n) = enumerate (S - {LEAST n. n \<in> S}) n"
|
wenzelm@20809
|
540 |
|
wenzelm@20809
|
541 |
lemma enumerate_Suc':
|
wenzelm@20809
|
542 |
"enumerate S (Suc n) = enumerate (S - {enumerate S 0}) n"
|
wenzelm@20809
|
543 |
by simp
|
wenzelm@20809
|
544 |
|
wenzelm@20809
|
545 |
lemma enumerate_in_set: "infinite S \<Longrightarrow> enumerate S n : S"
|
nipkow@29838
|
546 |
apply (induct n arbitrary: S)
|
nipkow@29838
|
547 |
apply (fastsimp intro: LeastI dest!: infinite_imp_nonempty)
|
nipkow@29838
|
548 |
apply simp
|
nipkow@29838
|
549 |
apply (metis Collect_def Collect_mem_eq DiffE infinite_remove)
|
nipkow@29838
|
550 |
done
|
wenzelm@20809
|
551 |
|
wenzelm@20809
|
552 |
declare enumerate_0 [simp del] enumerate_Suc [simp del]
|
wenzelm@20809
|
553 |
|
wenzelm@20809
|
554 |
lemma enumerate_step: "infinite S \<Longrightarrow> enumerate S n < enumerate S (Suc n)"
|
wenzelm@20809
|
555 |
apply (induct n arbitrary: S)
|
wenzelm@20809
|
556 |
apply (rule order_le_neq_trans)
|
wenzelm@20809
|
557 |
apply (simp add: enumerate_0 Least_le enumerate_in_set)
|
wenzelm@20809
|
558 |
apply (simp only: enumerate_Suc')
|
wenzelm@20809
|
559 |
apply (subgoal_tac "enumerate (S - {enumerate S 0}) 0 : S - {enumerate S 0}")
|
wenzelm@20809
|
560 |
apply (blast intro: sym)
|
wenzelm@20809
|
561 |
apply (simp add: enumerate_in_set del: Diff_iff)
|
wenzelm@20809
|
562 |
apply (simp add: enumerate_Suc')
|
wenzelm@20809
|
563 |
done
|
wenzelm@20809
|
564 |
|
wenzelm@20809
|
565 |
lemma enumerate_mono: "m<n \<Longrightarrow> infinite S \<Longrightarrow> enumerate S m < enumerate S n"
|
wenzelm@20809
|
566 |
apply (erule less_Suc_induct)
|
wenzelm@20809
|
567 |
apply (auto intro: enumerate_step)
|
wenzelm@20809
|
568 |
done
|
wenzelm@20809
|
569 |
|
wenzelm@20809
|
570 |
|
wenzelm@20809
|
571 |
subsection "Miscellaneous"
|
wenzelm@20809
|
572 |
|
wenzelm@20809
|
573 |
text {*
|
wenzelm@20809
|
574 |
A few trivial lemmas about sets that contain at most one element.
|
wenzelm@20809
|
575 |
These simplify the reasoning about deterministic automata.
|
wenzelm@20809
|
576 |
*}
|
wenzelm@20809
|
577 |
|
wenzelm@20809
|
578 |
definition
|
wenzelm@21404
|
579 |
atmost_one :: "'a set \<Rightarrow> bool" where
|
wenzelm@20809
|
580 |
"atmost_one S = (\<forall>x y. x\<in>S \<and> y\<in>S \<longrightarrow> x=y)"
|
wenzelm@20809
|
581 |
|
wenzelm@20809
|
582 |
lemma atmost_one_empty: "S = {} \<Longrightarrow> atmost_one S"
|
wenzelm@20809
|
583 |
by (simp add: atmost_one_def)
|
wenzelm@20809
|
584 |
|
wenzelm@20809
|
585 |
lemma atmost_one_singleton: "S = {x} \<Longrightarrow> atmost_one S"
|
wenzelm@20809
|
586 |
by (simp add: atmost_one_def)
|
wenzelm@20809
|
587 |
|
wenzelm@20809
|
588 |
lemma atmost_one_unique [elim]: "atmost_one S \<Longrightarrow> x \<in> S \<Longrightarrow> y \<in> S \<Longrightarrow> y = x"
|
wenzelm@20809
|
589 |
by (simp add: atmost_one_def)
|
wenzelm@20809
|
590 |
|
wenzelm@20809
|
591 |
end
|