author | nipkow |
Tue, 07 Sep 2010 10:05:19 +0200 | |
changeset 39198 | f967a16dfcdd |
parent 38857 | 97775f3e8722 |
child 39302 | d7728f65b353 |
permissions | -rw-r--r-- |
31596 | 1 |
(* Author: Florian Haftmann, TU Muenchen *) |
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header {* Finite types as explicit enumerations *} |
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theory Enum |
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Main is (Complex_Main) base entry point in library theories
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imports Map Main |
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begin |
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subsection {* Class @{text enum} *} |
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class enum = |
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fixes enum :: "'a list" |
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assumes UNIV_enum: "UNIV = set enum" |
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and enum_distinct: "distinct enum" |
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begin |
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subclass finite proof |
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qed (simp add: UNIV_enum) |
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lemma enum_all: "set enum = UNIV" unfolding UNIV_enum .. |
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lemma in_enum [intro]: "x \<in> set enum" |
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unfolding enum_all by auto |
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lemma enum_eq_I: |
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assumes "\<And>x. x \<in> set xs" |
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shows "set enum = set xs" |
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proof - |
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from assms UNIV_eq_I have "UNIV = set xs" by auto |
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with enum_all show ?thesis by simp |
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qed |
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end |
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subsection {* Equality and order on functions *} |
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instantiation "fun" :: (enum, equal) equal |
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begin |
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definition |
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"HOL.equal f g \<longleftrightarrow> (\<forall>x \<in> set enum. f x = g x)" |
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instance proof |
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qed (simp_all add: equal_fun_def enum_all ext_iff) |
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end |
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lemma [code nbe]: |
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"HOL.equal (f :: _ \<Rightarrow> _) f \<longleftrightarrow> True" |
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by (fact equal_refl) |
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lemma order_fun [code]: |
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fixes f g :: "'a\<Colon>enum \<Rightarrow> 'b\<Colon>order" |
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shows "f \<le> g \<longleftrightarrow> list_all (\<lambda>x. f x \<le> g x) enum" |
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and "f < g \<longleftrightarrow> f \<le> g \<and> list_ex (\<lambda>x. f x \<noteq> g x) enum" |
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by (simp_all add: list_all_iff list_ex_iff enum_all ext_iff le_fun_def order_less_le) |
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subsection {* Quantifiers *} |
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lemma all_code [code]: "(\<forall>x. P x) \<longleftrightarrow> list_all P enum" |
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by (simp add: list_all_iff enum_all) |
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lemma exists_code [code]: "(\<exists>x. P x) \<longleftrightarrow> list_ex P enum" |
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by (simp add: list_ex_iff enum_all) |
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subsection {* Default instances *} |
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primrec n_lists :: "nat \<Rightarrow> 'a list \<Rightarrow> 'a list list" where |
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"n_lists 0 xs = [[]]" |
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| "n_lists (Suc n) xs = concat (map (\<lambda>ys. map (\<lambda>y. y # ys) xs) (n_lists n xs))" |
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lemma n_lists_Nil [simp]: "n_lists n [] = (if n = 0 then [[]] else [])" |
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by (induct n) simp_all |
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lemma length_n_lists: "length (n_lists n xs) = length xs ^ n" |
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by (induct n) (auto simp add: length_concat o_def listsum_triv) |
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lemma length_n_lists_elem: "ys \<in> set (n_lists n xs) \<Longrightarrow> length ys = n" |
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by (induct n arbitrary: ys) auto |
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lemma set_n_lists: "set (n_lists n xs) = {ys. length ys = n \<and> set ys \<subseteq> set xs}" |
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proof (rule set_ext) |
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fix ys :: "'a list" |
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show "ys \<in> set (n_lists n xs) \<longleftrightarrow> ys \<in> {ys. length ys = n \<and> set ys \<subseteq> set xs}" |
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proof - |
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have "ys \<in> set (n_lists n xs) \<Longrightarrow> length ys = n" |
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by (induct n arbitrary: ys) auto |
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moreover have "\<And>x. ys \<in> set (n_lists n xs) \<Longrightarrow> x \<in> set ys \<Longrightarrow> x \<in> set xs" |
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by (induct n arbitrary: ys) auto |
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moreover have "set ys \<subseteq> set xs \<Longrightarrow> ys \<in> set (n_lists (length ys) xs)" |
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by (induct ys) auto |
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ultimately show ?thesis by auto |
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qed |
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qed |
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lemma distinct_n_lists: |
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assumes "distinct xs" |
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shows "distinct (n_lists n xs)" |
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proof (rule card_distinct) |
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from assms have card_length: "card (set xs) = length xs" by (rule distinct_card) |
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have "card (set (n_lists n xs)) = card (set xs) ^ n" |
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proof (induct n) |
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case 0 then show ?case by simp |
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next |
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case (Suc n) |
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moreover have "card (\<Union>ys\<in>set (n_lists n xs). (\<lambda>y. y # ys) ` set xs) |
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= (\<Sum>ys\<in>set (n_lists n xs). card ((\<lambda>y. y # ys) ` set xs))" |
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by (rule card_UN_disjoint) auto |
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moreover have "\<And>ys. card ((\<lambda>y. y # ys) ` set xs) = card (set xs)" |
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by (rule card_image) (simp add: inj_on_def) |
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ultimately show ?case by auto |
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qed |
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also have "\<dots> = length xs ^ n" by (simp add: card_length) |
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finally show "card (set (n_lists n xs)) = length (n_lists n xs)" |
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by (simp add: length_n_lists) |
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qed |
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lemma map_of_zip_enum_is_Some: |
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assumes "length ys = length (enum \<Colon> 'a\<Colon>enum list)" |
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shows "\<exists>y. map_of (zip (enum \<Colon> 'a\<Colon>enum list) ys) x = Some y" |
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proof - |
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from assms have "x \<in> set (enum \<Colon> 'a\<Colon>enum list) \<longleftrightarrow> |
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(\<exists>y. map_of (zip (enum \<Colon> 'a\<Colon>enum list) ys) x = Some y)" |
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by (auto intro!: map_of_zip_is_Some) |
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then show ?thesis using enum_all by auto |
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qed |
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lemma map_of_zip_enum_inject: |
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fixes xs ys :: "'b\<Colon>enum list" |
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assumes length: "length xs = length (enum \<Colon> 'a\<Colon>enum list)" |
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"length ys = length (enum \<Colon> 'a\<Colon>enum list)" |
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and map_of: "the \<circ> map_of (zip (enum \<Colon> 'a\<Colon>enum list) xs) = the \<circ> map_of (zip (enum \<Colon> 'a\<Colon>enum list) ys)" |
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shows "xs = ys" |
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proof - |
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have "map_of (zip (enum \<Colon> 'a list) xs) = map_of (zip (enum \<Colon> 'a list) ys)" |
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proof |
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fix x :: 'a |
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from length map_of_zip_enum_is_Some obtain y1 y2 |
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where "map_of (zip (enum \<Colon> 'a list) xs) x = Some y1" |
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and "map_of (zip (enum \<Colon> 'a list) ys) x = Some y2" by blast |
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moreover from map_of have "the (map_of (zip (enum \<Colon> 'a\<Colon>enum list) xs) x) = the (map_of (zip (enum \<Colon> 'a\<Colon>enum list) ys) x)" |
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by (auto dest: fun_cong) |
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ultimately show "map_of (zip (enum \<Colon> 'a\<Colon>enum list) xs) x = map_of (zip (enum \<Colon> 'a\<Colon>enum list) ys) x" |
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by simp |
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qed |
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with length enum_distinct show "xs = ys" by (rule map_of_zip_inject) |
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qed |
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instantiation "fun" :: (enum, enum) enum |
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begin |
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definition |
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"enum = map (\<lambda>ys. the o map_of (zip (enum\<Colon>'a list) ys)) (n_lists (length (enum\<Colon>'a\<Colon>enum list)) enum)" |
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instance proof |
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show "UNIV = set (enum \<Colon> ('a \<Rightarrow> 'b) list)" |
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proof (rule UNIV_eq_I) |
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fix f :: "'a \<Rightarrow> 'b" |
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have "f = the \<circ> map_of (zip (enum \<Colon> 'a\<Colon>enum list) (map f enum))" |
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by (auto simp add: map_of_zip_map ext_iff) |
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then show "f \<in> set enum" |
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by (auto simp add: enum_fun_def set_n_lists) |
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qed |
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next |
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from map_of_zip_enum_inject |
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show "distinct (enum \<Colon> ('a \<Rightarrow> 'b) list)" |
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by (auto intro!: inj_onI simp add: enum_fun_def |
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distinct_map distinct_n_lists enum_distinct set_n_lists enum_all) |
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qed |
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end |
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lemma enum_fun_code [code]: "enum = (let enum_a = (enum \<Colon> 'a\<Colon>{enum, equal} list) |
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in map (\<lambda>ys. the o map_of (zip enum_a ys)) (n_lists (length enum_a) enum))" |
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by (simp add: enum_fun_def Let_def) |
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instantiation unit :: enum |
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begin |
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definition |
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"enum = [()]" |
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instance proof |
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qed (simp_all add: enum_unit_def UNIV_unit) |
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end |
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instantiation bool :: enum |
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begin |
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definition |
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"enum = [False, True]" |
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instance proof |
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qed (simp_all add: enum_bool_def UNIV_bool) |
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end |
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primrec product :: "'a list \<Rightarrow> 'b list \<Rightarrow> ('a \<times> 'b) list" where |
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"product [] _ = []" |
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| "product (x#xs) ys = map (Pair x) ys @ product xs ys" |
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lemma product_list_set: |
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"set (product xs ys) = set xs \<times> set ys" |
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by (induct xs) auto |
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lemma distinct_product: |
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assumes "distinct xs" and "distinct ys" |
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shows "distinct (product xs ys)" |
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using assms by (induct xs) |
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(auto intro: inj_onI simp add: product_list_set distinct_map) |
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"prod" and "sum" replace "*" and "+" respectively
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instantiation prod :: (enum, enum) enum |
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begin |
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definition |
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"enum = product enum enum" |
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instance by default |
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(simp_all add: enum_prod_def product_list_set distinct_product enum_all enum_distinct) |
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end |
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instantiation sum :: (enum, enum) enum |
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begin |
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definition |
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"enum = map Inl enum @ map Inr enum" |
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instance by default |
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(auto simp add: enum_all enum_sum_def, case_tac x, auto intro: inj_onI simp add: distinct_map enum_distinct) |
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end |
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primrec sublists :: "'a list \<Rightarrow> 'a list list" where |
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"sublists [] = [[]]" |
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| "sublists (x#xs) = (let xss = sublists xs in map (Cons x) xss @ xss)" |
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lemma length_sublists: |
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"length (sublists xs) = Suc (Suc (0\<Colon>nat)) ^ length xs" |
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by (induct xs) (simp_all add: Let_def) |
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lemma sublists_powset: |
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"set ` set (sublists xs) = Pow (set xs)" |
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proof - |
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have aux: "\<And>x A. set ` Cons x ` A = insert x ` set ` A" |
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by (auto simp add: image_def) |
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have "set (map set (sublists xs)) = Pow (set xs)" |
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by (induct xs) |
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(simp_all add: aux Let_def Pow_insert Un_commute comp_def del: map_map) |
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then show ?thesis by simp |
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qed |
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lemma distinct_set_sublists: |
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assumes "distinct xs" |
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shows "distinct (map set (sublists xs))" |
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proof (rule card_distinct) |
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have "finite (set xs)" by rule |
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then have "card (Pow (set xs)) = Suc (Suc 0) ^ card (set xs)" by (rule card_Pow) |
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with assms distinct_card [of xs] |
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have "card (Pow (set xs)) = Suc (Suc 0) ^ length xs" by simp |
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then show "card (set (map set (sublists xs))) = length (map set (sublists xs))" |
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by (simp add: sublists_powset length_sublists) |
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qed |
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instantiation nibble :: enum |
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begin |
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definition |
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"enum = [Nibble0, Nibble1, Nibble2, Nibble3, Nibble4, Nibble5, Nibble6, Nibble7, |
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Nibble8, Nibble9, NibbleA, NibbleB, NibbleC, NibbleD, NibbleE, NibbleF]" |
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instance proof |
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qed (simp_all add: enum_nibble_def UNIV_nibble) |
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end |
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instantiation char :: enum |
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begin |
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definition |
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"enum = map (split Char) (product enum enum)" |
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lemma enum_chars [code]: |
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"enum = chars" |
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unfolding enum_char_def chars_def enum_nibble_def by simp |
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instance proof |
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qed (auto intro: char.exhaust injI simp add: enum_char_def product_list_set enum_all full_SetCompr_eq [symmetric] |
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distinct_map distinct_product enum_distinct) |
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end |
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instantiation option :: (enum) enum |
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begin |
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definition |
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"enum = None # map Some enum" |
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instance proof |
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qed (auto simp add: enum_all enum_option_def, rule option.exhaust, auto intro: simp add: distinct_map enum_distinct) |
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end |
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end |