src/HOL/Library/Cardinality.thy
author wenzelm
Sat May 25 15:37:53 2013 +0200 (2013-05-25)
changeset 52143 36ffe23b25f8
parent 51188 9b5bf1a9a710
child 52147 9943f8067f11
permissions -rw-r--r--
syntax translations always depend on context;
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(*  Title:      HOL/Library/Cardinality.thy
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    Author:     Brian Huffman, Andreas Lochbihler
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*)
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header {* Cardinality of types *}
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theory Cardinality
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imports Phantom_Type
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begin
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subsection {* Preliminary lemmas *}
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(* These should be moved elsewhere *)
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lemma (in type_definition) univ:
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  "UNIV = Abs ` A"
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proof
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  show "Abs ` A \<subseteq> UNIV" by (rule subset_UNIV)
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  show "UNIV \<subseteq> Abs ` A"
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  proof
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    fix x :: 'b
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    have "x = Abs (Rep x)" by (rule Rep_inverse [symmetric])
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    moreover have "Rep x \<in> A" by (rule Rep)
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    ultimately show "x \<in> Abs ` A" by (rule image_eqI)
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  qed
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qed
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lemma (in type_definition) card: "card (UNIV :: 'b set) = card A"
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  by (simp add: univ card_image inj_on_def Abs_inject)
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lemma finite_range_Some: "finite (range (Some :: 'a \<Rightarrow> 'a option)) = finite (UNIV :: 'a set)"
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by(auto dest: finite_imageD intro: inj_Some)
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lemma infinite_literal: "\<not> finite (UNIV :: String.literal set)"
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proof -
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  have "inj STR" by(auto intro: injI)
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  thus ?thesis
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    by(auto simp add: type_definition.univ[OF type_definition_literal] infinite_UNIV_listI dest: finite_imageD)
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qed
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subsection {* Cardinalities of types *}
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syntax "_type_card" :: "type => nat" ("(1CARD/(1'(_')))")
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translations "CARD('t)" => "CONST card (CONST UNIV \<Colon> 't set)"
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typed_print_translation {*
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  let
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    fun card_univ_tr' ctxt _ [Const (@{const_syntax UNIV}, Type (_, [T]))] =
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      Syntax.const @{syntax_const "_type_card"} $ Syntax_Phases.term_of_typ ctxt T
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  in [(@{const_syntax card}, card_univ_tr')] end
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*}
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lemma card_prod [simp]: "CARD('a \<times> 'b) = CARD('a) * CARD('b)"
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  unfolding UNIV_Times_UNIV [symmetric] by (simp only: card_cartesian_product)
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lemma card_UNIV_sum: "CARD('a + 'b) = (if CARD('a) \<noteq> 0 \<and> CARD('b) \<noteq> 0 then CARD('a) + CARD('b) else 0)"
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unfolding UNIV_Plus_UNIV[symmetric]
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by(auto simp add: card_eq_0_iff card_Plus simp del: UNIV_Plus_UNIV)
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lemma card_sum [simp]: "CARD('a + 'b) = CARD('a::finite) + CARD('b::finite)"
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by(simp add: card_UNIV_sum)
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lemma card_UNIV_option: "CARD('a option) = (if CARD('a) = 0 then 0 else CARD('a) + 1)"
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proof -
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  have "(None :: 'a option) \<notin> range Some" by clarsimp
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  thus ?thesis
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    by(simp add: UNIV_option_conv card_eq_0_iff finite_range_Some card_insert_disjoint card_image)
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qed
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lemma card_option [simp]: "CARD('a option) = Suc CARD('a::finite)"
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by(simp add: card_UNIV_option)
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lemma card_UNIV_set: "CARD('a set) = (if CARD('a) = 0 then 0 else 2 ^ CARD('a))"
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by(simp add: Pow_UNIV[symmetric] card_eq_0_iff card_Pow del: Pow_UNIV)
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lemma card_set [simp]: "CARD('a set) = 2 ^ CARD('a::finite)"
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by(simp add: card_UNIV_set)
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lemma card_nat [simp]: "CARD(nat) = 0"
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  by (simp add: card_eq_0_iff)
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lemma card_fun: "CARD('a \<Rightarrow> 'b) = (if CARD('a) \<noteq> 0 \<and> CARD('b) \<noteq> 0 \<or> CARD('b) = 1 then CARD('b) ^ CARD('a) else 0)"
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proof -
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  {  assume "0 < CARD('a)" and "0 < CARD('b)"
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    hence fina: "finite (UNIV :: 'a set)" and finb: "finite (UNIV :: 'b set)"
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      by(simp_all only: card_ge_0_finite)
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    from finite_distinct_list[OF finb] obtain bs 
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      where bs: "set bs = (UNIV :: 'b set)" and distb: "distinct bs" by blast
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    from finite_distinct_list[OF fina] obtain as
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      where as: "set as = (UNIV :: 'a set)" and dista: "distinct as" by blast
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    have cb: "CARD('b) = length bs"
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      unfolding bs[symmetric] distinct_card[OF distb] ..
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    have ca: "CARD('a) = length as"
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      unfolding as[symmetric] distinct_card[OF dista] ..
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    let ?xs = "map (\<lambda>ys. the o map_of (zip as ys)) (List.n_lists (length as) bs)"
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    have "UNIV = set ?xs"
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    proof(rule UNIV_eq_I)
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      fix f :: "'a \<Rightarrow> 'b"
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      from as have "f = the \<circ> map_of (zip as (map f as))"
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        by(auto simp add: map_of_zip_map)
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      thus "f \<in> set ?xs" using bs by(auto simp add: set_n_lists)
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    qed
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    moreover have "distinct ?xs" unfolding distinct_map
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    proof(intro conjI distinct_n_lists distb inj_onI)
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      fix xs ys :: "'b list"
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      assume xs: "xs \<in> set (List.n_lists (length as) bs)"
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        and ys: "ys \<in> set (List.n_lists (length as) bs)"
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        and eq: "the \<circ> map_of (zip as xs) = the \<circ> map_of (zip as ys)"
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      from xs ys have [simp]: "length xs = length as" "length ys = length as"
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        by(simp_all add: length_n_lists_elem)
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      have "map_of (zip as xs) = map_of (zip as ys)"
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      proof
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        fix x
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        from as bs have "\<exists>y. map_of (zip as xs) x = Some y" "\<exists>y. map_of (zip as ys) x = Some y"
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          by(simp_all add: map_of_zip_is_Some[symmetric])
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        with eq show "map_of (zip as xs) x = map_of (zip as ys) x"
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          by(auto dest: fun_cong[where x=x])
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      qed
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      with dista show "xs = ys" by(simp add: map_of_zip_inject)
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    qed
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    hence "card (set ?xs) = length ?xs" by(simp only: distinct_card)
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    moreover have "length ?xs = length bs ^ length as" by(simp add: length_n_lists)
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    ultimately have "CARD('a \<Rightarrow> 'b) = CARD('b) ^ CARD('a)" using cb ca by simp }
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  moreover {
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    assume cb: "CARD('b) = 1"
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    then obtain b where b: "UNIV = {b :: 'b}" by(auto simp add: card_Suc_eq)
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    have eq: "UNIV = {\<lambda>x :: 'a. b ::'b}"
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    proof(rule UNIV_eq_I)
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      fix x :: "'a \<Rightarrow> 'b"
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      { fix y
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        have "x y \<in> UNIV" ..
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        hence "x y = b" unfolding b by simp }
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      thus "x \<in> {\<lambda>x. b}" by(auto)
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    qed
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    have "CARD('a \<Rightarrow> 'b) = 1" unfolding eq by simp }
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  ultimately show ?thesis
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    by(auto simp del: One_nat_def)(auto simp add: card_eq_0_iff dest: finite_fun_UNIVD2 finite_fun_UNIVD1)
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qed
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corollary finite_UNIV_fun:
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  "finite (UNIV :: ('a \<Rightarrow> 'b) set) \<longleftrightarrow>
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   finite (UNIV :: 'a set) \<and> finite (UNIV :: 'b set) \<or> CARD('b) = 1"
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  (is "?lhs \<longleftrightarrow> ?rhs")
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proof -
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  have "?lhs \<longleftrightarrow> CARD('a \<Rightarrow> 'b) > 0" by(simp add: card_gt_0_iff)
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  also have "\<dots> \<longleftrightarrow> CARD('a) > 0 \<and> CARD('b) > 0 \<or> CARD('b) = 1"
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    by(simp add: card_fun)
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  also have "\<dots> = ?rhs" by(simp add: card_gt_0_iff)
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  finally show ?thesis .
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qed
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lemma card_nibble: "CARD(nibble) = 16"
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unfolding UNIV_nibble by simp
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lemma card_UNIV_char: "CARD(char) = 256"
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proof -
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  have "inj (\<lambda>(x, y). Char x y)" by(auto intro: injI)
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  thus ?thesis unfolding UNIV_char by(simp add: card_image card_nibble)
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qed
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lemma card_literal: "CARD(String.literal) = 0"
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by(simp add: card_eq_0_iff infinite_literal)
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subsection {* Classes with at least 1 and 2  *}
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text {* Class finite already captures "at least 1" *}
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lemma zero_less_card_finite [simp]: "0 < CARD('a::finite)"
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  unfolding neq0_conv [symmetric] by simp
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lemma one_le_card_finite [simp]: "Suc 0 \<le> CARD('a::finite)"
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  by (simp add: less_Suc_eq_le [symmetric])
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text {* Class for cardinality "at least 2" *}
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class card2 = finite + 
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  assumes two_le_card: "2 \<le> CARD('a)"
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lemma one_less_card: "Suc 0 < CARD('a::card2)"
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  using two_le_card [where 'a='a] by simp
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lemma one_less_int_card: "1 < int CARD('a::card2)"
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  using one_less_card [where 'a='a] by simp
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subsection {* A type class for deciding finiteness of types *}
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type_synonym 'a finite_UNIV = "('a, bool) phantom"
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class finite_UNIV = 
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  fixes finite_UNIV :: "('a, bool) phantom"
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  assumes finite_UNIV: "finite_UNIV = Phantom('a) (finite (UNIV :: 'a set))"
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lemma finite_UNIV_code [code_unfold]:
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  "finite (UNIV :: 'a :: finite_UNIV set)
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  \<longleftrightarrow> of_phantom (finite_UNIV :: 'a finite_UNIV)"
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by(simp add: finite_UNIV)
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subsection {* A type class for computing the cardinality of types *}
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definition is_list_UNIV :: "'a list \<Rightarrow> bool"
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where "is_list_UNIV xs = (let c = CARD('a) in if c = 0 then False else size (remdups xs) = c)"
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lemma is_list_UNIV_iff: "is_list_UNIV xs \<longleftrightarrow> set xs = UNIV"
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by(auto simp add: is_list_UNIV_def Let_def card_eq_0_iff List.card_set[symmetric] 
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   dest: subst[where P="finite", OF _ finite_set] card_eq_UNIV_imp_eq_UNIV)
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type_synonym 'a card_UNIV = "('a, nat) phantom"
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class card_UNIV = finite_UNIV +
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  fixes card_UNIV :: "'a card_UNIV"
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  assumes card_UNIV: "card_UNIV = Phantom('a) CARD('a)"
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subsection {* Instantiations for @{text "card_UNIV"} *}
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instantiation nat :: card_UNIV begin
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definition "finite_UNIV = Phantom(nat) False"
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definition "card_UNIV = Phantom(nat) 0"
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instance by intro_classes (simp_all add: finite_UNIV_nat_def card_UNIV_nat_def)
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end
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instantiation int :: card_UNIV begin
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definition "finite_UNIV = Phantom(int) False"
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definition "card_UNIV = Phantom(int) 0"
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instance by intro_classes (simp_all add: card_UNIV_int_def finite_UNIV_int_def infinite_UNIV_int)
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end
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instantiation natural :: card_UNIV begin
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definition "finite_UNIV = Phantom(natural) False"
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definition "card_UNIV = Phantom(natural) 0"
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instance proof
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qed (auto simp add: finite_UNIV_natural_def card_UNIV_natural_def card_eq_0_iff
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  type_definition.univ [OF type_definition_natural] natural_eq_iff
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  dest!: finite_imageD intro: inj_onI)
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end
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instantiation integer :: card_UNIV begin
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definition "finite_UNIV = Phantom(integer) False"
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definition "card_UNIV = Phantom(integer) 0"
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instance proof
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qed (auto simp add: finite_UNIV_integer_def card_UNIV_integer_def card_eq_0_iff
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  type_definition.univ [OF type_definition_integer] infinite_UNIV_int
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  dest!: finite_imageD intro: inj_onI)
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end
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instantiation list :: (type) card_UNIV begin
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definition "finite_UNIV = Phantom('a list) False"
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definition "card_UNIV = Phantom('a list) 0"
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instance by intro_classes (simp_all add: card_UNIV_list_def finite_UNIV_list_def infinite_UNIV_listI)
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end
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instantiation unit :: card_UNIV begin
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definition "finite_UNIV = Phantom(unit) True"
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definition "card_UNIV = Phantom(unit) 1"
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instance by intro_classes (simp_all add: card_UNIV_unit_def finite_UNIV_unit_def)
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end
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instantiation bool :: card_UNIV begin
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definition "finite_UNIV = Phantom(bool) True"
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definition "card_UNIV = Phantom(bool) 2"
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instance by(intro_classes)(simp_all add: card_UNIV_bool_def finite_UNIV_bool_def)
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end
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instantiation nibble :: card_UNIV begin
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definition "finite_UNIV = Phantom(nibble) True"
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definition "card_UNIV = Phantom(nibble) 16"
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instance by(intro_classes)(simp_all add: card_UNIV_nibble_def card_nibble finite_UNIV_nibble_def)
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end
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instantiation char :: card_UNIV begin
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definition "finite_UNIV = Phantom(char) True"
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definition "card_UNIV = Phantom(char) 256"
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instance by intro_classes (simp_all add: card_UNIV_char_def card_UNIV_char finite_UNIV_char_def)
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end
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instantiation prod :: (finite_UNIV, finite_UNIV) finite_UNIV begin
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definition "finite_UNIV = Phantom('a \<times> 'b) 
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  (of_phantom (finite_UNIV :: 'a finite_UNIV) \<and> of_phantom (finite_UNIV :: 'b finite_UNIV))"
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instance by intro_classes (simp add: finite_UNIV_prod_def finite_UNIV finite_prod)
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end
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instantiation prod :: (card_UNIV, card_UNIV) card_UNIV begin
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definition "card_UNIV = Phantom('a \<times> 'b) 
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  (of_phantom (card_UNIV :: 'a card_UNIV) * of_phantom (card_UNIV :: 'b card_UNIV))"
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instance by intro_classes (simp add: card_UNIV_prod_def card_UNIV)
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end
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instantiation sum :: (finite_UNIV, finite_UNIV) finite_UNIV begin
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definition "finite_UNIV = Phantom('a + 'b)
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  (of_phantom (finite_UNIV :: 'a finite_UNIV) \<and> of_phantom (finite_UNIV :: 'b finite_UNIV))"
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instance
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  by intro_classes (simp add: UNIV_Plus_UNIV[symmetric] finite_UNIV_sum_def finite_UNIV del: UNIV_Plus_UNIV)
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end
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instantiation sum :: (card_UNIV, card_UNIV) card_UNIV begin
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definition "card_UNIV = Phantom('a + 'b)
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   297
  (let ca = of_phantom (card_UNIV :: 'a card_UNIV); 
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   298
       cb = of_phantom (card_UNIV :: 'b card_UNIV)
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   299
   in if ca \<noteq> 0 \<and> cb \<noteq> 0 then ca + cb else 0)"
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   300
instance by intro_classes (auto simp add: card_UNIV_sum_def card_UNIV card_UNIV_sum)
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   301
end
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   302
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   303
instantiation "fun" :: (finite_UNIV, card_UNIV) finite_UNIV begin
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   304
definition "finite_UNIV = Phantom('a \<Rightarrow> 'b)
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   305
  (let cb = of_phantom (card_UNIV :: 'b card_UNIV)
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   306
   in cb = 1 \<or> of_phantom (finite_UNIV :: 'a finite_UNIV) \<and> cb \<noteq> 0)"
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   307
instance
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   308
  by intro_classes (auto simp add: finite_UNIV_fun_def Let_def card_UNIV finite_UNIV finite_UNIV_fun card_gt_0_iff)
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   309
end
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   310
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   311
instantiation "fun" :: (card_UNIV, card_UNIV) card_UNIV begin
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   312
definition "card_UNIV = Phantom('a \<Rightarrow> 'b)
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   313
  (let ca = of_phantom (card_UNIV :: 'a card_UNIV);
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   314
       cb = of_phantom (card_UNIV :: 'b card_UNIV)
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   315
   in if ca \<noteq> 0 \<and> cb \<noteq> 0 \<or> cb = 1 then cb ^ ca else 0)"
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   316
instance by intro_classes (simp add: card_UNIV_fun_def card_UNIV Let_def card_fun)
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   317
end
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   318
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   319
instantiation option :: (finite_UNIV) finite_UNIV begin
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   320
definition "finite_UNIV = Phantom('a option) (of_phantom (finite_UNIV :: 'a finite_UNIV))"
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   321
instance by intro_classes (simp add: finite_UNIV_option_def finite_UNIV)
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   322
end
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   323
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   324
instantiation option :: (card_UNIV) card_UNIV begin
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   325
definition "card_UNIV = Phantom('a option)
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   326
  (let c = of_phantom (card_UNIV :: 'a card_UNIV) in if c \<noteq> 0 then Suc c else 0)"
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   327
instance by intro_classes (simp add: card_UNIV_option_def card_UNIV card_UNIV_option)
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   328
end
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   329
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   330
instantiation String.literal :: card_UNIV begin
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   331
definition "finite_UNIV = Phantom(String.literal) False"
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   332
definition "card_UNIV = Phantom(String.literal) 0"
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   333
instance
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   334
  by intro_classes (simp_all add: card_UNIV_literal_def finite_UNIV_literal_def infinite_literal card_literal)
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   335
end
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   336
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   337
instantiation set :: (finite_UNIV) finite_UNIV begin
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   338
definition "finite_UNIV = Phantom('a set) (of_phantom (finite_UNIV :: 'a finite_UNIV))"
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   339
instance by intro_classes (simp add: finite_UNIV_set_def finite_UNIV Finite_Set.finite_set)
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   340
end
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   341
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   342
instantiation set :: (card_UNIV) card_UNIV begin
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   343
definition "card_UNIV = Phantom('a set)
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   344
  (let c = of_phantom (card_UNIV :: 'a card_UNIV) in if c = 0 then 0 else 2 ^ c)"
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   345
instance by intro_classes (simp add: card_UNIV_set_def card_UNIV_set card_UNIV)
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   346
end
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   347
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   348
lemma UNIV_finite_1: "UNIV = set [finite_1.a\<^isub>1]"
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   349
by(auto intro: finite_1.exhaust)
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   350
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   351
lemma UNIV_finite_2: "UNIV = set [finite_2.a\<^isub>1, finite_2.a\<^isub>2]"
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   352
by(auto intro: finite_2.exhaust)
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   353
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   354
lemma UNIV_finite_3: "UNIV = set [finite_3.a\<^isub>1, finite_3.a\<^isub>2, finite_3.a\<^isub>3]"
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   355
by(auto intro: finite_3.exhaust)
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   356
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   357
lemma UNIV_finite_4: "UNIV = set [finite_4.a\<^isub>1, finite_4.a\<^isub>2, finite_4.a\<^isub>3, finite_4.a\<^isub>4]"
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   358
by(auto intro: finite_4.exhaust)
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   359
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   360
lemma UNIV_finite_5:
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   361
  "UNIV = set [finite_5.a\<^isub>1, finite_5.a\<^isub>2, finite_5.a\<^isub>3, finite_5.a\<^isub>4, finite_5.a\<^isub>5]"
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   362
by(auto intro: finite_5.exhaust)
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   363
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   364
instantiation Enum.finite_1 :: card_UNIV begin
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   365
definition "finite_UNIV = Phantom(Enum.finite_1) True"
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   366
definition "card_UNIV = Phantom(Enum.finite_1) 1"
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   367
instance
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   368
  by intro_classes (simp_all add: UNIV_finite_1 card_UNIV_finite_1_def finite_UNIV_finite_1_def)
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   369
end
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   370
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   371
instantiation Enum.finite_2 :: card_UNIV begin
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   372
definition "finite_UNIV = Phantom(Enum.finite_2) True"
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   373
definition "card_UNIV = Phantom(Enum.finite_2) 2"
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   374
instance
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   375
  by intro_classes (simp_all add: UNIV_finite_2 card_UNIV_finite_2_def finite_UNIV_finite_2_def)
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   376
end
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   377
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   378
instantiation Enum.finite_3 :: card_UNIV begin
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   379
definition "finite_UNIV = Phantom(Enum.finite_3) True"
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   380
definition "card_UNIV = Phantom(Enum.finite_3) 3"
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   381
instance
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   382
  by intro_classes (simp_all add: UNIV_finite_3 card_UNIV_finite_3_def finite_UNIV_finite_3_def)
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   383
end
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   384
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   385
instantiation Enum.finite_4 :: card_UNIV begin
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   386
definition "finite_UNIV = Phantom(Enum.finite_4) True"
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   387
definition "card_UNIV = Phantom(Enum.finite_4) 4"
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   388
instance
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   389
  by intro_classes (simp_all add: UNIV_finite_4 card_UNIV_finite_4_def finite_UNIV_finite_4_def)
Andreas@48060
   390
end
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   391
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   392
instantiation Enum.finite_5 :: card_UNIV begin
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   393
definition "finite_UNIV = Phantom(Enum.finite_5) True"
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   394
definition "card_UNIV = Phantom(Enum.finite_5) 5"
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   395
instance
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   396
  by intro_classes (simp_all add: UNIV_finite_5 card_UNIV_finite_5_def finite_UNIV_finite_5_def)
Andreas@48051
   397
end
Andreas@48051
   398
Andreas@48062
   399
subsection {* Code setup for sets *}
Andreas@48051
   400
Andreas@51116
   401
text {*
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   402
  Implement @{term "CARD('a)"} via @{term card_UNIV} and provide
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   403
  implementations for @{term "finite"}, @{term "card"}, @{term "op \<subseteq>"}, 
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   404
  and @{term "op ="}if the calling context already provides @{class finite_UNIV}
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   405
  and @{class card_UNIV} instances. If we implemented the latter
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   406
  always via @{term card_UNIV}, we would require instances of essentially all 
Andreas@51139
   407
  element types, i.e., a lot of instantiation proofs and -- at run time --
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   408
  possibly slow dictionary constructions.
Andreas@51116
   409
*}
Andreas@51116
   410
Andreas@51139
   411
definition card_UNIV' :: "'a card_UNIV"
Andreas@51139
   412
where [code del]: "card_UNIV' = Phantom('a) CARD('a)"
Andreas@51139
   413
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   414
lemma CARD_code [code_unfold]:
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   415
  "CARD('a) = of_phantom (card_UNIV' :: 'a card_UNIV)"
Andreas@51139
   416
by(simp add: card_UNIV'_def)
Andreas@51139
   417
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   418
lemma card_UNIV'_code [code]:
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   419
  "card_UNIV' = card_UNIV"
Andreas@51139
   420
by(simp add: card_UNIV card_UNIV'_def)
Andreas@51139
   421
Andreas@51139
   422
hide_const (open) card_UNIV'
Andreas@51139
   423
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   424
lemma card_Compl:
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   425
  "finite A \<Longrightarrow> card (- A) = card (UNIV :: 'a set) - card (A :: 'a set)"
Andreas@48051
   426
by (metis Compl_eq_Diff_UNIV card_Diff_subset top_greatest)
Andreas@48051
   427
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   428
context fixes xs :: "'a :: finite_UNIV list"
Andreas@51139
   429
begin
Andreas@48062
   430
Andreas@51139
   431
definition finite' :: "'a set \<Rightarrow> bool"
Andreas@51139
   432
where [simp, code del, code_abbrev]: "finite' = finite"
Andreas@51139
   433
Andreas@51139
   434
lemma finite'_code [code]:
Andreas@51139
   435
  "finite' (set xs) \<longleftrightarrow> True"
Andreas@51139
   436
  "finite' (List.coset xs) \<longleftrightarrow> of_phantom (finite_UNIV :: 'a finite_UNIV)"
Andreas@48176
   437
by(simp_all add: card_gt_0_iff finite_UNIV)
Andreas@48062
   438
Andreas@51139
   439
end
Andreas@51139
   440
Andreas@51139
   441
context fixes xs :: "'a :: card_UNIV list"
Andreas@51139
   442
begin
Andreas@51139
   443
Andreas@51139
   444
definition card' :: "'a set \<Rightarrow> nat" 
Andreas@51139
   445
where [simp, code del, code_abbrev]: "card' = card"
Andreas@51139
   446
 
Andreas@51139
   447
lemma card'_code [code]:
Andreas@51139
   448
  "card' (set xs) = length (remdups xs)"
Andreas@51139
   449
  "card' (List.coset xs) = of_phantom (card_UNIV :: 'a card_UNIV) - length (remdups xs)"
Andreas@51139
   450
by(simp_all add: List.card_set card_Compl card_UNIV)
Andreas@51139
   451
Andreas@51139
   452
Andreas@51139
   453
definition subset' :: "'a set \<Rightarrow> 'a set \<Rightarrow> bool"
Andreas@51139
   454
where [simp, code del, code_abbrev]: "subset' = op \<subseteq>"
Andreas@51139
   455
Andreas@51139
   456
lemma subset'_code [code]:
Andreas@51139
   457
  "subset' A (List.coset ys) \<longleftrightarrow> (\<forall>y \<in> set ys. y \<notin> A)"
Andreas@51139
   458
  "subset' (set ys) B \<longleftrightarrow> (\<forall>y \<in> set ys. y \<in> B)"
Andreas@51139
   459
  "subset' (List.coset xs) (set ys) \<longleftrightarrow> (let n = CARD('a) in n > 0 \<and> card(set (xs @ ys)) = n)"
Andreas@48062
   460
by(auto simp add: Let_def card_gt_0_iff dest: card_eq_UNIV_imp_eq_UNIV intro: arg_cong[where f=card])
Andreas@48062
   461
  (metis finite_compl finite_set rev_finite_subset)
Andreas@48062
   462
Andreas@51139
   463
definition eq_set :: "'a set \<Rightarrow> 'a set \<Rightarrow> bool"
Andreas@51139
   464
where [simp, code del, code_abbrev]: "eq_set = op ="
Andreas@51139
   465
Andreas@51139
   466
lemma eq_set_code [code]:
Andreas@51139
   467
  fixes ys
Andreas@48051
   468
  defines "rhs \<equiv> 
Andreas@48059
   469
  let n = CARD('a)
Andreas@48051
   470
  in if n = 0 then False else 
Andreas@48051
   471
        let xs' = remdups xs; ys' = remdups ys 
Andreas@48051
   472
        in length xs' + length ys' = n \<and> (\<forall>x \<in> set xs'. x \<notin> set ys') \<and> (\<forall>y \<in> set ys'. y \<notin> set xs')"
Andreas@51139
   473
  shows "eq_set (List.coset xs) (set ys) \<longleftrightarrow> rhs" (is ?thesis1)
Andreas@51139
   474
  and "eq_set (set ys) (List.coset xs) \<longleftrightarrow> rhs" (is ?thesis2)
Andreas@51139
   475
  and "eq_set (set xs) (set ys) \<longleftrightarrow> (\<forall>x \<in> set xs. x \<in> set ys) \<and> (\<forall>y \<in> set ys. y \<in> set xs)" (is ?thesis3)
Andreas@51139
   476
  and "eq_set (List.coset xs) (List.coset ys) \<longleftrightarrow> (\<forall>x \<in> set xs. x \<in> set ys) \<and> (\<forall>y \<in> set ys. y \<in> set xs)" (is ?thesis4)
Andreas@48051
   477
proof -
Andreas@48051
   478
  show ?thesis1 (is "?lhs \<longleftrightarrow> ?rhs")
Andreas@48051
   479
  proof
Andreas@48051
   480
    assume ?lhs thus ?rhs
Andreas@51139
   481
      by(auto simp add: rhs_def Let_def List.card_set[symmetric] card_Un_Int[where A="set xs" and B="- set xs"] card_UNIV Compl_partition card_gt_0_iff dest: sym)(metis finite_compl finite_set)
Andreas@48051
   482
  next
Andreas@48051
   483
    assume ?rhs
Andreas@48051
   484
    moreover have "\<lbrakk> \<forall>y\<in>set xs. y \<notin> set ys; \<forall>x\<in>set ys. x \<notin> set xs \<rbrakk> \<Longrightarrow> set xs \<inter> set ys = {}" by blast
Andreas@48051
   485
    ultimately show ?lhs
Andreas@51139
   486
      by(auto simp add: rhs_def Let_def List.card_set[symmetric] card_UNIV card_gt_0_iff card_Un_Int[where A="set xs" and B="set ys"] dest: card_eq_UNIV_imp_eq_UNIV split: split_if_asm)
Andreas@48051
   487
  qed
Andreas@51139
   488
  thus ?thesis2 unfolding eq_set_def by blast
Andreas@51139
   489
  show ?thesis3 ?thesis4 unfolding eq_set_def List.coset_def by blast+
Andreas@48051
   490
qed
Andreas@48051
   491
Andreas@51139
   492
end
Andreas@51139
   493
Andreas@51139
   494
text {* 
Andreas@51139
   495
  Provide more informative exceptions than Match for non-rewritten cases.
Andreas@51139
   496
  If generated code raises one these exceptions, then a code equation calls
Andreas@51139
   497
  the mentioned operator for an element type that is not an instance of
Andreas@51139
   498
  @{class card_UNIV} and is therefore not implemented via @{term card_UNIV}.
Andreas@51139
   499
  Constrain the element type with sort @{class card_UNIV} to change this.
Andreas@51139
   500
*}
Andreas@51139
   501
Andreas@51139
   502
definition card_coset_requires_card_UNIV :: "'a list \<Rightarrow> nat"
Andreas@51139
   503
where [code del, simp]: "card_coset_requires_card_UNIV xs = card (List.coset xs)"
Andreas@51139
   504
Andreas@51139
   505
code_abort card_coset_requires_card_UNIV
Andreas@51139
   506
Andreas@51139
   507
lemma card_coset_error [code]:
Andreas@51139
   508
  "card (List.coset xs) = card_coset_requires_card_UNIV xs"
Andreas@51139
   509
by(simp)
Andreas@51139
   510
Andreas@51139
   511
definition coset_subseteq_set_requires_card_UNIV :: "'a list \<Rightarrow> 'a list \<Rightarrow> bool"
Andreas@51139
   512
where [code del, simp]: "coset_subseteq_set_requires_card_UNIV xs ys \<longleftrightarrow> List.coset xs \<subseteq> set ys"
Andreas@51139
   513
Andreas@51139
   514
code_abort coset_subseteq_set_requires_card_UNIV
Andreas@51139
   515
Andreas@51139
   516
lemma coset_subseteq_set_code [code]:
Andreas@51139
   517
  "List.coset xs \<subseteq> set ys \<longleftrightarrow> 
Andreas@51139
   518
  (if xs = [] \<and> ys = [] then False else coset_subseteq_set_requires_card_UNIV xs ys)"
Andreas@51139
   519
by simp
Andreas@51139
   520
Andreas@51139
   521
notepad begin -- "test code setup"
Andreas@51139
   522
have "List.coset [True] = set [False] \<and> 
Andreas@51139
   523
      List.coset [] \<subseteq> List.set [True, False] \<and> 
Andreas@51139
   524
      finite (List.coset [True])"
Andreas@48062
   525
  by eval
Andreas@48062
   526
end
Andreas@48062
   527
Andreas@51139
   528
hide_const (open) card' finite' subset' eq_set
Andreas@51139
   529
Andreas@48051
   530
end
haftmann@49948
   531