src/HOL/List.thy
author wenzelm
Wed Mar 04 19:53:18 2015 +0100 (2015-03-04)
changeset 59582 0fbed69ff081
parent 59516 d92b74f3f6e3
child 59728 0bb88aa34768
permissions -rw-r--r--
tuned signature -- prefer qualified names;
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(*  Title:      HOL/List.thy
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    Author:     Tobias Nipkow
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*)
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section {* The datatype of finite lists *}
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theory List
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imports Sledgehammer Code_Numeral Lifting_Set
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begin
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datatype (set: 'a) list =
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    Nil  ("[]")
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  | Cons (hd: 'a) (tl: "'a list")  (infixr "#" 65)
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for
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  map: map
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  rel: list_all2
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where
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  "tl [] = []"
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datatype_compat list
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lemma [case_names Nil Cons, cases type: list]:
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  -- {* for backward compatibility -- names of variables differ *}
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  "(y = [] \<Longrightarrow> P) \<Longrightarrow> (\<And>a list. y = a # list \<Longrightarrow> P) \<Longrightarrow> P"
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by (rule list.exhaust)
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lemma [case_names Nil Cons, induct type: list]:
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  -- {* for backward compatibility -- names of variables differ *}
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  "P [] \<Longrightarrow> (\<And>a list. P list \<Longrightarrow> P (a # list)) \<Longrightarrow> P list"
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by (rule list.induct)
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text {* Compatibility: *}
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setup {* Sign.mandatory_path "list" *}
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lemmas inducts = list.induct
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lemmas recs = list.rec
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lemmas cases = list.case
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setup {* Sign.parent_path *}
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lemmas set_simps = list.set (* legacy *)
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syntax
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  -- {* list Enumeration *}
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  "_list" :: "args => 'a list"    ("[(_)]")
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translations
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  "[x, xs]" == "x#[xs]"
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  "[x]" == "x#[]"
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subsection {* Basic list processing functions *}
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primrec (nonexhaustive) last :: "'a list \<Rightarrow> 'a" where
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"last (x # xs) = (if xs = [] then x else last xs)"
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primrec butlast :: "'a list \<Rightarrow> 'a list" where
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"butlast [] = []" |
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"butlast (x # xs) = (if xs = [] then [] else x # butlast xs)"
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lemma set_rec: "set xs = rec_list {} (\<lambda>x _. insert x) xs"
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  by (induct xs) auto
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definition coset :: "'a list \<Rightarrow> 'a set" where
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[simp]: "coset xs = - set xs"
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primrec append :: "'a list \<Rightarrow> 'a list \<Rightarrow> 'a list" (infixr "@" 65) where
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append_Nil: "[] @ ys = ys" |
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append_Cons: "(x#xs) @ ys = x # xs @ ys"
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primrec rev :: "'a list \<Rightarrow> 'a list" where
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"rev [] = []" |
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"rev (x # xs) = rev xs @ [x]"
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primrec filter:: "('a \<Rightarrow> bool) \<Rightarrow> 'a list \<Rightarrow> 'a list" where
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"filter P [] = []" |
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"filter P (x # xs) = (if P x then x # filter P xs else filter P xs)"
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syntax
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  -- {* Special syntax for filter *}
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  "_filter" :: "[pttrn, 'a list, bool] => 'a list"    ("(1[_<-_./ _])")
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translations
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  "[x<-xs . P]"== "CONST filter (%x. P) xs"
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syntax (xsymbols)
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  "_filter" :: "[pttrn, 'a list, bool] => 'a list"("(1[_\<leftarrow>_ ./ _])")
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syntax (HTML output)
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  "_filter" :: "[pttrn, 'a list, bool] => 'a list"("(1[_\<leftarrow>_ ./ _])")
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primrec fold :: "('a \<Rightarrow> 'b \<Rightarrow> 'b) \<Rightarrow> 'a list \<Rightarrow> 'b \<Rightarrow> 'b" where
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fold_Nil:  "fold f [] = id" |
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fold_Cons: "fold f (x # xs) = fold f xs \<circ> f x"
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primrec foldr :: "('a \<Rightarrow> 'b \<Rightarrow> 'b) \<Rightarrow> 'a list \<Rightarrow> 'b \<Rightarrow> 'b" where
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foldr_Nil:  "foldr f [] = id" |
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foldr_Cons: "foldr f (x # xs) = f x \<circ> foldr f xs"
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primrec foldl :: "('b \<Rightarrow> 'a \<Rightarrow> 'b) \<Rightarrow> 'b \<Rightarrow> 'a list \<Rightarrow> 'b" where
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foldl_Nil:  "foldl f a [] = a" |
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foldl_Cons: "foldl f a (x # xs) = foldl f (f a x) xs"
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primrec concat:: "'a list list \<Rightarrow> 'a list" where
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"concat [] = []" |
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"concat (x # xs) = x @ concat xs"
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primrec drop:: "nat \<Rightarrow> 'a list \<Rightarrow> 'a list" where
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drop_Nil: "drop n [] = []" |
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drop_Cons: "drop n (x # xs) = (case n of 0 \<Rightarrow> x # xs | Suc m \<Rightarrow> drop m xs)"
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  -- {*Warning: simpset does not contain this definition, but separate
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       theorems for @{text "n = 0"} and @{text "n = Suc k"} *}
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primrec take:: "nat \<Rightarrow> 'a list \<Rightarrow> 'a list" where
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take_Nil:"take n [] = []" |
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take_Cons: "take n (x # xs) = (case n of 0 \<Rightarrow> [] | Suc m \<Rightarrow> x # take m xs)"
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  -- {*Warning: simpset does not contain this definition, but separate
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       theorems for @{text "n = 0"} and @{text "n = Suc k"} *}
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primrec (nonexhaustive) nth :: "'a list => nat => 'a" (infixl "!" 100) where
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nth_Cons: "(x # xs) ! n = (case n of 0 \<Rightarrow> x | Suc k \<Rightarrow> xs ! k)"
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  -- {*Warning: simpset does not contain this definition, but separate
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       theorems for @{text "n = 0"} and @{text "n = Suc k"} *}
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primrec list_update :: "'a list \<Rightarrow> nat \<Rightarrow> 'a \<Rightarrow> 'a list" where
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"list_update [] i v = []" |
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"list_update (x # xs) i v =
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  (case i of 0 \<Rightarrow> v # xs | Suc j \<Rightarrow> x # list_update xs j v)"
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nonterminal lupdbinds and lupdbind
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syntax
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  "_lupdbind":: "['a, 'a] => lupdbind"    ("(2_ :=/ _)")
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  "" :: "lupdbind => lupdbinds"    ("_")
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  "_lupdbinds" :: "[lupdbind, lupdbinds] => lupdbinds"    ("_,/ _")
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  "_LUpdate" :: "['a, lupdbinds] => 'a"    ("_/[(_)]" [900,0] 900)
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translations
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  "_LUpdate xs (_lupdbinds b bs)" == "_LUpdate (_LUpdate xs b) bs"
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  "xs[i:=x]" == "CONST list_update xs i x"
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primrec takeWhile :: "('a \<Rightarrow> bool) \<Rightarrow> 'a list \<Rightarrow> 'a list" where
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"takeWhile P [] = []" |
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"takeWhile P (x # xs) = (if P x then x # takeWhile P xs else [])"
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primrec dropWhile :: "('a \<Rightarrow> bool) \<Rightarrow> 'a list \<Rightarrow> 'a list" where
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"dropWhile P [] = []" |
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"dropWhile P (x # xs) = (if P x then dropWhile P xs else x # xs)"
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primrec zip :: "'a list \<Rightarrow> 'b list \<Rightarrow> ('a \<times> 'b) list" where
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"zip xs [] = []" |
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zip_Cons: "zip xs (y # ys) =
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  (case xs of [] => [] | z # zs => (z, y) # zip zs ys)"
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  -- {*Warning: simpset does not contain this definition, but separate
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       theorems for @{text "xs = []"} and @{text "xs = z # zs"} *}
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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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hide_const (open) product
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primrec product_lists :: "'a list list \<Rightarrow> 'a list list" where
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"product_lists [] = [[]]" |
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"product_lists (xs # xss) = concat (map (\<lambda>x. map (Cons x) (product_lists xss)) xs)"
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primrec upt :: "nat \<Rightarrow> nat \<Rightarrow> nat list" ("(1[_..</_'])") where
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upt_0: "[i..<0] = []" |
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upt_Suc: "[i..<(Suc j)] = (if i <= j then [i..<j] @ [j] else [])"
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definition insert :: "'a \<Rightarrow> 'a list \<Rightarrow> 'a list" where
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"insert x xs = (if x \<in> set xs then xs else x # xs)"
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definition union :: "'a list \<Rightarrow> 'a list \<Rightarrow> 'a list" where
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"union = fold insert"
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hide_const (open) insert union
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hide_fact (open) insert_def union_def
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primrec find :: "('a \<Rightarrow> bool) \<Rightarrow> 'a list \<Rightarrow> 'a option" where
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"find _ [] = None" |
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"find P (x#xs) = (if P x then Some x else find P xs)"
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hide_const (open) find
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definition
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   "extract" :: "('a \<Rightarrow> bool) \<Rightarrow> 'a list \<Rightarrow> ('a list * 'a * 'a list) option"
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where "extract P xs =
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  (case dropWhile (Not o P) xs of
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     [] \<Rightarrow> None |
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     y#ys \<Rightarrow> Some(takeWhile (Not o P) xs, y, ys))"
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hide_const (open) "extract"
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primrec those :: "'a option list \<Rightarrow> 'a list option"
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where
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"those [] = Some []" |
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"those (x # xs) = (case x of
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  None \<Rightarrow> None
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| Some y \<Rightarrow> map_option (Cons y) (those xs))"
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primrec remove1 :: "'a \<Rightarrow> 'a list \<Rightarrow> 'a list" where
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"remove1 x [] = []" |
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"remove1 x (y # xs) = (if x = y then xs else y # remove1 x xs)"
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primrec removeAll :: "'a \<Rightarrow> 'a list \<Rightarrow> 'a list" where
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"removeAll x [] = []" |
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"removeAll x (y # xs) = (if x = y then removeAll x xs else y # removeAll x xs)"
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primrec distinct :: "'a list \<Rightarrow> bool" where
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"distinct [] \<longleftrightarrow> True" |
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"distinct (x # xs) \<longleftrightarrow> x \<notin> set xs \<and> distinct xs"
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primrec remdups :: "'a list \<Rightarrow> 'a list" where
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"remdups [] = []" |
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"remdups (x # xs) = (if x \<in> set xs then remdups xs else x # remdups xs)"
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fun remdups_adj :: "'a list \<Rightarrow> 'a list" where
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"remdups_adj [] = []" |
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"remdups_adj [x] = [x]" |
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"remdups_adj (x # y # xs) = (if x = y then remdups_adj (x # xs) else x # remdups_adj (y # xs))"
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primrec replicate :: "nat \<Rightarrow> 'a \<Rightarrow> 'a list" where
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replicate_0: "replicate 0 x = []" |
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replicate_Suc: "replicate (Suc n) x = x # replicate n x"
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text {*
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  Function @{text size} is overloaded for all datatypes. Users may
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  refer to the list version as @{text length}. *}
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abbreviation length :: "'a list \<Rightarrow> nat" where
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"length \<equiv> size"
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definition enumerate :: "nat \<Rightarrow> 'a list \<Rightarrow> (nat \<times> 'a) list" where
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enumerate_eq_zip: "enumerate n xs = zip [n..<n + length xs] xs"
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primrec rotate1 :: "'a list \<Rightarrow> 'a list" where
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"rotate1 [] = []" |
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"rotate1 (x # xs) = xs @ [x]"
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definition rotate :: "nat \<Rightarrow> 'a list \<Rightarrow> 'a list" where
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"rotate n = rotate1 ^^ n"
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definition sublist :: "'a list => nat set => 'a list" where
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"sublist xs A = map fst (filter (\<lambda>p. snd p \<in> A) (zip xs [0..<size xs]))"
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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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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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hide_const (open) n_lists
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fun splice :: "'a list \<Rightarrow> 'a list \<Rightarrow> 'a list" where
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"splice [] ys = ys" |
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"splice xs [] = xs" |
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"splice (x#xs) (y#ys) = x # y # splice xs ys"
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text{*
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\begin{figure}[htbp]
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\fbox{
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\begin{tabular}{l}
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@{lemma "[a,b]@[c,d] = [a,b,c,d]" by simp}\\
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@{lemma "length [a,b,c] = 3" by simp}\\
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@{lemma "set [a,b,c] = {a,b,c}" by simp}\\
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@{lemma "map f [a,b,c] = [f a, f b, f c]" by simp}\\
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@{lemma "rev [a,b,c] = [c,b,a]" by simp}\\
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@{lemma "hd [a,b,c,d] = a" by simp}\\
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@{lemma "tl [a,b,c,d] = [b,c,d]" by simp}\\
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@{lemma "last [a,b,c,d] = d" by simp}\\
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@{lemma "butlast [a,b,c,d] = [a,b,c]" by simp}\\
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@{lemma[source] "filter (\<lambda>n::nat. n<2) [0,2,1] = [0,1]" by simp}\\
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@{lemma "concat [[a,b],[c,d,e],[],[f]] = [a,b,c,d,e,f]" by simp}\\
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@{lemma "fold f [a,b,c] x = f c (f b (f a x))" by simp}\\
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@{lemma "foldr f [a,b,c] x = f a (f b (f c x))" by simp}\\
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@{lemma "foldl f x [a,b,c] = f (f (f x a) b) c" by simp}\\
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@{lemma "zip [a,b,c] [x,y,z] = [(a,x),(b,y),(c,z)]" by simp}\\
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@{lemma "zip [a,b] [x,y,z] = [(a,x),(b,y)]" by simp}\\
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@{lemma "enumerate 3 [a,b,c] = [(3,a),(4,b),(5,c)]" by normalization}\\
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@{lemma "List.product [a,b] [c,d] = [(a, c), (a, d), (b, c), (b, d)]" by simp}\\
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@{lemma "product_lists [[a,b], [c], [d,e]] = [[a,c,d], [a,c,e], [b,c,d], [b,c,e]]" by simp}\\
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@{lemma "splice [a,b,c] [x,y,z] = [a,x,b,y,c,z]" by simp}\\
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@{lemma "splice [a,b,c,d] [x,y] = [a,x,b,y,c,d]" by simp}\\
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@{lemma "take 2 [a,b,c,d] = [a,b]" by simp}\\
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@{lemma "take 6 [a,b,c,d] = [a,b,c,d]" by simp}\\
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@{lemma "drop 2 [a,b,c,d] = [c,d]" by simp}\\
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@{lemma "drop 6 [a,b,c,d] = []" by simp}\\
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@{lemma "takeWhile (%n::nat. n<3) [1,2,3,0] = [1,2]" by simp}\\
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@{lemma "dropWhile (%n::nat. n<3) [1,2,3,0] = [3,0]" by simp}\\
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@{lemma "distinct [2,0,1::nat]" by simp}\\
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@{lemma "remdups [2,0,2,1::nat,2] = [0,1,2]" by simp}\\
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@{lemma "remdups_adj [2,2,3,1,1::nat,2,1] = [2,3,1,2,1]" by simp}\\
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@{lemma "List.insert 2 [0::nat,1,2] = [0,1,2]" by (simp add: List.insert_def)}\\
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@{lemma "List.insert 3 [0::nat,1,2] = [3,0,1,2]" by (simp add: List.insert_def)}\\
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@{lemma "List.union [2,3,4] [0::int,1,2] = [4,3,0,1,2]" by (simp add: List.insert_def List.union_def)}\\
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   299
@{lemma "List.find (%i::int. i>0) [0,0] = None" by simp}\\
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   300
@{lemma "List.find (%i::int. i>0) [0,1,0,2] = Some 1" by simp}\\
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   301
@{lemma "List.extract (%i::int. i>0) [0,0] = None" by(simp add: extract_def)}\\
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   302
@{lemma "List.extract (%i::int. i>0) [0,1,0,2] = Some([0], 1, [0,2])" by(simp add: extract_def)}\\
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   303
@{lemma "remove1 2 [2,0,2,1::nat,2] = [0,2,1,2]" by simp}\\
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   304
@{lemma "removeAll 2 [2,0,2,1::nat,2] = [0,1]" by simp}\\
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   305
@{lemma "nth [a,b,c,d] 2 = c" by simp}\\
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   306
@{lemma "[a,b,c,d][2 := x] = [a,b,x,d]" by simp}\\
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   307
@{lemma "sublist [a,b,c,d,e] {0,2,3} = [a,c,d]" by (simp add:sublist_def)}\\
haftmann@49948
   308
@{lemma "sublists [a,b] = [[a, b], [a], [b], []]" by simp}\\
haftmann@49948
   309
@{lemma "List.n_lists 2 [a,b,c] = [[a, a], [b, a], [c, a], [a, b], [b, b], [c, b], [a, c], [b, c], [c, c]]" by (simp add: eval_nat_numeral)}\\
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@{lemma "rotate1 [a,b,c,d] = [b,c,d,a]" by simp}\\
blanchet@46440
   311
@{lemma "rotate 3 [a,b,c,d] = [d,a,b,c]" by (simp add:rotate_def eval_nat_numeral)}\\
nipkow@40077
   312
@{lemma "replicate 4 a = [a,a,a,a]" by (simp add:eval_nat_numeral)}\\
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   313
@{lemma "[2..<5] = [2,3,4]" by (simp add:eval_nat_numeral)}
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\end{tabular}}
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\caption{Characteristic examples}
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   316
\label{fig:Characteristic}
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\end{figure}
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   318
Figure~\ref{fig:Characteristic} shows characteristic examples
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   319
that should give an intuitive understanding of the above functions.
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*}
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   321
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   322
text{* The following simple sort functions are intended for proofs,
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not for efficient implementations. *}
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   324
wenzelm@25221
   325
context linorder
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   326
begin
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   327
haftmann@39915
   328
inductive sorted :: "'a list \<Rightarrow> bool" where
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   329
  Nil [iff]: "sorted []"
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   330
| Cons: "\<forall>y\<in>set xs. x \<le> y \<Longrightarrow> sorted xs \<Longrightarrow> sorted (x # xs)"
haftmann@39915
   331
nipkow@58807
   332
lemma sorted_single [iff]: "sorted [x]"
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   333
by (rule sorted.Cons) auto
nipkow@58807
   334
nipkow@58807
   335
lemma sorted_many: "x \<le> y \<Longrightarrow> sorted (y # zs) \<Longrightarrow> sorted (x # y # zs)"
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   336
by (rule sorted.Cons) (cases "y # zs" rule: sorted.cases, auto)
haftmann@39915
   337
haftmann@39915
   338
lemma sorted_many_eq [simp, code]:
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   339
  "sorted (x # y # zs) \<longleftrightarrow> x \<le> y \<and> sorted (y # zs)"
nipkow@58807
   340
by (auto intro: sorted_many elim: sorted.cases)
haftmann@39915
   341
haftmann@39915
   342
lemma [code]:
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   343
  "sorted [] \<longleftrightarrow> True"
haftmann@39915
   344
  "sorted [x] \<longleftrightarrow> True"
nipkow@58807
   345
by simp_all
nipkow@24697
   346
hoelzl@33639
   347
primrec insort_key :: "('b \<Rightarrow> 'a) \<Rightarrow> 'b \<Rightarrow> 'b list \<Rightarrow> 'b list" where
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   348
"insort_key f x [] = [x]" |
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   349
"insort_key f x (y#ys) =
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   350
  (if f x \<le> f y then (x#y#ys) else y#(insort_key f x ys))"
hoelzl@33639
   351
haftmann@35195
   352
definition sort_key :: "('b \<Rightarrow> 'a) \<Rightarrow> 'b list \<Rightarrow> 'b list" where
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   353
"sort_key f xs = foldr (insort_key f) xs []"
hoelzl@33639
   354
haftmann@40210
   355
definition insort_insert_key :: "('b \<Rightarrow> 'a) \<Rightarrow> 'b \<Rightarrow> 'b list \<Rightarrow> 'b list" where
nipkow@50548
   356
"insort_insert_key f x xs =
nipkow@50548
   357
  (if f x \<in> f ` set xs then xs else insort_key f x xs)"
haftmann@40210
   358
hoelzl@33639
   359
abbreviation "sort \<equiv> sort_key (\<lambda>x. x)"
hoelzl@33639
   360
abbreviation "insort \<equiv> insort_key (\<lambda>x. x)"
haftmann@40210
   361
abbreviation "insort_insert \<equiv> insort_insert_key (\<lambda>x. x)"
haftmann@35608
   362
wenzelm@25221
   363
end
wenzelm@25221
   364
nipkow@24616
   365
wenzelm@23388
   366
subsubsection {* List comprehension *}
nipkow@23192
   367
nipkow@24349
   368
text{* Input syntax for Haskell-like list comprehension notation.
nipkow@24349
   369
Typical example: @{text"[(x,y). x \<leftarrow> xs, y \<leftarrow> ys, x \<noteq> y]"},
nipkow@24349
   370
the list of all pairs of distinct elements from @{text xs} and @{text ys}.
nipkow@24349
   371
The syntax is as in Haskell, except that @{text"|"} becomes a dot
nipkow@24349
   372
(like in Isabelle's set comprehension): @{text"[e. x \<leftarrow> xs, \<dots>]"} rather than
nipkow@24349
   373
\verb![e| x <- xs, ...]!.
nipkow@24349
   374
nipkow@24349
   375
The qualifiers after the dot are
nipkow@24349
   376
\begin{description}
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   377
\item[generators] @{text"p \<leftarrow> xs"},
nipkow@24476
   378
 where @{text p} is a pattern and @{text xs} an expression of list type, or
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   379
\item[guards] @{text"b"}, where @{text b} is a boolean expression.
nipkow@24476
   380
%\item[local bindings] @ {text"let x = e"}.
nipkow@24349
   381
\end{description}
nipkow@23240
   382
nipkow@24476
   383
Just like in Haskell, list comprehension is just a shorthand. To avoid
nipkow@24476
   384
misunderstandings, the translation into desugared form is not reversed
nipkow@24476
   385
upon output. Note that the translation of @{text"[e. x \<leftarrow> xs]"} is
nipkow@24476
   386
optmized to @{term"map (%x. e) xs"}.
nipkow@23240
   387
nipkow@24349
   388
It is easy to write short list comprehensions which stand for complex
nipkow@24349
   389
expressions. During proofs, they may become unreadable (and
nipkow@24349
   390
mangled). In such cases it can be advisable to introduce separate
nipkow@24349
   391
definitions for the list comprehensions in question.  *}
nipkow@24349
   392
wenzelm@46138
   393
nonterminal lc_qual and lc_quals
nipkow@23192
   394
nipkow@23192
   395
syntax
wenzelm@46138
   396
  "_listcompr" :: "'a \<Rightarrow> lc_qual \<Rightarrow> lc_quals \<Rightarrow> 'a list"  ("[_ . __")
wenzelm@46138
   397
  "_lc_gen" :: "'a \<Rightarrow> 'a list \<Rightarrow> lc_qual"  ("_ <- _")
wenzelm@46138
   398
  "_lc_test" :: "bool \<Rightarrow> lc_qual" ("_")
wenzelm@46138
   399
  (*"_lc_let" :: "letbinds => lc_qual"  ("let _")*)
wenzelm@46138
   400
  "_lc_end" :: "lc_quals" ("]")
wenzelm@46138
   401
  "_lc_quals" :: "lc_qual \<Rightarrow> lc_quals \<Rightarrow> lc_quals"  (", __")
wenzelm@46138
   402
  "_lc_abs" :: "'a => 'b list => 'b list"
nipkow@23192
   403
nipkow@24476
   404
(* These are easier than ML code but cannot express the optimized
nipkow@24476
   405
   translation of [e. p<-xs]
nipkow@23192
   406
translations
wenzelm@46138
   407
  "[e. p<-xs]" => "concat(map (_lc_abs p [e]) xs)"
wenzelm@46138
   408
  "_listcompr e (_lc_gen p xs) (_lc_quals Q Qs)"
wenzelm@46138
   409
   => "concat (map (_lc_abs p (_listcompr e Q Qs)) xs)"
wenzelm@46138
   410
  "[e. P]" => "if P then [e] else []"
wenzelm@46138
   411
  "_listcompr e (_lc_test P) (_lc_quals Q Qs)"
wenzelm@46138
   412
   => "if P then (_listcompr e Q Qs) else []"
wenzelm@46138
   413
  "_listcompr e (_lc_let b) (_lc_quals Q Qs)"
wenzelm@46138
   414
   => "_Let b (_listcompr e Q Qs)"
nipkow@24476
   415
*)
nipkow@23240
   416
nipkow@23279
   417
syntax (xsymbols)
wenzelm@46138
   418
  "_lc_gen" :: "'a \<Rightarrow> 'a list \<Rightarrow> lc_qual"  ("_ \<leftarrow> _")
nipkow@23279
   419
syntax (HTML output)
wenzelm@46138
   420
  "_lc_gen" :: "'a \<Rightarrow> 'a list \<Rightarrow> lc_qual"  ("_ \<leftarrow> _")
nipkow@24349
   421
wenzelm@52143
   422
parse_translation {*
wenzelm@46138
   423
  let
wenzelm@46138
   424
    val NilC = Syntax.const @{const_syntax Nil};
wenzelm@46138
   425
    val ConsC = Syntax.const @{const_syntax Cons};
wenzelm@46138
   426
    val mapC = Syntax.const @{const_syntax map};
wenzelm@46138
   427
    val concatC = Syntax.const @{const_syntax concat};
wenzelm@46138
   428
    val IfC = Syntax.const @{const_syntax If};
wenzelm@46138
   429
wenzelm@46138
   430
    fun single x = ConsC $ x $ NilC;
wenzelm@46138
   431
wenzelm@46138
   432
    fun pat_tr ctxt p e opti = (* %x. case x of p => e | _ => [] *)
wenzelm@46138
   433
      let
wenzelm@46138
   434
        (* FIXME proper name context!? *)
wenzelm@46138
   435
        val x =
wenzelm@46138
   436
          Free (singleton (Name.variant_list (fold Term.add_free_names [p, e] [])) "x", dummyT);
wenzelm@46138
   437
        val e = if opti then single e else e;
wenzelm@46138
   438
        val case1 = Syntax.const @{syntax_const "_case1"} $ p $ e;
wenzelm@46138
   439
        val case2 =
wenzelm@46138
   440
          Syntax.const @{syntax_const "_case1"} $
wenzelm@56241
   441
            Syntax.const @{const_syntax Pure.dummy_pattern} $ NilC;
wenzelm@46138
   442
        val cs = Syntax.const @{syntax_const "_case2"} $ case1 $ case2;
traytel@51678
   443
      in Syntax_Trans.abs_tr [x, Case_Translation.case_tr false ctxt [x, cs]] end;
wenzelm@46138
   444
wenzelm@46138
   445
    fun abs_tr ctxt p e opti =
wenzelm@46138
   446
      (case Term_Position.strip_positions p of
wenzelm@46138
   447
        Free (s, T) =>
wenzelm@46138
   448
          let
wenzelm@46138
   449
            val thy = Proof_Context.theory_of ctxt;
wenzelm@46138
   450
            val s' = Proof_Context.intern_const ctxt s;
wenzelm@46138
   451
          in
wenzelm@46138
   452
            if Sign.declared_const thy s'
wenzelm@46138
   453
            then (pat_tr ctxt p e opti, false)
wenzelm@46138
   454
            else (Syntax_Trans.abs_tr [p, e], true)
wenzelm@46138
   455
          end
wenzelm@46138
   456
      | _ => (pat_tr ctxt p e opti, false));
wenzelm@46138
   457
wenzelm@46138
   458
    fun lc_tr ctxt [e, Const (@{syntax_const "_lc_test"}, _) $ b, qs] =
wenzelm@46138
   459
          let
wenzelm@46138
   460
            val res =
wenzelm@46138
   461
              (case qs of
wenzelm@46138
   462
                Const (@{syntax_const "_lc_end"}, _) => single e
wenzelm@46138
   463
              | Const (@{syntax_const "_lc_quals"}, _) $ q $ qs => lc_tr ctxt [e, q, qs]);
wenzelm@46138
   464
          in IfC $ b $ res $ NilC end
wenzelm@46138
   465
      | lc_tr ctxt
wenzelm@46138
   466
            [e, Const (@{syntax_const "_lc_gen"}, _) $ p $ es,
wenzelm@46138
   467
              Const(@{syntax_const "_lc_end"}, _)] =
wenzelm@46138
   468
          (case abs_tr ctxt p e true of
wenzelm@46138
   469
            (f, true) => mapC $ f $ es
wenzelm@46138
   470
          | (f, false) => concatC $ (mapC $ f $ es))
wenzelm@46138
   471
      | lc_tr ctxt
wenzelm@46138
   472
            [e, Const (@{syntax_const "_lc_gen"}, _) $ p $ es,
wenzelm@46138
   473
              Const (@{syntax_const "_lc_quals"}, _) $ q $ qs] =
wenzelm@46138
   474
          let val e' = lc_tr ctxt [e, q, qs];
wenzelm@46138
   475
          in concatC $ (mapC $ (fst (abs_tr ctxt p e' false)) $ es) end;
wenzelm@46138
   476
wenzelm@46138
   477
  in [(@{syntax_const "_listcompr"}, lc_tr)] end
nipkow@24349
   478
*}
nipkow@23279
   479
wenzelm@51272
   480
ML_val {*
wenzelm@42167
   481
  let
wenzelm@42167
   482
    val read = Syntax.read_term @{context};
wenzelm@42167
   483
    fun check s1 s2 = read s1 aconv read s2 orelse error ("Check failed: " ^ quote s1);
wenzelm@42167
   484
  in
wenzelm@42167
   485
    check "[(x,y,z). b]" "if b then [(x, y, z)] else []";
wenzelm@42167
   486
    check "[(x,y,z). x\<leftarrow>xs]" "map (\<lambda>x. (x, y, z)) xs";
wenzelm@42167
   487
    check "[e x y. x\<leftarrow>xs, y\<leftarrow>ys]" "concat (map (\<lambda>x. map (\<lambda>y. e x y) ys) xs)";
wenzelm@42167
   488
    check "[(x,y,z). x<a, x>b]" "if x < a then if b < x then [(x, y, z)] else [] else []";
wenzelm@42167
   489
    check "[(x,y,z). x\<leftarrow>xs, x>b]" "concat (map (\<lambda>x. if b < x then [(x, y, z)] else []) xs)";
wenzelm@42167
   490
    check "[(x,y,z). x<a, x\<leftarrow>xs]" "if x < a then map (\<lambda>x. (x, y, z)) xs else []";
wenzelm@42167
   491
    check "[(x,y). Cons True x \<leftarrow> xs]"
wenzelm@42167
   492
      "concat (map (\<lambda>xa. case xa of [] \<Rightarrow> [] | True # x \<Rightarrow> [(x, y)] | False # x \<Rightarrow> []) xs)";
wenzelm@42167
   493
    check "[(x,y,z). Cons x [] \<leftarrow> xs]"
wenzelm@42167
   494
      "concat (map (\<lambda>xa. case xa of [] \<Rightarrow> [] | [x] \<Rightarrow> [(x, y, z)] | x # aa # lista \<Rightarrow> []) xs)";
wenzelm@42167
   495
    check "[(x,y,z). x<a, x>b, x=d]"
wenzelm@42167
   496
      "if x < a then if b < x then if x = d then [(x, y, z)] else [] else [] else []";
wenzelm@42167
   497
    check "[(x,y,z). x<a, x>b, y\<leftarrow>ys]"
wenzelm@42167
   498
      "if x < a then if b < x then map (\<lambda>y. (x, y, z)) ys else [] else []";
wenzelm@42167
   499
    check "[(x,y,z). x<a, x\<leftarrow>xs,y>b]"
wenzelm@42167
   500
      "if x < a then concat (map (\<lambda>x. if b < y then [(x, y, z)] else []) xs) else []";
wenzelm@42167
   501
    check "[(x,y,z). x<a, x\<leftarrow>xs, y\<leftarrow>ys]"
wenzelm@42167
   502
      "if x < a then concat (map (\<lambda>x. map (\<lambda>y. (x, y, z)) ys) xs) else []";
wenzelm@42167
   503
    check "[(x,y,z). x\<leftarrow>xs, x>b, y<a]"
wenzelm@42167
   504
      "concat (map (\<lambda>x. if b < x then if y < a then [(x, y, z)] else [] else []) xs)";
wenzelm@42167
   505
    check "[(x,y,z). x\<leftarrow>xs, x>b, y\<leftarrow>ys]"
wenzelm@42167
   506
      "concat (map (\<lambda>x. if b < x then map (\<lambda>y. (x, y, z)) ys else []) xs)";
wenzelm@42167
   507
    check "[(x,y,z). x\<leftarrow>xs, y\<leftarrow>ys,y>x]"
wenzelm@42167
   508
      "concat (map (\<lambda>x. concat (map (\<lambda>y. if x < y then [(x, y, z)] else []) ys)) xs)";
wenzelm@42167
   509
    check "[(x,y,z). x\<leftarrow>xs, y\<leftarrow>ys,z\<leftarrow>zs]"
wenzelm@42167
   510
      "concat (map (\<lambda>x. concat (map (\<lambda>y. map (\<lambda>z. (x, y, z)) zs) ys)) xs)"
wenzelm@42167
   511
  end;
wenzelm@42167
   512
*}
wenzelm@42167
   513
wenzelm@35115
   514
(*
nipkow@24349
   515
term "[(x,y). x\<leftarrow>xs, let xx = x+x, y\<leftarrow>ys, y \<noteq> xx]"
nipkow@23192
   516
*)
nipkow@23192
   517
wenzelm@42167
   518
wenzelm@50422
   519
ML {*
wenzelm@50422
   520
(* Simproc for rewriting list comprehensions applied to List.set to set
wenzelm@50422
   521
   comprehension. *)
wenzelm@50422
   522
wenzelm@50422
   523
signature LIST_TO_SET_COMPREHENSION =
wenzelm@50422
   524
sig
wenzelm@51717
   525
  val simproc : Proof.context -> cterm -> thm option
wenzelm@50422
   526
end
wenzelm@50422
   527
wenzelm@50422
   528
structure List_to_Set_Comprehension : LIST_TO_SET_COMPREHENSION =
wenzelm@50422
   529
struct
wenzelm@50422
   530
wenzelm@50422
   531
(* conversion *)
wenzelm@50422
   532
wenzelm@50422
   533
fun all_exists_conv cv ctxt ct =
wenzelm@50422
   534
  (case Thm.term_of ct of
wenzelm@50422
   535
    Const (@{const_name HOL.Ex}, _) $ Abs _ =>
wenzelm@50422
   536
      Conv.arg_conv (Conv.abs_conv (all_exists_conv cv o #2) ctxt) ct
wenzelm@50422
   537
  | _ => cv ctxt ct)
wenzelm@50422
   538
wenzelm@50422
   539
fun all_but_last_exists_conv cv ctxt ct =
wenzelm@50422
   540
  (case Thm.term_of ct of
wenzelm@50422
   541
    Const (@{const_name HOL.Ex}, _) $ Abs (_, _, Const (@{const_name HOL.Ex}, _) $ _) =>
wenzelm@50422
   542
      Conv.arg_conv (Conv.abs_conv (all_but_last_exists_conv cv o #2) ctxt) ct
wenzelm@50422
   543
  | _ => cv ctxt ct)
wenzelm@50422
   544
wenzelm@50422
   545
fun Collect_conv cv ctxt ct =
wenzelm@50422
   546
  (case Thm.term_of ct of
wenzelm@50422
   547
    Const (@{const_name Set.Collect}, _) $ Abs _ => Conv.arg_conv (Conv.abs_conv cv ctxt) ct
wenzelm@50422
   548
  | _ => raise CTERM ("Collect_conv", [ct]))
wenzelm@50422
   549
wenzelm@50422
   550
fun rewr_conv' th = Conv.rewr_conv (mk_meta_eq th)
wenzelm@50422
   551
wenzelm@50422
   552
fun conjunct_assoc_conv ct =
wenzelm@50422
   553
  Conv.try_conv
wenzelm@51315
   554
    (rewr_conv' @{thm conj_assoc} then_conv HOLogic.conj_conv Conv.all_conv conjunct_assoc_conv) ct
wenzelm@50422
   555
wenzelm@50422
   556
fun right_hand_set_comprehension_conv conv ctxt =
wenzelm@51315
   557
  HOLogic.Trueprop_conv (HOLogic.eq_conv Conv.all_conv
wenzelm@50422
   558
    (Collect_conv (all_exists_conv conv o #2) ctxt))
wenzelm@50422
   559
wenzelm@50422
   560
wenzelm@50422
   561
(* term abstraction of list comprehension patterns *)
wenzelm@50422
   562
wenzelm@50422
   563
datatype termlets = If | Case of (typ * int)
wenzelm@50422
   564
wenzelm@51717
   565
fun simproc ctxt redex =
wenzelm@50422
   566
  let
blanchet@57816
   567
    val set_Nil_I = @{thm trans} OF [@{thm list.set(1)}, @{thm empty_def}]
wenzelm@50422
   568
    val set_singleton = @{lemma "set [a] = {x. x = a}" by simp}
wenzelm@50422
   569
    val inst_Collect_mem_eq = @{lemma "set A = {x. x : set A}" by simp}
wenzelm@50422
   570
    val del_refl_eq = @{lemma "(t = t & P) == P" by simp}
wenzelm@50422
   571
    fun mk_set T = Const (@{const_name List.set}, HOLogic.listT T --> HOLogic.mk_setT T)
wenzelm@50422
   572
    fun dest_set (Const (@{const_name List.set}, _) $ xs) = xs
wenzelm@50422
   573
    fun dest_singleton_list (Const (@{const_name List.Cons}, _)
wenzelm@50422
   574
          $ t $ (Const (@{const_name List.Nil}, _))) = t
wenzelm@50422
   575
      | dest_singleton_list t = raise TERM ("dest_singleton_list", [t])
wenzelm@50422
   576
    (* We check that one case returns a singleton list and all other cases
wenzelm@50422
   577
       return [], and return the index of the one singleton list case *)
wenzelm@50422
   578
    fun possible_index_of_singleton_case cases =
wenzelm@50422
   579
      let
wenzelm@50422
   580
        fun check (i, case_t) s =
wenzelm@50422
   581
          (case strip_abs_body case_t of
wenzelm@50422
   582
            (Const (@{const_name List.Nil}, _)) => s
traytel@53412
   583
          | _ => (case s of SOME NONE => SOME (SOME i) | _ => NONE))
wenzelm@50422
   584
      in
traytel@53412
   585
        fold_index check cases (SOME NONE) |> the_default NONE
wenzelm@50422
   586
      end
blanchet@54404
   587
    (* returns (case_expr type index chosen_case constr_name) option  *)
wenzelm@50422
   588
    fun dest_case case_term =
wenzelm@50422
   589
      let
wenzelm@50422
   590
        val (case_const, args) = strip_comb case_term
wenzelm@50422
   591
      in
wenzelm@50422
   592
        (case try dest_Const case_const of
wenzelm@50422
   593
          SOME (c, T) =>
blanchet@54404
   594
            (case Ctr_Sugar.ctr_sugar_of_case ctxt c of
blanchet@54404
   595
              SOME {ctrs, ...} =>
wenzelm@50422
   596
                (case possible_index_of_singleton_case (fst (split_last args)) of
wenzelm@50422
   597
                  SOME i =>
wenzelm@50422
   598
                    let
blanchet@54404
   599
                      val constr_names = map (fst o dest_Const) ctrs
wenzelm@50422
   600
                      val (Ts, _) = strip_type T
wenzelm@50422
   601
                      val T' = List.last Ts
blanchet@54404
   602
                    in SOME (List.last args, T', i, nth args i, nth constr_names i) end
wenzelm@50422
   603
                | NONE => NONE)
wenzelm@50422
   604
            | NONE => NONE)
wenzelm@50422
   605
        | NONE => NONE)
wenzelm@50422
   606
      end
wenzelm@50422
   607
    (* returns condition continuing term option *)
wenzelm@50422
   608
    fun dest_if (Const (@{const_name If}, _) $ cond $ then_t $ Const (@{const_name Nil}, _)) =
wenzelm@50422
   609
          SOME (cond, then_t)
wenzelm@50422
   610
      | dest_if _ = NONE
wenzelm@50422
   611
    fun tac _ [] = rtac set_singleton 1 ORELSE rtac inst_Collect_mem_eq 1
wenzelm@50422
   612
      | tac ctxt (If :: cont) =
wenzelm@58956
   613
          Splitter.split_tac ctxt [@{thm split_if}] 1
wenzelm@50422
   614
          THEN rtac @{thm conjI} 1
wenzelm@50422
   615
          THEN rtac @{thm impI} 1
wenzelm@50422
   616
          THEN Subgoal.FOCUS (fn {prems, context, ...} =>
wenzelm@50422
   617
            CONVERSION (right_hand_set_comprehension_conv (K
wenzelm@51315
   618
              (HOLogic.conj_conv (Conv.rewr_conv (List.last prems RS @{thm Eq_TrueI})) Conv.all_conv
wenzelm@50422
   619
               then_conv
wenzelm@50422
   620
               rewr_conv' @{lemma "(True & P) = P" by simp})) context) 1) ctxt 1
wenzelm@50422
   621
          THEN tac ctxt cont
wenzelm@50422
   622
          THEN rtac @{thm impI} 1
wenzelm@50422
   623
          THEN Subgoal.FOCUS (fn {prems, context, ...} =>
wenzelm@50422
   624
              CONVERSION (right_hand_set_comprehension_conv (K
wenzelm@51315
   625
                (HOLogic.conj_conv (Conv.rewr_conv (List.last prems RS @{thm Eq_FalseI})) Conv.all_conv
wenzelm@50422
   626
                 then_conv rewr_conv' @{lemma "(False & P) = False" by simp})) context) 1) ctxt 1
wenzelm@50422
   627
          THEN rtac set_Nil_I 1
wenzelm@50422
   628
      | tac ctxt (Case (T, i) :: cont) =
wenzelm@50422
   629
          let
blanchet@54404
   630
            val SOME {injects, distincts, case_thms, split, ...} =
blanchet@54404
   631
              Ctr_Sugar.ctr_sugar_of ctxt (fst (dest_Type T))
wenzelm@50422
   632
          in
wenzelm@50422
   633
            (* do case distinction *)
wenzelm@58956
   634
            Splitter.split_tac ctxt [split] 1
wenzelm@50422
   635
            THEN EVERY (map_index (fn (i', _) =>
blanchet@54404
   636
              (if i' < length case_thms - 1 then rtac @{thm conjI} 1 else all_tac)
wenzelm@50422
   637
              THEN REPEAT_DETERM (rtac @{thm allI} 1)
wenzelm@50422
   638
              THEN rtac @{thm impI} 1
wenzelm@50422
   639
              THEN (if i' = i then
wenzelm@50422
   640
                (* continue recursively *)
wenzelm@50422
   641
                Subgoal.FOCUS (fn {prems, context, ...} =>
wenzelm@50422
   642
                  CONVERSION (Thm.eta_conversion then_conv right_hand_set_comprehension_conv (K
wenzelm@51315
   643
                      ((HOLogic.conj_conv
wenzelm@51315
   644
                        (HOLogic.eq_conv Conv.all_conv (rewr_conv' (List.last prems)) then_conv
blanchet@54404
   645
                          (Conv.try_conv (Conv.rewrs_conv (map mk_meta_eq injects))))
wenzelm@50422
   646
                        Conv.all_conv)
wenzelm@50422
   647
                        then_conv (Conv.try_conv (Conv.rewr_conv del_refl_eq))
wenzelm@50422
   648
                        then_conv conjunct_assoc_conv)) context
wenzelm@51315
   649
                    then_conv (HOLogic.Trueprop_conv (HOLogic.eq_conv Conv.all_conv (Collect_conv (fn (_, ctxt) =>
wenzelm@50422
   650
                      Conv.repeat_conv
wenzelm@50422
   651
                        (all_but_last_exists_conv
wenzelm@50422
   652
                          (K (rewr_conv'
wenzelm@50422
   653
                            @{lemma "(EX x. x = t & P x) = P t" by simp})) ctxt)) context)))) 1) ctxt 1
wenzelm@50422
   654
                THEN tac ctxt cont
wenzelm@50422
   655
              else
wenzelm@50422
   656
                Subgoal.FOCUS (fn {prems, context, ...} =>
wenzelm@50422
   657
                  CONVERSION
wenzelm@50422
   658
                    (right_hand_set_comprehension_conv (K
wenzelm@51315
   659
                      (HOLogic.conj_conv
wenzelm@51315
   660
                        ((HOLogic.eq_conv Conv.all_conv
wenzelm@50422
   661
                          (rewr_conv' (List.last prems))) then_conv
blanchet@54404
   662
                          (Conv.rewrs_conv (map (fn th => th RS @{thm Eq_FalseI}) distincts)))
wenzelm@50422
   663
                        Conv.all_conv then_conv
wenzelm@50422
   664
                        (rewr_conv' @{lemma "(False & P) = False" by simp}))) context then_conv
wenzelm@51314
   665
                      HOLogic.Trueprop_conv
wenzelm@51315
   666
                        (HOLogic.eq_conv Conv.all_conv
wenzelm@50422
   667
                          (Collect_conv (fn (_, ctxt) =>
wenzelm@50422
   668
                            Conv.repeat_conv
wenzelm@50422
   669
                              (Conv.bottom_conv
wenzelm@50422
   670
                                (K (rewr_conv'
wenzelm@50422
   671
                                  @{lemma "(EX x. P) = P" by simp})) ctxt)) context))) 1) ctxt 1
blanchet@54404
   672
                THEN rtac set_Nil_I 1)) case_thms)
wenzelm@50422
   673
          end
wenzelm@50422
   674
    fun make_inner_eqs bound_vs Tis eqs t =
wenzelm@50422
   675
      (case dest_case t of
blanchet@54404
   676
        SOME (x, T, i, cont, constr_name) =>
wenzelm@50422
   677
          let
wenzelm@52131
   678
            val (vs, body) = strip_abs (Envir.eta_long (map snd bound_vs) cont)
wenzelm@50422
   679
            val x' = incr_boundvars (length vs) x
wenzelm@50422
   680
            val eqs' = map (incr_boundvars (length vs)) eqs
wenzelm@50422
   681
            val constr_t =
wenzelm@50422
   682
              list_comb
wenzelm@50422
   683
                (Const (constr_name, map snd vs ---> T), map Bound (((length vs) - 1) downto 0))
wenzelm@50422
   684
            val constr_eq = Const (@{const_name HOL.eq}, T --> T --> @{typ bool}) $ constr_t $ x'
wenzelm@50422
   685
          in
wenzelm@50422
   686
            make_inner_eqs (rev vs @ bound_vs) (Case (T, i) :: Tis) (constr_eq :: eqs') body
wenzelm@50422
   687
          end
wenzelm@50422
   688
      | NONE =>
wenzelm@50422
   689
          (case dest_if t of
wenzelm@50422
   690
            SOME (condition, cont) => make_inner_eqs bound_vs (If :: Tis) (condition :: eqs) cont
wenzelm@50422
   691
          | NONE =>
wenzelm@50422
   692
            if eqs = [] then NONE (* no rewriting, nothing to be done *)
wenzelm@50422
   693
            else
wenzelm@50422
   694
              let
wenzelm@50422
   695
                val Type (@{type_name List.list}, [rT]) = fastype_of1 (map snd bound_vs, t)
wenzelm@50422
   696
                val pat_eq =
wenzelm@50422
   697
                  (case try dest_singleton_list t of
wenzelm@50422
   698
                    SOME t' =>
wenzelm@50422
   699
                      Const (@{const_name HOL.eq}, rT --> rT --> @{typ bool}) $
wenzelm@50422
   700
                        Bound (length bound_vs) $ t'
wenzelm@50422
   701
                  | NONE =>
wenzelm@50422
   702
                      Const (@{const_name Set.member}, rT --> HOLogic.mk_setT rT --> @{typ bool}) $
wenzelm@50422
   703
                        Bound (length bound_vs) $ (mk_set rT $ t))
wenzelm@50422
   704
                val reverse_bounds = curry subst_bounds
wenzelm@50422
   705
                  ((map Bound ((length bound_vs - 1) downto 0)) @ [Bound (length bound_vs)])
wenzelm@50422
   706
                val eqs' = map reverse_bounds eqs
wenzelm@50422
   707
                val pat_eq' = reverse_bounds pat_eq
wenzelm@50422
   708
                val inner_t =
wenzelm@50422
   709
                  fold (fn (_, T) => fn t => HOLogic.exists_const T $ absdummy T t)
wenzelm@50422
   710
                    (rev bound_vs) (fold (curry HOLogic.mk_conj) eqs' pat_eq')
wenzelm@59582
   711
                val lhs = Thm.term_of redex
wenzelm@50422
   712
                val rhs = HOLogic.mk_Collect ("x", rT, inner_t)
wenzelm@50422
   713
                val rewrite_rule_t = HOLogic.mk_Trueprop (HOLogic.mk_eq (lhs, rhs))
wenzelm@50422
   714
              in
wenzelm@50422
   715
                SOME
wenzelm@50422
   716
                  ((Goal.prove ctxt [] [] rewrite_rule_t
wenzelm@50422
   717
                    (fn {context, ...} => tac context (rev Tis))) RS @{thm eq_reflection})
wenzelm@50422
   718
              end))
wenzelm@50422
   719
  in
wenzelm@59582
   720
    make_inner_eqs [] [] [] (dest_set (Thm.term_of redex))
wenzelm@50422
   721
  end
wenzelm@50422
   722
wenzelm@50422
   723
end
wenzelm@50422
   724
*}
bulwahn@41463
   725
bulwahn@41463
   726
simproc_setup list_to_set_comprehension ("set xs") = {* K List_to_Set_Comprehension.simproc *}
bulwahn@41463
   727
haftmann@46133
   728
code_datatype set coset
haftmann@46133
   729
haftmann@46133
   730
hide_const (open) coset
wenzelm@35115
   731
haftmann@49948
   732
haftmann@21061
   733
subsubsection {* @{const Nil} and @{const Cons} *}
haftmann@21061
   734
haftmann@21061
   735
lemma not_Cons_self [simp]:
haftmann@21061
   736
  "xs \<noteq> x # xs"
nipkow@13145
   737
by (induct xs) auto
wenzelm@13114
   738
nipkow@58807
   739
lemma not_Cons_self2 [simp]: "x # xs \<noteq> xs"
wenzelm@41697
   740
by (rule not_Cons_self [symmetric])
wenzelm@13114
   741
wenzelm@13142
   742
lemma neq_Nil_conv: "(xs \<noteq> []) = (\<exists>y ys. xs = y # ys)"
nipkow@13145
   743
by (induct xs) auto
wenzelm@13114
   744
nipkow@53689
   745
lemma tl_Nil: "tl xs = [] \<longleftrightarrow> xs = [] \<or> (EX x. xs = [x])"
nipkow@53689
   746
by (cases xs) auto
nipkow@53689
   747
nipkow@53689
   748
lemma Nil_tl: "[] = tl xs \<longleftrightarrow> xs = [] \<or> (EX x. xs = [x])"
nipkow@53689
   749
by (cases xs) auto
nipkow@53689
   750
wenzelm@13142
   751
lemma length_induct:
haftmann@21061
   752
  "(\<And>xs. \<forall>ys. length ys < length xs \<longrightarrow> P ys \<Longrightarrow> P xs) \<Longrightarrow> P xs"
nipkow@53689
   753
by (fact measure_induct)
wenzelm@13114
   754
haftmann@37289
   755
lemma list_nonempty_induct [consumes 1, case_names single cons]:
haftmann@37289
   756
  assumes "xs \<noteq> []"
haftmann@37289
   757
  assumes single: "\<And>x. P [x]"
haftmann@37289
   758
  assumes cons: "\<And>x xs. xs \<noteq> [] \<Longrightarrow> P xs \<Longrightarrow> P (x # xs)"
haftmann@37289
   759
  shows "P xs"
haftmann@37289
   760
using `xs \<noteq> []` proof (induct xs)
haftmann@37289
   761
  case Nil then show ?case by simp
haftmann@37289
   762
next
wenzelm@53374
   763
  case (Cons x xs)
wenzelm@53374
   764
  show ?case
wenzelm@53374
   765
  proof (cases xs)
wenzelm@53374
   766
    case Nil
wenzelm@53374
   767
    with single show ?thesis by simp
haftmann@37289
   768
  next
wenzelm@53374
   769
    case Cons
wenzelm@53374
   770
    show ?thesis
wenzelm@53374
   771
    proof (rule cons)
wenzelm@53374
   772
      from Cons show "xs \<noteq> []" by simp
wenzelm@53374
   773
      with Cons.hyps show "P xs" .
wenzelm@53374
   774
    qed
haftmann@37289
   775
  qed
haftmann@37289
   776
qed
haftmann@37289
   777
hoelzl@45714
   778
lemma inj_split_Cons: "inj_on (\<lambda>(xs, n). n#xs) X"
hoelzl@45714
   779
  by (auto intro!: inj_onI)
wenzelm@13114
   780
haftmann@49948
   781
haftmann@21061
   782
subsubsection {* @{const length} *}
wenzelm@13114
   783
wenzelm@13142
   784
text {*
haftmann@21061
   785
  Needs to come before @{text "@"} because of theorem @{text
haftmann@21061
   786
  append_eq_append_conv}.
wenzelm@13142
   787
*}
wenzelm@13114
   788
wenzelm@13142
   789
lemma length_append [simp]: "length (xs @ ys) = length xs + length ys"
nipkow@13145
   790
by (induct xs) auto
wenzelm@13114
   791
wenzelm@13142
   792
lemma length_map [simp]: "length (map f xs) = length xs"
nipkow@13145
   793
by (induct xs) auto
wenzelm@13114
   794
wenzelm@13142
   795
lemma length_rev [simp]: "length (rev xs) = length xs"
nipkow@13145
   796
by (induct xs) auto
wenzelm@13114
   797
wenzelm@13142
   798
lemma length_tl [simp]: "length (tl xs) = length xs - 1"
nipkow@13145
   799
by (cases xs) auto
wenzelm@13114
   800
wenzelm@13142
   801
lemma length_0_conv [iff]: "(length xs = 0) = (xs = [])"
nipkow@13145
   802
by (induct xs) auto
wenzelm@13114
   803
wenzelm@13142
   804
lemma length_greater_0_conv [iff]: "(0 < length xs) = (xs \<noteq> [])"
nipkow@13145
   805
by (induct xs) auto
wenzelm@13114
   806
nipkow@23479
   807
lemma length_pos_if_in_set: "x : set xs \<Longrightarrow> length xs > 0"
nipkow@23479
   808
by auto
nipkow@23479
   809
wenzelm@13114
   810
lemma length_Suc_conv:
nipkow@13145
   811
"(length xs = Suc n) = (\<exists>y ys. xs = y # ys \<and> length ys = n)"
nipkow@13145
   812
by (induct xs) auto
wenzelm@13142
   813
nipkow@14025
   814
lemma Suc_length_conv:
nipkow@58807
   815
  "(Suc n = length xs) = (\<exists>y ys. xs = y # ys \<and> length ys = n)"
paulson@14208
   816
apply (induct xs, simp, simp)
nipkow@14025
   817
apply blast
nipkow@14025
   818
done
nipkow@14025
   819
wenzelm@25221
   820
lemma impossible_Cons: "length xs <= length ys ==> xs = x # ys = False"
nipkow@58807
   821
by (induct xs) auto
wenzelm@25221
   822
haftmann@26442
   823
lemma list_induct2 [consumes 1, case_names Nil Cons]:
haftmann@26442
   824
  "length xs = length ys \<Longrightarrow> P [] [] \<Longrightarrow>
haftmann@26442
   825
   (\<And>x xs y ys. length xs = length ys \<Longrightarrow> P xs ys \<Longrightarrow> P (x#xs) (y#ys))
haftmann@26442
   826
   \<Longrightarrow> P xs ys"
haftmann@26442
   827
proof (induct xs arbitrary: ys)
haftmann@26442
   828
  case Nil then show ?case by simp
haftmann@26442
   829
next
haftmann@26442
   830
  case (Cons x xs ys) then show ?case by (cases ys) simp_all
haftmann@26442
   831
qed
haftmann@26442
   832
haftmann@26442
   833
lemma list_induct3 [consumes 2, case_names Nil Cons]:
haftmann@26442
   834
  "length xs = length ys \<Longrightarrow> length ys = length zs \<Longrightarrow> P [] [] [] \<Longrightarrow>
haftmann@26442
   835
   (\<And>x xs y ys z zs. length xs = length ys \<Longrightarrow> length ys = length zs \<Longrightarrow> P xs ys zs \<Longrightarrow> P (x#xs) (y#ys) (z#zs))
haftmann@26442
   836
   \<Longrightarrow> P xs ys zs"
haftmann@26442
   837
proof (induct xs arbitrary: ys zs)
haftmann@26442
   838
  case Nil then show ?case by simp
haftmann@26442
   839
next
haftmann@26442
   840
  case (Cons x xs ys zs) then show ?case by (cases ys, simp_all)
haftmann@26442
   841
    (cases zs, simp_all)
haftmann@26442
   842
qed
wenzelm@13114
   843
kaliszyk@36154
   844
lemma list_induct4 [consumes 3, case_names Nil Cons]:
kaliszyk@36154
   845
  "length xs = length ys \<Longrightarrow> length ys = length zs \<Longrightarrow> length zs = length ws \<Longrightarrow>
kaliszyk@36154
   846
   P [] [] [] [] \<Longrightarrow> (\<And>x xs y ys z zs w ws. length xs = length ys \<Longrightarrow>
kaliszyk@36154
   847
   length ys = length zs \<Longrightarrow> length zs = length ws \<Longrightarrow> P xs ys zs ws \<Longrightarrow>
kaliszyk@36154
   848
   P (x#xs) (y#ys) (z#zs) (w#ws)) \<Longrightarrow> P xs ys zs ws"
kaliszyk@36154
   849
proof (induct xs arbitrary: ys zs ws)
kaliszyk@36154
   850
  case Nil then show ?case by simp
kaliszyk@36154
   851
next
kaliszyk@36154
   852
  case (Cons x xs ys zs ws) then show ?case by ((cases ys, simp_all), (cases zs,simp_all)) (cases ws, simp_all)
kaliszyk@36154
   853
qed
kaliszyk@36154
   854
krauss@22493
   855
lemma list_induct2': 
krauss@22493
   856
  "\<lbrakk> P [] [];
krauss@22493
   857
  \<And>x xs. P (x#xs) [];
krauss@22493
   858
  \<And>y ys. P [] (y#ys);
krauss@22493
   859
   \<And>x xs y ys. P xs ys  \<Longrightarrow> P (x#xs) (y#ys) \<rbrakk>
krauss@22493
   860
 \<Longrightarrow> P xs ys"
krauss@22493
   861
by (induct xs arbitrary: ys) (case_tac x, auto)+
krauss@22493
   862
blanchet@55524
   863
lemma list_all2_iff:
blanchet@55524
   864
  "list_all2 P xs ys \<longleftrightarrow> length xs = length ys \<and> (\<forall>(x, y) \<in> set (zip xs ys). P x y)"
blanchet@55524
   865
by (induct xs ys rule: list_induct2') auto
blanchet@55524
   866
nipkow@22143
   867
lemma neq_if_length_neq: "length xs \<noteq> length ys \<Longrightarrow> (xs = ys) == False"
nipkow@24349
   868
by (rule Eq_FalseI) auto
wenzelm@24037
   869
wenzelm@24037
   870
simproc_setup list_neq ("(xs::'a list) = ys") = {*
nipkow@22143
   871
(*
nipkow@22143
   872
Reduces xs=ys to False if xs and ys cannot be of the same length.
nipkow@22143
   873
This is the case if the atomic sublists of one are a submultiset
nipkow@22143
   874
of those of the other list and there are fewer Cons's in one than the other.
nipkow@22143
   875
*)
wenzelm@24037
   876
wenzelm@24037
   877
let
nipkow@22143
   878
huffman@29856
   879
fun len (Const(@{const_name Nil},_)) acc = acc
huffman@29856
   880
  | len (Const(@{const_name Cons},_) $ _ $ xs) (ts,n) = len xs (ts,n+1)
huffman@29856
   881
  | len (Const(@{const_name append},_) $ xs $ ys) acc = len xs (len ys acc)
huffman@29856
   882
  | len (Const(@{const_name rev},_) $ xs) acc = len xs acc
huffman@29856
   883
  | len (Const(@{const_name map},_) $ _ $ xs) acc = len xs acc
nipkow@22143
   884
  | len t (ts,n) = (t::ts,n);
nipkow@22143
   885
wenzelm@51717
   886
val ss = simpset_of @{context};
wenzelm@51717
   887
wenzelm@51717
   888
fun list_neq ctxt ct =
nipkow@22143
   889
  let
wenzelm@24037
   890
    val (Const(_,eqT) $ lhs $ rhs) = Thm.term_of ct;
nipkow@22143
   891
    val (ls,m) = len lhs ([],0) and (rs,n) = len rhs ([],0);
nipkow@22143
   892
    fun prove_neq() =
nipkow@22143
   893
      let
nipkow@22143
   894
        val Type(_,listT::_) = eqT;
haftmann@22994
   895
        val size = HOLogic.size_const listT;
nipkow@22143
   896
        val eq_len = HOLogic.mk_eq (size $ lhs, size $ rhs);
nipkow@22143
   897
        val neq_len = HOLogic.mk_Trueprop (HOLogic.Not $ eq_len);
wenzelm@51717
   898
        val thm = Goal.prove ctxt [] [] neq_len
wenzelm@51717
   899
          (K (simp_tac (put_simpset ss ctxt) 1));
haftmann@22633
   900
      in SOME (thm RS @{thm neq_if_length_neq}) end
nipkow@22143
   901
  in
wenzelm@23214
   902
    if m < n andalso submultiset (op aconv) (ls,rs) orelse
wenzelm@23214
   903
       n < m andalso submultiset (op aconv) (rs,ls)
nipkow@22143
   904
    then prove_neq() else NONE
nipkow@22143
   905
  end;
wenzelm@51717
   906
in K list_neq end;
nipkow@22143
   907
*}
nipkow@22143
   908
nipkow@22143
   909
nipkow@15392
   910
subsubsection {* @{text "@"} -- append *}
wenzelm@13114
   911
wenzelm@13142
   912
lemma append_assoc [simp]: "(xs @ ys) @ zs = xs @ (ys @ zs)"
nipkow@13145
   913
by (induct xs) auto
wenzelm@13114
   914
wenzelm@13142
   915
lemma append_Nil2 [simp]: "xs @ [] = xs"
nipkow@13145
   916
by (induct xs) auto
nipkow@3507
   917
wenzelm@13142
   918
lemma append_is_Nil_conv [iff]: "(xs @ ys = []) = (xs = [] \<and> ys = [])"
nipkow@13145
   919
by (induct xs) auto
wenzelm@13114
   920
wenzelm@13142
   921
lemma Nil_is_append_conv [iff]: "([] = xs @ ys) = (xs = [] \<and> ys = [])"
nipkow@13145
   922
by (induct xs) auto
wenzelm@13114
   923
wenzelm@13142
   924
lemma append_self_conv [iff]: "(xs @ ys = xs) = (ys = [])"
nipkow@13145
   925
by (induct xs) auto
wenzelm@13114
   926
wenzelm@13142
   927
lemma self_append_conv [iff]: "(xs = xs @ ys) = (ys = [])"
nipkow@13145
   928
by (induct xs) auto
wenzelm@13114
   929
blanchet@54147
   930
lemma append_eq_append_conv [simp]:
nipkow@58807
   931
  "length xs = length ys \<or> length us = length vs
nipkow@58807
   932
  ==> (xs@us = ys@vs) = (xs=ys \<and> us=vs)"
nipkow@24526
   933
apply (induct xs arbitrary: ys)
paulson@14208
   934
 apply (case_tac ys, simp, force)
paulson@14208
   935
apply (case_tac ys, force, simp)
nipkow@13145
   936
done
wenzelm@13142
   937
nipkow@24526
   938
lemma append_eq_append_conv2: "(xs @ ys = zs @ ts) =
nipkow@24526
   939
  (EX us. xs = zs @ us & us @ ys = ts | xs @ us = zs & ys = us@ ts)"
nipkow@24526
   940
apply (induct xs arbitrary: ys zs ts)
nipkow@44890
   941
 apply fastforce
nipkow@14495
   942
apply(case_tac zs)
nipkow@14495
   943
 apply simp
nipkow@44890
   944
apply fastforce
nipkow@14495
   945
done
nipkow@14495
   946
berghofe@34910
   947
lemma same_append_eq [iff, induct_simp]: "(xs @ ys = xs @ zs) = (ys = zs)"
nipkow@13145
   948
by simp
wenzelm@13142
   949
wenzelm@13142
   950
lemma append1_eq_conv [iff]: "(xs @ [x] = ys @ [y]) = (xs = ys \<and> x = y)"
nipkow@13145
   951
by simp
wenzelm@13114
   952
berghofe@34910
   953
lemma append_same_eq [iff, induct_simp]: "(ys @ xs = zs @ xs) = (ys = zs)"
nipkow@13145
   954
by simp
wenzelm@13114
   955
wenzelm@13142
   956
lemma append_self_conv2 [iff]: "(xs @ ys = ys) = (xs = [])"
nipkow@13145
   957
using append_same_eq [of _ _ "[]"] by auto
nipkow@3507
   958
wenzelm@13142
   959
lemma self_append_conv2 [iff]: "(ys = xs @ ys) = (xs = [])"
nipkow@13145
   960
using append_same_eq [of "[]"] by auto
wenzelm@13114
   961
blanchet@54147
   962
lemma hd_Cons_tl [simp]: "xs \<noteq> [] ==> hd xs # tl xs = xs"
nipkow@13145
   963
by (induct xs) auto
wenzelm@13114
   964
wenzelm@13142
   965
lemma hd_append: "hd (xs @ ys) = (if xs = [] then hd ys else hd xs)"
nipkow@13145
   966
by (induct xs) auto
wenzelm@13114
   967
wenzelm@13142
   968
lemma hd_append2 [simp]: "xs \<noteq> [] ==> hd (xs @ ys) = hd xs"
nipkow@13145
   969
by (simp add: hd_append split: list.split)
wenzelm@13114
   970
wenzelm@13142
   971
lemma tl_append: "tl (xs @ ys) = (case xs of [] => tl ys | z#zs => zs @ ys)"
nipkow@13145
   972
by (simp split: list.split)
wenzelm@13114
   973
wenzelm@13142
   974
lemma tl_append2 [simp]: "xs \<noteq> [] ==> tl (xs @ ys) = tl xs @ ys"
nipkow@13145
   975
by (simp add: tl_append split: list.split)
wenzelm@13114
   976
wenzelm@13114
   977
nipkow@14300
   978
lemma Cons_eq_append_conv: "x#xs = ys@zs =
nipkow@14300
   979
 (ys = [] & x#xs = zs | (EX ys'. x#ys' = ys & xs = ys'@zs))"
nipkow@14300
   980
by(cases ys) auto
nipkow@14300
   981
nipkow@15281
   982
lemma append_eq_Cons_conv: "(ys@zs = x#xs) =
nipkow@15281
   983
 (ys = [] & zs = x#xs | (EX ys'. ys = x#ys' & ys'@zs = xs))"
nipkow@15281
   984
by(cases ys) auto
nipkow@15281
   985
nipkow@14300
   986
wenzelm@13142
   987
text {* Trivial rules for solving @{text "@"}-equations automatically. *}
wenzelm@13114
   988
wenzelm@13114
   989
lemma eq_Nil_appendI: "xs = ys ==> xs = [] @ ys"
nipkow@13145
   990
by simp
wenzelm@13114
   991
wenzelm@13142
   992
lemma Cons_eq_appendI:
nipkow@13145
   993
"[| x # xs1 = ys; xs = xs1 @ zs |] ==> x # xs = ys @ zs"
nipkow@13145
   994
by (drule sym) simp
wenzelm@13114
   995
wenzelm@13142
   996
lemma append_eq_appendI:
nipkow@13145
   997
"[| xs @ xs1 = zs; ys = xs1 @ us |] ==> xs @ ys = zs @ us"
nipkow@13145
   998
by (drule sym) simp
wenzelm@13114
   999
wenzelm@13114
  1000
wenzelm@13142
  1001
text {*
nipkow@13145
  1002
Simplification procedure for all list equalities.
nipkow@13145
  1003
Currently only tries to rearrange @{text "@"} to see if
nipkow@13145
  1004
- both lists end in a singleton list,
nipkow@13145
  1005
- or both lists end in the same list.
wenzelm@13142
  1006
*}
wenzelm@13142
  1007
wenzelm@43594
  1008
simproc_setup list_eq ("(xs::'a list) = ys")  = {*
wenzelm@13462
  1009
  let
wenzelm@43594
  1010
    fun last (cons as Const (@{const_name Cons}, _) $ _ $ xs) =
wenzelm@43594
  1011
          (case xs of Const (@{const_name Nil}, _) => cons | _ => last xs)
wenzelm@43594
  1012
      | last (Const(@{const_name append},_) $ _ $ ys) = last ys
wenzelm@43594
  1013
      | last t = t;
wenzelm@43594
  1014
    
wenzelm@43594
  1015
    fun list1 (Const(@{const_name Cons},_) $ _ $ Const(@{const_name Nil},_)) = true
wenzelm@43594
  1016
      | list1 _ = false;
wenzelm@43594
  1017
    
wenzelm@43594
  1018
    fun butlast ((cons as Const(@{const_name Cons},_) $ x) $ xs) =
wenzelm@43594
  1019
          (case xs of Const (@{const_name Nil}, _) => xs | _ => cons $ butlast xs)
wenzelm@43594
  1020
      | butlast ((app as Const (@{const_name append}, _) $ xs) $ ys) = app $ butlast ys
wenzelm@43594
  1021
      | butlast xs = Const(@{const_name Nil}, fastype_of xs);
wenzelm@43594
  1022
    
wenzelm@43594
  1023
    val rearr_ss =
wenzelm@51717
  1024
      simpset_of (put_simpset HOL_basic_ss @{context}
wenzelm@51717
  1025
        addsimps [@{thm append_assoc}, @{thm append_Nil}, @{thm append_Cons}]);
wenzelm@43594
  1026
    
wenzelm@51717
  1027
    fun list_eq ctxt (F as (eq as Const(_,eqT)) $ lhs $ rhs) =
wenzelm@13462
  1028
      let
wenzelm@43594
  1029
        val lastl = last lhs and lastr = last rhs;
wenzelm@43594
  1030
        fun rearr conv =
wenzelm@43594
  1031
          let
wenzelm@43594
  1032
            val lhs1 = butlast lhs and rhs1 = butlast rhs;
wenzelm@43594
  1033
            val Type(_,listT::_) = eqT
wenzelm@43594
  1034
            val appT = [listT,listT] ---> listT
wenzelm@43594
  1035
            val app = Const(@{const_name append},appT)
wenzelm@43594
  1036
            val F2 = eq $ (app$lhs1$lastl) $ (app$rhs1$lastr)
wenzelm@43594
  1037
            val eq = HOLogic.mk_Trueprop (HOLogic.mk_eq (F,F2));
wenzelm@51717
  1038
            val thm = Goal.prove ctxt [] [] eq
wenzelm@51717
  1039
              (K (simp_tac (put_simpset rearr_ss ctxt) 1));
wenzelm@43594
  1040
          in SOME ((conv RS (thm RS trans)) RS eq_reflection) end;
wenzelm@43594
  1041
      in
wenzelm@43594
  1042
        if list1 lastl andalso list1 lastr then rearr @{thm append1_eq_conv}
wenzelm@43594
  1043
        else if lastl aconv lastr then rearr @{thm append_same_eq}
wenzelm@43594
  1044
        else NONE
wenzelm@43594
  1045
      end;
wenzelm@59582
  1046
  in fn _ => fn ctxt => fn ct => list_eq ctxt (Thm.term_of ct) end;
wenzelm@13114
  1047
*}
wenzelm@13114
  1048
wenzelm@13114
  1049
haftmann@49948
  1050
subsubsection {* @{const map} *}
wenzelm@13114
  1051
nipkow@58807
  1052
lemma hd_map: "xs \<noteq> [] \<Longrightarrow> hd (map f xs) = f (hd xs)"
nipkow@58807
  1053
by (cases xs) simp_all
nipkow@58807
  1054
nipkow@58807
  1055
lemma map_tl: "map f (tl xs) = tl (map f xs)"
nipkow@58807
  1056
by (cases xs) simp_all
haftmann@40210
  1057
wenzelm@13142
  1058
lemma map_ext: "(!!x. x : set xs --> f x = g x) ==> map f xs = map g xs"
nipkow@13145
  1059
by (induct xs) simp_all
wenzelm@13114
  1060
wenzelm@13142
  1061
lemma map_ident [simp]: "map (\<lambda>x. x) = (\<lambda>xs. xs)"
nipkow@13145
  1062
by (rule ext, induct_tac xs) auto
wenzelm@13114
  1063
wenzelm@13142
  1064
lemma map_append [simp]: "map f (xs @ ys) = map f xs @ map f ys"
nipkow@13145
  1065
by (induct xs) auto
wenzelm@13114
  1066
hoelzl@33639
  1067
lemma map_map [simp]: "map f (map g xs) = map (f \<circ> g) xs"
hoelzl@33639
  1068
by (induct xs) auto
hoelzl@33639
  1069
nipkow@35208
  1070
lemma map_comp_map[simp]: "((map f) o (map g)) = map(f o g)"
nipkow@58807
  1071
by (rule ext) simp
nipkow@35208
  1072
wenzelm@13142
  1073
lemma rev_map: "rev (map f xs) = map f (rev xs)"
nipkow@13145
  1074
by (induct xs) auto
wenzelm@13114
  1075
nipkow@13737
  1076
lemma map_eq_conv[simp]: "(map f xs = map g xs) = (!x : set xs. f x = g x)"
nipkow@13737
  1077
by (induct xs) auto
nipkow@13737
  1078
krauss@44013
  1079
lemma map_cong [fundef_cong]:
haftmann@40122
  1080
  "xs = ys \<Longrightarrow> (\<And>x. x \<in> set ys \<Longrightarrow> f x = g x) \<Longrightarrow> map f xs = map g ys"
nipkow@58807
  1081
by simp
wenzelm@13114
  1082
wenzelm@13142
  1083
lemma map_is_Nil_conv [iff]: "(map f xs = []) = (xs = [])"
nipkow@13145
  1084
by (cases xs) auto
wenzelm@13114
  1085
wenzelm@13142
  1086
lemma Nil_is_map_conv [iff]: "([] = map f xs) = (xs = [])"
nipkow@13145
  1087
by (cases xs) auto
wenzelm@13114
  1088
paulson@18447
  1089
lemma map_eq_Cons_conv:
nipkow@58807
  1090
  "(map f xs = y#ys) = (\<exists>z zs. xs = z#zs \<and> f z = y \<and> map f zs = ys)"
nipkow@13145
  1091
by (cases xs) auto
wenzelm@13114
  1092
paulson@18447
  1093
lemma Cons_eq_map_conv:
nipkow@58807
  1094
  "(x#xs = map f ys) = (\<exists>z zs. ys = z#zs \<and> x = f z \<and> xs = map f zs)"
nipkow@14025
  1095
by (cases ys) auto
nipkow@14025
  1096
paulson@18447
  1097
lemmas map_eq_Cons_D = map_eq_Cons_conv [THEN iffD1]
paulson@18447
  1098
lemmas Cons_eq_map_D = Cons_eq_map_conv [THEN iffD1]
paulson@18447
  1099
declare map_eq_Cons_D [dest!]  Cons_eq_map_D [dest!]
paulson@18447
  1100
nipkow@14111
  1101
lemma ex_map_conv:
nipkow@14111
  1102
  "(EX xs. ys = map f xs) = (ALL y : set ys. EX x. y = f x)"
paulson@18447
  1103
by(induct ys, auto simp add: Cons_eq_map_conv)
nipkow@14111
  1104
nipkow@15110
  1105
lemma map_eq_imp_length_eq:
paulson@35510
  1106
  assumes "map f xs = map g ys"
haftmann@26734
  1107
  shows "length xs = length ys"
wenzelm@53374
  1108
  using assms
wenzelm@53374
  1109
proof (induct ys arbitrary: xs)
haftmann@26734
  1110
  case Nil then show ?case by simp
haftmann@26734
  1111
next
haftmann@26734
  1112
  case (Cons y ys) then obtain z zs where xs: "xs = z # zs" by auto
paulson@35510
  1113
  from Cons xs have "map f zs = map g ys" by simp
wenzelm@53374
  1114
  with Cons have "length zs = length ys" by blast
haftmann@26734
  1115
  with xs show ?case by simp
haftmann@26734
  1116
qed
haftmann@26734
  1117
  
nipkow@15110
  1118
lemma map_inj_on:
nipkow@15110
  1119
 "[| map f xs = map f ys; inj_on f (set xs Un set ys) |]
nipkow@15110
  1120
  ==> xs = ys"
nipkow@15110
  1121
apply(frule map_eq_imp_length_eq)
nipkow@15110
  1122
apply(rotate_tac -1)
nipkow@15110
  1123
apply(induct rule:list_induct2)
nipkow@15110
  1124
 apply simp
nipkow@15110
  1125
apply(simp)
nipkow@15110
  1126
apply (blast intro:sym)
nipkow@15110
  1127
done
nipkow@15110
  1128
nipkow@15110
  1129
lemma inj_on_map_eq_map:
nipkow@58807
  1130
  "inj_on f (set xs Un set ys) \<Longrightarrow> (map f xs = map f ys) = (xs = ys)"
nipkow@15110
  1131
by(blast dest:map_inj_on)
nipkow@15110
  1132
wenzelm@13114
  1133
lemma map_injective:
nipkow@58807
  1134
  "map f xs = map f ys ==> inj f ==> xs = ys"
nipkow@24526
  1135
by (induct ys arbitrary: xs) (auto dest!:injD)
wenzelm@13114
  1136
nipkow@14339
  1137
lemma inj_map_eq_map[simp]: "inj f \<Longrightarrow> (map f xs = map f ys) = (xs = ys)"
nipkow@14339
  1138
by(blast dest:map_injective)
nipkow@14339
  1139
wenzelm@13114
  1140
lemma inj_mapI: "inj f ==> inj (map f)"
nipkow@17589
  1141
by (iprover dest: map_injective injD intro: inj_onI)
wenzelm@13114
  1142
wenzelm@13114
  1143
lemma inj_mapD: "inj (map f) ==> inj f"
paulson@14208
  1144
apply (unfold inj_on_def, clarify)
nipkow@13145
  1145
apply (erule_tac x = "[x]" in ballE)
paulson@14208
  1146
 apply (erule_tac x = "[y]" in ballE, simp, blast)
nipkow@13145
  1147
apply blast
nipkow@13145
  1148
done
wenzelm@13114
  1149
nipkow@14339
  1150
lemma inj_map[iff]: "inj (map f) = inj f"
nipkow@13145
  1151
by (blast dest: inj_mapD intro: inj_mapI)
wenzelm@13114
  1152
nipkow@15303
  1153
lemma inj_on_mapI: "inj_on f (\<Union>(set ` A)) \<Longrightarrow> inj_on (map f) A"
nipkow@15303
  1154
apply(rule inj_onI)
nipkow@15303
  1155
apply(erule map_inj_on)
nipkow@15303
  1156
apply(blast intro:inj_onI dest:inj_onD)
nipkow@15303
  1157
done
nipkow@15303
  1158
kleing@14343
  1159
lemma map_idI: "(\<And>x. x \<in> set xs \<Longrightarrow> f x = x) \<Longrightarrow> map f xs = xs"
kleing@14343
  1160
by (induct xs, auto)
wenzelm@13114
  1161
nipkow@14402
  1162
lemma map_fun_upd [simp]: "y \<notin> set xs \<Longrightarrow> map (f(y:=v)) xs = map f xs"
nipkow@14402
  1163
by (induct xs) auto
nipkow@14402
  1164
nipkow@15110
  1165
lemma map_fst_zip[simp]:
nipkow@15110
  1166
  "length xs = length ys \<Longrightarrow> map fst (zip xs ys) = xs"
nipkow@15110
  1167
by (induct rule:list_induct2, simp_all)
nipkow@15110
  1168
nipkow@15110
  1169
lemma map_snd_zip[simp]:
nipkow@15110
  1170
  "length xs = length ys \<Longrightarrow> map snd (zip xs ys) = ys"
nipkow@15110
  1171
by (induct rule:list_induct2, simp_all)
nipkow@15110
  1172
blanchet@55467
  1173
functor map: map
nipkow@47122
  1174
by (simp_all add: id_def)
nipkow@47122
  1175
haftmann@49948
  1176
declare map.id [simp]
haftmann@49948
  1177
haftmann@49948
  1178
haftmann@49948
  1179
subsubsection {* @{const rev} *}
wenzelm@13114
  1180
wenzelm@13142
  1181
lemma rev_append [simp]: "rev (xs @ ys) = rev ys @ rev xs"
nipkow@13145
  1182
by (induct xs) auto
wenzelm@13114
  1183
wenzelm@13142
  1184
lemma rev_rev_ident [simp]: "rev (rev xs) = xs"
nipkow@13145
  1185
by (induct xs) auto
wenzelm@13114
  1186
kleing@15870
  1187
lemma rev_swap: "(rev xs = ys) = (xs = rev ys)"
kleing@15870
  1188
by auto
kleing@15870
  1189
wenzelm@13142
  1190
lemma rev_is_Nil_conv [iff]: "(rev xs = []) = (xs = [])"
nipkow@13145
  1191
by (induct xs) auto
wenzelm@13114
  1192
wenzelm@13142
  1193
lemma Nil_is_rev_conv [iff]: "([] = rev xs) = (xs = [])"
nipkow@13145
  1194
by (induct xs) auto
wenzelm@13114
  1195
kleing@15870
  1196
lemma rev_singleton_conv [simp]: "(rev xs = [x]) = (xs = [x])"
kleing@15870
  1197
by (cases xs) auto
kleing@15870
  1198
kleing@15870
  1199
lemma singleton_rev_conv [simp]: "([x] = rev xs) = (xs = [x])"
kleing@15870
  1200
by (cases xs) auto
kleing@15870
  1201
blanchet@54147
  1202
lemma rev_is_rev_conv [iff]: "(rev xs = rev ys) = (xs = ys)"
haftmann@21061
  1203
apply (induct xs arbitrary: ys, force)
paulson@14208
  1204
apply (case_tac ys, simp, force)
nipkow@13145
  1205
done
wenzelm@13114
  1206
nipkow@15439
  1207
lemma inj_on_rev[iff]: "inj_on rev A"
nipkow@15439
  1208
by(simp add:inj_on_def)
nipkow@15439
  1209
wenzelm@13366
  1210
lemma rev_induct [case_names Nil snoc]:
wenzelm@13366
  1211
  "[| P []; !!x xs. P xs ==> P (xs @ [x]) |] ==> P xs"
berghofe@15489
  1212
apply(simplesubst rev_rev_ident[symmetric])
nipkow@13145
  1213
apply(rule_tac list = "rev xs" in list.induct, simp_all)
nipkow@13145
  1214
done
wenzelm@13114
  1215
wenzelm@13366
  1216
lemma rev_exhaust [case_names Nil snoc]:
wenzelm@13366
  1217
  "(xs = [] ==> P) ==>(!!ys y. xs = ys @ [y] ==> P) ==> P"
nipkow@13145
  1218
by (induct xs rule: rev_induct) auto
wenzelm@13114
  1219
wenzelm@13366
  1220
lemmas rev_cases = rev_exhaust
wenzelm@13366
  1221
haftmann@57577
  1222
lemma rev_nonempty_induct [consumes 1, case_names single snoc]:
haftmann@57577
  1223
  assumes "xs \<noteq> []"
haftmann@57577
  1224
  and single: "\<And>x. P [x]"
haftmann@57577
  1225
  and snoc': "\<And>x xs. xs \<noteq> [] \<Longrightarrow> P xs \<Longrightarrow> P (xs@[x])"
haftmann@57577
  1226
  shows "P xs"
haftmann@57577
  1227
using `xs \<noteq> []` proof (induct xs rule: rev_induct)
haftmann@57577
  1228
  case (snoc x xs) then show ?case
haftmann@57577
  1229
  proof (cases xs)
haftmann@57577
  1230
    case Nil thus ?thesis by (simp add: single)
haftmann@57577
  1231
  next
haftmann@57577
  1232
    case Cons with snoc show ?thesis by (fastforce intro!: snoc')
haftmann@57577
  1233
  qed
haftmann@57577
  1234
qed simp
haftmann@57577
  1235
nipkow@18423
  1236
lemma rev_eq_Cons_iff[iff]: "(rev xs = y#ys) = (xs = rev ys @ [y])"
nipkow@18423
  1237
by(rule rev_cases[of xs]) auto
nipkow@18423
  1238
wenzelm@13114
  1239
haftmann@49948
  1240
subsubsection {* @{const set} *}
wenzelm@13114
  1241
blanchet@57816
  1242
declare list.set[code_post]  --"pretty output"
blanchet@57816
  1243
wenzelm@13142
  1244
lemma finite_set [iff]: "finite (set xs)"
nipkow@13145
  1245
by (induct xs) auto
wenzelm@13114
  1246
wenzelm@13142
  1247
lemma set_append [simp]: "set (xs @ ys) = (set xs \<union> set ys)"
nipkow@13145
  1248
by (induct xs) auto
wenzelm@13114
  1249
nipkow@17830
  1250
lemma hd_in_set[simp]: "xs \<noteq> [] \<Longrightarrow> hd xs : set xs"
nipkow@17830
  1251
by(cases xs) auto
oheimb@14099
  1252
wenzelm@13142
  1253
lemma set_subset_Cons: "set xs \<subseteq> set (x # xs)"
nipkow@13145
  1254
by auto
wenzelm@13114
  1255
oheimb@14099
  1256
lemma set_ConsD: "y \<in> set (x # xs) \<Longrightarrow> y=x \<or> y \<in> set xs" 
oheimb@14099
  1257
by auto
oheimb@14099
  1258
wenzelm@13142
  1259
lemma set_empty [iff]: "(set xs = {}) = (xs = [])"
nipkow@13145
  1260
by (induct xs) auto
wenzelm@13114
  1261
nipkow@15245
  1262
lemma set_empty2[iff]: "({} = set xs) = (xs = [])"
nipkow@15245
  1263
by(induct xs) auto
nipkow@15245
  1264
wenzelm@13142
  1265
lemma set_rev [simp]: "set (rev xs) = set xs"
nipkow@13145
  1266
by (induct xs) auto
wenzelm@13114
  1267
wenzelm@13142
  1268
lemma set_map [simp]: "set (map f xs) = f`(set xs)"
nipkow@13145
  1269
by (induct xs) auto
wenzelm@13114
  1270
wenzelm@13142
  1271
lemma set_filter [simp]: "set (filter P xs) = {x. x : set xs \<and> P x}"
nipkow@13145
  1272
by (induct xs) auto
wenzelm@13114
  1273
nipkow@32417
  1274
lemma set_upt [simp]: "set[i..<j] = {i..<j}"
bulwahn@41463
  1275
by (induct j) auto
wenzelm@13114
  1276
wenzelm@13142
  1277
wenzelm@25221
  1278
lemma split_list: "x : set xs \<Longrightarrow> \<exists>ys zs. xs = ys @ x # zs"
nipkow@18049
  1279
proof (induct xs)
nipkow@26073
  1280
  case Nil thus ?case by simp
nipkow@26073
  1281
next
nipkow@26073
  1282
  case Cons thus ?case by (auto intro: Cons_eq_appendI)
nipkow@26073
  1283
qed
nipkow@26073
  1284
haftmann@26734
  1285
lemma in_set_conv_decomp: "x \<in> set xs \<longleftrightarrow> (\<exists>ys zs. xs = ys @ x # zs)"
haftmann@26734
  1286
  by (auto elim: split_list)
nipkow@26073
  1287
nipkow@26073
  1288
lemma split_list_first: "x : set xs \<Longrightarrow> \<exists>ys zs. xs = ys @ x # zs \<and> x \<notin> set ys"
nipkow@26073
  1289
proof (induct xs)
nipkow@26073
  1290
  case Nil thus ?case by simp
nipkow@18049
  1291
next
nipkow@18049
  1292
  case (Cons a xs)
nipkow@18049
  1293
  show ?case
nipkow@18049
  1294
  proof cases
nipkow@44890
  1295
    assume "x = a" thus ?case using Cons by fastforce
nipkow@18049
  1296
  next
nipkow@44890
  1297
    assume "x \<noteq> a" thus ?case using Cons by(fastforce intro!: Cons_eq_appendI)
nipkow@26073
  1298
  qed
nipkow@26073
  1299
qed
nipkow@26073
  1300
nipkow@26073
  1301
lemma in_set_conv_decomp_first:
nipkow@26073
  1302
  "(x : set xs) = (\<exists>ys zs. xs = ys @ x # zs \<and> x \<notin> set ys)"
haftmann@26734
  1303
  by (auto dest!: split_list_first)
nipkow@26073
  1304
haftmann@40122
  1305
lemma split_list_last: "x \<in> set xs \<Longrightarrow> \<exists>ys zs. xs = ys @ x # zs \<and> x \<notin> set zs"
haftmann@40122
  1306
proof (induct xs rule: rev_induct)
nipkow@26073
  1307
  case Nil thus ?case by simp
nipkow@26073
  1308
next
nipkow@26073
  1309
  case (snoc a xs)
nipkow@26073
  1310
  show ?case
nipkow@26073
  1311
  proof cases
blanchet@56085
  1312
    assume "x = a" thus ?case using snoc by (auto intro!: exI)
nipkow@26073
  1313
  next
nipkow@44890
  1314
    assume "x \<noteq> a" thus ?case using snoc by fastforce
nipkow@18049
  1315
  qed
nipkow@18049
  1316
qed
nipkow@18049
  1317
nipkow@26073
  1318
lemma in_set_conv_decomp_last:
nipkow@26073
  1319
  "(x : set xs) = (\<exists>ys zs. xs = ys @ x # zs \<and> x \<notin> set zs)"
haftmann@26734
  1320
  by (auto dest!: split_list_last)
nipkow@26073
  1321
nipkow@26073
  1322
lemma split_list_prop: "\<exists>x \<in> set xs. P x \<Longrightarrow> \<exists>ys x zs. xs = ys @ x # zs & P x"
nipkow@26073
  1323
proof (induct xs)
nipkow@26073
  1324
  case Nil thus ?case by simp
nipkow@26073
  1325
next
nipkow@26073
  1326
  case Cons thus ?case
nipkow@26073
  1327
    by(simp add:Bex_def)(metis append_Cons append.simps(1))
nipkow@26073
  1328
qed
nipkow@26073
  1329
nipkow@26073
  1330
lemma split_list_propE:
haftmann@26734
  1331
  assumes "\<exists>x \<in> set xs. P x"
haftmann@26734
  1332
  obtains ys x zs where "xs = ys @ x # zs" and "P x"
haftmann@26734
  1333
using split_list_prop [OF assms] by blast
nipkow@26073
  1334
nipkow@26073
  1335
lemma split_list_first_prop:
nipkow@26073
  1336
  "\<exists>x \<in> set xs. P x \<Longrightarrow>
nipkow@26073
  1337
   \<exists>ys x zs. xs = ys@x#zs \<and> P x \<and> (\<forall>y \<in> set ys. \<not> P y)"
haftmann@26734
  1338
proof (induct xs)
nipkow@26073
  1339
  case Nil thus ?case by simp
nipkow@26073
  1340
next
nipkow@26073
  1341
  case (Cons x xs)
nipkow@26073
  1342
  show ?case
nipkow@26073
  1343
  proof cases
nipkow@26073
  1344
    assume "P x"
blanchet@56085
  1345
    hence "x # xs = [] @ x # xs \<and> P x \<and> (\<forall>y\<in>set []. \<not> P y)" by simp
blanchet@56085
  1346
    thus ?thesis by fast
nipkow@26073
  1347
  next
nipkow@26073
  1348
    assume "\<not> P x"
nipkow@26073
  1349
    hence "\<exists>x\<in>set xs. P x" using Cons(2) by simp
nipkow@26073
  1350
    thus ?thesis using `\<not> P x` Cons(1) by (metis append_Cons set_ConsD)
nipkow@26073
  1351
  qed
nipkow@26073
  1352
qed
nipkow@26073
  1353
nipkow@26073
  1354
lemma split_list_first_propE:
haftmann@26734
  1355
  assumes "\<exists>x \<in> set xs. P x"
haftmann@26734
  1356
  obtains ys x zs where "xs = ys @ x # zs" and "P x" and "\<forall>y \<in> set ys. \<not> P y"
haftmann@26734
  1357
using split_list_first_prop [OF assms] by blast
nipkow@26073
  1358
nipkow@26073
  1359
lemma split_list_first_prop_iff:
nipkow@26073
  1360
  "(\<exists>x \<in> set xs. P x) \<longleftrightarrow>
nipkow@26073
  1361
   (\<exists>ys x zs. xs = ys@x#zs \<and> P x \<and> (\<forall>y \<in> set ys. \<not> P y))"
haftmann@26734
  1362
by (rule, erule split_list_first_prop) auto
nipkow@26073
  1363
nipkow@26073
  1364
lemma split_list_last_prop:
nipkow@26073
  1365
  "\<exists>x \<in> set xs. P x \<Longrightarrow>
nipkow@26073
  1366
   \<exists>ys x zs. xs = ys@x#zs \<and> P x \<and> (\<forall>z \<in> set zs. \<not> P z)"
nipkow@26073
  1367
proof(induct xs rule:rev_induct)
nipkow@26073
  1368
  case Nil thus ?case by simp
nipkow@26073
  1369
next
nipkow@26073
  1370
  case (snoc x xs)
nipkow@26073
  1371
  show ?case
nipkow@26073
  1372
  proof cases
blanchet@56085
  1373
    assume "P x" thus ?thesis by (auto intro!: exI)
nipkow@26073
  1374
  next
nipkow@26073
  1375
    assume "\<not> P x"
nipkow@26073
  1376
    hence "\<exists>x\<in>set xs. P x" using snoc(2) by simp
nipkow@44890
  1377
    thus ?thesis using `\<not> P x` snoc(1) by fastforce
nipkow@26073
  1378
  qed
nipkow@26073
  1379
qed
nipkow@26073
  1380
nipkow@26073
  1381
lemma split_list_last_propE:
haftmann@26734
  1382
  assumes "\<exists>x \<in> set xs. P x"
haftmann@26734
  1383
  obtains ys x zs where "xs = ys @ x # zs" and "P x" and "\<forall>z \<in> set zs. \<not> P z"
haftmann@26734
  1384
using split_list_last_prop [OF assms] by blast
nipkow@26073
  1385
nipkow@26073
  1386
lemma split_list_last_prop_iff:
nipkow@26073
  1387
  "(\<exists>x \<in> set xs. P x) \<longleftrightarrow>
nipkow@26073
  1388
   (\<exists>ys x zs. xs = ys@x#zs \<and> P x \<and> (\<forall>z \<in> set zs. \<not> P z))"
blanchet@56085
  1389
  by rule (erule split_list_last_prop, auto)
blanchet@56085
  1390
nipkow@26073
  1391
nipkow@26073
  1392
lemma finite_list: "finite A ==> EX xs. set xs = A"
blanchet@57816
  1393
  by (erule finite_induct) (auto simp add: list.set(2)[symmetric] simp del: list.set(2))
paulson@13508
  1394
kleing@14388
  1395
lemma card_length: "card (set xs) \<le> length xs"
kleing@14388
  1396
by (induct xs) (auto simp add: card_insert_if)
wenzelm@13114
  1397
haftmann@26442
  1398
lemma set_minus_filter_out:
haftmann@26442
  1399
  "set xs - {y} = set (filter (\<lambda>x. \<not> (x = y)) xs)"
haftmann@26442
  1400
  by (induct xs) auto
paulson@15168
  1401
wenzelm@35115
  1402
haftmann@49948
  1403
subsubsection {* @{const filter} *}
wenzelm@13114
  1404
wenzelm@13142
  1405
lemma filter_append [simp]: "filter P (xs @ ys) = filter P xs @ filter P ys"
nipkow@13145
  1406
by (induct xs) auto
wenzelm@13114
  1407
nipkow@15305
  1408
lemma rev_filter: "rev (filter P xs) = filter P (rev xs)"
nipkow@15305
  1409
by (induct xs) simp_all
nipkow@15305
  1410
wenzelm@13142
  1411
lemma filter_filter [simp]: "filter P (filter Q xs) = filter (\<lambda>x. Q x \<and> P x) xs"
nipkow@13145
  1412
by (induct xs) auto
wenzelm@13114
  1413
nipkow@16998
  1414
lemma length_filter_le [simp]: "length (filter P xs) \<le> length xs"
nipkow@16998
  1415
by (induct xs) (auto simp add: le_SucI)
nipkow@16998
  1416
nipkow@18423
  1417
lemma sum_length_filter_compl:
nipkow@18423
  1418
  "length(filter P xs) + length(filter (%x. ~P x) xs) = length xs"
nipkow@18423
  1419
by(induct xs) simp_all
nipkow@18423
  1420
wenzelm@13142
  1421
lemma filter_True [simp]: "\<forall>x \<in> set xs. P x ==> filter P xs = xs"
nipkow@13145
  1422
by (induct xs) auto
wenzelm@13114
  1423
wenzelm@13142
  1424
lemma filter_False [simp]: "\<forall>x \<in> set xs. \<not> P x ==> filter P xs = []"
nipkow@13145
  1425
by (induct xs) auto
wenzelm@13114
  1426
nipkow@16998
  1427
lemma filter_empty_conv: "(filter P xs = []) = (\<forall>x\<in>set xs. \<not> P x)" 
nipkow@24349
  1428
by (induct xs) simp_all
nipkow@16998
  1429
nipkow@16998
  1430
lemma filter_id_conv: "(filter P xs = xs) = (\<forall>x\<in>set xs. P x)"
nipkow@16998
  1431
apply (induct xs)
nipkow@16998
  1432
 apply auto
nipkow@16998
  1433
apply(cut_tac P=P and xs=xs in length_filter_le)
nipkow@16998
  1434
apply simp
nipkow@16998
  1435
done
wenzelm@13114
  1436
nipkow@58807
  1437
lemma filter_map: "filter P (map f xs) = map f (filter (P o f) xs)"
nipkow@16965
  1438
by (induct xs) simp_all
nipkow@16965
  1439
nipkow@16965
  1440
lemma length_filter_map[simp]:
nipkow@16965
  1441
  "length (filter P (map f xs)) = length(filter (P o f) xs)"
nipkow@16965
  1442
by (simp add:filter_map)
nipkow@16965
  1443
wenzelm@13142
  1444
lemma filter_is_subset [simp]: "set (filter P xs) \<le> set xs"
nipkow@13145
  1445
by auto
wenzelm@13114
  1446
nipkow@15246
  1447
lemma length_filter_less:
nipkow@15246
  1448
  "\<lbrakk> x : set xs; ~ P x \<rbrakk> \<Longrightarrow> length(filter P xs) < length xs"
nipkow@15246
  1449
proof (induct xs)
nipkow@15246
  1450
  case Nil thus ?case by simp
nipkow@15246
  1451
next
nipkow@15246
  1452
  case (Cons x xs) thus ?case
nipkow@15246
  1453
    apply (auto split:split_if_asm)
nipkow@15246
  1454
    using length_filter_le[of P xs] apply arith
nipkow@15246
  1455
  done
nipkow@15246
  1456
qed
wenzelm@13114
  1457
nipkow@15281
  1458
lemma length_filter_conv_card:
nipkow@58807
  1459
  "length(filter p xs) = card{i. i < length xs & p(xs!i)}"
nipkow@15281
  1460
proof (induct xs)
nipkow@15281
  1461
  case Nil thus ?case by simp
nipkow@15281
  1462
next
nipkow@15281
  1463
  case (Cons x xs)
nipkow@15281
  1464
  let ?S = "{i. i < length xs & p(xs!i)}"
nipkow@15281
  1465
  have fin: "finite ?S" by(fast intro: bounded_nat_set_is_finite)
nipkow@15281
  1466
  show ?case (is "?l = card ?S'")
nipkow@15281
  1467
  proof (cases)
nipkow@15281
  1468
    assume "p x"
nipkow@15281
  1469
    hence eq: "?S' = insert 0 (Suc ` ?S)"
nipkow@25162
  1470
      by(auto simp: image_def split:nat.split dest:gr0_implies_Suc)
nipkow@15281
  1471
    have "length (filter p (x # xs)) = Suc(card ?S)"
wenzelm@23388
  1472
      using Cons `p x` by simp
nipkow@15281
  1473
    also have "\<dots> = Suc(card(Suc ` ?S))" using fin
huffman@44921
  1474
      by (simp add: card_image)
nipkow@15281
  1475
    also have "\<dots> = card ?S'" using eq fin
nipkow@15281
  1476
      by (simp add:card_insert_if) (simp add:image_def)
nipkow@15281
  1477
    finally show ?thesis .
nipkow@15281
  1478
  next
nipkow@15281
  1479
    assume "\<not> p x"
nipkow@15281
  1480
    hence eq: "?S' = Suc ` ?S"
nipkow@25162
  1481
      by(auto simp add: image_def split:nat.split elim:lessE)
nipkow@15281
  1482
    have "length (filter p (x # xs)) = card ?S"
wenzelm@23388
  1483
      using Cons `\<not> p x` by simp
nipkow@15281
  1484
    also have "\<dots> = card(Suc ` ?S)" using fin
huffman@44921
  1485
      by (simp add: card_image)
nipkow@15281
  1486
    also have "\<dots> = card ?S'" using eq fin
nipkow@15281
  1487
      by (simp add:card_insert_if)
nipkow@15281
  1488
    finally show ?thesis .
nipkow@15281
  1489
  qed
nipkow@15281
  1490
qed
nipkow@15281
  1491
nipkow@17629
  1492
lemma Cons_eq_filterD:
nipkow@58807
  1493
  "x#xs = filter P ys \<Longrightarrow>
nipkow@17629
  1494
  \<exists>us vs. ys = us @ x # vs \<and> (\<forall>u\<in>set us. \<not> P u) \<and> P x \<and> xs = filter P vs"
wenzelm@19585
  1495
  (is "_ \<Longrightarrow> \<exists>us vs. ?P ys us vs")
nipkow@17629
  1496
proof(induct ys)
nipkow@17629
  1497
  case Nil thus ?case by simp
nipkow@17629
  1498
next
nipkow@17629
  1499
  case (Cons y ys)
nipkow@17629
  1500
  show ?case (is "\<exists>x. ?Q x")
nipkow@17629
  1501
  proof cases
nipkow@17629
  1502
    assume Py: "P y"
nipkow@17629
  1503
    show ?thesis
nipkow@17629
  1504
    proof cases
wenzelm@25221
  1505
      assume "x = y"
wenzelm@25221
  1506
      with Py Cons.prems have "?Q []" by simp
wenzelm@25221
  1507
      then show ?thesis ..
nipkow@17629
  1508
    next
wenzelm@25221
  1509
      assume "x \<noteq> y"
wenzelm@25221
  1510
      with Py Cons.prems show ?thesis by simp
nipkow@17629
  1511
    qed
nipkow@17629
  1512
  next
wenzelm@25221
  1513
    assume "\<not> P y"
nipkow@44890
  1514
    with Cons obtain us vs where "?P (y#ys) (y#us) vs" by fastforce
wenzelm@25221
  1515
    then have "?Q (y#us)" by simp
wenzelm@25221
  1516
    then show ?thesis ..
nipkow@17629
  1517
  qed
nipkow@17629
  1518
qed
nipkow@17629
  1519
nipkow@17629
  1520
lemma filter_eq_ConsD:
nipkow@58807
  1521
  "filter P ys = x#xs \<Longrightarrow>
nipkow@17629
  1522
  \<exists>us vs. ys = us @ x # vs \<and> (\<forall>u\<in>set us. \<not> P u) \<and> P x \<and> xs = filter P vs"
nipkow@17629
  1523
by(rule Cons_eq_filterD) simp
nipkow@17629
  1524
nipkow@17629
  1525
lemma filter_eq_Cons_iff:
nipkow@58807
  1526
  "(filter P ys = x#xs) =
nipkow@17629
  1527
  (\<exists>us vs. ys = us @ x # vs \<and> (\<forall>u\<in>set us. \<not> P u) \<and> P x \<and> xs = filter P vs)"
nipkow@17629
  1528
by(auto dest:filter_eq_ConsD)
nipkow@17629
  1529
nipkow@17629
  1530
lemma Cons_eq_filter_iff:
nipkow@58807
  1531
  "(x#xs = filter P ys) =
nipkow@17629
  1532
  (\<exists>us vs. ys = us @ x # vs \<and> (\<forall>u\<in>set us. \<not> P u) \<and> P x \<and> xs = filter P vs)"
nipkow@17629
  1533
by(auto dest:Cons_eq_filterD)
nipkow@17629
  1534
krauss@44013
  1535
lemma filter_cong[fundef_cong]:
nipkow@58807
  1536
  "xs = ys \<Longrightarrow> (\<And>x. x \<in> set ys \<Longrightarrow> P x = Q x) \<Longrightarrow> filter P xs = filter Q ys"
nipkow@17501
  1537
apply simp
nipkow@17501
  1538
apply(erule thin_rl)
nipkow@17501
  1539
by (induct ys) simp_all
nipkow@17501
  1540
nipkow@15281
  1541
haftmann@26442
  1542
subsubsection {* List partitioning *}
haftmann@26442
  1543
haftmann@26442
  1544
primrec partition :: "('a \<Rightarrow> bool) \<Rightarrow>'a list \<Rightarrow> 'a list \<times> 'a list" where
nipkow@50548
  1545
"partition P [] = ([], [])" |
nipkow@50548
  1546
"partition P (x # xs) = 
nipkow@50548
  1547
  (let (yes, no) = partition P xs
nipkow@50548
  1548
   in if P x then (x # yes, no) else (yes, x # no))"
haftmann@26442
  1549
nipkow@58807
  1550
lemma partition_filter1: "fst (partition P xs) = filter P xs"
haftmann@26442
  1551
by (induct xs) (auto simp add: Let_def split_def)
haftmann@26442
  1552
nipkow@58807
  1553
lemma partition_filter2: "snd (partition P xs) = filter (Not o P) xs"
haftmann@26442
  1554
by (induct xs) (auto simp add: Let_def split_def)
haftmann@26442
  1555
haftmann@26442
  1556
lemma partition_P:
haftmann@26442
  1557
  assumes "partition P xs = (yes, no)"
haftmann@26442
  1558
  shows "(\<forall>p \<in> set yes.  P p) \<and> (\<forall>p  \<in> set no. \<not> P p)"
haftmann@26442
  1559
proof -
haftmann@26442
  1560
  from assms have "yes = fst (partition P xs)" and "no = snd (partition P xs)"
haftmann@26442
  1561
    by simp_all
haftmann@26442
  1562
  then show ?thesis by (simp_all add: partition_filter1 partition_filter2)
haftmann@26442
  1563
qed
haftmann@26442
  1564
haftmann@26442
  1565
lemma partition_set:
haftmann@26442
  1566
  assumes "partition P xs = (yes, no)"
haftmann@26442
  1567
  shows "set yes \<union> set no = set xs"
haftmann@26442
  1568
proof -
haftmann@26442
  1569
  from assms have "yes = fst (partition P xs)" and "no = snd (partition P xs)"
haftmann@26442
  1570
    by simp_all
haftmann@26442
  1571
  then show ?thesis by (auto simp add: partition_filter1 partition_filter2) 
haftmann@26442
  1572
qed
haftmann@26442
  1573
hoelzl@33639
  1574
lemma partition_filter_conv[simp]:
hoelzl@33639
  1575
  "partition f xs = (filter f xs,filter (Not o f) xs)"
hoelzl@33639
  1576
unfolding partition_filter2[symmetric]
hoelzl@33639
  1577
unfolding partition_filter1[symmetric] by simp
hoelzl@33639
  1578
hoelzl@33639
  1579
declare partition.simps[simp del]
haftmann@26442
  1580
wenzelm@35115
  1581
haftmann@49948
  1582
subsubsection {* @{const concat} *}
wenzelm@13114
  1583
wenzelm@13142
  1584
lemma concat_append [simp]: "concat (xs @ ys) = concat xs @ concat ys"
nipkow@13145
  1585
by (induct xs) auto
wenzelm@13114
  1586
paulson@18447
  1587
lemma concat_eq_Nil_conv [simp]: "(concat xss = []) = (\<forall>xs \<in> set xss. xs = [])"
nipkow@13145
  1588
by (induct xss) auto
wenzelm@13114
  1589
paulson@18447
  1590
lemma Nil_eq_concat_conv [simp]: "([] = concat xss) = (\<forall>xs \<in> set xss. xs = [])"
nipkow@13145
  1591
by (induct xss) auto
wenzelm@13114
  1592
nipkow@24308
  1593
lemma set_concat [simp]: "set (concat xs) = (UN x:set xs. set x)"
nipkow@13145
  1594
by (induct xs) auto
wenzelm@13114
  1595
nipkow@24476
  1596
lemma concat_map_singleton[simp]: "concat(map (%x. [f x]) xs) = map f xs"
nipkow@24349
  1597
by (induct xs) auto
nipkow@24349
  1598
wenzelm@13142
  1599
lemma map_concat: "map f (concat xs) = concat (map (map f) xs)"
nipkow@13145
  1600
by (induct xs) auto
wenzelm@13114
  1601
wenzelm@13142
  1602
lemma filter_concat: "filter p (concat xs) = concat (map (filter p) xs)"
nipkow@13145
  1603
by (induct xs) auto
wenzelm@13114
  1604
wenzelm@13142
  1605
lemma rev_concat: "rev (concat xs) = concat (map rev (rev xs))"
nipkow@13145
  1606
by (induct xs) auto
wenzelm@13114
  1607
bulwahn@40365
  1608
lemma concat_eq_concat_iff: "\<forall>(x, y) \<in> set (zip xs ys). length x = length y ==> length xs = length ys ==> (concat xs = concat ys) = (xs = ys)"
bulwahn@40365
  1609
proof (induct xs arbitrary: ys)
bulwahn@40365
  1610
  case (Cons x xs ys)
bulwahn@40365
  1611
  thus ?case by (cases ys) auto
bulwahn@40365
  1612
qed (auto)
bulwahn@40365
  1613
bulwahn@40365
  1614
lemma concat_injective: "concat xs = concat ys ==> length xs = length ys ==> \<forall>(x, y) \<in> set (zip xs ys). length x = length y ==> xs = ys"
bulwahn@40365
  1615
by (simp add: concat_eq_concat_iff)
bulwahn@40365
  1616
wenzelm@13114
  1617
haftmann@49948
  1618
subsubsection {* @{const nth} *}
wenzelm@13114
  1619
haftmann@29827
  1620
lemma nth_Cons_0 [simp, code]: "(x # xs)!0 = x"
nipkow@13145
  1621
by auto
wenzelm@13114
  1622
haftmann@29827
  1623
lemma nth_Cons_Suc [simp, code]: "(x # xs)!(Suc n) = xs!n"
nipkow@13145
  1624
by auto
wenzelm@13114
  1625
wenzelm@13142
  1626
declare nth.simps [simp del]
wenzelm@13114
  1627
nipkow@41842
  1628
lemma nth_Cons_pos[simp]: "0 < n \<Longrightarrow> (x#xs) ! n = xs ! (n - 1)"
nipkow@41842
  1629
by(auto simp: Nat.gr0_conv_Suc)
nipkow@41842
  1630
wenzelm@13114
  1631
lemma nth_append:
nipkow@24526
  1632
  "(xs @ ys)!n = (if n < length xs then xs!n else ys!(n - length xs))"
nipkow@24526
  1633
apply (induct xs arbitrary: n, simp)
paulson@14208
  1634
apply (case_tac n, auto)
nipkow@13145
  1635
done
wenzelm@13114
  1636
nipkow@14402
  1637
lemma nth_append_length [simp]: "(xs @ x # ys) ! length xs = x"
wenzelm@25221
  1638
by (induct xs) auto
nipkow@14402
  1639
nipkow@14402
  1640
lemma nth_append_length_plus[simp]: "(xs @ ys) ! (length xs + n) = ys ! n"
wenzelm@25221
  1641
by (induct xs) auto
nipkow@14402
  1642
nipkow@24526
  1643
lemma nth_map [simp]: "n < length xs ==> (map f xs)!n = f(xs!n)"
nipkow@24526
  1644
apply (induct xs arbitrary: n, simp)
paulson@14208
  1645
apply (case_tac n, auto)
nipkow@13145
  1646
done
wenzelm@13114
  1647
noschinl@45841
  1648
lemma nth_tl:
noschinl@45841
  1649
  assumes "n < length (tl x)" shows "tl x ! n = x ! Suc n"
noschinl@45841
  1650
using assms by (induct x) auto
noschinl@45841
  1651
nipkow@18423
  1652
lemma hd_conv_nth: "xs \<noteq> [] \<Longrightarrow> hd xs = xs!0"
nipkow@18423
  1653
by(cases xs) simp_all
nipkow@18423
  1654
nipkow@18049
  1655
nipkow@18049
  1656
lemma list_eq_iff_nth_eq:
nipkow@58807
  1657
  "(xs = ys) = (length xs = length ys \<and> (ALL i<length xs. xs!i = ys!i))"
nipkow@24526
  1658
apply(induct xs arbitrary: ys)
paulson@24632
  1659
 apply force
nipkow@18049
  1660
apply(case_tac ys)
nipkow@18049
  1661
 apply simp
nipkow@18049
  1662
apply(simp add:nth_Cons split:nat.split)apply blast
nipkow@18049
  1663
done
nipkow@18049
  1664
wenzelm@13142
  1665
lemma set_conv_nth: "set xs = {xs!i | i. i < length xs}"
paulson@15251
  1666
apply (induct xs, simp, simp)
nipkow@13145
  1667
apply safe
blanchet@55642
  1668
apply (metis nat.case(1) nth.simps zero_less_Suc)
paulson@24632
  1669
apply (metis less_Suc_eq_0_disj nth_Cons_Suc)
paulson@14208
  1670
apply (case_tac i, simp)
blanchet@55642
  1671
apply (metis diff_Suc_Suc nat.case(2) nth.simps zero_less_diff)
nipkow@13145
  1672
done
wenzelm@13114
  1673
nipkow@17501
  1674
lemma in_set_conv_nth: "(x \<in> set xs) = (\<exists>i < length xs. xs!i = x)"
nipkow@17501
  1675
by(auto simp:set_conv_nth)
nipkow@17501
  1676
haftmann@51160
  1677
lemma nth_equal_first_eq:
haftmann@51160
  1678
  assumes "x \<notin> set xs"
haftmann@51160
  1679
  assumes "n \<le> length xs"
haftmann@51160
  1680
  shows "(x # xs) ! n = x \<longleftrightarrow> n = 0" (is "?lhs \<longleftrightarrow> ?rhs")
haftmann@51160
  1681
proof
haftmann@51160
  1682
  assume ?lhs
haftmann@51160
  1683
  show ?rhs
haftmann@51160
  1684
  proof (rule ccontr)
haftmann@51160
  1685
    assume "n \<noteq> 0"
haftmann@51160
  1686
    then have "n > 0" by simp
haftmann@51160
  1687
    with `?lhs` have "xs ! (n - 1) = x" by simp
haftmann@51160
  1688
    moreover from `n > 0` `n \<le> length xs` have "n - 1 < length xs" by simp
haftmann@51160
  1689
    ultimately have "\<exists>i<length xs. xs ! i = x" by auto
haftmann@51160
  1690
    with `x \<notin> set xs` in_set_conv_nth [of x xs] show False by simp
haftmann@51160
  1691
  qed
haftmann@51160
  1692
next
haftmann@51160
  1693
  assume ?rhs then show ?lhs by simp
haftmann@51160
  1694
qed
haftmann@51160
  1695
haftmann@51160
  1696
lemma nth_non_equal_first_eq:
haftmann@51160
  1697
  assumes "x \<noteq> y"
haftmann@51160
  1698
  shows "(x # xs) ! n = y \<longleftrightarrow> xs ! (n - 1) = y \<and> n > 0" (is "?lhs \<longleftrightarrow> ?rhs")
haftmann@51160
  1699
proof
haftmann@51160
  1700
  assume "?lhs" with assms have "n > 0" by (cases n) simp_all
haftmann@51160
  1701
  with `?lhs` show ?rhs by simp
haftmann@51160
  1702
next
haftmann@51160
  1703
  assume "?rhs" then show "?lhs" by simp
haftmann@51160
  1704
qed
haftmann@51160
  1705
nipkow@13145
  1706
lemma list_ball_nth: "[| n < length xs; !x : set xs. P x|] ==> P(xs!n)"
nipkow@13145
  1707
by (auto simp add: set_conv_nth)
wenzelm@13114
  1708
wenzelm@13142
  1709
lemma nth_mem [simp]: "n < length xs ==> xs!n : set xs"
nipkow@13145
  1710
by (auto simp add: set_conv_nth)
wenzelm@13114
  1711
wenzelm@13114
  1712
lemma all_nth_imp_all_set:
nipkow@58807
  1713
  "[| !i < length xs. P(xs!i); x : set xs|] ==> P x"
nipkow@13145
  1714
by (auto simp add: set_conv_nth)
wenzelm@13114
  1715
wenzelm@13114
  1716
lemma all_set_conv_all_nth:
nipkow@58807
  1717
  "(\<forall>x \<in> set xs. P x) = (\<forall>i. i < length xs --> P (xs ! i))"
nipkow@13145
  1718
by (auto simp add: set_conv_nth)
wenzelm@13114
  1719
kleing@25296
  1720
lemma rev_nth:
kleing@25296
  1721
  "n < size xs \<Longrightarrow> rev xs ! n = xs ! (length xs - Suc n)"
kleing@25296
  1722
proof (induct xs arbitrary: n)
kleing@25296
  1723
  case Nil thus ?case by simp
kleing@25296
  1724
next
kleing@25296
  1725
  case (Cons x xs)
kleing@25296
  1726
  hence n: "n < Suc (length xs)" by simp
kleing@25296
  1727
  moreover
kleing@25296
  1728
  { assume "n < length xs"
wenzelm@53374
  1729
    with n obtain n' where n': "length xs - n = Suc n'"
kleing@25296
  1730
      by (cases "length xs - n", auto)
kleing@25296
  1731
    moreover
wenzelm@53374
  1732
    from n' have "length xs - Suc n = n'" by simp
kleing@25296
  1733
    ultimately
kleing@25296
  1734
    have "xs ! (length xs - Suc n) = (x # xs) ! (length xs - n)" by simp
kleing@25296
  1735
  }
kleing@25296
  1736
  ultimately
kleing@25296
  1737
  show ?case by (clarsimp simp add: Cons nth_append)
kleing@25296
  1738
qed
wenzelm@13114
  1739
nipkow@31159
  1740
lemma Skolem_list_nth:
nipkow@31159
  1741
  "(ALL i<k. EX x. P i x) = (EX xs. size xs = k & (ALL i<k. P i (xs!i)))"
nipkow@31159
  1742
  (is "_ = (EX xs. ?P k xs)")
nipkow@31159
  1743
proof(induct k)
nipkow@31159
  1744
  case 0 show ?case by simp
nipkow@31159
  1745
next
nipkow@31159
  1746
  case (Suc k)
nipkow@31159
  1747
  show ?case (is "?L = ?R" is "_ = (EX xs. ?P' xs)")
nipkow@31159
  1748
  proof
nipkow@31159
  1749
    assume "?R" thus "?L" using Suc by auto
nipkow@31159
  1750
  next
nipkow@31159
  1751
    assume "?L"
nipkow@31159
  1752
    with Suc obtain x xs where "?P k xs & P k x" by (metis less_Suc_eq)
nipkow@31159
  1753
    hence "?P'(xs@[x])" by(simp add:nth_append less_Suc_eq)
nipkow@31159
  1754
    thus "?R" ..
nipkow@31159
  1755
  qed
nipkow@31159
  1756
qed
nipkow@31159
  1757
nipkow@31159
  1758
haftmann@49948
  1759
subsubsection {* @{const list_update} *}
wenzelm@13114
  1760
nipkow@24526
  1761
lemma length_list_update [simp]: "length(xs[i:=x]) = length xs"
nipkow@24526
  1762
by (induct xs arbitrary: i) (auto split: nat.split)
wenzelm@13114
  1763
wenzelm@13114
  1764
lemma nth_list_update:
nipkow@24526
  1765
"i < length xs==> (xs[i:=x])!j = (if i = j then x else xs!j)"
nipkow@24526
  1766
by (induct xs arbitrary: i j) (auto simp add: nth_Cons split: nat.split)
wenzelm@13114
  1767
wenzelm@13142
  1768
lemma nth_list_update_eq [simp]: "i < length xs ==> (xs[i:=x])!i = x"
nipkow@13145
  1769
by (simp add: nth_list_update)
wenzelm@13114
  1770
nipkow@24526
  1771
lemma nth_list_update_neq [simp]: "i \<noteq> j ==> xs[i:=x]!j = xs!j"
nipkow@24526
  1772
by (induct xs arbitrary: i j) (auto simp add: nth_Cons split: nat.split)
wenzelm@13114
  1773
nipkow@24526
  1774
lemma list_update_id[simp]: "xs[i := xs!i] = xs"
nipkow@24526
  1775
by (induct xs arbitrary: i) (simp_all split:nat.splits)
nipkow@24526
  1776
nipkow@24526
  1777
lemma list_update_beyond[simp]: "length xs \<le> i \<Longrightarrow> xs[i:=x] = xs"
nipkow@24526
  1778
apply (induct xs arbitrary: i)
nipkow@17501
  1779
 apply simp
nipkow@17501
  1780
apply (case_tac i)
nipkow@17501
  1781
apply simp_all
nipkow@17501
  1782
done
nipkow@17501
  1783
nipkow@31077
  1784
lemma list_update_nonempty[simp]: "xs[k:=x] = [] \<longleftrightarrow> xs=[]"
blanchet@56085
  1785
by (simp only: length_0_conv[symmetric] length_list_update)
nipkow@31077
  1786
wenzelm@13114
  1787
lemma list_update_same_conv:
nipkow@58807
  1788
  "i < length xs ==> (xs[i := x] = xs) = (xs!i = x)"
nipkow@24526
  1789
by (induct xs arbitrary: i) (auto split: nat.split)
wenzelm@13114
  1790
nipkow@14187
  1791
lemma list_update_append1:
nipkow@58807
  1792
  "i < size xs \<Longrightarrow> (xs @ ys)[i:=x] = xs[i:=x] @ ys"
nipkow@58807
  1793
by (induct xs arbitrary: i)(auto split:nat.split)
nipkow@14187
  1794
kleing@15868
  1795
lemma list_update_append:
nipkow@24526
  1796
  "(xs @ ys) [n:= x] = 
kleing@15868
  1797
  (if n < length xs then xs[n:= x] @ ys else xs @ (ys [n-length xs:= x]))"
nipkow@24526
  1798
by (induct xs arbitrary: n) (auto split:nat.splits)
kleing@15868
  1799
nipkow@14402
  1800
lemma list_update_length [simp]:
nipkow@58807
  1801
  "(xs @ x # ys)[length xs := y] = (xs @ y # ys)"
nipkow@14402
  1802
by (induct xs, auto)
nipkow@14402
  1803
nipkow@31264
  1804
lemma map_update: "map f (xs[k:= y]) = (map f xs)[k := f y]"
nipkow@31264
  1805
by(induct xs arbitrary: k)(auto split:nat.splits)
nipkow@31264
  1806
nipkow@31264
  1807
lemma rev_update:
nipkow@31264
  1808
  "k < length xs \<Longrightarrow> rev (xs[k:= y]) = (rev xs)[length xs - k - 1 := y]"
nipkow@31264
  1809
by (induct xs arbitrary: k) (auto simp: list_update_append split:nat.splits)
nipkow@31264
  1810
wenzelm@13114
  1811
lemma update_zip:
nipkow@31080
  1812
  "(zip xs ys)[i:=xy] = zip (xs[i:=fst xy]) (ys[i:=snd xy])"
nipkow@24526
  1813
by (induct ys arbitrary: i xy xs) (auto, case_tac xs, auto split: nat.split)
nipkow@24526
  1814
nipkow@24526
  1815
lemma set_update_subset_insert: "set(xs[i:=x]) <= insert x (set xs)"
nipkow@24526
  1816
by (induct xs arbitrary: i) (auto split: nat.split)
wenzelm@13114
  1817
wenzelm@13114
  1818
lemma set_update_subsetI: "[| set xs <= A; x:A |] ==> set(xs[i := x]) <= A"
nipkow@13145
  1819
by (blast dest!: set_update_subset_insert [THEN subsetD])
wenzelm@13114
  1820
nipkow@24526
  1821
lemma set_update_memI: "n < length xs \<Longrightarrow> x \<in> set (xs[n := x])"
nipkow@24526
  1822
by (induct xs arbitrary: n) (auto split:nat.splits)
kleing@15868
  1823
nipkow@31077
  1824
lemma list_update_overwrite[simp]:
haftmann@24796
  1825
  "xs [i := x, i := y] = xs [i := y]"
nipkow@31077
  1826
apply (induct xs arbitrary: i) apply simp
nipkow@31077
  1827
apply (case_tac i, simp_all)
haftmann@24796
  1828
done
haftmann@24796
  1829
haftmann@24796
  1830
lemma list_update_swap:
haftmann@24796
  1831
  "i \<noteq> i' \<Longrightarrow> xs [i := x, i' := x'] = xs [i' := x', i := x]"
haftmann@24796
  1832
apply (induct xs arbitrary: i i')
nipkow@57537
  1833
 apply simp
haftmann@24796
  1834
apply (case_tac i, case_tac i')
nipkow@57537
  1835
  apply auto
haftmann@24796
  1836
apply (case_tac i')
haftmann@24796
  1837
apply auto
haftmann@24796
  1838
done
haftmann@24796
  1839
haftmann@29827
  1840
lemma list_update_code [code]:
haftmann@29827
  1841
  "[][i := y] = []"
haftmann@29827
  1842
  "(x # xs)[0 := y] = y # xs"
haftmann@29827
  1843
  "(x # xs)[Suc i := y] = x # xs[i := y]"
nipkow@58807
  1844
by simp_all
haftmann@29827
  1845
wenzelm@13114
  1846
haftmann@49948
  1847
subsubsection {* @{const last} and @{const butlast} *}
wenzelm@13114
  1848
wenzelm@13142
  1849
lemma last_snoc [simp]: "last (xs @ [x]) = x"
nipkow@13145
  1850
by (induct xs) auto
wenzelm@13114
  1851
wenzelm@13142
  1852
lemma butlast_snoc [simp]: "butlast (xs @ [x]) = xs"
nipkow@13145
  1853
by (induct xs) auto
wenzelm@13114
  1854
nipkow@14302
  1855
lemma last_ConsL: "xs = [] \<Longrightarrow> last(x#xs) = x"
nipkow@58807
  1856
by simp
nipkow@14302
  1857
nipkow@14302
  1858
lemma last_ConsR: "xs \<noteq> [] \<Longrightarrow> last(x#xs) = last xs"
nipkow@58807
  1859
by simp
nipkow@14302
  1860
nipkow@14302
  1861
lemma last_append: "last(xs @ ys) = (if ys = [] then last xs else last ys)"
nipkow@14302
  1862
by (induct xs) (auto)
nipkow@14302
  1863
nipkow@14302
  1864
lemma last_appendL[simp]: "ys = [] \<Longrightarrow> last(xs @ ys) = last xs"
nipkow@14302
  1865
by(simp add:last_append)
nipkow@14302
  1866
nipkow@14302
  1867
lemma last_appendR[simp]: "ys \<noteq> [] \<Longrightarrow> last(xs @ ys) = last ys"
nipkow@14302
  1868
by(simp add:last_append)
nipkow@14302
  1869
noschinl@45841
  1870
lemma last_tl: "xs = [] \<or> tl xs \<noteq> [] \<Longrightarrow>last (tl xs) = last xs"
noschinl@45841
  1871
by (induct xs) simp_all
noschinl@45841
  1872
noschinl@45841
  1873
lemma butlast_tl: "butlast (tl xs) = tl (butlast xs)"
noschinl@45841
  1874
by (induct xs) simp_all
noschinl@45841
  1875
nipkow@17762
  1876
lemma hd_rev: "xs \<noteq> [] \<Longrightarrow> hd(rev xs) = last xs"
nipkow@17762
  1877
by(rule rev_exhaust[of xs]) simp_all
nipkow@17762
  1878
nipkow@17762
  1879
lemma last_rev: "xs \<noteq> [] \<Longrightarrow> last(rev xs) = hd xs"
nipkow@17762
  1880
by(cases xs) simp_all
nipkow@17762
  1881
nipkow@17765
  1882
lemma last_in_set[simp]: "as \<noteq> [] \<Longrightarrow> last as \<in> set as"
nipkow@17765
  1883
by (induct as) auto
nipkow@17762
  1884
wenzelm@13142
  1885
lemma length_butlast [simp]: "length (butlast xs) = length xs - 1"
nipkow@13145
  1886
by (induct xs rule: rev_induct) auto
wenzelm@13114
  1887
wenzelm@13114
  1888
lemma butlast_append:
nipkow@24526
  1889
  "butlast (xs @ ys) = (if ys = [] then butlast xs else xs @ butlast ys)"
nipkow@24526
  1890
by (induct xs arbitrary: ys) auto
wenzelm@13114
  1891
wenzelm@13142
  1892
lemma append_butlast_last_id [simp]:
nipkow@58807
  1893
  "xs \<noteq> [] ==> butlast xs @ [last xs] = xs"
nipkow@13145
  1894
by (induct xs) auto
wenzelm@13114
  1895
wenzelm@13142
  1896
lemma in_set_butlastD: "x : set (butlast xs) ==> x : set xs"
nipkow@13145
  1897
by (induct xs) (auto split: split_if_asm)
wenzelm@13114
  1898
wenzelm@13114
  1899
lemma in_set_butlast_appendI:
nipkow@58807
  1900
  "x : set (butlast xs) | x : set (butlast ys) ==> x : set (butlast (xs @ ys))"
nipkow@13145
  1901
by (auto dest: in_set_butlastD simp add: butlast_append)
wenzelm@13114
  1902
nipkow@24526
  1903
lemma last_drop[simp]: "n < length xs \<Longrightarrow> last (drop n xs) = last xs"
nipkow@58807
  1904
by (induct xs arbitrary: n)(auto split:nat.split)
nipkow@17501
  1905
noschinl@45841
  1906
lemma nth_butlast:
noschinl@45841
  1907
  assumes "n < length (butlast xs)" shows "butlast xs ! n = xs ! n"
noschinl@45841
  1908
proof (cases xs)
noschinl@45841
  1909
  case (Cons y ys)
noschinl@45841
  1910
  moreover from assms have "butlast xs ! n = (butlast xs @ [last xs]) ! n"
noschinl@45841
  1911
    by (simp add: nth_append)
noschinl@45841
  1912
  ultimately show ?thesis using append_butlast_last_id by simp
noschinl@45841
  1913
qed simp
noschinl@45841
  1914
huffman@30128
  1915
lemma last_conv_nth: "xs\<noteq>[] \<Longrightarrow> last xs = xs!(length xs - 1)"
nipkow@17589
  1916
by(induct xs)(auto simp:neq_Nil_conv)
nipkow@17589
  1917
huffman@30128
  1918
lemma butlast_conv_take: "butlast xs = take (length xs - 1) xs"
huffman@26584
  1919
by (induct xs, simp, case_tac xs, simp_all)
huffman@26584
  1920
nipkow@31077
  1921
lemma last_list_update:
nipkow@31077
  1922
  "xs \<noteq> [] \<Longrightarrow> last(xs[k:=x]) = (if k = size xs - 1 then x else last xs)"
nipkow@31077
  1923
by (auto simp: last_conv_nth)
nipkow@31077
  1924
nipkow@31077
  1925
lemma butlast_list_update:
nipkow@31077
  1926
  "butlast(xs[k:=x]) =
nipkow@58807
  1927
  (if k = size xs - 1 then butlast xs else (butlast xs)[k:=x])"
nipkow@58807
  1928
by(cases xs rule:rev_cases)(auto simp: list_update_append split: nat.splits)
nipkow@58807
  1929
nipkow@58807
  1930
lemma last_map: "xs \<noteq> [] \<Longrightarrow> last (map f xs) = f (last xs)"
nipkow@58807
  1931
by (cases xs rule: rev_cases) simp_all
nipkow@58807
  1932
nipkow@58807
  1933
lemma map_butlast: "map f (butlast xs) = butlast (map f xs)"
nipkow@58807
  1934
by (induct xs) simp_all
haftmann@36851
  1935
nipkow@40230
  1936
lemma snoc_eq_iff_butlast:
nipkow@40230
  1937
  "xs @ [x] = ys \<longleftrightarrow> (ys \<noteq> [] & butlast ys = xs & last ys = x)"
blanchet@56085
  1938
by fastforce
nipkow@40230
  1939
haftmann@24796
  1940
haftmann@49948
  1941
subsubsection {* @{const take} and @{const drop} *}
wenzelm@13114
  1942
wenzelm@13142
  1943
lemma take_0 [simp]: "take 0 xs = []"
nipkow@13145
  1944
by (induct xs) auto
wenzelm@13114
  1945
wenzelm@13142
  1946
lemma drop_0 [simp]: "drop 0 xs = xs"
nipkow@13145
  1947
by (induct xs) auto
wenzelm@13114
  1948
wenzelm@13142
  1949
lemma take_Suc_Cons [simp]: "take (Suc n) (x # xs) = x # take n xs"
nipkow@13145
  1950
by simp
wenzelm@13114
  1951
wenzelm@13142
  1952
lemma drop_Suc_Cons [simp]: "drop (Suc n) (x # xs) = drop n xs"
nipkow@13145
  1953
by simp
wenzelm@13114
  1954
wenzelm@13142
  1955
declare take_Cons [simp del] and drop_Cons [simp del]
wenzelm@13114
  1956
nipkow@15110
  1957
lemma take_Suc: "xs ~= [] ==> take (Suc n) xs = hd xs # take n (tl xs)"
nipkow@15110
  1958
by(clarsimp simp add:neq_Nil_conv)
nipkow@15110
  1959
nipkow@14187
  1960
lemma drop_Suc: "drop (Suc n) xs = drop n (tl xs)"
nipkow@14187
  1961
by(cases xs, simp_all)
nipkow@14187
  1962
huffman@26584
  1963
lemma take_tl: "take n (tl xs) = tl (take (Suc n) xs)"
huffman@26584
  1964
by (induct xs arbitrary: n) simp_all
huffman@26584
  1965
nipkow@24526
  1966
lemma drop_tl: "drop n (tl xs) = tl(drop n xs)"
nipkow@24526
  1967
by(induct xs arbitrary: n, simp_all add:drop_Cons drop_Suc split:nat.split)
nipkow@24526
  1968
huffman@26584
  1969
lemma tl_take: "tl (take n xs) = take (n - 1) (tl xs)"
huffman@26584
  1970
by (cases n, simp, cases xs, auto)
huffman@26584
  1971
huffman@26584
  1972
lemma tl_drop: "tl (drop n xs) = drop n (tl xs)"
huffman@26584
  1973
by (simp only: drop_tl)
huffman@26584
  1974
nipkow@24526
  1975
lemma nth_via_drop: "drop n xs = y#ys \<Longrightarrow> xs!n = y"
nipkow@58807
  1976
by (induct xs arbitrary: n, simp)(auto simp: drop_Cons nth_Cons split: nat.splits)
nipkow@14187
  1977
nipkow@13913
  1978
lemma take_Suc_conv_app_nth:
nipkow@24526
  1979
  "i < length xs \<Longrightarrow> take (Suc i) xs = take i xs @ [xs!i]"
nipkow@24526
  1980
apply (induct xs arbitrary: i, simp)
paulson@14208
  1981
apply (case_tac i, auto)
nipkow@13913
  1982
done
nipkow@13913
  1983
nipkow@58247
  1984
lemma Cons_nth_drop_Suc:
nipkow@24526
  1985
  "i < length xs \<Longrightarrow> (xs!i) # (drop (Suc i) xs) = drop i xs"
nipkow@24526
  1986
apply (induct xs arbitrary: i, simp)
mehta@14591
  1987
apply (case_tac i, auto)
mehta@14591
  1988
done
mehta@14591
  1989
nipkow@24526
  1990
lemma length_take [simp]: "length (take n xs) = min (length xs) n"
nipkow@24526
  1991
by (induct n arbitrary: xs) (auto, case_tac xs, auto)
nipkow@24526
  1992
nipkow@24526
  1993
lemma length_drop [simp]: "length (drop n xs) = (length xs - n)"
nipkow@24526
  1994
by (induct n arbitrary: xs) (auto, case_tac xs, auto)
nipkow@24526
  1995
nipkow@24526
  1996
lemma take_all [simp]: "length xs <= n ==> take n xs = xs"
nipkow@24526
  1997
by (induct n arbitrary: xs) (auto, case_tac xs, auto)
nipkow@24526
  1998
nipkow@24526
  1999
lemma drop_all [simp]: "length xs <= n ==> drop n xs = []"
nipkow@24526
  2000
by (induct n arbitrary: xs) (auto, case_tac xs, auto)
wenzelm@13114
  2001
wenzelm@13142
  2002
lemma take_append [simp]:
nipkow@24526
  2003
  "take n (xs @ ys) = (take n xs @ take (n - length xs) ys)"
nipkow@24526
  2004
by (induct n arbitrary: xs) (auto, case_tac xs, auto)
wenzelm@13114
  2005
wenzelm@13142
  2006
lemma drop_append [simp]:
nipkow@24526
  2007
  "drop n (xs @ ys) = drop n xs @ drop (n - length xs) ys"
nipkow@24526
  2008
by (induct n arbitrary: xs) (auto, case_tac xs, auto)
nipkow@24526
  2009
nipkow@24526
  2010
lemma take_take [simp]: "take n (take m xs) = take (min n m) xs"
nipkow@24526
  2011
apply (induct m arbitrary: xs n, auto)
nipkow@58807
  2012
 apply (case_tac xs, auto)
nipkow@15236
  2013
apply (case_tac n, auto)
nipkow@13145
  2014
done
wenzelm@13114
  2015
nipkow@24526
  2016
lemma drop_drop [simp]: "drop n (drop m xs) = drop (n + m) xs"
nipkow@24526
  2017
apply (induct m arbitrary: xs, auto)
nipkow@58807
  2018
 apply (case_tac xs, auto)
nipkow@13145
  2019
done
wenzelm@13114
  2020
nipkow@24526
  2021
lemma take_drop: "take n (drop m xs) = drop m (take (n + m) xs)"
nipkow@24526
  2022
apply (induct m arbitrary: xs n, auto)
nipkow@58807
  2023
 apply (case_tac xs, auto)
nipkow@13145
  2024
done
wenzelm@13114
  2025
nipkow@24526
  2026
lemma drop_take: "drop n (take m xs) = take (m-n) (drop n xs)"
nipkow@58807
  2027
by(induct xs arbitrary: m n)(auto simp: take_Cons drop_Cons split: nat.split)
nipkow@14802
  2028
nipkow@24526
  2029
lemma append_take_drop_id [simp]: "take n xs @ drop n xs = xs"
nipkow@24526
  2030
apply (induct n arbitrary: xs, auto)
paulson@14208
  2031
apply (case_tac xs, auto)
nipkow@13145
  2032
done
wenzelm@13114
  2033
nipkow@24526
  2034
lemma take_eq_Nil[simp]: "(take n xs = []) = (n = 0 \<or> xs = [])"
nipkow@58807
  2035
by(induct xs arbitrary: n)(auto simp: take_Cons split:nat.split)
nipkow@15110
  2036
nipkow@24526
  2037
lemma drop_eq_Nil[simp]: "(drop n xs = []) = (length xs <= n)"
nipkow@58807
  2038
by (induct xs arbitrary: n) (auto simp: drop_Cons split:nat.split)
nipkow@15110
  2039
nipkow@24526
  2040
lemma take_map: "take n (map f xs) = map f (take n xs)"
nipkow@24526
  2041
apply (induct n arbitrary: xs, auto)
nipkow@58807
  2042
 apply (case_tac xs, auto)
nipkow@13145
  2043
done
wenzelm@13114
  2044
nipkow@24526
  2045
lemma drop_map: "drop n (map f xs) = map f (drop n xs)"
nipkow@24526
  2046
apply (induct n arbitrary: xs, auto)
nipkow@58807
  2047
 apply (case_tac xs, auto)
nipkow@13145
  2048
done
wenzelm@13114
  2049
nipkow@24526
  2050
lemma rev_take: "rev (take i xs) = drop (length xs - i) (rev xs)"
nipkow@24526
  2051
apply (induct xs arbitrary: i, auto)
nipkow@58807
  2052
 apply (case_tac i, auto)
nipkow@13145
  2053
done
wenzelm@13114
  2054
nipkow@24526
  2055
lemma rev_drop: "rev (drop i xs) = take (length xs - i) (rev xs)"
nipkow@24526
  2056
apply (induct xs arbitrary: i, auto)
nipkow@58807
  2057
 apply (case_tac i, auto)
nipkow@13145
  2058
done
wenzelm@13114
  2059
nipkow@24526
  2060
lemma nth_take [simp]: "i < n ==> (take n xs)!i = xs!i"
nipkow@24526
  2061
apply (induct xs arbitrary: i n, auto)
nipkow@58807
  2062
 apply (case_tac n, blast)
paulson@14208
  2063
apply (case_tac i, auto)
nipkow@13145
  2064
done
wenzelm@13114
  2065
wenzelm@13142
  2066
lemma nth_drop [simp]:
nipkow@24526
  2067
  "n + i <= length xs ==> (drop n xs)!i = xs!(n + i)"
nipkow@24526
  2068
apply (induct n arbitrary: xs i, auto)
nipkow@58807
  2069
 apply (case_tac xs, auto)
nipkow@13145
  2070
done
nipkow@3507
  2071
huffman@26584
  2072
lemma butlast_take:
huffman@30128
  2073
  "n <= length xs ==> butlast (take n xs) = take (n - 1) xs"
haftmann@54863
  2074
by (simp add: butlast_conv_take min.absorb1 min.absorb2)
huffman@26584
  2075
huffman@26584
  2076
lemma butlast_drop: "butlast (drop n xs) = drop n (butlast xs)"
haftmann@57514
  2077
by (simp add: butlast_conv_take drop_take ac_simps)
huffman@26584
  2078
huffman@26584
  2079
lemma take_butlast: "n < length xs ==> take n (butlast xs) = take n xs"
haftmann@54863
  2080
by (simp add: butlast_conv_take min.absorb1)
huffman@26584
  2081
huffman@26584
  2082
lemma drop_butlast: "drop n (butlast xs) = butlast (drop n xs)"
haftmann@57514
  2083
by (simp add: butlast_conv_take drop_take ac_simps)
huffman@26584
  2084
bulwahn@46500
  2085
lemma hd_drop_conv_nth: "n < length xs \<Longrightarrow> hd(drop n xs) = xs!n"
nipkow@18423
  2086
by(simp add: hd_conv_nth)
nipkow@18423
  2087
nipkow@35248
  2088
lemma set_take_subset_set_take:
nipkow@35248
  2089
  "m <= n \<Longrightarrow> set(take m xs) <= set(take n xs)"
bulwahn@41463
  2090
apply (induct xs arbitrary: m n)
nipkow@58807
  2091
 apply simp
bulwahn@41463
  2092
apply (case_tac n)
bulwahn@41463
  2093
apply (auto simp: take_Cons)
bulwahn@41463
  2094
done
nipkow@35248
  2095
nipkow@24526
  2096
lemma set_take_subset: "set(take n xs) \<subseteq> set xs"
nipkow@24526
  2097
by(induct xs arbitrary: n)(auto simp:take_Cons split:nat.split)
nipkow@24526
  2098
nipkow@24526
  2099
lemma set_drop_subset: "set(drop n xs) \<subseteq> set xs"
nipkow@24526
  2100
by(induct xs arbitrary: n)(auto simp:drop_Cons split:nat.split)
nipkow@14025
  2101
nipkow@35248
  2102
lemma set_drop_subset_set_drop:
nipkow@35248
  2103
  "m >= n \<Longrightarrow> set(drop m xs) <= set(drop n xs)"
nipkow@35248
  2104
apply(induct xs arbitrary: m n)
nipkow@58807
  2105
 apply(auto simp:drop_Cons split:nat.split)
blanchet@56085
  2106
by (metis set_drop_subset subset_iff)
nipkow@35248
  2107
nipkow@14187
  2108
lemma in_set_takeD: "x : set(take n xs) \<Longrightarrow> x : set xs"
nipkow@14187
  2109
using set_take_subset by fast
nipkow@14187
  2110
nipkow@14187
  2111
lemma in_set_dropD: "x : set(drop n xs) \<Longrightarrow> x : set xs"
nipkow@14187
  2112
using set_drop_subset by fast
nipkow@14187
  2113
wenzelm@13114
  2114
lemma append_eq_conv_conj:
nipkow@24526
  2115
  "(xs @ ys = zs) = (xs = take (length xs) zs \<and> ys = drop (length xs) zs)"
nipkow@24526
  2116
apply (induct xs arbitrary: zs, simp, clarsimp)
nipkow@58807
  2117
 apply (case_tac zs, auto)
nipkow@13145
  2118
done
wenzelm@13142
  2119
nipkow@58807
  2120
lemma take_add:  "take (i+j) xs = take i xs @ take j (drop i xs)"
nipkow@24526
  2121
apply (induct xs arbitrary: i, auto) 
nipkow@58807
  2122
 apply (case_tac i, simp_all)
paulson@14050
  2123
done
paulson@14050
  2124
nipkow@14300
  2125
lemma append_eq_append_conv_if:
nipkow@58807
  2126
  "(xs\<^sub>1 @ xs\<^sub>2 = ys\<^sub>1 @ ys\<^sub>2) =
wenzelm@53015
  2127
  (if size xs\<^sub>1 \<le> size ys\<^sub>1
wenzelm@53015
  2128
   then xs\<^sub>1 = take (size xs\<^sub>1) ys\<^sub>1 \<and> xs\<^sub>2 = drop (size xs\<^sub>1) ys\<^sub>1 @ ys\<^sub>2
wenzelm@53015
  2129
   else take (size ys\<^sub>1) xs\<^sub>1 = ys\<^sub>1 \<and> drop (size ys\<^sub>1) xs\<^sub>1 @ xs\<^sub>2 = ys\<^sub>2)"
wenzelm@53015
  2130
apply(induct xs\<^sub>1 arbitrary: ys\<^sub>1)
nipkow@14300
  2131
 apply simp
wenzelm@53015
  2132
apply(case_tac ys\<^sub>1)
nipkow@14300
  2133
apply simp_all
nipkow@14300
  2134
done
nipkow@14300
  2135
nipkow@15110
  2136
lemma take_hd_drop:
huffman@30079
  2137
  "n < length xs \<Longrightarrow> take n xs @ [hd (drop n xs)] = take (Suc n) xs"
nipkow@24526
  2138
apply(induct xs arbitrary: n)
nipkow@58807
  2139
 apply simp
nipkow@15110
  2140
apply(simp add:drop_Cons split:nat.split)
nipkow@15110
  2141
done
nipkow@15110
  2142
nipkow@17501
  2143
lemma id_take_nth_drop:
nipkow@58807
  2144
  "i < length xs \<Longrightarrow> xs = take i xs @ xs!i # drop (Suc i) xs" 
nipkow@17501
  2145
proof -
nipkow@17501
  2146
  assume si: "i < length xs"
nipkow@17501
  2147
  hence "xs = take (Suc i) xs @ drop (Suc i) xs" by auto
nipkow@17501
  2148
  moreover
nipkow@17501
  2149
  from si have "take (Suc i) xs = take i xs @ [xs!i]"
nipkow@17501
  2150
    apply (rule_tac take_Suc_conv_app_nth) by arith
nipkow@17501
  2151
  ultimately show ?thesis by auto
nipkow@17501
  2152
qed
nipkow@17501
  2153
  
nipkow@17501
  2154
lemma upd_conv_take_nth_drop:
nipkow@58807
  2155
  "i < length xs \<Longrightarrow> xs[i:=a] = take i xs @ a # drop (Suc i) xs"
nipkow@17501
  2156
proof -
nipkow@17501
  2157
  assume i: "i < length xs"
nipkow@17501
  2158
  have "xs[i:=a] = (take i xs @ xs!i # drop (Suc i) xs)[i:=a]"
nipkow@17501
  2159
    by(rule arg_cong[OF id_take_nth_drop[OF i]])
nipkow@17501
  2160
  also have "\<dots> = take i xs @ a # drop (Suc i) xs"
nipkow@17501
  2161
    using i by (simp add: list_update_append)
nipkow@17501
  2162
  finally show ?thesis .
nipkow@17501
  2163
qed
nipkow@17501
  2164
wenzelm@13114
  2165
haftmann@49948
  2166
subsubsection {* @{const takeWhile} and @{const dropWhile} *}
wenzelm@13114
  2167
hoelzl@33639
  2168
lemma length_takeWhile_le: "length (takeWhile P xs) \<le> length xs"
nipkow@58807
  2169
by (induct xs) auto
hoelzl@33639
  2170
wenzelm@13142
  2171
lemma takeWhile_dropWhile_id [simp]: "takeWhile P xs @ dropWhile P xs = xs"
nipkow@13145
  2172
by (induct xs) auto
wenzelm@13114
  2173
wenzelm@13142
  2174
lemma takeWhile_append1 [simp]:
nipkow@58807
  2175
  "[| x:set xs; ~P(x)|] ==> takeWhile P (xs @ ys) = takeWhile P xs"
nipkow@13145
  2176
by (induct xs) auto
wenzelm@13114
  2177
wenzelm@13142
  2178
lemma takeWhile_append2 [simp]:
nipkow@58807
  2179
  "(!!x. x : set xs ==> P x) ==> takeWhile P (xs @ ys) = xs @ takeWhile P ys"
nipkow@13145
  2180
by (induct xs) auto
wenzelm@13114
  2181
wenzelm@13142
  2182
lemma takeWhile_tail: "\<not> P x ==> takeWhile P (xs @ (x#l)) = takeWhile P xs"
nipkow@13145
  2183
by (induct xs) auto
wenzelm@13114
  2184
hoelzl@33639
  2185
lemma takeWhile_nth: "j < length (takeWhile P xs) \<Longrightarrow> takeWhile P xs ! j = xs ! j"
hoelzl@33639
  2186
apply (subst (3) takeWhile_dropWhile_id[symmetric]) unfolding nth_append by auto
hoelzl@33639
  2187
nipkow@58807
  2188
lemma dropWhile_nth: "j < length (dropWhile P xs) \<Longrightarrow>
nipkow@58807
  2189
  dropWhile P xs ! j = xs ! (j + length (takeWhile P xs))"
hoelzl@33639
  2190
apply (subst (3) takeWhile_dropWhile_id[symmetric]) unfolding nth_append by auto
hoelzl@33639
  2191
hoelzl@33639
  2192
lemma length_dropWhile_le: "length (dropWhile P xs) \<le> length xs"
hoelzl@33639
  2193
by (induct xs) auto
hoelzl@33639
  2194
wenzelm@13142
  2195
lemma dropWhile_append1 [simp]:
nipkow@58807
  2196
  "[| x : set xs; ~P(x)|] ==> dropWhile P (xs @ ys) = (dropWhile P xs)@ys"
nipkow@13145
  2197
by (induct xs) auto
wenzelm@13114
  2198
wenzelm@13142
  2199
lemma dropWhile_append2 [simp]:
nipkow@58807
  2200
  "(!!x. x:set xs ==> P(x)) ==> dropWhile P (xs @ ys) = dropWhile P ys"
nipkow@13145
  2201
by (induct xs) auto
wenzelm@13114
  2202
noschinl@45841
  2203
lemma dropWhile_append3:
noschinl@45841
  2204
  "\<not> P y \<Longrightarrow>dropWhile P (xs @ y # ys) = dropWhile P xs @ y # ys"
noschinl@45841
  2205
by (induct xs) auto
noschinl@45841
  2206
noschinl@45841
  2207
lemma dropWhile_last:
noschinl@45841
  2208
  "x \<in> set xs \<Longrightarrow> \<not> P x \<Longrightarrow> last (dropWhile P xs) = last xs"
noschinl@45841
  2209
by (auto simp add: dropWhile_append3 in_set_conv_decomp)
noschinl@45841
  2210
noschinl@45841
  2211
lemma set_dropWhileD: "x \<in> set (dropWhile P xs) \<Longrightarrow> x \<in> set xs"
noschinl@45841
  2212
by (induct xs) (auto split: split_if_asm)
noschinl@45841
  2213
krauss@23971
  2214
lemma set_takeWhileD: "x : set (takeWhile P xs) ==> x : set xs \<and> P x"
nipkow@13145
  2215
by (induct xs) (auto split: split_if_asm)
wenzelm@13114
  2216
nipkow@13913
  2217
lemma takeWhile_eq_all_conv[simp]:
nipkow@58807
  2218
  "(takeWhile P xs = xs) = (\<forall>x \<in> set xs. P x)"
nipkow@13913
  2219
by(induct xs, auto)
nipkow@13913
  2220
nipkow@13913
  2221
lemma dropWhile_eq_Nil_conv[simp]:
nipkow@58807
  2222
  "(dropWhile P xs = []) = (\<forall>x \<in> set xs. P x)"
nipkow@13913
  2223
by(induct xs, auto)
nipkow@13913
  2224
nipkow@13913
  2225
lemma dropWhile_eq_Cons_conv:
nipkow@58807
  2226
  "(dropWhile P xs = y#ys) = (xs = takeWhile P xs @ y # ys & \<not> P y)"
nipkow@13913
  2227
by(induct xs, auto)
nipkow@13913
  2228
nipkow@31077
  2229
lemma distinct_takeWhile[simp]: "distinct xs ==> distinct (takeWhile P xs)"
nipkow@31077
  2230
by (induct xs) (auto dest: set_takeWhileD)
nipkow@31077
  2231
nipkow@31077
  2232
lemma distinct_dropWhile[simp]: "distinct xs ==> distinct (dropWhile P xs)"
nipkow@31077
  2233
by (induct xs) auto
nipkow@31077
  2234
hoelzl@33639
  2235
lemma takeWhile_map: "takeWhile P (map f xs) = map f (takeWhile (P \<circ> f) xs)"
hoelzl@33639
  2236
by (induct xs) auto
hoelzl@33639
  2237
hoelzl@33639
  2238
lemma dropWhile_map: "dropWhile P (map f xs) = map f (dropWhile (P \<circ> f) xs)"
hoelzl@33639
  2239
by (induct xs) auto
hoelzl@33639
  2240
hoelzl@33639
  2241
lemma takeWhile_eq_take: "takeWhile P xs = take (length (takeWhile P xs)) xs"
hoelzl@33639
  2242
by (induct xs) auto
hoelzl@33639
  2243
hoelzl@33639
  2244
lemma dropWhile_eq_drop: "dropWhile P xs = drop (length (takeWhile P xs)) xs"
hoelzl@33639
  2245
by (induct xs) auto
hoelzl@33639
  2246
nipkow@58807
  2247
lemma hd_dropWhile: "dropWhile P xs \<noteq> [] \<Longrightarrow> \<not> P (hd (dropWhile P xs))"
hoelzl@33639
  2248
using assms by (induct xs) auto
hoelzl@33639
  2249
hoelzl@33639
  2250
lemma takeWhile_eq_filter:
hoelzl@33639
  2251
  assumes "\<And> x. x \<in> set (dropWhile P xs) \<Longrightarrow> \<not> P x"
hoelzl@33639
  2252
  shows "takeWhile P xs = filter P xs"
hoelzl@33639
  2253
proof -
hoelzl@33639
  2254
  have A: "filter P xs = filter P (takeWhile P xs @ dropWhile P xs)"
hoelzl@33639
  2255
    by simp
hoelzl@33639
  2256
  have B: "filter P (dropWhile P xs) = []"
hoelzl@33639
  2257
    unfolding filter_empty_conv using assms by blast
hoelzl@33639
  2258
  have "filter P xs = takeWhile P xs"
hoelzl@33639
  2259
    unfolding A filter_append B
hoelzl@33639
  2260
    by (auto simp add: filter_id_conv dest: set_takeWhileD)
hoelzl@33639
  2261
  thus ?thesis ..
hoelzl@33639
  2262
qed
hoelzl@33639
  2263
hoelzl@33639
  2264
lemma takeWhile_eq_take_P_nth:
hoelzl@33639
  2265
  "\<lbrakk> \<And> i. \<lbrakk> i < n ; i < length xs \<rbrakk> \<Longrightarrow> P (xs ! i) ; n < length xs \<Longrightarrow> \<not> P (xs ! n) \<rbrakk> \<Longrightarrow>
hoelzl@33639
  2266
  takeWhile P xs = take n xs"
hoelzl@33639
  2267
proof (induct xs arbitrary: n)
hoelzl@33639
  2268
  case (Cons x xs)
hoelzl@33639
  2269
  thus ?case
hoelzl@33639
  2270
  proof (cases n)
hoelzl@33639
  2271
    case (Suc n') note this[simp]
hoelzl@33639
  2272
    have "P x" using Cons.prems(1)[of 0] by simp
hoelzl@33639
  2273
    moreover have "takeWhile P xs = take n' xs"
hoelzl@33639
  2274
    proof (rule Cons.hyps)
hoelzl@33639
  2275
      case goal1 thus "P (xs ! i)" using Cons.prems(1)[of "Suc i"] by simp
hoelzl@33639
  2276
    next case goal2 thus ?case using Cons by auto
hoelzl@33639
  2277
    qed
hoelzl@33639
  2278
    ultimately show ?thesis by simp
hoelzl@33639
  2279
   qed simp
hoelzl@33639
  2280
qed simp
hoelzl@33639
  2281
hoelzl@33639
  2282
lemma nth_length_takeWhile:
hoelzl@33639
  2283
  "length (takeWhile P xs) < length xs \<Longrightarrow> \<not> P (xs ! length (takeWhile P xs))"
hoelzl@33639
  2284
by (induct xs) auto
hoelzl@33639
  2285
hoelzl@33639
  2286
lemma length_takeWhile_less_P_nth:
hoelzl@33639
  2287
  assumes all: "\<And> i. i < j \<Longrightarrow> P (xs ! i)" and "j \<le> length xs"
hoelzl@33639
  2288
  shows "j \<le> length (takeWhile P xs)"
hoelzl@33639
  2289
proof (rule classical)
hoelzl@33639
  2290
  assume "\<not> ?thesis"
hoelzl@33639
  2291
  hence "length (takeWhile P xs) < length xs" using assms by simp
hoelzl@33639
  2292
  thus ?thesis using all `\<not> ?thesis` nth_length_takeWhile[of P xs] by auto
hoelzl@33639
  2293
qed
nipkow@31077
  2294
nipkow@17501
  2295
lemma takeWhile_neq_rev: "\<lbrakk>distinct xs; x \<in> set xs\<rbrakk> \<Longrightarrow>
nipkow@58807
  2296
  takeWhile (\<lambda>y. y \<noteq> x) (rev xs) = rev (tl (dropWhile (\<lambda>y. y \<noteq> x) xs))"
nipkow@17501
  2297
by(induct xs) (auto simp: takeWhile_tail[where l="[]"])
nipkow@17501
  2298
nipkow@17501
  2299
lemma dropWhile_neq_rev: "\<lbrakk>distinct xs; x \<in> set xs\<rbrakk> \<Longrightarrow>
nipkow@17501
  2300
  dropWhile (\<lambda>y. y \<noteq> x) (rev xs) = x # rev (takeWhile (\<lambda>y. y \<noteq> x) xs)"
nipkow@17501
  2301
apply(induct xs)
nipkow@17501
  2302
 apply simp
nipkow@17501
  2303
apply auto
nipkow@17501
  2304
apply(subst dropWhile_append2)
nipkow@17501
  2305
apply auto
nipkow@17501
  2306
done
nipkow@17501
  2307
nipkow@18423
  2308
lemma takeWhile_not_last:
nipkow@58807
  2309
  "distinct xs \<Longrightarrow> takeWhile (\<lambda>y. y \<noteq> last xs) xs = butlast xs"
nipkow@18423
  2310
apply(induct xs)
nipkow@18423
  2311
 apply simp
nipkow@18423
  2312
apply(case_tac xs)
nipkow@18423
  2313
apply(auto)
nipkow@18423
  2314
done
nipkow@18423
  2315
krauss@44013
  2316
lemma takeWhile_cong [fundef_cong]:
krauss@18336
  2317
  "[| l = k; !!x. x : set l ==> P x = Q x |] 
krauss@18336
  2318
  ==> takeWhile P l = takeWhile Q k"
nipkow@24349
  2319
by (induct k arbitrary: l) (simp_all)
krauss@18336
  2320
krauss@44013
  2321
lemma dropWhile_cong [fundef_cong]:
krauss@18336
  2322
  "[| l = k; !!x. x : set l ==> P x = Q x |] 
krauss@18336
  2323
  ==> dropWhile P l = dropWhile Q k"
nipkow@24349
  2324
by (induct k arbitrary: l, simp_all)
krauss@18336
  2325
haftmann@52380
  2326
lemma takeWhile_idem [simp]:
haftmann@52380
  2327
  "takeWhile P (takeWhile P xs) = takeWhile P xs"
nipkow@58807
  2328
by (induct xs) auto
haftmann@52380
  2329
haftmann@52380
  2330
lemma dropWhile_idem [simp]:
haftmann@52380
  2331
  "dropWhile P (dropWhile P xs) = dropWhile P xs"
nipkow@58807
  2332
by (induct xs) auto
haftmann@52380
  2333
wenzelm@13114
  2334
haftmann@49948
  2335
subsubsection {* @{const zip} *}
wenzelm@13114
  2336
wenzelm@13142
  2337
lemma zip_Nil [simp]: "zip [] ys = []"
nipkow@13145
  2338
by (induct ys) auto
wenzelm@13114
  2339
wenzelm@13142
  2340
lemma zip_Cons_Cons [simp]: "zip (x # xs) (y # ys) = (x, y) # zip xs ys"
nipkow@13145
  2341
by simp
wenzelm@13114
  2342
wenzelm@13142
  2343
declare zip_Cons [simp del]
wenzelm@13114
  2344
haftmann@36198
  2345
lemma [code]:
haftmann@36198
  2346
  "zip [] ys = []"
haftmann@36198
  2347
  "zip xs [] = []"
haftmann@36198
  2348
  "zip (x # xs) (y # ys) = (x, y) # zip xs ys"
nipkow@58807
  2349
by (fact zip_Nil zip.simps(1) zip_Cons_Cons)+
haftmann@36198
  2350
nipkow@15281
  2351
lemma zip_Cons1:
nipkow@58807
  2352
  "zip (x#xs) ys = (case ys of [] \<Rightarrow> [] | y#ys \<Rightarrow> (x,y)#zip xs ys)"
nipkow@15281
  2353
by(auto split:list.split)
nipkow@15281
  2354
wenzelm@13142
  2355
lemma length_zip [simp]:
nipkow@58807
  2356
  "length (zip xs ys) = min (length xs) (length ys)"
krauss@22493
  2357
by (induct xs ys rule:list_induct2') auto
wenzelm@13114
  2358
haftmann@34978
  2359
lemma zip_obtain_same_length:
haftmann@34978
  2360
  assumes "\<And>zs ws n. length zs = length ws \<Longrightarrow> n = min (length xs) (length ys)
haftmann@34978
  2361
    \<Longrightarrow> zs = take n xs \<Longrightarrow> ws = take n ys \<Longrightarrow> P (zip zs ws)"
haftmann@34978
  2362
  shows "P (zip xs ys)"
haftmann@34978
  2363
proof -
haftmann@34978
  2364
  let ?n = "min (length xs) (length ys)"
haftmann@34978
  2365
  have "P (zip (take ?n xs) (take ?n ys))"
haftmann@34978
  2366
    by (rule assms) simp_all
haftmann@34978
  2367
  moreover have "zip xs ys = zip (take ?n xs) (take ?n ys)"
haftmann@34978
  2368
  proof (induct xs arbitrary: ys)
haftmann@34978
  2369
    case Nil then show ?case by simp
haftmann@34978
  2370
  next
haftmann@34978
  2371
    case (Cons x xs) then show ?case by (cases ys) simp_all
haftmann@34978
  2372
  qed
haftmann@34978
  2373
  ultimately show ?thesis by simp
haftmann@34978
  2374
qed
haftmann@34978
  2375
wenzelm@13114
  2376
lemma zip_append1:
nipkow@58807
  2377
  "zip (xs @ ys) zs =
nipkow@58807
  2378
  zip xs (take (length xs) zs) @ zip ys (drop (length xs) zs)"
krauss@22493
  2379
by (induct xs zs rule:list_induct2') auto
wenzelm@13114
  2380
wenzelm@13114
  2381
lemma zip_append2:
nipkow@58807
  2382
  "zip xs (ys @ zs) =
nipkow@58807
  2383
  zip (take (length ys) xs) ys @ zip (drop (length ys) xs) zs"
krauss@22493
  2384
by (induct xs ys rule:list_induct2') auto
wenzelm@13114
  2385
wenzelm@13142
  2386
lemma zip_append [simp]:
nipkow@58807
  2387
  "[| length xs = length us |] ==>
nipkow@58807
  2388
  zip (xs@ys) (us@vs) = zip xs us @ zip ys vs"
nipkow@13145
  2389
by (simp add: zip_append1)
wenzelm@13114
  2390
wenzelm@13114
  2391
lemma zip_rev:
nipkow@58807
  2392
  "length xs = length ys ==> zip (rev xs) (rev ys) = rev (zip xs ys)"
nipkow@14247
  2393
by (induct rule:list_induct2, simp_all)
wenzelm@13114
  2394
hoelzl@33639
  2395
lemma zip_map_map:
hoelzl@33639
  2396
  "zip (map f xs) (map g ys) = map (\<lambda> (x, y). (f x, g y)) (zip xs ys)"
hoelzl@33639
  2397
proof (induct xs arbitrary: ys)
hoelzl@33639
  2398
  case (Cons x xs) note Cons_x_xs = Cons.hyps
hoelzl@33639
  2399
  show ?case
hoelzl@33639
  2400
  proof (cases ys)
hoelzl@33639
  2401
    case (Cons y ys')
hoelzl@33639
  2402
    show ?thesis unfolding Cons using Cons_x_xs by simp
hoelzl@33639
  2403
  qed simp
hoelzl@33639
  2404
qed simp
hoelzl@33639
  2405
hoelzl@33639
  2406
lemma zip_map1:
hoelzl@33639
  2407
  "zip (map f xs) ys = map (\<lambda>(x, y). (f x, y)) (zip xs ys)"
hoelzl@33639
  2408
using zip_map_map[of f xs "\<lambda>x. x" ys] by simp
hoelzl@33639
  2409
hoelzl@33639
  2410
lemma zip_map2:
hoelzl@33639
  2411
  "zip xs (map f ys) = map (\<lambda>(x, y). (x, f y)) (zip xs ys)"
hoelzl@33639
  2412
using zip_map_map[of "\<lambda>x. x" xs f ys] by simp
hoelzl@33639
  2413
nipkow@23096
  2414
lemma map_zip_map:
hoelzl@33639
  2415
  "map f (zip (map g xs) ys) = map (%(x,y). f(g x, y)) (zip xs ys)"
nipkow@58807
  2416
by (auto simp: zip_map1)
nipkow@23096
  2417
nipkow@23096
  2418
lemma map_zip_map2:
hoelzl@33639
  2419
  "map f (zip xs (map g ys)) = map (%(x,y). f(x, g y)) (zip xs ys)"
nipkow@58807
  2420
by (auto simp: zip_map2)
nipkow@23096
  2421
nipkow@31080
  2422
text{* Courtesy of Andreas Lochbihler: *}
nipkow@31080
  2423
lemma zip_same_conv_map: "zip xs xs = map (\<lambda>x. (x, x)) xs"
nipkow@31080
  2424
by(induct xs) auto
nipkow@31080
  2425
wenzelm@13142
  2426
lemma nth_zip [simp]:
nipkow@58807
  2427
  "[| i < length xs; i < length ys|] ==> (zip xs ys)!i = (xs!i, ys!i)"
nipkow@24526
  2428
apply (induct ys arbitrary: i xs, simp)
nipkow@13145
  2429
apply (case_tac xs)
nipkow@13145
  2430
 apply (simp_all add: nth.simps split: nat.split)
nipkow@13145
  2431
done
wenzelm@13114
  2432
wenzelm@13114
  2433
lemma set_zip:
nipkow@58807
  2434
  "set (zip xs ys) = {(xs!i, ys!i) | i. i < min (length xs) (length ys)}"
nipkow@31080
  2435
by(simp add: set_conv_nth cong: rev_conj_cong)
wenzelm@13114
  2436
hoelzl@33639
  2437
lemma zip_same: "((a,b) \<in> set (zip xs xs)) = (a \<in> set xs \<and> a = b)"
hoelzl@33639
  2438
by(induct xs) auto
hoelzl@33639
  2439
wenzelm@13114
  2440
lemma zip_update:
nipkow@31080
  2441
  "zip (xs[i:=x]) (ys[i:=y]) = (zip xs ys)[i:=(x,y)]"
nipkow@31080
  2442
by(rule sym, simp add: update_zip)
wenzelm@13114
  2443
wenzelm@13142
  2444
lemma zip_replicate [simp]:
nipkow@24526
  2445
  "zip (replicate i x) (replicate j y) = replicate (min i j) (x,y)"
nipkow@24526
  2446
apply (induct i arbitrary: j, auto)
paulson@14208
  2447
apply (case_tac j, auto)
nipkow@13145
  2448
done
wenzelm@13114
  2449
nipkow@19487
  2450
lemma take_zip:
nipkow@24526
  2451
  "take n (zip xs ys) = zip (take n xs) (take n ys)"
nipkow@24526
  2452
apply (induct n arbitrary: xs ys)
nipkow@19487
  2453
 apply simp
nipkow@19487
  2454
apply (case_tac xs, simp)
nipkow@19487
  2455
apply (case_tac ys, simp_all)
nipkow@19487
  2456
done
nipkow@19487
  2457
nipkow@19487
  2458
lemma drop_zip:
nipkow@24526
  2459
  "drop n (zip xs ys) = zip (drop n xs) (drop n ys)"
nipkow@24526
  2460
apply (induct n arbitrary: xs ys)
nipkow@19487
  2461
 apply simp
nipkow@19487
  2462
apply (case_tac xs, simp)
nipkow@19487
  2463
apply (case_tac ys, simp_all)
nipkow@19487
  2464
done
nipkow@19487
  2465
hoelzl@33639
  2466
lemma zip_takeWhile_fst: "zip (takeWhile P xs) ys = takeWhile (P \<circ> fst) (zip xs ys)"
hoelzl@33639
  2467
proof (induct xs arbitrary: ys)
hoelzl@33639
  2468
  case (Cons x xs) thus ?case by (cases ys) auto
hoelzl@33639
  2469
qed simp
hoelzl@33639
  2470
hoelzl@33639
  2471
lemma zip_takeWhile_snd: "zip xs (takeWhile P ys) = takeWhile (P \<circ> snd) (zip xs ys)"
hoelzl@33639
  2472
proof (induct xs arbitrary: ys)
hoelzl@33639
  2473
  case (Cons x xs) thus ?case by (cases ys) auto
hoelzl@33639
  2474
qed simp
hoelzl@33639
  2475
nipkow@58807
  2476
lemma set_zip_leftD: "(x,y)\<in> set (zip xs ys) \<Longrightarrow> x \<in> set xs"
krauss@22493
  2477
by (induct xs ys rule:list_induct2') auto
krauss@22493
  2478
nipkow@58807
  2479
lemma set_zip_rightD: "(x,y)\<in> set (zip xs ys) \<Longrightarrow> y \<in> set ys"
krauss@22493
  2480
by (induct xs ys rule:list_induct2') auto
wenzelm@13142
  2481
nipkow@23983
  2482
lemma in_set_zipE:
nipkow@23983
  2483
  "(x,y) : set(zip xs ys) \<Longrightarrow> (\<lbrakk> x : set xs; y : set ys \<rbrakk> \<Longrightarrow> R) \<Longrightarrow> R"
nipkow@23983
  2484
by(blast dest: set_zip_leftD set_zip_rightD)
nipkow@23983
  2485
nipkow@58807
  2486
lemma zip_map_fst_snd: "zip (map fst zs) (map snd zs) = zs"
nipkow@58807
  2487
by (induct zs) simp_all
haftmann@29829
  2488
haftmann@29829
  2489
lemma zip_eq_conv:
haftmann@29829
  2490
  "length xs = length ys \<Longrightarrow> zip xs ys = zs \<longleftrightarrow> map fst zs = xs \<and> map snd zs = ys"
nipkow@58807
  2491
by (auto simp add: zip_map_fst_snd)
haftmann@29829
  2492
haftmann@51173
  2493
lemma in_set_zip:
haftmann@51173
  2494
  "p \<in> set (zip xs ys) \<longleftrightarrow> (\<exists>n. xs ! n = fst p \<and> ys ! n = snd p
nipkow@58807
  2495
  \<and> n < length xs \<and> n < length ys)"
nipkow@58807
  2496
by (cases p) (auto simp add: set_zip)
haftmann@51173
  2497
haftmann@51173
  2498
lemma pair_list_eqI:
haftmann@51173
  2499
  assumes "map fst xs = map fst ys" and "map snd xs = map snd ys"
haftmann@51173
  2500
  shows "xs = ys"
haftmann@51173
  2501
proof -
haftmann@51173
  2502
  from assms(1) have "length xs = length ys" by (rule map_eq_imp_length_eq)
haftmann@51173
  2503
  from this assms show ?thesis
haftmann@51173
  2504
    by (induct xs ys rule: list_induct2) (simp_all add: prod_eqI)
haftmann@51173
  2505
qed
haftmann@51173
  2506
wenzelm@35115
  2507
haftmann@49948
  2508
subsubsection {* @{const list_all2} *}
wenzelm@13114
  2509
kleing@14316
  2510
lemma list_all2_lengthD [intro?]: 
kleing@14316
  2511
  "list_all2 P xs ys ==> length xs = length ys"
blanchet@55524
  2512
by (simp add: list_all2_iff)
haftmann@19607
  2513
haftmann@19787
  2514
lemma list_all2_Nil [iff, code]: "list_all2 P [] ys = (ys = [])"
blanchet@55524
  2515
by (simp add: list_all2_iff)
haftmann@19607
  2516
haftmann@19787
  2517
lemma list_all2_Nil2 [iff, code]: "list_all2 P xs [] = (xs = [])"
blanchet@55524
  2518
by (simp add: list_all2_iff)
haftmann@19607
  2519
haftmann@19607
  2520
lemma list_all2_Cons [iff, code]:
haftmann@19607
  2521
  "list_all2 P (x # xs) (y # ys) = (P x y \<and> list_all2 P xs ys)"
blanchet@55524
  2522
by (auto simp add: list_all2_iff)
wenzelm@13114
  2523
wenzelm@13114
  2524
lemma list_all2_Cons1:
nipkow@58807
  2525
  "list_all2 P (x # xs) ys = (\<exists>z zs. ys = z # zs \<and> P x z \<and> list_all2 P xs zs)"
nipkow@13145
  2526
by (cases ys) auto
wenzelm@13114
  2527
wenzelm@13114
  2528
lemma list_all2_Cons2:
nipkow@58807
  2529
  "list_all2 P xs (y # ys) = (\<exists>z zs. xs = z # zs \<and> P z y \<and> list_all2 P zs ys)"
nipkow@13145
  2530
by (cases xs) auto
wenzelm@13114
  2531
huffman@45794
  2532
lemma list_all2_induct
huffman@45794
  2533
  [consumes 1, case_names Nil Cons, induct set: list_all2]:
huffman@45794
  2534
  assumes P: "list_all2 P xs ys"
huffman@45794
  2535
  assumes Nil: "R [] []"
huffman@47640
  2536
  assumes Cons: "\<And>x xs y ys.
huffman@47640
  2537
    \<lbrakk>P x y; list_all2 P xs ys; R xs ys\<rbrakk> \<Longrightarrow> R (x # xs) (y # ys)"
huffman@45794
  2538
  shows "R xs ys"
huffman@45794
  2539
using P
huffman@45794
  2540
by (induct xs arbitrary: ys) (auto simp add: list_all2_Cons1 Nil Cons)
huffman@45794
  2541
wenzelm@13142
  2542
lemma list_all2_rev [iff]:
nipkow@58807
  2543
  "list_all2 P (rev xs) (rev ys) = list_all2 P xs ys"
blanchet@55524
  2544
by (simp add: list_all2_iff zip_rev cong: conj_cong)
wenzelm@13114
  2545
kleing@13863
  2546
lemma list_all2_rev1:
nipkow@58807
  2547
  "list_all2 P (rev xs) ys = list_all2 P xs (rev ys)"
kleing@13863
  2548
by (subst list_all2_rev [symmetric]) simp
kleing@13863
  2549
wenzelm@13114
  2550
lemma list_all2_append1:
nipkow@58807
  2551
  "list_all2 P (xs @ ys) zs =
nipkow@58807
  2552
  (EX us vs. zs = us @ vs \<and> length us = length xs \<and> length vs = length ys \<and>
nipkow@58807
  2553
    list_all2 P xs us \<and> list_all2 P ys vs)"
blanchet@55524
  2554
apply (simp add: list_all2_iff zip_append1)
nipkow@13145
  2555
apply (rule iffI)
nipkow@13145
  2556
 apply (rule_tac x = "take (length xs) zs" in exI)
nipkow@13145
  2557
 apply (rule_tac x = "drop (length xs) zs" in exI)
paulson@14208
  2558
 apply (force split: nat_diff_split simp add: min_def, clarify)
nipkow@13145
  2559
apply (simp add: ball_Un)
nipkow@13145
  2560
done
wenzelm@13114
  2561
wenzelm@13114
  2562
lemma list_all2_append2:
nipkow@58807
  2563
  "list_all2 P xs (ys @ zs) =
nipkow@58807
  2564
  (EX us vs. xs = us @ vs \<and> length us = length ys \<and> length vs = length zs \<and>
nipkow@58807
  2565
    list_all2 P us ys \<and> list_all2 P vs zs)"
blanchet@55524
  2566
apply (simp add: list_all2_iff zip_append2)
nipkow@13145
  2567
apply (rule iffI)
nipkow@13145
  2568
 apply (rule_tac x = "take (length ys) xs" in exI)
nipkow@13145
  2569
 apply (rule_tac x = "drop (length ys) xs" in exI)
paulson@14208
  2570
 apply (force split: nat_diff_split simp add: min_def, clarify)
nipkow@13145
  2571
apply (simp add: ball_Un)
nipkow@13145
  2572
done
wenzelm@13114
  2573
kleing@13863
  2574
lemma list_all2_append:
nipkow@14247
  2575
  "length xs = length ys \<Longrightarrow>
nipkow@14247
  2576
  list_all2 P (xs@us) (ys@vs) = (list_all2 P xs ys \<and> list_all2 P us vs)"
nipkow@14247
  2577
by (induct rule:list_induct2, simp_all)
kleing@13863
  2578
kleing@13863
  2579
lemma list_all2_appendI [intro?, trans]:
kleing@13863
  2580
  "\<lbrakk> list_all2 P a b; list_all2 P c d \<rbrakk> \<Longrightarrow> list_all2 P (a@c) (b@d)"
nipkow@24349
  2581
by (simp add: list_all2_append list_all2_lengthD)
kleing@13863
  2582
wenzelm@13114
  2583
lemma list_all2_conv_all_nth:
nipkow@58807
  2584
  "list_all2 P xs ys =
ni