src/HOL/List.thy
author haftmann
Mon Jul 12 10:48:37 2010 +0200 (2010-07-12)
changeset 37767 a2b7a20d6ea3
parent 37605 625bc011768a
child 37880 3b9ca8d2c5fb
permissions -rw-r--r--
dropped superfluous [code del]s
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(*  Title:      HOL/List.thy
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    Author:     Tobias Nipkow
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*)
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header {* The datatype of finite lists *}
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theory List
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imports Plain Quotient Presburger Code_Numeral Sledgehammer Recdef
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uses ("Tools/list_code.ML")
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begin
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datatype 'a list =
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    Nil    ("[]")
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  | Cons 'a  "'a list"    (infixr "#" 65)
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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
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  hd :: "'a list \<Rightarrow> 'a" where
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  "hd (x # xs) = x"
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primrec
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  tl :: "'a list \<Rightarrow> 'a list" where
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    "tl [] = []"
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  | "tl (x # xs) = xs"
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primrec
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  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
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  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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primrec
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  set :: "'a list \<Rightarrow> 'a set" where
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    "set [] = {}"
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  | "set (x # xs) = insert x (set xs)"
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primrec
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  map :: "('a \<Rightarrow> 'b) \<Rightarrow> 'a list \<Rightarrow> 'b list" where
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    "map f [] = []"
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  | "map f (x # xs) = f x # map f xs"
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primrec
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  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
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  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
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  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
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  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
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  foldr :: "('a \<Rightarrow> 'b \<Rightarrow> 'b) \<Rightarrow> 'a list \<Rightarrow> 'b \<Rightarrow> 'b" where
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    "foldr f [] a = a"
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  | "foldr f (x # xs) a = f x (foldr f xs a)"
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primrec
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  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 (in monoid_add)
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  listsum :: "'a list \<Rightarrow> 'a" where
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    "listsum [] = 0"
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  | "listsum (x # xs) = x + listsum xs"
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primrec
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  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
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  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
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  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
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  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 = (case i of 0 \<Rightarrow> v # xs | Suc j \<Rightarrow> x # list_update xs j v)"
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nonterminals lupdbinds 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
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  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
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  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
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  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) = (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 
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  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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primrec
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  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
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  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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definition
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  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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hide_const (open) insert
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hide_fact (open) insert_def
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primrec
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  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
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  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
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  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
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  length :: "'a list \<Rightarrow> nat" where
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  "length \<equiv> size"
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definition
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  rotate1 :: "'a list \<Rightarrow> 'a list" where
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  "rotate1 xs = (case xs of [] \<Rightarrow> [] | x#xs \<Rightarrow> xs @ [x])"
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definition
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  rotate :: "nat \<Rightarrow> 'a list \<Rightarrow> 'a list" where
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  "rotate n = rotate1 ^^ n"
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definition
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  list_all2 :: "('a => 'b => bool) => 'a list => 'b list => bool" where
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  "list_all2 P xs ys =
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    (length xs = length ys \<and> (\<forall>(x, y) \<in> set (zip xs ys). P x y))"
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definition
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  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
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  splice :: "'a list \<Rightarrow> 'a list \<Rightarrow> 'a list" where
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    "splice [] ys = ys"
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  | "splice (x # xs) ys = (if ys = [] then x # xs else x # hd ys # splice xs (tl ys))"
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    -- {*Warning: simpset does not contain the second eqn but a derived one. *}
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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 "foldl f x [a,b,c] = f (f (f x a) b) c" 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 "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 "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 "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 "remove1 2 [2,0,2,1::nat,2] = [0,2,1,2]" by simp}\\
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@{lemma "removeAll 2 [2,0,2,1::nat,2] = [0,1]" by simp}\\
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@{lemma "nth [a,b,c,d] 2 = c" by simp}\\
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@{lemma "[a,b,c,d][2 := x] = [a,b,x,d]" by simp}\\
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@{lemma "sublist [a,b,c,d,e] {0,2,3} = [a,c,d]" by (simp add:sublist_def)}\\
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@{lemma "rotate1 [a,b,c,d] = [b,c,d,a]" by (simp add:rotate1_def)}\\
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@{lemma "rotate 3 [a,b,c,d] = [d,a,b,c]" by (simp add:rotate1_def rotate_def nat_number')}\\
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@{lemma "replicate 4 a = [a,a,a,a]" by (simp add:nat_number')}\\
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@{lemma "[2..<5] = [2,3,4]" by (simp add:nat_number')}\\
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@{lemma "listsum [1,2,3::nat] = 6" by simp}
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\end{tabular}}
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\caption{Characteristic examples}
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\label{fig:Characteristic}
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\end{figure}
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Figure~\ref{fig:Characteristic} shows characteristic examples
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that should give an intuitive understanding of the above functions.
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*}
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text{* The following simple sort functions are intended for proofs,
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not for efficient implementations. *}
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context linorder
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begin
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fun sorted :: "'a list \<Rightarrow> bool" where
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"sorted [] \<longleftrightarrow> True" |
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"sorted [x] \<longleftrightarrow> True" |
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"sorted (x#y#zs) \<longleftrightarrow> x <= y \<and> sorted (y#zs)"
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primrec insort_key :: "('b \<Rightarrow> 'a) \<Rightarrow> 'b \<Rightarrow> 'b list \<Rightarrow> 'b list" where
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"insort_key f x [] = [x]" |
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"insort_key f x (y#ys) = (if f x \<le> f y then (x#y#ys) else y#(insort_key f x ys))"
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definition sort_key :: "('b \<Rightarrow> 'a) \<Rightarrow> 'b list \<Rightarrow> 'b list" where
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"sort_key f xs = foldr (insort_key f) xs []"
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abbreviation "sort \<equiv> sort_key (\<lambda>x. x)"
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abbreviation "insort \<equiv> insort_key (\<lambda>x. x)"
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definition insort_insert :: "'a \<Rightarrow> 'a list \<Rightarrow> 'a list" where
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  "insort_insert x xs = (if x \<in> set xs then xs else insort x xs)"
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end
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subsubsection {* List comprehension *}
nipkow@23192
   301
nipkow@24349
   302
text{* Input syntax for Haskell-like list comprehension notation.
nipkow@24349
   303
Typical example: @{text"[(x,y). x \<leftarrow> xs, y \<leftarrow> ys, x \<noteq> y]"},
nipkow@24349
   304
the list of all pairs of distinct elements from @{text xs} and @{text ys}.
nipkow@24349
   305
The syntax is as in Haskell, except that @{text"|"} becomes a dot
nipkow@24349
   306
(like in Isabelle's set comprehension): @{text"[e. x \<leftarrow> xs, \<dots>]"} rather than
nipkow@24349
   307
\verb![e| x <- xs, ...]!.
nipkow@24349
   308
nipkow@24349
   309
The qualifiers after the dot are
nipkow@24349
   310
\begin{description}
nipkow@24349
   311
\item[generators] @{text"p \<leftarrow> xs"},
nipkow@24476
   312
 where @{text p} is a pattern and @{text xs} an expression of list type, or
nipkow@24476
   313
\item[guards] @{text"b"}, where @{text b} is a boolean expression.
nipkow@24476
   314
%\item[local bindings] @ {text"let x = e"}.
nipkow@24349
   315
\end{description}
nipkow@23240
   316
nipkow@24476
   317
Just like in Haskell, list comprehension is just a shorthand. To avoid
nipkow@24476
   318
misunderstandings, the translation into desugared form is not reversed
nipkow@24476
   319
upon output. Note that the translation of @{text"[e. x \<leftarrow> xs]"} is
nipkow@24476
   320
optmized to @{term"map (%x. e) xs"}.
nipkow@23240
   321
nipkow@24349
   322
It is easy to write short list comprehensions which stand for complex
nipkow@24349
   323
expressions. During proofs, they may become unreadable (and
nipkow@24349
   324
mangled). In such cases it can be advisable to introduce separate
nipkow@24349
   325
definitions for the list comprehensions in question.  *}
nipkow@24349
   326
nipkow@23209
   327
(*
nipkow@23240
   328
Proper theorem proving support would be nice. For example, if
nipkow@23192
   329
@{text"set[f x y. x \<leftarrow> xs, y \<leftarrow> ys, P x y]"}
nipkow@23192
   330
produced something like
nipkow@23209
   331
@{term"{z. EX x: set xs. EX y:set ys. P x y \<and> z = f x y}"}.
nipkow@23209
   332
*)
nipkow@23209
   333
nipkow@23240
   334
nonterminals lc_qual lc_quals
nipkow@23192
   335
nipkow@23192
   336
syntax
nipkow@23240
   337
"_listcompr" :: "'a \<Rightarrow> lc_qual \<Rightarrow> lc_quals \<Rightarrow> 'a list"  ("[_ . __")
nipkow@24349
   338
"_lc_gen" :: "'a \<Rightarrow> 'a list \<Rightarrow> lc_qual" ("_ <- _")
nipkow@23240
   339
"_lc_test" :: "bool \<Rightarrow> lc_qual" ("_")
nipkow@24476
   340
(*"_lc_let" :: "letbinds => lc_qual"  ("let _")*)
nipkow@23240
   341
"_lc_end" :: "lc_quals" ("]")
nipkow@23240
   342
"_lc_quals" :: "lc_qual \<Rightarrow> lc_quals \<Rightarrow> lc_quals" (", __")
nipkow@24349
   343
"_lc_abs" :: "'a => 'b list => 'b list"
nipkow@23192
   344
nipkow@24476
   345
(* These are easier than ML code but cannot express the optimized
nipkow@24476
   346
   translation of [e. p<-xs]
nipkow@23192
   347
translations
nipkow@24349
   348
"[e. p<-xs]" => "concat(map (_lc_abs p [e]) xs)"
nipkow@23240
   349
"_listcompr e (_lc_gen p xs) (_lc_quals Q Qs)"
nipkow@24349
   350
 => "concat (map (_lc_abs p (_listcompr e Q Qs)) xs)"
nipkow@23240
   351
"[e. P]" => "if P then [e] else []"
nipkow@23240
   352
"_listcompr e (_lc_test P) (_lc_quals Q Qs)"
nipkow@23240
   353
 => "if P then (_listcompr e Q Qs) else []"
nipkow@24349
   354
"_listcompr e (_lc_let b) (_lc_quals Q Qs)"
nipkow@24349
   355
 => "_Let b (_listcompr e Q Qs)"
nipkow@24476
   356
*)
nipkow@23240
   357
nipkow@23279
   358
syntax (xsymbols)
nipkow@24349
   359
"_lc_gen" :: "'a \<Rightarrow> 'a list \<Rightarrow> lc_qual" ("_ \<leftarrow> _")
nipkow@23279
   360
syntax (HTML output)
nipkow@24349
   361
"_lc_gen" :: "'a \<Rightarrow> 'a list \<Rightarrow> lc_qual" ("_ \<leftarrow> _")
nipkow@24349
   362
nipkow@24349
   363
parse_translation (advanced) {*
nipkow@24349
   364
let
wenzelm@35256
   365
  val NilC = Syntax.const @{const_syntax Nil};
wenzelm@35256
   366
  val ConsC = Syntax.const @{const_syntax Cons};
wenzelm@35256
   367
  val mapC = Syntax.const @{const_syntax map};
wenzelm@35256
   368
  val concatC = Syntax.const @{const_syntax concat};
wenzelm@35256
   369
  val IfC = Syntax.const @{const_syntax If};
wenzelm@35115
   370
nipkow@24476
   371
  fun singl x = ConsC $ x $ NilC;
nipkow@24476
   372
wenzelm@35115
   373
  fun pat_tr ctxt p e opti = (* %x. case x of p => e | _ => [] *)
nipkow@24349
   374
    let
wenzelm@29281
   375
      val x = Free (Name.variant (fold Term.add_free_names [p, e] []) "x", dummyT);
nipkow@24476
   376
      val e = if opti then singl e else e;
wenzelm@35115
   377
      val case1 = Syntax.const @{syntax_const "_case1"} $ p $ e;
wenzelm@35256
   378
      val case2 =
wenzelm@35256
   379
        Syntax.const @{syntax_const "_case1"} $
wenzelm@35256
   380
          Syntax.const @{const_syntax dummy_pattern} $ NilC;
wenzelm@35115
   381
      val cs = Syntax.const @{syntax_const "_case2"} $ case1 $ case2;
wenzelm@35115
   382
      val ft = Datatype_Case.case_tr false Datatype.info_of_constr ctxt [x, cs];
nipkow@24349
   383
    in lambda x ft end;
nipkow@24349
   384
wenzelm@35256
   385
  fun abs_tr ctxt (p as Free (s, T)) e opti =
wenzelm@35115
   386
        let
wenzelm@35115
   387
          val thy = ProofContext.theory_of ctxt;
wenzelm@35115
   388
          val s' = Sign.intern_const thy s;
wenzelm@35115
   389
        in
wenzelm@35115
   390
          if Sign.declared_const thy s'
wenzelm@35115
   391
          then (pat_tr ctxt p e opti, false)
wenzelm@35115
   392
          else (lambda p e, true)
nipkow@24349
   393
        end
nipkow@24476
   394
    | abs_tr ctxt p e opti = (pat_tr ctxt p e opti, false);
nipkow@24476
   395
wenzelm@35115
   396
  fun lc_tr ctxt [e, Const (@{syntax_const "_lc_test"}, _) $ b, qs] =
wenzelm@35115
   397
        let
wenzelm@35115
   398
          val res =
wenzelm@35115
   399
            (case qs of
wenzelm@35115
   400
              Const (@{syntax_const "_lc_end"}, _) => singl e
wenzelm@35115
   401
            | Const (@{syntax_const "_lc_quals"}, _) $ q $ qs => lc_tr ctxt [e, q, qs]);
nipkow@24476
   402
        in IfC $ b $ res $ NilC end
wenzelm@35115
   403
    | lc_tr ctxt
wenzelm@35115
   404
          [e, Const (@{syntax_const "_lc_gen"}, _) $ p $ es,
wenzelm@35115
   405
            Const(@{syntax_const "_lc_end"}, _)] =
nipkow@24476
   406
        (case abs_tr ctxt p e true of
wenzelm@35115
   407
          (f, true) => mapC $ f $ es
wenzelm@35115
   408
        | (f, false) => concatC $ (mapC $ f $ es))
wenzelm@35115
   409
    | lc_tr ctxt
wenzelm@35115
   410
          [e, Const (@{syntax_const "_lc_gen"}, _) $ p $ es,
wenzelm@35115
   411
            Const (@{syntax_const "_lc_quals"}, _) $ q $ qs] =
wenzelm@35115
   412
        let val e' = lc_tr ctxt [e, q, qs];
wenzelm@35115
   413
        in concatC $ (mapC $ (fst (abs_tr ctxt p e' false)) $ es) end;
wenzelm@35115
   414
wenzelm@35115
   415
in [(@{syntax_const "_listcompr"}, lc_tr)] end
nipkow@24349
   416
*}
nipkow@23279
   417
nipkow@23240
   418
term "[(x,y,z). b]"
nipkow@24476
   419
term "[(x,y,z). x\<leftarrow>xs]"
nipkow@24476
   420
term "[e x y. x\<leftarrow>xs, y\<leftarrow>ys]"
nipkow@24476
   421
term "[(x,y,z). x<a, x>b]"
nipkow@24476
   422
term "[(x,y,z). x\<leftarrow>xs, x>b]"
nipkow@24476
   423
term "[(x,y,z). x<a, x\<leftarrow>xs]"
nipkow@24349
   424
term "[(x,y). Cons True x \<leftarrow> xs]"
nipkow@24349
   425
term "[(x,y,z). Cons x [] \<leftarrow> xs]"
nipkow@23240
   426
term "[(x,y,z). x<a, x>b, x=d]"
nipkow@23240
   427
term "[(x,y,z). x<a, x>b, y\<leftarrow>ys]"
nipkow@23240
   428
term "[(x,y,z). x<a, x\<leftarrow>xs,y>b]"
nipkow@23240
   429
term "[(x,y,z). x<a, x\<leftarrow>xs, y\<leftarrow>ys]"
nipkow@23240
   430
term "[(x,y,z). x\<leftarrow>xs, x>b, y<a]"
nipkow@23240
   431
term "[(x,y,z). x\<leftarrow>xs, x>b, y\<leftarrow>ys]"
nipkow@23240
   432
term "[(x,y,z). x\<leftarrow>xs, y\<leftarrow>ys,y>x]"
nipkow@23240
   433
term "[(x,y,z). x\<leftarrow>xs, y\<leftarrow>ys,z\<leftarrow>zs]"
wenzelm@35115
   434
(*
nipkow@24349
   435
term "[(x,y). x\<leftarrow>xs, let xx = x+x, y\<leftarrow>ys, y \<noteq> xx]"
nipkow@23192
   436
*)
nipkow@23192
   437
wenzelm@35115
   438
haftmann@21061
   439
subsubsection {* @{const Nil} and @{const Cons} *}
haftmann@21061
   440
haftmann@21061
   441
lemma not_Cons_self [simp]:
haftmann@21061
   442
  "xs \<noteq> x # xs"
nipkow@13145
   443
by (induct xs) auto
wenzelm@13114
   444
wenzelm@13142
   445
lemmas not_Cons_self2 [simp] = not_Cons_self [symmetric]
wenzelm@13114
   446
wenzelm@13142
   447
lemma neq_Nil_conv: "(xs \<noteq> []) = (\<exists>y ys. xs = y # ys)"
nipkow@13145
   448
by (induct xs) auto
wenzelm@13114
   449
wenzelm@13142
   450
lemma length_induct:
haftmann@21061
   451
  "(\<And>xs. \<forall>ys. length ys < length xs \<longrightarrow> P ys \<Longrightarrow> P xs) \<Longrightarrow> P xs"
nipkow@17589
   452
by (rule measure_induct [of length]) iprover
wenzelm@13114
   453
haftmann@37289
   454
lemma list_nonempty_induct [consumes 1, case_names single cons]:
haftmann@37289
   455
  assumes "xs \<noteq> []"
haftmann@37289
   456
  assumes single: "\<And>x. P [x]"
haftmann@37289
   457
  assumes cons: "\<And>x xs. xs \<noteq> [] \<Longrightarrow> P xs \<Longrightarrow> P (x # xs)"
haftmann@37289
   458
  shows "P xs"
haftmann@37289
   459
using `xs \<noteq> []` proof (induct xs)
haftmann@37289
   460
  case Nil then show ?case by simp
haftmann@37289
   461
next
haftmann@37289
   462
  case (Cons x xs) show ?case proof (cases xs)
haftmann@37289
   463
    case Nil with single show ?thesis by simp
haftmann@37289
   464
  next
haftmann@37289
   465
    case Cons then have "xs \<noteq> []" by simp
haftmann@37289
   466
    moreover with Cons.hyps have "P xs" .
haftmann@37289
   467
    ultimately show ?thesis by (rule cons)
haftmann@37289
   468
  qed
haftmann@37289
   469
qed
haftmann@37289
   470
wenzelm@13114
   471
haftmann@21061
   472
subsubsection {* @{const length} *}
wenzelm@13114
   473
wenzelm@13142
   474
text {*
haftmann@21061
   475
  Needs to come before @{text "@"} because of theorem @{text
haftmann@21061
   476
  append_eq_append_conv}.
wenzelm@13142
   477
*}
wenzelm@13114
   478
wenzelm@13142
   479
lemma length_append [simp]: "length (xs @ ys) = length xs + length ys"
nipkow@13145
   480
by (induct xs) auto
wenzelm@13114
   481
wenzelm@13142
   482
lemma length_map [simp]: "length (map f xs) = length xs"
nipkow@13145
   483
by (induct xs) auto
wenzelm@13114
   484
wenzelm@13142
   485
lemma length_rev [simp]: "length (rev xs) = length xs"
nipkow@13145
   486
by (induct xs) auto
wenzelm@13114
   487
wenzelm@13142
   488
lemma length_tl [simp]: "length (tl xs) = length xs - 1"
nipkow@13145
   489
by (cases xs) auto
wenzelm@13114
   490
wenzelm@13142
   491
lemma length_0_conv [iff]: "(length xs = 0) = (xs = [])"
nipkow@13145
   492
by (induct xs) auto
wenzelm@13114
   493
wenzelm@13142
   494
lemma length_greater_0_conv [iff]: "(0 < length xs) = (xs \<noteq> [])"
nipkow@13145
   495
by (induct xs) auto
wenzelm@13114
   496
nipkow@23479
   497
lemma length_pos_if_in_set: "x : set xs \<Longrightarrow> length xs > 0"
nipkow@23479
   498
by auto
nipkow@23479
   499
wenzelm@13114
   500
lemma length_Suc_conv:
nipkow@13145
   501
"(length xs = Suc n) = (\<exists>y ys. xs = y # ys \<and> length ys = n)"
nipkow@13145
   502
by (induct xs) auto
wenzelm@13142
   503
nipkow@14025
   504
lemma Suc_length_conv:
nipkow@14025
   505
"(Suc n = length xs) = (\<exists>y ys. xs = y # ys \<and> length ys = n)"
paulson@14208
   506
apply (induct xs, simp, simp)
nipkow@14025
   507
apply blast
nipkow@14025
   508
done
nipkow@14025
   509
wenzelm@25221
   510
lemma impossible_Cons: "length xs <= length ys ==> xs = x # ys = False"
wenzelm@25221
   511
  by (induct xs) auto
wenzelm@25221
   512
haftmann@26442
   513
lemma list_induct2 [consumes 1, case_names Nil Cons]:
haftmann@26442
   514
  "length xs = length ys \<Longrightarrow> P [] [] \<Longrightarrow>
haftmann@26442
   515
   (\<And>x xs y ys. length xs = length ys \<Longrightarrow> P xs ys \<Longrightarrow> P (x#xs) (y#ys))
haftmann@26442
   516
   \<Longrightarrow> P xs ys"
haftmann@26442
   517
proof (induct xs arbitrary: ys)
haftmann@26442
   518
  case Nil then show ?case by simp
haftmann@26442
   519
next
haftmann@26442
   520
  case (Cons x xs ys) then show ?case by (cases ys) simp_all
haftmann@26442
   521
qed
haftmann@26442
   522
haftmann@26442
   523
lemma list_induct3 [consumes 2, case_names Nil Cons]:
haftmann@26442
   524
  "length xs = length ys \<Longrightarrow> length ys = length zs \<Longrightarrow> P [] [] [] \<Longrightarrow>
haftmann@26442
   525
   (\<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
   526
   \<Longrightarrow> P xs ys zs"
haftmann@26442
   527
proof (induct xs arbitrary: ys zs)
haftmann@26442
   528
  case Nil then show ?case by simp
haftmann@26442
   529
next
haftmann@26442
   530
  case (Cons x xs ys zs) then show ?case by (cases ys, simp_all)
haftmann@26442
   531
    (cases zs, simp_all)
haftmann@26442
   532
qed
wenzelm@13114
   533
kaliszyk@36154
   534
lemma list_induct4 [consumes 3, case_names Nil Cons]:
kaliszyk@36154
   535
  "length xs = length ys \<Longrightarrow> length ys = length zs \<Longrightarrow> length zs = length ws \<Longrightarrow>
kaliszyk@36154
   536
   P [] [] [] [] \<Longrightarrow> (\<And>x xs y ys z zs w ws. length xs = length ys \<Longrightarrow>
kaliszyk@36154
   537
   length ys = length zs \<Longrightarrow> length zs = length ws \<Longrightarrow> P xs ys zs ws \<Longrightarrow>
kaliszyk@36154
   538
   P (x#xs) (y#ys) (z#zs) (w#ws)) \<Longrightarrow> P xs ys zs ws"
kaliszyk@36154
   539
proof (induct xs arbitrary: ys zs ws)
kaliszyk@36154
   540
  case Nil then show ?case by simp
kaliszyk@36154
   541
next
kaliszyk@36154
   542
  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
   543
qed
kaliszyk@36154
   544
krauss@22493
   545
lemma list_induct2': 
krauss@22493
   546
  "\<lbrakk> P [] [];
krauss@22493
   547
  \<And>x xs. P (x#xs) [];
krauss@22493
   548
  \<And>y ys. P [] (y#ys);
krauss@22493
   549
   \<And>x xs y ys. P xs ys  \<Longrightarrow> P (x#xs) (y#ys) \<rbrakk>
krauss@22493
   550
 \<Longrightarrow> P xs ys"
krauss@22493
   551
by (induct xs arbitrary: ys) (case_tac x, auto)+
krauss@22493
   552
nipkow@22143
   553
lemma neq_if_length_neq: "length xs \<noteq> length ys \<Longrightarrow> (xs = ys) == False"
nipkow@24349
   554
by (rule Eq_FalseI) auto
wenzelm@24037
   555
wenzelm@24037
   556
simproc_setup list_neq ("(xs::'a list) = ys") = {*
nipkow@22143
   557
(*
nipkow@22143
   558
Reduces xs=ys to False if xs and ys cannot be of the same length.
nipkow@22143
   559
This is the case if the atomic sublists of one are a submultiset
nipkow@22143
   560
of those of the other list and there are fewer Cons's in one than the other.
nipkow@22143
   561
*)
wenzelm@24037
   562
wenzelm@24037
   563
let
nipkow@22143
   564
huffman@29856
   565
fun len (Const(@{const_name Nil},_)) acc = acc
huffman@29856
   566
  | len (Const(@{const_name Cons},_) $ _ $ xs) (ts,n) = len xs (ts,n+1)
huffman@29856
   567
  | len (Const(@{const_name append},_) $ xs $ ys) acc = len xs (len ys acc)
huffman@29856
   568
  | len (Const(@{const_name rev},_) $ xs) acc = len xs acc
huffman@29856
   569
  | len (Const(@{const_name map},_) $ _ $ xs) acc = len xs acc
nipkow@22143
   570
  | len t (ts,n) = (t::ts,n);
nipkow@22143
   571
wenzelm@24037
   572
fun list_neq _ ss ct =
nipkow@22143
   573
  let
wenzelm@24037
   574
    val (Const(_,eqT) $ lhs $ rhs) = Thm.term_of ct;
nipkow@22143
   575
    val (ls,m) = len lhs ([],0) and (rs,n) = len rhs ([],0);
nipkow@22143
   576
    fun prove_neq() =
nipkow@22143
   577
      let
nipkow@22143
   578
        val Type(_,listT::_) = eqT;
haftmann@22994
   579
        val size = HOLogic.size_const listT;
nipkow@22143
   580
        val eq_len = HOLogic.mk_eq (size $ lhs, size $ rhs);
nipkow@22143
   581
        val neq_len = HOLogic.mk_Trueprop (HOLogic.Not $ eq_len);
nipkow@22143
   582
        val thm = Goal.prove (Simplifier.the_context ss) [] [] neq_len
haftmann@22633
   583
          (K (simp_tac (Simplifier.inherit_context ss @{simpset}) 1));
haftmann@22633
   584
      in SOME (thm RS @{thm neq_if_length_neq}) end
nipkow@22143
   585
  in
wenzelm@23214
   586
    if m < n andalso submultiset (op aconv) (ls,rs) orelse
wenzelm@23214
   587
       n < m andalso submultiset (op aconv) (rs,ls)
nipkow@22143
   588
    then prove_neq() else NONE
nipkow@22143
   589
  end;
wenzelm@24037
   590
in list_neq end;
nipkow@22143
   591
*}
nipkow@22143
   592
nipkow@22143
   593
nipkow@15392
   594
subsubsection {* @{text "@"} -- append *}
wenzelm@13114
   595
wenzelm@13142
   596
lemma append_assoc [simp]: "(xs @ ys) @ zs = xs @ (ys @ zs)"
nipkow@13145
   597
by (induct xs) auto
wenzelm@13114
   598
wenzelm@13142
   599
lemma append_Nil2 [simp]: "xs @ [] = xs"
nipkow@13145
   600
by (induct xs) auto
nipkow@3507
   601
wenzelm@13142
   602
lemma append_is_Nil_conv [iff]: "(xs @ ys = []) = (xs = [] \<and> ys = [])"
nipkow@13145
   603
by (induct xs) auto
wenzelm@13114
   604
wenzelm@13142
   605
lemma Nil_is_append_conv [iff]: "([] = xs @ ys) = (xs = [] \<and> ys = [])"
nipkow@13145
   606
by (induct xs) auto
wenzelm@13114
   607
wenzelm@13142
   608
lemma append_self_conv [iff]: "(xs @ ys = xs) = (ys = [])"
nipkow@13145
   609
by (induct xs) auto
wenzelm@13114
   610
wenzelm@13142
   611
lemma self_append_conv [iff]: "(xs = xs @ ys) = (ys = [])"
nipkow@13145
   612
by (induct xs) auto
wenzelm@13114
   613
blanchet@35828
   614
lemma append_eq_append_conv [simp, no_atp]:
nipkow@24526
   615
 "length xs = length ys \<or> length us = length vs
berghofe@13883
   616
 ==> (xs@us = ys@vs) = (xs=ys \<and> us=vs)"
nipkow@24526
   617
apply (induct xs arbitrary: ys)
paulson@14208
   618
 apply (case_tac ys, simp, force)
paulson@14208
   619
apply (case_tac ys, force, simp)
nipkow@13145
   620
done
wenzelm@13142
   621
nipkow@24526
   622
lemma append_eq_append_conv2: "(xs @ ys = zs @ ts) =
nipkow@24526
   623
  (EX us. xs = zs @ us & us @ ys = ts | xs @ us = zs & ys = us@ ts)"
nipkow@24526
   624
apply (induct xs arbitrary: ys zs ts)
nipkow@14495
   625
 apply fastsimp
nipkow@14495
   626
apply(case_tac zs)
nipkow@14495
   627
 apply simp
nipkow@14495
   628
apply fastsimp
nipkow@14495
   629
done
nipkow@14495
   630
berghofe@34910
   631
lemma same_append_eq [iff, induct_simp]: "(xs @ ys = xs @ zs) = (ys = zs)"
nipkow@13145
   632
by simp
wenzelm@13142
   633
wenzelm@13142
   634
lemma append1_eq_conv [iff]: "(xs @ [x] = ys @ [y]) = (xs = ys \<and> x = y)"
nipkow@13145
   635
by simp
wenzelm@13114
   636
berghofe@34910
   637
lemma append_same_eq [iff, induct_simp]: "(ys @ xs = zs @ xs) = (ys = zs)"
nipkow@13145
   638
by simp
wenzelm@13114
   639
wenzelm@13142
   640
lemma append_self_conv2 [iff]: "(xs @ ys = ys) = (xs = [])"
nipkow@13145
   641
using append_same_eq [of _ _ "[]"] by auto
nipkow@3507
   642
wenzelm@13142
   643
lemma self_append_conv2 [iff]: "(ys = xs @ ys) = (xs = [])"
nipkow@13145
   644
using append_same_eq [of "[]"] by auto
wenzelm@13114
   645
blanchet@35828
   646
lemma hd_Cons_tl [simp,no_atp]: "xs \<noteq> [] ==> hd xs # tl xs = xs"
nipkow@13145
   647
by (induct xs) auto
wenzelm@13114
   648
wenzelm@13142
   649
lemma hd_append: "hd (xs @ ys) = (if xs = [] then hd ys else hd xs)"
nipkow@13145
   650
by (induct xs) auto
wenzelm@13114
   651
wenzelm@13142
   652
lemma hd_append2 [simp]: "xs \<noteq> [] ==> hd (xs @ ys) = hd xs"
nipkow@13145
   653
by (simp add: hd_append split: list.split)
wenzelm@13114
   654
wenzelm@13142
   655
lemma tl_append: "tl (xs @ ys) = (case xs of [] => tl ys | z#zs => zs @ ys)"
nipkow@13145
   656
by (simp split: list.split)
wenzelm@13114
   657
wenzelm@13142
   658
lemma tl_append2 [simp]: "xs \<noteq> [] ==> tl (xs @ ys) = tl xs @ ys"
nipkow@13145
   659
by (simp add: tl_append split: list.split)
wenzelm@13114
   660
wenzelm@13114
   661
nipkow@14300
   662
lemma Cons_eq_append_conv: "x#xs = ys@zs =
nipkow@14300
   663
 (ys = [] & x#xs = zs | (EX ys'. x#ys' = ys & xs = ys'@zs))"
nipkow@14300
   664
by(cases ys) auto
nipkow@14300
   665
nipkow@15281
   666
lemma append_eq_Cons_conv: "(ys@zs = x#xs) =
nipkow@15281
   667
 (ys = [] & zs = x#xs | (EX ys'. ys = x#ys' & ys'@zs = xs))"
nipkow@15281
   668
by(cases ys) auto
nipkow@15281
   669
nipkow@14300
   670
wenzelm@13142
   671
text {* Trivial rules for solving @{text "@"}-equations automatically. *}
wenzelm@13114
   672
wenzelm@13114
   673
lemma eq_Nil_appendI: "xs = ys ==> xs = [] @ ys"
nipkow@13145
   674
by simp
wenzelm@13114
   675
wenzelm@13142
   676
lemma Cons_eq_appendI:
nipkow@13145
   677
"[| x # xs1 = ys; xs = xs1 @ zs |] ==> x # xs = ys @ zs"
nipkow@13145
   678
by (drule sym) simp
wenzelm@13114
   679
wenzelm@13142
   680
lemma append_eq_appendI:
nipkow@13145
   681
"[| xs @ xs1 = zs; ys = xs1 @ us |] ==> xs @ ys = zs @ us"
nipkow@13145
   682
by (drule sym) simp
wenzelm@13114
   683
wenzelm@13114
   684
wenzelm@13142
   685
text {*
nipkow@13145
   686
Simplification procedure for all list equalities.
nipkow@13145
   687
Currently only tries to rearrange @{text "@"} to see if
nipkow@13145
   688
- both lists end in a singleton list,
nipkow@13145
   689
- or both lists end in the same list.
wenzelm@13142
   690
*}
wenzelm@13142
   691
wenzelm@26480
   692
ML {*
nipkow@3507
   693
local
nipkow@3507
   694
huffman@29856
   695
fun last (cons as Const(@{const_name Cons},_) $ _ $ xs) =
huffman@29856
   696
  (case xs of Const(@{const_name Nil},_) => cons | _ => last xs)
huffman@29856
   697
  | last (Const(@{const_name append},_) $ _ $ ys) = last ys
wenzelm@13462
   698
  | last t = t;
wenzelm@13114
   699
huffman@29856
   700
fun list1 (Const(@{const_name Cons},_) $ _ $ Const(@{const_name Nil},_)) = true
wenzelm@13462
   701
  | list1 _ = false;
wenzelm@13114
   702
huffman@29856
   703
fun butlast ((cons as Const(@{const_name Cons},_) $ x) $ xs) =
huffman@29856
   704
  (case xs of Const(@{const_name Nil},_) => xs | _ => cons $ butlast xs)
huffman@29856
   705
  | butlast ((app as Const(@{const_name append},_) $ xs) $ ys) = app $ butlast ys
huffman@29856
   706
  | butlast xs = Const(@{const_name Nil},fastype_of xs);
wenzelm@13114
   707
haftmann@22633
   708
val rearr_ss = HOL_basic_ss addsimps [@{thm append_assoc},
haftmann@22633
   709
  @{thm append_Nil}, @{thm append_Cons}];
wenzelm@16973
   710
wenzelm@20044
   711
fun list_eq ss (F as (eq as Const(_,eqT)) $ lhs $ rhs) =
wenzelm@13462
   712
  let
wenzelm@13462
   713
    val lastl = last lhs and lastr = last rhs;
wenzelm@13462
   714
    fun rearr conv =
wenzelm@13462
   715
      let
wenzelm@13462
   716
        val lhs1 = butlast lhs and rhs1 = butlast rhs;
wenzelm@13462
   717
        val Type(_,listT::_) = eqT
wenzelm@13462
   718
        val appT = [listT,listT] ---> listT
huffman@29856
   719
        val app = Const(@{const_name append},appT)
wenzelm@13462
   720
        val F2 = eq $ (app$lhs1$lastl) $ (app$rhs1$lastr)
wenzelm@13480
   721
        val eq = HOLogic.mk_Trueprop (HOLogic.mk_eq (F,F2));
wenzelm@20044
   722
        val thm = Goal.prove (Simplifier.the_context ss) [] [] eq
wenzelm@17877
   723
          (K (simp_tac (Simplifier.inherit_context ss rearr_ss) 1));
skalberg@15531
   724
      in SOME ((conv RS (thm RS trans)) RS eq_reflection) end;
wenzelm@13114
   725
wenzelm@13462
   726
  in
haftmann@22633
   727
    if list1 lastl andalso list1 lastr then rearr @{thm append1_eq_conv}
haftmann@22633
   728
    else if lastl aconv lastr then rearr @{thm append_same_eq}
skalberg@15531
   729
    else NONE
wenzelm@13462
   730
  end;
wenzelm@13462
   731
wenzelm@13114
   732
in
wenzelm@13462
   733
wenzelm@13462
   734
val list_eq_simproc =
wenzelm@32010
   735
  Simplifier.simproc @{theory} "list_eq" ["(xs::'a list) = ys"] (K list_eq);
wenzelm@13462
   736
wenzelm@13114
   737
end;
wenzelm@13114
   738
wenzelm@13114
   739
Addsimprocs [list_eq_simproc];
wenzelm@13114
   740
*}
wenzelm@13114
   741
wenzelm@13114
   742
nipkow@15392
   743
subsubsection {* @{text map} *}
wenzelm@13114
   744
wenzelm@13142
   745
lemma map_ext: "(!!x. x : set xs --> f x = g x) ==> map f xs = map g xs"
nipkow@13145
   746
by (induct xs) simp_all
wenzelm@13114
   747
wenzelm@13142
   748
lemma map_ident [simp]: "map (\<lambda>x. x) = (\<lambda>xs. xs)"
nipkow@13145
   749
by (rule ext, induct_tac xs) auto
wenzelm@13114
   750
wenzelm@13142
   751
lemma map_append [simp]: "map f (xs @ ys) = map f xs @ map f ys"
nipkow@13145
   752
by (induct xs) auto
wenzelm@13114
   753
hoelzl@33639
   754
lemma map_map [simp]: "map f (map g xs) = map (f \<circ> g) xs"
hoelzl@33639
   755
by (induct xs) auto
hoelzl@33639
   756
nipkow@35208
   757
lemma map_comp_map[simp]: "((map f) o (map g)) = map(f o g)"
nipkow@35208
   758
apply(rule ext)
nipkow@35208
   759
apply(simp)
nipkow@35208
   760
done
nipkow@35208
   761
wenzelm@13142
   762
lemma rev_map: "rev (map f xs) = map f (rev xs)"
nipkow@13145
   763
by (induct xs) auto
wenzelm@13114
   764
nipkow@13737
   765
lemma map_eq_conv[simp]: "(map f xs = map g xs) = (!x : set xs. f x = g x)"
nipkow@13737
   766
by (induct xs) auto
nipkow@13737
   767
krauss@19770
   768
lemma map_cong [fundef_cong, recdef_cong]:
nipkow@13145
   769
"xs = ys ==> (!!x. x : set ys ==> f x = g x) ==> map f xs = map g ys"
nipkow@13145
   770
-- {* a congruence rule for @{text map} *}
nipkow@13737
   771
by simp
wenzelm@13114
   772
wenzelm@13142
   773
lemma map_is_Nil_conv [iff]: "(map f xs = []) = (xs = [])"
nipkow@13145
   774
by (cases xs) auto
wenzelm@13114
   775
wenzelm@13142
   776
lemma Nil_is_map_conv [iff]: "([] = map f xs) = (xs = [])"
nipkow@13145
   777
by (cases xs) auto
wenzelm@13114
   778
paulson@18447
   779
lemma map_eq_Cons_conv:
nipkow@14025
   780
 "(map f xs = y#ys) = (\<exists>z zs. xs = z#zs \<and> f z = y \<and> map f zs = ys)"
nipkow@13145
   781
by (cases xs) auto
wenzelm@13114
   782
paulson@18447
   783
lemma Cons_eq_map_conv:
nipkow@14025
   784
 "(x#xs = map f ys) = (\<exists>z zs. ys = z#zs \<and> x = f z \<and> xs = map f zs)"
nipkow@14025
   785
by (cases ys) auto
nipkow@14025
   786
paulson@18447
   787
lemmas map_eq_Cons_D = map_eq_Cons_conv [THEN iffD1]
paulson@18447
   788
lemmas Cons_eq_map_D = Cons_eq_map_conv [THEN iffD1]
paulson@18447
   789
declare map_eq_Cons_D [dest!]  Cons_eq_map_D [dest!]
paulson@18447
   790
nipkow@14111
   791
lemma ex_map_conv:
nipkow@14111
   792
  "(EX xs. ys = map f xs) = (ALL y : set ys. EX x. y = f x)"
paulson@18447
   793
by(induct ys, auto simp add: Cons_eq_map_conv)
nipkow@14111
   794
nipkow@15110
   795
lemma map_eq_imp_length_eq:
paulson@35510
   796
  assumes "map f xs = map g ys"
haftmann@26734
   797
  shows "length xs = length ys"
haftmann@26734
   798
using assms proof (induct ys arbitrary: xs)
haftmann@26734
   799
  case Nil then show ?case by simp
haftmann@26734
   800
next
haftmann@26734
   801
  case (Cons y ys) then obtain z zs where xs: "xs = z # zs" by auto
paulson@35510
   802
  from Cons xs have "map f zs = map g ys" by simp
haftmann@26734
   803
  moreover with Cons have "length zs = length ys" by blast
haftmann@26734
   804
  with xs show ?case by simp
haftmann@26734
   805
qed
haftmann@26734
   806
  
nipkow@15110
   807
lemma map_inj_on:
nipkow@15110
   808
 "[| map f xs = map f ys; inj_on f (set xs Un set ys) |]
nipkow@15110
   809
  ==> xs = ys"
nipkow@15110
   810
apply(frule map_eq_imp_length_eq)
nipkow@15110
   811
apply(rotate_tac -1)
nipkow@15110
   812
apply(induct rule:list_induct2)
nipkow@15110
   813
 apply simp
nipkow@15110
   814
apply(simp)
nipkow@15110
   815
apply (blast intro:sym)
nipkow@15110
   816
done
nipkow@15110
   817
nipkow@15110
   818
lemma inj_on_map_eq_map:
nipkow@15110
   819
 "inj_on f (set xs Un set ys) \<Longrightarrow> (map f xs = map f ys) = (xs = ys)"
nipkow@15110
   820
by(blast dest:map_inj_on)
nipkow@15110
   821
wenzelm@13114
   822
lemma map_injective:
nipkow@24526
   823
 "map f xs = map f ys ==> inj f ==> xs = ys"
nipkow@24526
   824
by (induct ys arbitrary: xs) (auto dest!:injD)
wenzelm@13114
   825
nipkow@14339
   826
lemma inj_map_eq_map[simp]: "inj f \<Longrightarrow> (map f xs = map f ys) = (xs = ys)"
nipkow@14339
   827
by(blast dest:map_injective)
nipkow@14339
   828
wenzelm@13114
   829
lemma inj_mapI: "inj f ==> inj (map f)"
nipkow@17589
   830
by (iprover dest: map_injective injD intro: inj_onI)
wenzelm@13114
   831
wenzelm@13114
   832
lemma inj_mapD: "inj (map f) ==> inj f"
paulson@14208
   833
apply (unfold inj_on_def, clarify)
nipkow@13145
   834
apply (erule_tac x = "[x]" in ballE)
paulson@14208
   835
 apply (erule_tac x = "[y]" in ballE, simp, blast)
nipkow@13145
   836
apply blast
nipkow@13145
   837
done
wenzelm@13114
   838
nipkow@14339
   839
lemma inj_map[iff]: "inj (map f) = inj f"
nipkow@13145
   840
by (blast dest: inj_mapD intro: inj_mapI)
wenzelm@13114
   841
nipkow@15303
   842
lemma inj_on_mapI: "inj_on f (\<Union>(set ` A)) \<Longrightarrow> inj_on (map f) A"
nipkow@15303
   843
apply(rule inj_onI)
nipkow@15303
   844
apply(erule map_inj_on)
nipkow@15303
   845
apply(blast intro:inj_onI dest:inj_onD)
nipkow@15303
   846
done
nipkow@15303
   847
kleing@14343
   848
lemma map_idI: "(\<And>x. x \<in> set xs \<Longrightarrow> f x = x) \<Longrightarrow> map f xs = xs"
kleing@14343
   849
by (induct xs, auto)
wenzelm@13114
   850
nipkow@14402
   851
lemma map_fun_upd [simp]: "y \<notin> set xs \<Longrightarrow> map (f(y:=v)) xs = map f xs"
nipkow@14402
   852
by (induct xs) auto
nipkow@14402
   853
nipkow@15110
   854
lemma map_fst_zip[simp]:
nipkow@15110
   855
  "length xs = length ys \<Longrightarrow> map fst (zip xs ys) = xs"
nipkow@15110
   856
by (induct rule:list_induct2, simp_all)
nipkow@15110
   857
nipkow@15110
   858
lemma map_snd_zip[simp]:
nipkow@15110
   859
  "length xs = length ys \<Longrightarrow> map snd (zip xs ys) = ys"
nipkow@15110
   860
by (induct rule:list_induct2, simp_all)
nipkow@15110
   861
nipkow@15110
   862
nipkow@15392
   863
subsubsection {* @{text rev} *}
wenzelm@13114
   864
wenzelm@13142
   865
lemma rev_append [simp]: "rev (xs @ ys) = rev ys @ rev xs"
nipkow@13145
   866
by (induct xs) auto
wenzelm@13114
   867
wenzelm@13142
   868
lemma rev_rev_ident [simp]: "rev (rev xs) = xs"
nipkow@13145
   869
by (induct xs) auto
wenzelm@13114
   870
kleing@15870
   871
lemma rev_swap: "(rev xs = ys) = (xs = rev ys)"
kleing@15870
   872
by auto
kleing@15870
   873
wenzelm@13142
   874
lemma rev_is_Nil_conv [iff]: "(rev xs = []) = (xs = [])"
nipkow@13145
   875
by (induct xs) auto
wenzelm@13114
   876
wenzelm@13142
   877
lemma Nil_is_rev_conv [iff]: "([] = rev xs) = (xs = [])"
nipkow@13145
   878
by (induct xs) auto
wenzelm@13114
   879
kleing@15870
   880
lemma rev_singleton_conv [simp]: "(rev xs = [x]) = (xs = [x])"
kleing@15870
   881
by (cases xs) auto
kleing@15870
   882
kleing@15870
   883
lemma singleton_rev_conv [simp]: "([x] = rev xs) = (xs = [x])"
kleing@15870
   884
by (cases xs) auto
kleing@15870
   885
haftmann@21061
   886
lemma rev_is_rev_conv [iff]: "(rev xs = rev ys) = (xs = ys)"
haftmann@21061
   887
apply (induct xs arbitrary: ys, force)
paulson@14208
   888
apply (case_tac ys, simp, force)
nipkow@13145
   889
done
wenzelm@13114
   890
nipkow@15439
   891
lemma inj_on_rev[iff]: "inj_on rev A"
nipkow@15439
   892
by(simp add:inj_on_def)
nipkow@15439
   893
wenzelm@13366
   894
lemma rev_induct [case_names Nil snoc]:
wenzelm@13366
   895
  "[| P []; !!x xs. P xs ==> P (xs @ [x]) |] ==> P xs"
berghofe@15489
   896
apply(simplesubst rev_rev_ident[symmetric])
nipkow@13145
   897
apply(rule_tac list = "rev xs" in list.induct, simp_all)
nipkow@13145
   898
done
wenzelm@13114
   899
wenzelm@13366
   900
lemma rev_exhaust [case_names Nil snoc]:
wenzelm@13366
   901
  "(xs = [] ==> P) ==>(!!ys y. xs = ys @ [y] ==> P) ==> P"
nipkow@13145
   902
by (induct xs rule: rev_induct) auto
wenzelm@13114
   903
wenzelm@13366
   904
lemmas rev_cases = rev_exhaust
wenzelm@13366
   905
nipkow@18423
   906
lemma rev_eq_Cons_iff[iff]: "(rev xs = y#ys) = (xs = rev ys @ [y])"
nipkow@18423
   907
by(rule rev_cases[of xs]) auto
nipkow@18423
   908
wenzelm@13114
   909
nipkow@15392
   910
subsubsection {* @{text set} *}
wenzelm@13114
   911
wenzelm@13142
   912
lemma finite_set [iff]: "finite (set xs)"
nipkow@13145
   913
by (induct xs) auto
wenzelm@13114
   914
wenzelm@13142
   915
lemma set_append [simp]: "set (xs @ ys) = (set xs \<union> set ys)"
nipkow@13145
   916
by (induct xs) auto
wenzelm@13114
   917
nipkow@17830
   918
lemma hd_in_set[simp]: "xs \<noteq> [] \<Longrightarrow> hd xs : set xs"
nipkow@17830
   919
by(cases xs) auto
oheimb@14099
   920
wenzelm@13142
   921
lemma set_subset_Cons: "set xs \<subseteq> set (x # xs)"
nipkow@13145
   922
by auto
wenzelm@13114
   923
oheimb@14099
   924
lemma set_ConsD: "y \<in> set (x # xs) \<Longrightarrow> y=x \<or> y \<in> set xs" 
oheimb@14099
   925
by auto
oheimb@14099
   926
wenzelm@13142
   927
lemma set_empty [iff]: "(set xs = {}) = (xs = [])"
nipkow@13145
   928
by (induct xs) auto
wenzelm@13114
   929
nipkow@15245
   930
lemma set_empty2[iff]: "({} = set xs) = (xs = [])"
nipkow@15245
   931
by(induct xs) auto
nipkow@15245
   932
wenzelm@13142
   933
lemma set_rev [simp]: "set (rev xs) = set xs"
nipkow@13145
   934
by (induct xs) auto
wenzelm@13114
   935
wenzelm@13142
   936
lemma set_map [simp]: "set (map f xs) = f`(set xs)"
nipkow@13145
   937
by (induct xs) auto
wenzelm@13114
   938
wenzelm@13142
   939
lemma set_filter [simp]: "set (filter P xs) = {x. x : set xs \<and> P x}"
nipkow@13145
   940
by (induct xs) auto
wenzelm@13114
   941
nipkow@32417
   942
lemma set_upt [simp]: "set[i..<j] = {i..<j}"
nipkow@32417
   943
by (induct j) (simp_all add: atLeastLessThanSuc)
wenzelm@13114
   944
wenzelm@13142
   945
wenzelm@25221
   946
lemma split_list: "x : set xs \<Longrightarrow> \<exists>ys zs. xs = ys @ x # zs"
nipkow@18049
   947
proof (induct xs)
nipkow@26073
   948
  case Nil thus ?case by simp
nipkow@26073
   949
next
nipkow@26073
   950
  case Cons thus ?case by (auto intro: Cons_eq_appendI)
nipkow@26073
   951
qed
nipkow@26073
   952
haftmann@26734
   953
lemma in_set_conv_decomp: "x \<in> set xs \<longleftrightarrow> (\<exists>ys zs. xs = ys @ x # zs)"
haftmann@26734
   954
  by (auto elim: split_list)
nipkow@26073
   955
nipkow@26073
   956
lemma split_list_first: "x : set xs \<Longrightarrow> \<exists>ys zs. xs = ys @ x # zs \<and> x \<notin> set ys"
nipkow@26073
   957
proof (induct xs)
nipkow@26073
   958
  case Nil thus ?case by simp
nipkow@18049
   959
next
nipkow@18049
   960
  case (Cons a xs)
nipkow@18049
   961
  show ?case
nipkow@18049
   962
  proof cases
wenzelm@25221
   963
    assume "x = a" thus ?case using Cons by fastsimp
nipkow@18049
   964
  next
nipkow@26073
   965
    assume "x \<noteq> a" thus ?case using Cons by(fastsimp intro!: Cons_eq_appendI)
nipkow@26073
   966
  qed
nipkow@26073
   967
qed
nipkow@26073
   968
nipkow@26073
   969
lemma in_set_conv_decomp_first:
nipkow@26073
   970
  "(x : set xs) = (\<exists>ys zs. xs = ys @ x # zs \<and> x \<notin> set ys)"
haftmann@26734
   971
  by (auto dest!: split_list_first)
nipkow@26073
   972
nipkow@26073
   973
lemma split_list_last: "x : set xs \<Longrightarrow> \<exists>ys zs. xs = ys @ x # zs \<and> x \<notin> set zs"
nipkow@26073
   974
proof (induct xs rule:rev_induct)
nipkow@26073
   975
  case Nil thus ?case by simp
nipkow@26073
   976
next
nipkow@26073
   977
  case (snoc a xs)
nipkow@26073
   978
  show ?case
nipkow@26073
   979
  proof cases
nipkow@26073
   980
    assume "x = a" thus ?case using snoc by simp (metis ex_in_conv set_empty2)
nipkow@26073
   981
  next
nipkow@26073
   982
    assume "x \<noteq> a" thus ?case using snoc by fastsimp
nipkow@18049
   983
  qed
nipkow@18049
   984
qed
nipkow@18049
   985
nipkow@26073
   986
lemma in_set_conv_decomp_last:
nipkow@26073
   987
  "(x : set xs) = (\<exists>ys zs. xs = ys @ x # zs \<and> x \<notin> set zs)"
haftmann@26734
   988
  by (auto dest!: split_list_last)
nipkow@26073
   989
nipkow@26073
   990
lemma split_list_prop: "\<exists>x \<in> set xs. P x \<Longrightarrow> \<exists>ys x zs. xs = ys @ x # zs & P x"
nipkow@26073
   991
proof (induct xs)
nipkow@26073
   992
  case Nil thus ?case by simp
nipkow@26073
   993
next
nipkow@26073
   994
  case Cons thus ?case
nipkow@26073
   995
    by(simp add:Bex_def)(metis append_Cons append.simps(1))
nipkow@26073
   996
qed
nipkow@26073
   997
nipkow@26073
   998
lemma split_list_propE:
haftmann@26734
   999
  assumes "\<exists>x \<in> set xs. P x"
haftmann@26734
  1000
  obtains ys x zs where "xs = ys @ x # zs" and "P x"
haftmann@26734
  1001
using split_list_prop [OF assms] by blast
nipkow@26073
  1002
nipkow@26073
  1003
lemma split_list_first_prop:
nipkow@26073
  1004
  "\<exists>x \<in> set xs. P x \<Longrightarrow>
nipkow@26073
  1005
   \<exists>ys x zs. xs = ys@x#zs \<and> P x \<and> (\<forall>y \<in> set ys. \<not> P y)"
haftmann@26734
  1006
proof (induct xs)
nipkow@26073
  1007
  case Nil thus ?case by simp
nipkow@26073
  1008
next
nipkow@26073
  1009
  case (Cons x xs)
nipkow@26073
  1010
  show ?case
nipkow@26073
  1011
  proof cases
nipkow@26073
  1012
    assume "P x"
haftmann@26734
  1013
    thus ?thesis by simp
haftmann@26734
  1014
      (metis Un_upper1 contra_subsetD in_set_conv_decomp_first self_append_conv2 set_append)
nipkow@26073
  1015
  next
nipkow@26073
  1016
    assume "\<not> P x"
nipkow@26073
  1017
    hence "\<exists>x\<in>set xs. P x" using Cons(2) by simp
nipkow@26073
  1018
    thus ?thesis using `\<not> P x` Cons(1) by (metis append_Cons set_ConsD)
nipkow@26073
  1019
  qed
nipkow@26073
  1020
qed
nipkow@26073
  1021
nipkow@26073
  1022
lemma split_list_first_propE:
haftmann@26734
  1023
  assumes "\<exists>x \<in> set xs. P x"
haftmann@26734
  1024
  obtains ys x zs where "xs = ys @ x # zs" and "P x" and "\<forall>y \<in> set ys. \<not> P y"
haftmann@26734
  1025
using split_list_first_prop [OF assms] by blast
nipkow@26073
  1026
nipkow@26073
  1027
lemma split_list_first_prop_iff:
nipkow@26073
  1028
  "(\<exists>x \<in> set xs. P x) \<longleftrightarrow>
nipkow@26073
  1029
   (\<exists>ys x zs. xs = ys@x#zs \<and> P x \<and> (\<forall>y \<in> set ys. \<not> P y))"
haftmann@26734
  1030
by (rule, erule split_list_first_prop) auto
nipkow@26073
  1031
nipkow@26073
  1032
lemma split_list_last_prop:
nipkow@26073
  1033
  "\<exists>x \<in> set xs. P x \<Longrightarrow>
nipkow@26073
  1034
   \<exists>ys x zs. xs = ys@x#zs \<and> P x \<and> (\<forall>z \<in> set zs. \<not> P z)"
nipkow@26073
  1035
proof(induct xs rule:rev_induct)
nipkow@26073
  1036
  case Nil thus ?case by simp
nipkow@26073
  1037
next
nipkow@26073
  1038
  case (snoc x xs)
nipkow@26073
  1039
  show ?case
nipkow@26073
  1040
  proof cases
nipkow@26073
  1041
    assume "P x" thus ?thesis by (metis emptyE set_empty)
nipkow@26073
  1042
  next
nipkow@26073
  1043
    assume "\<not> P x"
nipkow@26073
  1044
    hence "\<exists>x\<in>set xs. P x" using snoc(2) by simp
nipkow@26073
  1045
    thus ?thesis using `\<not> P x` snoc(1) by fastsimp
nipkow@26073
  1046
  qed
nipkow@26073
  1047
qed
nipkow@26073
  1048
nipkow@26073
  1049
lemma split_list_last_propE:
haftmann@26734
  1050
  assumes "\<exists>x \<in> set xs. P x"
haftmann@26734
  1051
  obtains ys x zs where "xs = ys @ x # zs" and "P x" and "\<forall>z \<in> set zs. \<not> P z"
haftmann@26734
  1052
using split_list_last_prop [OF assms] by blast
nipkow@26073
  1053
nipkow@26073
  1054
lemma split_list_last_prop_iff:
nipkow@26073
  1055
  "(\<exists>x \<in> set xs. P x) \<longleftrightarrow>
nipkow@26073
  1056
   (\<exists>ys x zs. xs = ys@x#zs \<and> P x \<and> (\<forall>z \<in> set zs. \<not> P z))"
haftmann@26734
  1057
by (metis split_list_last_prop [where P=P] in_set_conv_decomp)
nipkow@26073
  1058
nipkow@26073
  1059
lemma finite_list: "finite A ==> EX xs. set xs = A"
haftmann@26734
  1060
  by (erule finite_induct)
haftmann@26734
  1061
    (auto simp add: set.simps(2) [symmetric] simp del: set.simps(2))
paulson@13508
  1062
kleing@14388
  1063
lemma card_length: "card (set xs) \<le> length xs"
kleing@14388
  1064
by (induct xs) (auto simp add: card_insert_if)
wenzelm@13114
  1065
haftmann@26442
  1066
lemma set_minus_filter_out:
haftmann@26442
  1067
  "set xs - {y} = set (filter (\<lambda>x. \<not> (x = y)) xs)"
haftmann@26442
  1068
  by (induct xs) auto
paulson@15168
  1069
wenzelm@35115
  1070
nipkow@15392
  1071
subsubsection {* @{text filter} *}
wenzelm@13114
  1072
wenzelm@13142
  1073
lemma filter_append [simp]: "filter P (xs @ ys) = filter P xs @ filter P ys"
nipkow@13145
  1074
by (induct xs) auto
wenzelm@13114
  1075
nipkow@15305
  1076
lemma rev_filter: "rev (filter P xs) = filter P (rev xs)"
nipkow@15305
  1077
by (induct xs) simp_all
nipkow@15305
  1078
wenzelm@13142
  1079
lemma filter_filter [simp]: "filter P (filter Q xs) = filter (\<lambda>x. Q x \<and> P x) xs"
nipkow@13145
  1080
by (induct xs) auto
wenzelm@13114
  1081
nipkow@16998
  1082
lemma length_filter_le [simp]: "length (filter P xs) \<le> length xs"
nipkow@16998
  1083
by (induct xs) (auto simp add: le_SucI)
nipkow@16998
  1084
nipkow@18423
  1085
lemma sum_length_filter_compl:
nipkow@18423
  1086
  "length(filter P xs) + length(filter (%x. ~P x) xs) = length xs"
nipkow@18423
  1087
by(induct xs) simp_all
nipkow@18423
  1088
wenzelm@13142
  1089
lemma filter_True [simp]: "\<forall>x \<in> set xs. P x ==> filter P xs = xs"
nipkow@13145
  1090
by (induct xs) auto
wenzelm@13114
  1091
wenzelm@13142
  1092
lemma filter_False [simp]: "\<forall>x \<in> set xs. \<not> P x ==> filter P xs = []"
nipkow@13145
  1093
by (induct xs) auto
wenzelm@13114
  1094
nipkow@16998
  1095
lemma filter_empty_conv: "(filter P xs = []) = (\<forall>x\<in>set xs. \<not> P x)" 
nipkow@24349
  1096
by (induct xs) simp_all
nipkow@16998
  1097
nipkow@16998
  1098
lemma filter_id_conv: "(filter P xs = xs) = (\<forall>x\<in>set xs. P x)"
nipkow@16998
  1099
apply (induct xs)
nipkow@16998
  1100
 apply auto
nipkow@16998
  1101
apply(cut_tac P=P and xs=xs in length_filter_le)
nipkow@16998
  1102
apply simp
nipkow@16998
  1103
done
wenzelm@13114
  1104
nipkow@16965
  1105
lemma filter_map:
nipkow@16965
  1106
  "filter P (map f xs) = map f (filter (P o f) xs)"
nipkow@16965
  1107
by (induct xs) simp_all
nipkow@16965
  1108
nipkow@16965
  1109
lemma length_filter_map[simp]:
nipkow@16965
  1110
  "length (filter P (map f xs)) = length(filter (P o f) xs)"
nipkow@16965
  1111
by (simp add:filter_map)
nipkow@16965
  1112
wenzelm@13142
  1113
lemma filter_is_subset [simp]: "set (filter P xs) \<le> set xs"
nipkow@13145
  1114
by auto
wenzelm@13114
  1115
nipkow@15246
  1116
lemma length_filter_less:
nipkow@15246
  1117
  "\<lbrakk> x : set xs; ~ P x \<rbrakk> \<Longrightarrow> length(filter P xs) < length xs"
nipkow@15246
  1118
proof (induct xs)
nipkow@15246
  1119
  case Nil thus ?case by simp
nipkow@15246
  1120
next
nipkow@15246
  1121
  case (Cons x xs) thus ?case
nipkow@15246
  1122
    apply (auto split:split_if_asm)
nipkow@15246
  1123
    using length_filter_le[of P xs] apply arith
nipkow@15246
  1124
  done
nipkow@15246
  1125
qed
wenzelm@13114
  1126
nipkow@15281
  1127
lemma length_filter_conv_card:
nipkow@15281
  1128
 "length(filter p xs) = card{i. i < length xs & p(xs!i)}"
nipkow@15281
  1129
proof (induct xs)
nipkow@15281
  1130
  case Nil thus ?case by simp
nipkow@15281
  1131
next
nipkow@15281
  1132
  case (Cons x xs)
nipkow@15281
  1133
  let ?S = "{i. i < length xs & p(xs!i)}"
nipkow@15281
  1134
  have fin: "finite ?S" by(fast intro: bounded_nat_set_is_finite)
nipkow@15281
  1135
  show ?case (is "?l = card ?S'")
nipkow@15281
  1136
  proof (cases)
nipkow@15281
  1137
    assume "p x"
nipkow@15281
  1138
    hence eq: "?S' = insert 0 (Suc ` ?S)"
nipkow@25162
  1139
      by(auto simp: image_def split:nat.split dest:gr0_implies_Suc)
nipkow@15281
  1140
    have "length (filter p (x # xs)) = Suc(card ?S)"
wenzelm@23388
  1141
      using Cons `p x` by simp
nipkow@15281
  1142
    also have "\<dots> = Suc(card(Suc ` ?S))" using fin
nipkow@15281
  1143
      by (simp add: card_image inj_Suc)
nipkow@15281
  1144
    also have "\<dots> = card ?S'" using eq fin
nipkow@15281
  1145
      by (simp add:card_insert_if) (simp add:image_def)
nipkow@15281
  1146
    finally show ?thesis .
nipkow@15281
  1147
  next
nipkow@15281
  1148
    assume "\<not> p x"
nipkow@15281
  1149
    hence eq: "?S' = Suc ` ?S"
nipkow@25162
  1150
      by(auto simp add: image_def split:nat.split elim:lessE)
nipkow@15281
  1151
    have "length (filter p (x # xs)) = card ?S"
wenzelm@23388
  1152
      using Cons `\<not> p x` by simp
nipkow@15281
  1153
    also have "\<dots> = card(Suc ` ?S)" using fin
nipkow@15281
  1154
      by (simp add: card_image inj_Suc)
nipkow@15281
  1155
    also have "\<dots> = card ?S'" using eq fin
nipkow@15281
  1156
      by (simp add:card_insert_if)
nipkow@15281
  1157
    finally show ?thesis .
nipkow@15281
  1158
  qed
nipkow@15281
  1159
qed
nipkow@15281
  1160
nipkow@17629
  1161
lemma Cons_eq_filterD:
nipkow@17629
  1162
 "x#xs = filter P ys \<Longrightarrow>
nipkow@17629
  1163
  \<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
  1164
  (is "_ \<Longrightarrow> \<exists>us vs. ?P ys us vs")
nipkow@17629
  1165
proof(induct ys)
nipkow@17629
  1166
  case Nil thus ?case by simp
nipkow@17629
  1167
next
nipkow@17629
  1168
  case (Cons y ys)
nipkow@17629
  1169
  show ?case (is "\<exists>x. ?Q x")
nipkow@17629
  1170
  proof cases
nipkow@17629
  1171
    assume Py: "P y"
nipkow@17629
  1172
    show ?thesis
nipkow@17629
  1173
    proof cases
wenzelm@25221
  1174
      assume "x = y"
wenzelm@25221
  1175
      with Py Cons.prems have "?Q []" by simp
wenzelm@25221
  1176
      then show ?thesis ..
nipkow@17629
  1177
    next
wenzelm@25221
  1178
      assume "x \<noteq> y"
wenzelm@25221
  1179
      with Py Cons.prems show ?thesis by simp
nipkow@17629
  1180
    qed
nipkow@17629
  1181
  next
wenzelm@25221
  1182
    assume "\<not> P y"
wenzelm@25221
  1183
    with Cons obtain us vs where "?P (y#ys) (y#us) vs" by fastsimp
wenzelm@25221
  1184
    then have "?Q (y#us)" by simp
wenzelm@25221
  1185
    then show ?thesis ..
nipkow@17629
  1186
  qed
nipkow@17629
  1187
qed
nipkow@17629
  1188
nipkow@17629
  1189
lemma filter_eq_ConsD:
nipkow@17629
  1190
 "filter P ys = x#xs \<Longrightarrow>
nipkow@17629
  1191
  \<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
  1192
by(rule Cons_eq_filterD) simp
nipkow@17629
  1193
nipkow@17629
  1194
lemma filter_eq_Cons_iff:
nipkow@17629
  1195
 "(filter P ys = x#xs) =
nipkow@17629
  1196
  (\<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
  1197
by(auto dest:filter_eq_ConsD)
nipkow@17629
  1198
nipkow@17629
  1199
lemma Cons_eq_filter_iff:
nipkow@17629
  1200
 "(x#xs = filter P ys) =
nipkow@17629
  1201
  (\<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
  1202
by(auto dest:Cons_eq_filterD)
nipkow@17629
  1203
krauss@19770
  1204
lemma filter_cong[fundef_cong, recdef_cong]:
nipkow@17501
  1205
 "xs = ys \<Longrightarrow> (\<And>x. x \<in> set ys \<Longrightarrow> P x = Q x) \<Longrightarrow> filter P xs = filter Q ys"
nipkow@17501
  1206
apply simp
nipkow@17501
  1207
apply(erule thin_rl)
nipkow@17501
  1208
by (induct ys) simp_all
nipkow@17501
  1209
nipkow@15281
  1210
haftmann@26442
  1211
subsubsection {* List partitioning *}
haftmann@26442
  1212
haftmann@26442
  1213
primrec partition :: "('a \<Rightarrow> bool) \<Rightarrow>'a list \<Rightarrow> 'a list \<times> 'a list" where
haftmann@26442
  1214
  "partition P [] = ([], [])"
haftmann@26442
  1215
  | "partition P (x # xs) = 
haftmann@26442
  1216
      (let (yes, no) = partition P xs
haftmann@26442
  1217
      in if P x then (x # yes, no) else (yes, x # no))"
haftmann@26442
  1218
haftmann@26442
  1219
lemma partition_filter1:
haftmann@26442
  1220
    "fst (partition P xs) = filter P xs"
haftmann@26442
  1221
by (induct xs) (auto simp add: Let_def split_def)
haftmann@26442
  1222
haftmann@26442
  1223
lemma partition_filter2:
haftmann@26442
  1224
    "snd (partition P xs) = filter (Not o P) xs"
haftmann@26442
  1225
by (induct xs) (auto simp add: Let_def split_def)
haftmann@26442
  1226
haftmann@26442
  1227
lemma partition_P:
haftmann@26442
  1228
  assumes "partition P xs = (yes, no)"
haftmann@26442
  1229
  shows "(\<forall>p \<in> set yes.  P p) \<and> (\<forall>p  \<in> set no. \<not> P p)"
haftmann@26442
  1230
proof -
haftmann@26442
  1231
  from assms have "yes = fst (partition P xs)" and "no = snd (partition P xs)"
haftmann@26442
  1232
    by simp_all
haftmann@26442
  1233
  then show ?thesis by (simp_all add: partition_filter1 partition_filter2)
haftmann@26442
  1234
qed
haftmann@26442
  1235
haftmann@26442
  1236
lemma partition_set:
haftmann@26442
  1237
  assumes "partition P xs = (yes, no)"
haftmann@26442
  1238
  shows "set yes \<union> set no = set xs"
haftmann@26442
  1239
proof -
haftmann@26442
  1240
  from assms have "yes = fst (partition P xs)" and "no = snd (partition P xs)"
haftmann@26442
  1241
    by simp_all
haftmann@26442
  1242
  then show ?thesis by (auto simp add: partition_filter1 partition_filter2) 
haftmann@26442
  1243
qed
haftmann@26442
  1244
hoelzl@33639
  1245
lemma partition_filter_conv[simp]:
hoelzl@33639
  1246
  "partition f xs = (filter f xs,filter (Not o f) xs)"
hoelzl@33639
  1247
unfolding partition_filter2[symmetric]
hoelzl@33639
  1248
unfolding partition_filter1[symmetric] by simp
hoelzl@33639
  1249
hoelzl@33639
  1250
declare partition.simps[simp del]
haftmann@26442
  1251
wenzelm@35115
  1252
nipkow@15392
  1253
subsubsection {* @{text concat} *}
wenzelm@13114
  1254
wenzelm@13142
  1255
lemma concat_append [simp]: "concat (xs @ ys) = concat xs @ concat ys"
nipkow@13145
  1256
by (induct xs) auto
wenzelm@13114
  1257
paulson@18447
  1258
lemma concat_eq_Nil_conv [simp]: "(concat xss = []) = (\<forall>xs \<in> set xss. xs = [])"
nipkow@13145
  1259
by (induct xss) auto
wenzelm@13114
  1260
paulson@18447
  1261
lemma Nil_eq_concat_conv [simp]: "([] = concat xss) = (\<forall>xs \<in> set xss. xs = [])"
nipkow@13145
  1262
by (induct xss) auto
wenzelm@13114
  1263
nipkow@24308
  1264
lemma set_concat [simp]: "set (concat xs) = (UN x:set xs. set x)"
nipkow@13145
  1265
by (induct xs) auto
wenzelm@13114
  1266
nipkow@24476
  1267
lemma concat_map_singleton[simp]: "concat(map (%x. [f x]) xs) = map f xs"
nipkow@24349
  1268
by (induct xs) auto
nipkow@24349
  1269
wenzelm@13142
  1270
lemma map_concat: "map f (concat xs) = concat (map (map f) xs)"
nipkow@13145
  1271
by (induct xs) auto
wenzelm@13114
  1272
wenzelm@13142
  1273
lemma filter_concat: "filter p (concat xs) = concat (map (filter p) xs)"
nipkow@13145
  1274
by (induct xs) auto
wenzelm@13114
  1275
wenzelm@13142
  1276
lemma rev_concat: "rev (concat xs) = concat (map rev (rev xs))"
nipkow@13145
  1277
by (induct xs) auto
wenzelm@13114
  1278
wenzelm@13114
  1279
nipkow@15392
  1280
subsubsection {* @{text nth} *}
wenzelm@13114
  1281
haftmann@29827
  1282
lemma nth_Cons_0 [simp, code]: "(x # xs)!0 = x"
nipkow@13145
  1283
by auto
wenzelm@13114
  1284
haftmann@29827
  1285
lemma nth_Cons_Suc [simp, code]: "(x # xs)!(Suc n) = xs!n"
nipkow@13145
  1286
by auto
wenzelm@13114
  1287
wenzelm@13142
  1288
declare nth.simps [simp del]
wenzelm@13114
  1289
wenzelm@13114
  1290
lemma nth_append:
nipkow@24526
  1291
  "(xs @ ys)!n = (if n < length xs then xs!n else ys!(n - length xs))"
nipkow@24526
  1292
apply (induct xs arbitrary: n, simp)
paulson@14208
  1293
apply (case_tac n, auto)
nipkow@13145
  1294
done
wenzelm@13114
  1295
nipkow@14402
  1296
lemma nth_append_length [simp]: "(xs @ x # ys) ! length xs = x"
wenzelm@25221
  1297
by (induct xs) auto
nipkow@14402
  1298
nipkow@14402
  1299
lemma nth_append_length_plus[simp]: "(xs @ ys) ! (length xs + n) = ys ! n"
wenzelm@25221
  1300
by (induct xs) auto
nipkow@14402
  1301
nipkow@24526
  1302
lemma nth_map [simp]: "n < length xs ==> (map f xs)!n = f(xs!n)"
nipkow@24526
  1303
apply (induct xs arbitrary: n, simp)
paulson@14208
  1304
apply (case_tac n, auto)
nipkow@13145
  1305
done
wenzelm@13114
  1306
nipkow@18423
  1307
lemma hd_conv_nth: "xs \<noteq> [] \<Longrightarrow> hd xs = xs!0"
nipkow@18423
  1308
by(cases xs) simp_all
nipkow@18423
  1309
nipkow@18049
  1310
nipkow@18049
  1311
lemma list_eq_iff_nth_eq:
nipkow@24526
  1312
 "(xs = ys) = (length xs = length ys \<and> (ALL i<length xs. xs!i = ys!i))"
nipkow@24526
  1313
apply(induct xs arbitrary: ys)
paulson@24632
  1314
 apply force
nipkow@18049
  1315
apply(case_tac ys)
nipkow@18049
  1316
 apply simp
nipkow@18049
  1317
apply(simp add:nth_Cons split:nat.split)apply blast
nipkow@18049
  1318
done
nipkow@18049
  1319
wenzelm@13142
  1320
lemma set_conv_nth: "set xs = {xs!i | i. i < length xs}"
paulson@15251
  1321
apply (induct xs, simp, simp)
nipkow@13145
  1322
apply safe
paulson@24632
  1323
apply (metis nat_case_0 nth.simps zero_less_Suc)
paulson@24632
  1324
apply (metis less_Suc_eq_0_disj nth_Cons_Suc)
paulson@14208
  1325
apply (case_tac i, simp)
paulson@24632
  1326
apply (metis diff_Suc_Suc nat_case_Suc nth.simps zero_less_diff)
nipkow@13145
  1327
done
wenzelm@13114
  1328
nipkow@17501
  1329
lemma in_set_conv_nth: "(x \<in> set xs) = (\<exists>i < length xs. xs!i = x)"
nipkow@17501
  1330
by(auto simp:set_conv_nth)
nipkow@17501
  1331
nipkow@13145
  1332
lemma list_ball_nth: "[| n < length xs; !x : set xs. P x|] ==> P(xs!n)"
nipkow@13145
  1333
by (auto simp add: set_conv_nth)
wenzelm@13114
  1334
wenzelm@13142
  1335
lemma nth_mem [simp]: "n < length xs ==> xs!n : set xs"
nipkow@13145
  1336
by (auto simp add: set_conv_nth)
wenzelm@13114
  1337
wenzelm@13114
  1338
lemma all_nth_imp_all_set:
nipkow@13145
  1339
"[| !i < length xs. P(xs!i); x : set xs|] ==> P x"
nipkow@13145
  1340
by (auto simp add: set_conv_nth)
wenzelm@13114
  1341
wenzelm@13114
  1342
lemma all_set_conv_all_nth:
nipkow@13145
  1343
"(\<forall>x \<in> set xs. P x) = (\<forall>i. i < length xs --> P (xs ! i))"
nipkow@13145
  1344
by (auto simp add: set_conv_nth)
wenzelm@13114
  1345
kleing@25296
  1346
lemma rev_nth:
kleing@25296
  1347
  "n < size xs \<Longrightarrow> rev xs ! n = xs ! (length xs - Suc n)"
kleing@25296
  1348
proof (induct xs arbitrary: n)
kleing@25296
  1349
  case Nil thus ?case by simp
kleing@25296
  1350
next
kleing@25296
  1351
  case (Cons x xs)
kleing@25296
  1352
  hence n: "n < Suc (length xs)" by simp
kleing@25296
  1353
  moreover
kleing@25296
  1354
  { assume "n < length xs"
kleing@25296
  1355
    with n obtain n' where "length xs - n = Suc n'"
kleing@25296
  1356
      by (cases "length xs - n", auto)
kleing@25296
  1357
    moreover
kleing@25296
  1358
    then have "length xs - Suc n = n'" by simp
kleing@25296
  1359
    ultimately
kleing@25296
  1360
    have "xs ! (length xs - Suc n) = (x # xs) ! (length xs - n)" by simp
kleing@25296
  1361
  }
kleing@25296
  1362
  ultimately
kleing@25296
  1363
  show ?case by (clarsimp simp add: Cons nth_append)
kleing@25296
  1364
qed
wenzelm@13114
  1365
nipkow@31159
  1366
lemma Skolem_list_nth:
nipkow@31159
  1367
  "(ALL i<k. EX x. P i x) = (EX xs. size xs = k & (ALL i<k. P i (xs!i)))"
nipkow@31159
  1368
  (is "_ = (EX xs. ?P k xs)")
nipkow@31159
  1369
proof(induct k)
nipkow@31159
  1370
  case 0 show ?case by simp
nipkow@31159
  1371
next
nipkow@31159
  1372
  case (Suc k)
nipkow@31159
  1373
  show ?case (is "?L = ?R" is "_ = (EX xs. ?P' xs)")
nipkow@31159
  1374
  proof
nipkow@31159
  1375
    assume "?R" thus "?L" using Suc by auto
nipkow@31159
  1376
  next
nipkow@31159
  1377
    assume "?L"
nipkow@31159
  1378
    with Suc obtain x xs where "?P k xs & P k x" by (metis less_Suc_eq)
nipkow@31159
  1379
    hence "?P'(xs@[x])" by(simp add:nth_append less_Suc_eq)
nipkow@31159
  1380
    thus "?R" ..
nipkow@31159
  1381
  qed
nipkow@31159
  1382
qed
nipkow@31159
  1383
nipkow@31159
  1384
nipkow@15392
  1385
subsubsection {* @{text list_update} *}
wenzelm@13114
  1386
nipkow@24526
  1387
lemma length_list_update [simp]: "length(xs[i:=x]) = length xs"
nipkow@24526
  1388
by (induct xs arbitrary: i) (auto split: nat.split)
wenzelm@13114
  1389
wenzelm@13114
  1390
lemma nth_list_update:
nipkow@24526
  1391
"i < length xs==> (xs[i:=x])!j = (if i = j then x else xs!j)"
nipkow@24526
  1392
by (induct xs arbitrary: i j) (auto simp add: nth_Cons split: nat.split)
wenzelm@13114
  1393
wenzelm@13142
  1394
lemma nth_list_update_eq [simp]: "i < length xs ==> (xs[i:=x])!i = x"
nipkow@13145
  1395
by (simp add: nth_list_update)
wenzelm@13114
  1396
nipkow@24526
  1397
lemma nth_list_update_neq [simp]: "i \<noteq> j ==> xs[i:=x]!j = xs!j"
nipkow@24526
  1398
by (induct xs arbitrary: i j) (auto simp add: nth_Cons split: nat.split)
wenzelm@13114
  1399
nipkow@24526
  1400
lemma list_update_id[simp]: "xs[i := xs!i] = xs"
nipkow@24526
  1401
by (induct xs arbitrary: i) (simp_all split:nat.splits)
nipkow@24526
  1402
nipkow@24526
  1403
lemma list_update_beyond[simp]: "length xs \<le> i \<Longrightarrow> xs[i:=x] = xs"
nipkow@24526
  1404
apply (induct xs arbitrary: i)
nipkow@17501
  1405
 apply simp
nipkow@17501
  1406
apply (case_tac i)
nipkow@17501
  1407
apply simp_all
nipkow@17501
  1408
done
nipkow@17501
  1409
nipkow@31077
  1410
lemma list_update_nonempty[simp]: "xs[k:=x] = [] \<longleftrightarrow> xs=[]"
nipkow@31077
  1411
by(metis length_0_conv length_list_update)
nipkow@31077
  1412
wenzelm@13114
  1413
lemma list_update_same_conv:
nipkow@24526
  1414
"i < length xs ==> (xs[i := x] = xs) = (xs!i = x)"
nipkow@24526
  1415
by (induct xs arbitrary: i) (auto split: nat.split)
wenzelm@13114
  1416
nipkow@14187
  1417
lemma list_update_append1:
nipkow@24526
  1418
 "i < size xs \<Longrightarrow> (xs @ ys)[i:=x] = xs[i:=x] @ ys"
nipkow@24526
  1419
apply (induct xs arbitrary: i, simp)
nipkow@14187
  1420
apply(simp split:nat.split)
nipkow@14187
  1421
done
nipkow@14187
  1422
kleing@15868
  1423
lemma list_update_append:
nipkow@24526
  1424
  "(xs @ ys) [n:= x] = 
kleing@15868
  1425
  (if n < length xs then xs[n:= x] @ ys else xs @ (ys [n-length xs:= x]))"
nipkow@24526
  1426
by (induct xs arbitrary: n) (auto split:nat.splits)
kleing@15868
  1427
nipkow@14402
  1428
lemma list_update_length [simp]:
nipkow@14402
  1429
 "(xs @ x # ys)[length xs := y] = (xs @ y # ys)"
nipkow@14402
  1430
by (induct xs, auto)
nipkow@14402
  1431
nipkow@31264
  1432
lemma map_update: "map f (xs[k:= y]) = (map f xs)[k := f y]"
nipkow@31264
  1433
by(induct xs arbitrary: k)(auto split:nat.splits)
nipkow@31264
  1434
nipkow@31264
  1435
lemma rev_update:
nipkow@31264
  1436
  "k < length xs \<Longrightarrow> rev (xs[k:= y]) = (rev xs)[length xs - k - 1 := y]"
nipkow@31264
  1437
by (induct xs arbitrary: k) (auto simp: list_update_append split:nat.splits)
nipkow@31264
  1438
wenzelm@13114
  1439
lemma update_zip:
nipkow@31080
  1440
  "(zip xs ys)[i:=xy] = zip (xs[i:=fst xy]) (ys[i:=snd xy])"
nipkow@24526
  1441
by (induct ys arbitrary: i xy xs) (auto, case_tac xs, auto split: nat.split)
nipkow@24526
  1442
nipkow@24526
  1443
lemma set_update_subset_insert: "set(xs[i:=x]) <= insert x (set xs)"
nipkow@24526
  1444
by (induct xs arbitrary: i) (auto split: nat.split)
wenzelm@13114
  1445
wenzelm@13114
  1446
lemma set_update_subsetI: "[| set xs <= A; x:A |] ==> set(xs[i := x]) <= A"
nipkow@13145
  1447
by (blast dest!: set_update_subset_insert [THEN subsetD])
wenzelm@13114
  1448
nipkow@24526
  1449
lemma set_update_memI: "n < length xs \<Longrightarrow> x \<in> set (xs[n := x])"
nipkow@24526
  1450
by (induct xs arbitrary: n) (auto split:nat.splits)
kleing@15868
  1451
nipkow@31077
  1452
lemma list_update_overwrite[simp]:
haftmann@24796
  1453
  "xs [i := x, i := y] = xs [i := y]"
nipkow@31077
  1454
apply (induct xs arbitrary: i) apply simp
nipkow@31077
  1455
apply (case_tac i, simp_all)
haftmann@24796
  1456
done
haftmann@24796
  1457
haftmann@24796
  1458
lemma list_update_swap:
haftmann@24796
  1459
  "i \<noteq> i' \<Longrightarrow> xs [i := x, i' := x'] = xs [i' := x', i := x]"
haftmann@24796
  1460
apply (induct xs arbitrary: i i')
haftmann@24796
  1461
apply simp
haftmann@24796
  1462
apply (case_tac i, case_tac i')
haftmann@24796
  1463
apply auto
haftmann@24796
  1464
apply (case_tac i')
haftmann@24796
  1465
apply auto
haftmann@24796
  1466
done
haftmann@24796
  1467
haftmann@29827
  1468
lemma list_update_code [code]:
haftmann@29827
  1469
  "[][i := y] = []"
haftmann@29827
  1470
  "(x # xs)[0 := y] = y # xs"
haftmann@29827
  1471
  "(x # xs)[Suc i := y] = x # xs[i := y]"
haftmann@29827
  1472
  by simp_all
haftmann@29827
  1473
wenzelm@13114
  1474
nipkow@15392
  1475
subsubsection {* @{text last} and @{text butlast} *}
wenzelm@13114
  1476
wenzelm@13142
  1477
lemma last_snoc [simp]: "last (xs @ [x]) = x"
nipkow@13145
  1478
by (induct xs) auto
wenzelm@13114
  1479
wenzelm@13142
  1480
lemma butlast_snoc [simp]: "butlast (xs @ [x]) = xs"
nipkow@13145
  1481
by (induct xs) auto
wenzelm@13114
  1482
nipkow@14302
  1483
lemma last_ConsL: "xs = [] \<Longrightarrow> last(x#xs) = x"
nipkow@14302
  1484
by(simp add:last.simps)
nipkow@14302
  1485
nipkow@14302
  1486
lemma last_ConsR: "xs \<noteq> [] \<Longrightarrow> last(x#xs) = last xs"
nipkow@14302
  1487
by(simp add:last.simps)
nipkow@14302
  1488
nipkow@14302
  1489
lemma last_append: "last(xs @ ys) = (if ys = [] then last xs else last ys)"
nipkow@14302
  1490
by (induct xs) (auto)
nipkow@14302
  1491
nipkow@14302
  1492
lemma last_appendL[simp]: "ys = [] \<Longrightarrow> last(xs @ ys) = last xs"
nipkow@14302
  1493
by(simp add:last_append)
nipkow@14302
  1494
nipkow@14302
  1495
lemma last_appendR[simp]: "ys \<noteq> [] \<Longrightarrow> last(xs @ ys) = last ys"
nipkow@14302
  1496
by(simp add:last_append)
nipkow@14302
  1497
nipkow@17762
  1498
lemma hd_rev: "xs \<noteq> [] \<Longrightarrow> hd(rev xs) = last xs"
nipkow@17762
  1499
by(rule rev_exhaust[of xs]) simp_all
nipkow@17762
  1500
nipkow@17762
  1501
lemma last_rev: "xs \<noteq> [] \<Longrightarrow> last(rev xs) = hd xs"
nipkow@17762
  1502
by(cases xs) simp_all
nipkow@17762
  1503
nipkow@17765
  1504
lemma last_in_set[simp]: "as \<noteq> [] \<Longrightarrow> last as \<in> set as"
nipkow@17765
  1505
by (induct as) auto
nipkow@17762
  1506
wenzelm@13142
  1507
lemma length_butlast [simp]: "length (butlast xs) = length xs - 1"
nipkow@13145
  1508
by (induct xs rule: rev_induct) auto
wenzelm@13114
  1509
wenzelm@13114
  1510
lemma butlast_append:
nipkow@24526
  1511
  "butlast (xs @ ys) = (if ys = [] then butlast xs else xs @ butlast ys)"
nipkow@24526
  1512
by (induct xs arbitrary: ys) auto
wenzelm@13114
  1513
wenzelm@13142
  1514
lemma append_butlast_last_id [simp]:
nipkow@13145
  1515
"xs \<noteq> [] ==> butlast xs @ [last xs] = xs"
nipkow@13145
  1516
by (induct xs) auto
wenzelm@13114
  1517
wenzelm@13142
  1518
lemma in_set_butlastD: "x : set (butlast xs) ==> x : set xs"
nipkow@13145
  1519
by (induct xs) (auto split: split_if_asm)
wenzelm@13114
  1520
wenzelm@13114
  1521
lemma in_set_butlast_appendI:
nipkow@13145
  1522
"x : set (butlast xs) | x : set (butlast ys) ==> x : set (butlast (xs @ ys))"
nipkow@13145
  1523
by (auto dest: in_set_butlastD simp add: butlast_append)
wenzelm@13114
  1524
nipkow@24526
  1525
lemma last_drop[simp]: "n < length xs \<Longrightarrow> last (drop n xs) = last xs"
nipkow@24526
  1526
apply (induct xs arbitrary: n)
nipkow@17501
  1527
 apply simp
nipkow@17501
  1528
apply (auto split:nat.split)
nipkow@17501
  1529
done
nipkow@17501
  1530
huffman@30128
  1531
lemma last_conv_nth: "xs\<noteq>[] \<Longrightarrow> last xs = xs!(length xs - 1)"
nipkow@17589
  1532
by(induct xs)(auto simp:neq_Nil_conv)
nipkow@17589
  1533
huffman@30128
  1534
lemma butlast_conv_take: "butlast xs = take (length xs - 1) xs"
huffman@26584
  1535
by (induct xs, simp, case_tac xs, simp_all)
huffman@26584
  1536
nipkow@31077
  1537
lemma last_list_update:
nipkow@31077
  1538
  "xs \<noteq> [] \<Longrightarrow> last(xs[k:=x]) = (if k = size xs - 1 then x else last xs)"
nipkow@31077
  1539
by (auto simp: last_conv_nth)
nipkow@31077
  1540
nipkow@31077
  1541
lemma butlast_list_update:
nipkow@31077
  1542
  "butlast(xs[k:=x]) =
nipkow@31077
  1543
 (if k = size xs - 1 then butlast xs else (butlast xs)[k:=x])"
nipkow@31077
  1544
apply(cases xs rule:rev_cases)
nipkow@31077
  1545
apply simp
nipkow@31077
  1546
apply(simp add:list_update_append split:nat.splits)
nipkow@31077
  1547
done
nipkow@31077
  1548
haftmann@36851
  1549
lemma last_map:
haftmann@36851
  1550
  "xs \<noteq> [] \<Longrightarrow> last (map f xs) = f (last xs)"
haftmann@36851
  1551
  by (cases xs rule: rev_cases) simp_all
haftmann@36851
  1552
haftmann@36851
  1553
lemma map_butlast:
haftmann@36851
  1554
  "map f (butlast xs) = butlast (map f xs)"
haftmann@36851
  1555
  by (induct xs) simp_all
haftmann@36851
  1556
haftmann@24796
  1557
nipkow@15392
  1558
subsubsection {* @{text take} and @{text drop} *}
wenzelm@13114
  1559
wenzelm@13142
  1560
lemma take_0 [simp]: "take 0 xs = []"
nipkow@13145
  1561
by (induct xs) auto
wenzelm@13114
  1562
wenzelm@13142
  1563
lemma drop_0 [simp]: "drop 0 xs = xs"
nipkow@13145
  1564
by (induct xs) auto
wenzelm@13114
  1565
wenzelm@13142
  1566
lemma take_Suc_Cons [simp]: "take (Suc n) (x # xs) = x # take n xs"
nipkow@13145
  1567
by simp
wenzelm@13114
  1568
wenzelm@13142
  1569
lemma drop_Suc_Cons [simp]: "drop (Suc n) (x # xs) = drop n xs"
nipkow@13145
  1570
by simp
wenzelm@13114
  1571
wenzelm@13142
  1572
declare take_Cons [simp del] and drop_Cons [simp del]
wenzelm@13114
  1573
huffman@30128
  1574
lemma take_1_Cons [simp]: "take 1 (x # xs) = [x]"
huffman@30128
  1575
  unfolding One_nat_def by simp
huffman@30128
  1576
huffman@30128
  1577
lemma drop_1_Cons [simp]: "drop 1 (x # xs) = xs"
huffman@30128
  1578
  unfolding One_nat_def by simp
huffman@30128
  1579
nipkow@15110
  1580
lemma take_Suc: "xs ~= [] ==> take (Suc n) xs = hd xs # take n (tl xs)"
nipkow@15110
  1581
by(clarsimp simp add:neq_Nil_conv)
nipkow@15110
  1582
nipkow@14187
  1583
lemma drop_Suc: "drop (Suc n) xs = drop n (tl xs)"
nipkow@14187
  1584
by(cases xs, simp_all)
nipkow@14187
  1585
huffman@26584
  1586
lemma take_tl: "take n (tl xs) = tl (take (Suc n) xs)"
huffman@26584
  1587
by (induct xs arbitrary: n) simp_all
huffman@26584
  1588
nipkow@24526
  1589
lemma drop_tl: "drop n (tl xs) = tl(drop n xs)"
nipkow@24526
  1590
by(induct xs arbitrary: n, simp_all add:drop_Cons drop_Suc split:nat.split)
nipkow@24526
  1591
huffman@26584
  1592
lemma tl_take: "tl (take n xs) = take (n - 1) (tl xs)"
huffman@26584
  1593
by (cases n, simp, cases xs, auto)
huffman@26584
  1594
huffman@26584
  1595
lemma tl_drop: "tl (drop n xs) = drop n (tl xs)"
huffman@26584
  1596
by (simp only: drop_tl)
huffman@26584
  1597
nipkow@24526
  1598
lemma nth_via_drop: "drop n xs = y#ys \<Longrightarrow> xs!n = y"
nipkow@24526
  1599
apply (induct xs arbitrary: n, simp)
nipkow@14187
  1600
apply(simp add:drop_Cons nth_Cons split:nat.splits)
nipkow@14187
  1601
done
nipkow@14187
  1602
nipkow@13913
  1603
lemma take_Suc_conv_app_nth:
nipkow@24526
  1604
  "i < length xs \<Longrightarrow> take (Suc i) xs = take i xs @ [xs!i]"
nipkow@24526
  1605
apply (induct xs arbitrary: i, simp)
paulson@14208
  1606
apply (case_tac i, auto)
nipkow@13913
  1607
done
nipkow@13913
  1608
mehta@14591
  1609
lemma drop_Suc_conv_tl:
nipkow@24526
  1610
  "i < length xs \<Longrightarrow> (xs!i) # (drop (Suc i) xs) = drop i xs"
nipkow@24526
  1611
apply (induct xs arbitrary: i, simp)
mehta@14591
  1612
apply (case_tac i, auto)
mehta@14591
  1613
done
mehta@14591
  1614
nipkow@24526
  1615
lemma length_take [simp]: "length (take n xs) = min (length xs) n"
nipkow@24526
  1616
by (induct n arbitrary: xs) (auto, case_tac xs, auto)
nipkow@24526
  1617
nipkow@24526
  1618
lemma length_drop [simp]: "length (drop n xs) = (length xs - n)"
nipkow@24526
  1619
by (induct n arbitrary: xs) (auto, case_tac xs, auto)
nipkow@24526
  1620
nipkow@24526
  1621
lemma take_all [simp]: "length xs <= n ==> take n xs = xs"
nipkow@24526
  1622
by (induct n arbitrary: xs) (auto, case_tac xs, auto)
nipkow@24526
  1623
nipkow@24526
  1624
lemma drop_all [simp]: "length xs <= n ==> drop n xs = []"
nipkow@24526
  1625
by (induct n arbitrary: xs) (auto, case_tac xs, auto)
wenzelm@13114
  1626
wenzelm@13142
  1627
lemma take_append [simp]:
nipkow@24526
  1628
  "take n (xs @ ys) = (take n xs @ take (n - length xs) ys)"
nipkow@24526
  1629
by (induct n arbitrary: xs) (auto, case_tac xs, auto)
wenzelm@13114
  1630
wenzelm@13142
  1631
lemma drop_append [simp]:
nipkow@24526
  1632
  "drop n (xs @ ys) = drop n xs @ drop (n - length xs) ys"
nipkow@24526
  1633
by (induct n arbitrary: xs) (auto, case_tac xs, auto)
nipkow@24526
  1634
nipkow@24526
  1635
lemma take_take [simp]: "take n (take m xs) = take (min n m) xs"
nipkow@24526
  1636
apply (induct m arbitrary: xs n, auto)
paulson@14208
  1637
apply (case_tac xs, auto)
nipkow@15236
  1638
apply (case_tac n, auto)
nipkow@13145
  1639
done
wenzelm@13114
  1640
nipkow@24526
  1641
lemma drop_drop [simp]: "drop n (drop m xs) = drop (n + m) xs"
nipkow@24526
  1642
apply (induct m arbitrary: xs, auto)
paulson@14208
  1643
apply (case_tac xs, auto)
nipkow@13145
  1644
done
wenzelm@13114
  1645
nipkow@24526
  1646
lemma take_drop: "take n (drop m xs) = drop m (take (n + m) xs)"
nipkow@24526
  1647
apply (induct m arbitrary: xs n, auto)
paulson@14208
  1648
apply (case_tac xs, auto)
nipkow@13145
  1649
done
wenzelm@13114
  1650
nipkow@24526
  1651
lemma drop_take: "drop n (take m xs) = take (m-n) (drop n xs)"
nipkow@24526
  1652
apply(induct xs arbitrary: m n)
nipkow@14802
  1653
 apply simp
nipkow@14802
  1654
apply(simp add: take_Cons drop_Cons split:nat.split)
nipkow@14802
  1655
done
nipkow@14802
  1656
nipkow@24526
  1657
lemma append_take_drop_id [simp]: "take n xs @ drop n xs = xs"
nipkow@24526
  1658
apply (induct n arbitrary: xs, auto)
paulson@14208
  1659
apply (case_tac xs, auto)
nipkow@13145
  1660
done
wenzelm@13114
  1661
nipkow@24526
  1662
lemma take_eq_Nil[simp]: "(take n xs = []) = (n = 0 \<or> xs = [])"
nipkow@24526
  1663
apply(induct xs arbitrary: n)
nipkow@15110
  1664
 apply simp
nipkow@15110
  1665
apply(simp add:take_Cons split:nat.split)
nipkow@15110
  1666
done
nipkow@15110
  1667
nipkow@24526
  1668
lemma drop_eq_Nil[simp]: "(drop n xs = []) = (length xs <= n)"
nipkow@24526
  1669
apply(induct xs arbitrary: n)
nipkow@15110
  1670
apply simp
nipkow@15110
  1671
apply(simp add:drop_Cons split:nat.split)
nipkow@15110
  1672
done
nipkow@15110
  1673
nipkow@24526
  1674
lemma take_map: "take n (map f xs) = map f (take n xs)"
nipkow@24526
  1675
apply (induct n arbitrary: xs, auto)
paulson@14208
  1676
apply (case_tac xs, auto)
nipkow@13145
  1677
done
wenzelm@13114
  1678
nipkow@24526
  1679
lemma drop_map: "drop n (map f xs) = map f (drop n xs)"
nipkow@24526
  1680
apply (induct n arbitrary: xs, auto)
paulson@14208
  1681
apply (case_tac xs, auto)
nipkow@13145
  1682
done
wenzelm@13114
  1683
nipkow@24526
  1684
lemma rev_take: "rev (take i xs) = drop (length xs - i) (rev xs)"
nipkow@24526
  1685
apply (induct xs arbitrary: i, auto)
paulson@14208
  1686
apply (case_tac i, auto)
nipkow@13145
  1687
done
wenzelm@13114
  1688
nipkow@24526
  1689
lemma rev_drop: "rev (drop i xs) = take (length xs - i) (rev xs)"
nipkow@24526
  1690
apply (induct xs arbitrary: i, auto)
paulson@14208
  1691
apply (case_tac i, auto)
nipkow@13145
  1692
done
wenzelm@13114
  1693
nipkow@24526
  1694
lemma nth_take [simp]: "i < n ==> (take n xs)!i = xs!i"
nipkow@24526
  1695
apply (induct xs arbitrary: i n, auto)
paulson@14208
  1696
apply (case_tac n, blast)
paulson@14208
  1697
apply (case_tac i, auto)
nipkow@13145
  1698
done
wenzelm@13114
  1699
wenzelm@13142
  1700
lemma nth_drop [simp]:
nipkow@24526
  1701
  "n + i <= length xs ==> (drop n xs)!i = xs!(n + i)"
nipkow@24526
  1702
apply (induct n arbitrary: xs i, auto)
paulson@14208
  1703
apply (case_tac xs, auto)
nipkow@13145
  1704
done
nipkow@3507
  1705
huffman@26584
  1706
lemma butlast_take:
huffman@30128
  1707
  "n <= length xs ==> butlast (take n xs) = take (n - 1) xs"
huffman@26584
  1708
by (simp add: butlast_conv_take min_max.inf_absorb1 min_max.inf_absorb2)
huffman@26584
  1709
huffman@26584
  1710
lemma butlast_drop: "butlast (drop n xs) = drop n (butlast xs)"
huffman@30128
  1711
by (simp add: butlast_conv_take drop_take add_ac)
huffman@26584
  1712
huffman@26584
  1713
lemma take_butlast: "n < length xs ==> take n (butlast xs) = take n xs"
huffman@26584
  1714
by (simp add: butlast_conv_take min_max.inf_absorb1)
huffman@26584
  1715
huffman@26584
  1716
lemma drop_butlast: "drop n (butlast xs) = butlast (drop n xs)"
huffman@30128
  1717
by (simp add: butlast_conv_take drop_take add_ac)
huffman@26584
  1718
nipkow@18423
  1719
lemma hd_drop_conv_nth: "\<lbrakk> xs \<noteq> []; n < length xs \<rbrakk> \<Longrightarrow> hd(drop n xs) = xs!n"
nipkow@18423
  1720
by(simp add: hd_conv_nth)
nipkow@18423
  1721
nipkow@35248
  1722
lemma set_take_subset_set_take:
nipkow@35248
  1723
  "m <= n \<Longrightarrow> set(take m xs) <= set(take n xs)"
nipkow@35248
  1724
by(induct xs arbitrary: m n)(auto simp:take_Cons split:nat.split)
nipkow@35248
  1725
nipkow@24526
  1726
lemma set_take_subset: "set(take n xs) \<subseteq> set xs"
nipkow@24526
  1727
by(induct xs arbitrary: n)(auto simp:take_Cons split:nat.split)
nipkow@24526
  1728
nipkow@24526
  1729
lemma set_drop_subset: "set(drop n xs) \<subseteq> set xs"
nipkow@24526
  1730
by(induct xs arbitrary: n)(auto simp:drop_Cons split:nat.split)
nipkow@14025
  1731
nipkow@35248
  1732
lemma set_drop_subset_set_drop:
nipkow@35248
  1733
  "m >= n \<Longrightarrow> set(drop m xs) <= set(drop n xs)"
nipkow@35248
  1734
apply(induct xs arbitrary: m n)
nipkow@35248
  1735
apply(auto simp:drop_Cons split:nat.split)
nipkow@35248
  1736
apply (metis set_drop_subset subset_iff)
nipkow@35248
  1737
done
nipkow@35248
  1738
nipkow@14187
  1739
lemma in_set_takeD: "x : set(take n xs) \<Longrightarrow> x : set xs"
nipkow@14187
  1740
using set_take_subset by fast
nipkow@14187
  1741
nipkow@14187
  1742
lemma in_set_dropD: "x : set(drop n xs) \<Longrightarrow> x : set xs"
nipkow@14187
  1743
using set_drop_subset by fast
nipkow@14187
  1744
wenzelm@13114
  1745
lemma append_eq_conv_conj:
nipkow@24526
  1746
  "(xs @ ys = zs) = (xs = take (length xs) zs \<and> ys = drop (length xs) zs)"
nipkow@24526
  1747
apply (induct xs arbitrary: zs, simp, clarsimp)
paulson@14208
  1748
apply (case_tac zs, auto)
nipkow@13145
  1749
done
wenzelm@13142
  1750
nipkow@24526
  1751
lemma take_add: 
nipkow@24526
  1752
  "i+j \<le> length(xs) \<Longrightarrow> take (i+j) xs = take i xs @ take j (drop i xs)"
nipkow@24526
  1753
apply (induct xs arbitrary: i, auto) 
nipkow@24526
  1754
apply (case_tac i, simp_all)
paulson@14050
  1755
done
paulson@14050
  1756
nipkow@14300
  1757
lemma append_eq_append_conv_if:
nipkow@24526
  1758
 "(xs\<^isub>1 @ xs\<^isub>2 = ys\<^isub>1 @ ys\<^isub>2) =
nipkow@14300
  1759
  (if size xs\<^isub>1 \<le> size ys\<^isub>1
nipkow@14300
  1760
   then xs\<^isub>1 = take (size xs\<^isub>1) ys\<^isub>1 \<and> xs\<^isub>2 = drop (size xs\<^isub>1) ys\<^isub>1 @ ys\<^isub>2
nipkow@14300
  1761
   else take (size ys\<^isub>1) xs\<^isub>1 = ys\<^isub>1 \<and> drop (size ys\<^isub>1) xs\<^isub>1 @ xs\<^isub>2 = ys\<^isub>2)"
nipkow@24526
  1762
apply(induct xs\<^isub>1 arbitrary: ys\<^isub>1)
nipkow@14300
  1763
 apply simp
nipkow@14300
  1764
apply(case_tac ys\<^isub>1)
nipkow@14300
  1765
apply simp_all
nipkow@14300
  1766
done
nipkow@14300
  1767
nipkow@15110
  1768
lemma take_hd_drop:
huffman@30079
  1769
  "n < length xs \<Longrightarrow> take n xs @ [hd (drop n xs)] = take (Suc n) xs"
nipkow@24526
  1770
apply(induct xs arbitrary: n)
nipkow@15110
  1771
apply simp
nipkow@15110
  1772
apply(simp add:drop_Cons split:nat.split)
nipkow@15110
  1773
done
nipkow@15110
  1774
nipkow@17501
  1775
lemma id_take_nth_drop:
nipkow@17501
  1776
 "i < length xs \<Longrightarrow> xs = take i xs @ xs!i # drop (Suc i) xs" 
nipkow@17501
  1777
proof -
nipkow@17501
  1778
  assume si: "i < length xs"
nipkow@17501
  1779
  hence "xs = take (Suc i) xs @ drop (Suc i) xs" by auto
nipkow@17501
  1780
  moreover
nipkow@17501
  1781
  from si have "take (Suc i) xs = take i xs @ [xs!i]"
nipkow@17501
  1782
    apply (rule_tac take_Suc_conv_app_nth) by arith
nipkow@17501
  1783
  ultimately show ?thesis by auto
nipkow@17501
  1784
qed
nipkow@17501
  1785
  
nipkow@17501
  1786
lemma upd_conv_take_nth_drop:
nipkow@17501
  1787
 "i < length xs \<Longrightarrow> xs[i:=a] = take i xs @ a # drop (Suc i) xs"
nipkow@17501
  1788
proof -
nipkow@17501
  1789
  assume i: "i < length xs"
nipkow@17501
  1790
  have "xs[i:=a] = (take i xs @ xs!i # drop (Suc i) xs)[i:=a]"
nipkow@17501
  1791
    by(rule arg_cong[OF id_take_nth_drop[OF i]])
nipkow@17501
  1792
  also have "\<dots> = take i xs @ a # drop (Suc i) xs"
nipkow@17501
  1793
    using i by (simp add: list_update_append)
nipkow@17501
  1794
  finally show ?thesis .
nipkow@17501
  1795
qed
nipkow@17501
  1796
haftmann@24796
  1797
lemma nth_drop':
haftmann@24796
  1798
  "i < length xs \<Longrightarrow> xs ! i # drop (Suc i) xs = drop i xs"
haftmann@24796
  1799
apply (induct i arbitrary: xs)
haftmann@24796
  1800
apply (simp add: neq_Nil_conv)
haftmann@24796
  1801
apply (erule exE)+
haftmann@24796
  1802
apply simp
haftmann@24796
  1803
apply (case_tac xs)
haftmann@24796
  1804
apply simp_all
haftmann@24796
  1805
done
haftmann@24796
  1806
wenzelm@13114
  1807
nipkow@15392
  1808
subsubsection {* @{text takeWhile} and @{text dropWhile} *}
wenzelm@13114
  1809
hoelzl@33639
  1810
lemma length_takeWhile_le: "length (takeWhile P xs) \<le> length xs"
hoelzl@33639
  1811
  by (induct xs) auto
hoelzl@33639
  1812
wenzelm@13142
  1813
lemma takeWhile_dropWhile_id [simp]: "takeWhile P xs @ dropWhile P xs = xs"
nipkow@13145
  1814
by (induct xs) auto
wenzelm@13114
  1815
wenzelm@13142
  1816
lemma takeWhile_append1 [simp]:
nipkow@13145
  1817
"[| x:set xs; ~P(x)|] ==> takeWhile P (xs @ ys) = takeWhile P xs"
nipkow@13145
  1818
by (induct xs) auto
wenzelm@13114
  1819
wenzelm@13142
  1820
lemma takeWhile_append2 [simp]:
nipkow@13145
  1821
"(!!x. x : set xs ==> P x) ==> takeWhile P (xs @ ys) = xs @ takeWhile P ys"
nipkow@13145
  1822
by (induct xs) auto
wenzelm@13114
  1823
wenzelm@13142
  1824
lemma takeWhile_tail: "\<not> P x ==> takeWhile P (xs @ (x#l)) = takeWhile P xs"
nipkow@13145
  1825
by (induct xs) auto
wenzelm@13114
  1826
hoelzl@33639
  1827
lemma takeWhile_nth: "j < length (takeWhile P xs) \<Longrightarrow> takeWhile P xs ! j = xs ! j"
hoelzl@33639
  1828
apply (subst (3) takeWhile_dropWhile_id[symmetric]) unfolding nth_append by auto
hoelzl@33639
  1829
hoelzl@33639
  1830
lemma dropWhile_nth: "j < length (dropWhile P xs) \<Longrightarrow> dropWhile P xs ! j = xs ! (j + length (takeWhile P xs))"
hoelzl@33639
  1831
apply (subst (3) takeWhile_dropWhile_id[symmetric]) unfolding nth_append by auto
hoelzl@33639
  1832
hoelzl@33639
  1833
lemma length_dropWhile_le: "length (dropWhile P xs) \<le> length xs"
hoelzl@33639
  1834
by (induct xs) auto
hoelzl@33639
  1835
wenzelm@13142
  1836
lemma dropWhile_append1 [simp]:
nipkow@13145
  1837
"[| x : set xs; ~P(x)|] ==> dropWhile P (xs @ ys) = (dropWhile P xs)@ys"
nipkow@13145
  1838
by (induct xs) auto
wenzelm@13114
  1839
wenzelm@13142
  1840
lemma dropWhile_append2 [simp]:
nipkow@13145
  1841
"(!!x. x:set xs ==> P(x)) ==> dropWhile P (xs @ ys) = dropWhile P ys"
nipkow@13145
  1842
by (induct xs) auto
wenzelm@13114
  1843
krauss@23971
  1844
lemma set_takeWhileD: "x : set (takeWhile P xs) ==> x : set xs \<and> P x"
nipkow@13145
  1845
by (induct xs) (auto split: split_if_asm)
wenzelm@13114
  1846
nipkow@13913
  1847
lemma takeWhile_eq_all_conv[simp]:
nipkow@13913
  1848
 "(takeWhile P xs = xs) = (\<forall>x \<in> set xs. P x)"
nipkow@13913
  1849
by(induct xs, auto)
nipkow@13913
  1850
nipkow@13913
  1851
lemma dropWhile_eq_Nil_conv[simp]:
nipkow@13913
  1852
 "(dropWhile P xs = []) = (\<forall>x \<in> set xs. P x)"
nipkow@13913
  1853
by(induct xs, auto)
nipkow@13913
  1854
nipkow@13913
  1855
lemma dropWhile_eq_Cons_conv:
nipkow@13913
  1856
 "(dropWhile P xs = y#ys) = (xs = takeWhile P xs @ y # ys & \<not> P y)"
nipkow@13913
  1857
by(induct xs, auto)
nipkow@13913
  1858
nipkow@31077
  1859
lemma distinct_takeWhile[simp]: "distinct xs ==> distinct (takeWhile P xs)"
nipkow@31077
  1860
by (induct xs) (auto dest: set_takeWhileD)
nipkow@31077
  1861
nipkow@31077
  1862
lemma distinct_dropWhile[simp]: "distinct xs ==> distinct (dropWhile P xs)"
nipkow@31077
  1863
by (induct xs) auto
nipkow@31077
  1864
hoelzl@33639
  1865
lemma takeWhile_map: "takeWhile P (map f xs) = map f (takeWhile (P \<circ> f) xs)"
hoelzl@33639
  1866
by (induct xs) auto
hoelzl@33639
  1867
hoelzl@33639
  1868
lemma dropWhile_map: "dropWhile P (map f xs) = map f (dropWhile (P \<circ> f) xs)"
hoelzl@33639
  1869
by (induct xs) auto
hoelzl@33639
  1870
hoelzl@33639
  1871
lemma takeWhile_eq_take: "takeWhile P xs = take (length (takeWhile P xs)) xs"
hoelzl@33639
  1872
by (induct xs) auto
hoelzl@33639
  1873
hoelzl@33639
  1874
lemma dropWhile_eq_drop: "dropWhile P xs = drop (length (takeWhile P xs)) xs"
hoelzl@33639
  1875
by (induct xs) auto
hoelzl@33639
  1876
hoelzl@33639
  1877
lemma hd_dropWhile:
hoelzl@33639
  1878
  "dropWhile P xs \<noteq> [] \<Longrightarrow> \<not> P (hd (dropWhile P xs))"
hoelzl@33639
  1879
using assms by (induct xs) auto
hoelzl@33639
  1880
hoelzl@33639
  1881
lemma takeWhile_eq_filter:
hoelzl@33639
  1882
  assumes "\<And> x. x \<in> set (dropWhile P xs) \<Longrightarrow> \<not> P x"
hoelzl@33639
  1883
  shows "takeWhile P xs = filter P xs"
hoelzl@33639
  1884
proof -
hoelzl@33639
  1885
  have A: "filter P xs = filter P (takeWhile P xs @ dropWhile P xs)"
hoelzl@33639
  1886
    by simp
hoelzl@33639
  1887
  have B: "filter P (dropWhile P xs) = []"
hoelzl@33639
  1888
    unfolding filter_empty_conv using assms by blast
hoelzl@33639
  1889
  have "filter P xs = takeWhile P xs"
hoelzl@33639
  1890
    unfolding A filter_append B
hoelzl@33639
  1891
    by (auto simp add: filter_id_conv dest: set_takeWhileD)
hoelzl@33639
  1892
  thus ?thesis ..
hoelzl@33639
  1893
qed
hoelzl@33639
  1894
hoelzl@33639
  1895
lemma takeWhile_eq_take_P_nth:
hoelzl@33639
  1896
  "\<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
  1897
  takeWhile P xs = take n xs"
hoelzl@33639
  1898
proof (induct xs arbitrary: n)
hoelzl@33639
  1899
  case (Cons x xs)
hoelzl@33639
  1900
  thus ?case
hoelzl@33639
  1901
  proof (cases n)
hoelzl@33639
  1902
    case (Suc n') note this[simp]
hoelzl@33639
  1903
    have "P x" using Cons.prems(1)[of 0] by simp
hoelzl@33639
  1904
    moreover have "takeWhile P xs = take n' xs"
hoelzl@33639
  1905
    proof (rule Cons.hyps)
hoelzl@33639
  1906
      case goal1 thus "P (xs ! i)" using Cons.prems(1)[of "Suc i"] by simp
hoelzl@33639
  1907
    next case goal2 thus ?case using Cons by auto
hoelzl@33639
  1908
    qed
hoelzl@33639
  1909
    ultimately show ?thesis by simp
hoelzl@33639
  1910
   qed simp
hoelzl@33639
  1911
qed simp
hoelzl@33639
  1912
hoelzl@33639
  1913
lemma nth_length_takeWhile:
hoelzl@33639
  1914
  "length (takeWhile P xs) < length xs \<Longrightarrow> \<not> P (xs ! length (takeWhile P xs))"
hoelzl@33639
  1915
by (induct xs) auto
hoelzl@33639
  1916
hoelzl@33639
  1917
lemma length_takeWhile_less_P_nth:
hoelzl@33639
  1918
  assumes all: "\<And> i. i < j \<Longrightarrow> P (xs ! i)" and "j \<le> length xs"
hoelzl@33639
  1919
  shows "j \<le> length (takeWhile P xs)"
hoelzl@33639
  1920
proof (rule classical)
hoelzl@33639
  1921
  assume "\<not> ?thesis"
hoelzl@33639
  1922
  hence "length (takeWhile P xs) < length xs" using assms by simp
hoelzl@33639
  1923
  thus ?thesis using all `\<not> ?thesis` nth_length_takeWhile[of P xs] by auto
hoelzl@33639
  1924
qed
nipkow@31077
  1925
nipkow@17501
  1926
text{* The following two lemmmas could be generalized to an arbitrary
nipkow@17501
  1927
property. *}
nipkow@17501
  1928
nipkow@17501
  1929
lemma takeWhile_neq_rev: "\<lbrakk>distinct xs; x \<in> set xs\<rbrakk> \<Longrightarrow>
nipkow@17501
  1930
 takeWhile (\<lambda>y. y \<noteq> x) (rev xs) = rev (tl (dropWhile (\<lambda>y. y \<noteq> x) xs))"
nipkow@17501
  1931
by(induct xs) (auto simp: takeWhile_tail[where l="[]"])
nipkow@17501
  1932
nipkow@17501
  1933
lemma dropWhile_neq_rev: "\<lbrakk>distinct xs; x \<in> set xs\<rbrakk> \<Longrightarrow>
nipkow@17501
  1934
  dropWhile (\<lambda>y. y \<noteq> x) (rev xs) = x # rev (takeWhile (\<lambda>y. y \<noteq> x) xs)"
nipkow@17501
  1935
apply(induct xs)
nipkow@17501
  1936
 apply simp
nipkow@17501
  1937
apply auto
nipkow@17501
  1938
apply(subst dropWhile_append2)
nipkow@17501
  1939
apply auto
nipkow@17501
  1940
done
nipkow@17501
  1941
nipkow@18423
  1942
lemma takeWhile_not_last:
nipkow@18423
  1943
 "\<lbrakk> xs \<noteq> []; distinct xs\<rbrakk> \<Longrightarrow> takeWhile (\<lambda>y. y \<noteq> last xs) xs = butlast xs"
nipkow@18423
  1944
apply(induct xs)
nipkow@18423
  1945
 apply simp
nipkow@18423
  1946
apply(case_tac xs)
nipkow@18423
  1947
apply(auto)
nipkow@18423
  1948
done
nipkow@18423
  1949
krauss@19770
  1950
lemma takeWhile_cong [fundef_cong, recdef_cong]:
krauss@18336
  1951
  "[| l = k; !!x. x : set l ==> P x = Q x |] 
krauss@18336
  1952
  ==> takeWhile P l = takeWhile Q k"
nipkow@24349
  1953
by (induct k arbitrary: l) (simp_all)
krauss@18336
  1954
krauss@19770
  1955
lemma dropWhile_cong [fundef_cong, recdef_cong]:
krauss@18336
  1956
  "[| l = k; !!x. x : set l ==> P x = Q x |] 
krauss@18336
  1957
  ==> dropWhile P l = dropWhile Q k"
nipkow@24349
  1958
by (induct k arbitrary: l, simp_all)
krauss@18336
  1959
wenzelm@13114
  1960
nipkow@15392
  1961
subsubsection {* @{text zip} *}
wenzelm@13114
  1962
wenzelm@13142
  1963
lemma zip_Nil [simp]: "zip [] ys = []"
nipkow@13145
  1964
by (induct ys) auto
wenzelm@13114
  1965
wenzelm@13142
  1966
lemma zip_Cons_Cons [simp]: "zip (x # xs) (y # ys) = (x, y) # zip xs ys"
nipkow@13145
  1967
by simp
wenzelm@13114
  1968
wenzelm@13142
  1969
declare zip_Cons [simp del]
wenzelm@13114
  1970
haftmann@36198
  1971
lemma [code]:
haftmann@36198
  1972
  "zip [] ys = []"
haftmann@36198
  1973
  "zip xs [] = []"
haftmann@36198
  1974
  "zip (x # xs) (y # ys) = (x, y) # zip xs ys"
haftmann@36198
  1975
  by (fact zip_Nil zip.simps(1) zip_Cons_Cons)+
haftmann@36198
  1976
nipkow@15281
  1977
lemma zip_Cons1:
nipkow@15281
  1978
 "zip (x#xs) ys = (case ys of [] \<Rightarrow> [] | y#ys \<Rightarrow> (x,y)#zip xs ys)"
nipkow@15281
  1979
by(auto split:list.split)
nipkow@15281
  1980
wenzelm@13142
  1981
lemma length_zip [simp]:
krauss@22493
  1982
"length (zip xs ys) = min (length xs) (length ys)"
krauss@22493
  1983
by (induct xs ys rule:list_induct2') auto
wenzelm@13114
  1984
haftmann@34978
  1985
lemma zip_obtain_same_length:
haftmann@34978
  1986
  assumes "\<And>zs ws n. length zs = length ws \<Longrightarrow> n = min (length xs) (length ys)
haftmann@34978
  1987
    \<Longrightarrow> zs = take n xs \<Longrightarrow> ws = take n ys \<Longrightarrow> P (zip zs ws)"
haftmann@34978
  1988
  shows "P (zip xs ys)"
haftmann@34978
  1989
proof -
haftmann@34978
  1990
  let ?n = "min (length xs) (length ys)"
haftmann@34978
  1991
  have "P (zip (take ?n xs) (take ?n ys))"
haftmann@34978
  1992
    by (rule assms) simp_all
haftmann@34978
  1993
  moreover have "zip xs ys = zip (take ?n xs) (take ?n ys)"
haftmann@34978
  1994
  proof (induct xs arbitrary: ys)
haftmann@34978
  1995
    case Nil then show ?case by simp
haftmann@34978
  1996
  next
haftmann@34978
  1997
    case (Cons x xs) then show ?case by (cases ys) simp_all
haftmann@34978
  1998
  qed
haftmann@34978
  1999
  ultimately show ?thesis by simp
haftmann@34978
  2000
qed
haftmann@34978
  2001
wenzelm@13114
  2002
lemma zip_append1:
krauss@22493
  2003
"zip (xs @ ys) zs =
nipkow@13145
  2004
zip xs (take (length xs) zs) @ zip ys (drop (length xs) zs)"
krauss@22493
  2005
by (induct xs zs rule:list_induct2') auto
wenzelm@13114
  2006
wenzelm@13114
  2007
lemma zip_append2:
krauss@22493
  2008
"zip xs (ys @ zs) =
nipkow@13145
  2009
zip (take (length ys) xs) ys @ zip (drop (length ys) xs) zs"
krauss@22493
  2010
by (induct xs ys rule:list_induct2') auto
wenzelm@13114
  2011
wenzelm@13142
  2012
lemma zip_append [simp]:
wenzelm@13142
  2013
 "[| length xs = length us; length ys = length vs |] ==>
nipkow@13145
  2014
zip (xs@ys) (us@vs) = zip xs us @ zip ys vs"
nipkow@13145
  2015
by (simp add: zip_append1)
wenzelm@13114
  2016
wenzelm@13114
  2017
lemma zip_rev:
nipkow@14247
  2018
"length xs = length ys ==> zip (rev xs) (rev ys) = rev (zip xs ys)"
nipkow@14247
  2019
by (induct rule:list_induct2, simp_all)
wenzelm@13114
  2020
hoelzl@33639
  2021
lemma zip_map_map:
hoelzl@33639
  2022
  "zip (map f xs) (map g ys) = map (\<lambda> (x, y). (f x, g y)) (zip xs ys)"
hoelzl@33639
  2023
proof (induct xs arbitrary: ys)
hoelzl@33639
  2024
  case (Cons x xs) note Cons_x_xs = Cons.hyps
hoelzl@33639
  2025
  show ?case
hoelzl@33639
  2026
  proof (cases ys)
hoelzl@33639
  2027
    case (Cons y ys')
hoelzl@33639
  2028
    show ?thesis unfolding Cons using Cons_x_xs by simp
hoelzl@33639
  2029
  qed simp
hoelzl@33639
  2030
qed simp
hoelzl@33639
  2031
hoelzl@33639
  2032
lemma zip_map1:
hoelzl@33639
  2033
  "zip (map f xs) ys = map (\<lambda>(x, y). (f x, y)) (zip xs ys)"
hoelzl@33639
  2034
using zip_map_map[of f xs "\<lambda>x. x" ys] by simp
hoelzl@33639
  2035
hoelzl@33639
  2036
lemma zip_map2:
hoelzl@33639
  2037
  "zip xs (map f ys) = map (\<lambda>(x, y). (x, f y)) (zip xs ys)"
hoelzl@33639
  2038
using zip_map_map[of "\<lambda>x. x" xs f ys] by simp
hoelzl@33639
  2039
nipkow@23096
  2040
lemma map_zip_map:
hoelzl@33639
  2041
  "map f (zip (map g xs) ys) = map (%(x,y). f(g x, y)) (zip xs ys)"
hoelzl@33639
  2042
unfolding zip_map1 by auto
nipkow@23096
  2043
nipkow@23096
  2044
lemma map_zip_map2:
hoelzl@33639
  2045
  "map f (zip xs (map g ys)) = map (%(x,y). f(x, g y)) (zip xs ys)"
hoelzl@33639
  2046
unfolding zip_map2 by auto
nipkow@23096
  2047
nipkow@31080
  2048
text{* Courtesy of Andreas Lochbihler: *}
nipkow@31080
  2049
lemma zip_same_conv_map: "zip xs xs = map (\<lambda>x. (x, x)) xs"
nipkow@31080
  2050
by(induct xs) auto
nipkow@31080
  2051
wenzelm@13142
  2052
lemma nth_zip [simp]:
nipkow@24526
  2053
"[| i < length xs; i < length ys|] ==> (zip xs ys)!i = (xs!i, ys!i)"
nipkow@24526
  2054
apply (induct ys arbitrary: i xs, simp)
nipkow@13145
  2055
apply (case_tac xs)
nipkow@13145
  2056
 apply (simp_all add: nth.simps split: nat.split)
nipkow@13145
  2057
done
wenzelm@13114
  2058
wenzelm@13114
  2059
lemma set_zip:
nipkow@13145
  2060
"set (zip xs ys) = {(xs!i, ys!i) | i. i < min (length xs) (length ys)}"
nipkow@31080
  2061
by(simp add: set_conv_nth cong: rev_conj_cong)
wenzelm@13114
  2062
hoelzl@33639
  2063
lemma zip_same: "((a,b) \<in> set (zip xs xs)) = (a \<in> set xs \<and> a = b)"
hoelzl@33639
  2064
by(induct xs) auto
hoelzl@33639
  2065
wenzelm@13114
  2066
lemma zip_update:
nipkow@31080
  2067
  "zip (xs[i:=x]) (ys[i:=y]) = (zip xs ys)[i:=(x,y)]"
nipkow@31080
  2068
by(rule sym, simp add: update_zip)
wenzelm@13114
  2069
wenzelm@13142
  2070
lemma zip_replicate [simp]:
nipkow@24526
  2071
  "zip (replicate i x) (replicate j y) = replicate (min i j) (x,y)"
nipkow@24526
  2072
apply (induct i arbitrary: j, auto)
paulson@14208
  2073
apply (case_tac j, auto)
nipkow@13145
  2074
done
wenzelm@13114
  2075
nipkow@19487
  2076
lemma take_zip:
nipkow@24526
  2077
  "take n (zip xs ys) = zip (take n xs) (take n ys)"
nipkow@24526
  2078
apply (induct n arbitrary: xs ys)
nipkow@19487
  2079
 apply simp
nipkow@19487
  2080
apply (case_tac xs, simp)
nipkow@19487
  2081
apply (case_tac ys, simp_all)
nipkow@19487
  2082
done
nipkow@19487
  2083
nipkow@19487
  2084
lemma drop_zip:
nipkow@24526
  2085
  "drop n (zip xs ys) = zip (drop n xs) (drop n ys)"
nipkow@24526
  2086
apply (induct n arbitrary: xs ys)
nipkow@19487
  2087
 apply simp
nipkow@19487
  2088
apply (case_tac xs, simp)
nipkow@19487
  2089
apply (case_tac ys, simp_all)
nipkow@19487
  2090
done
nipkow@19487
  2091
hoelzl@33639
  2092
lemma zip_takeWhile_fst: "zip (takeWhile P xs) ys = takeWhile (P \<circ> fst) (zip xs ys)"
hoelzl@33639
  2093
proof (induct xs arbitrary: ys)
hoelzl@33639
  2094
  case (Cons x xs) thus ?case by (cases ys) auto
hoelzl@33639
  2095
qed simp
hoelzl@33639
  2096
hoelzl@33639
  2097
lemma zip_takeWhile_snd: "zip xs (takeWhile P ys) = takeWhile (P \<circ> snd) (zip xs ys)"
hoelzl@33639
  2098
proof (induct xs arbitrary: ys)
hoelzl@33639
  2099
  case (Cons x xs) thus ?case by (cases ys) auto
hoelzl@33639
  2100
qed simp
hoelzl@33639
  2101
krauss@22493
  2102
lemma set_zip_leftD:
krauss@22493
  2103
  "(x,y)\<in> set (zip xs ys) \<Longrightarrow> x \<in> set xs"
krauss@22493
  2104
by (induct xs ys rule:list_induct2') auto
krauss@22493
  2105
krauss@22493
  2106
lemma set_zip_rightD:
krauss@22493
  2107
  "(x,y)\<in> set (zip xs ys) \<Longrightarrow> y \<in> set ys"
krauss@22493
  2108
by (induct xs ys rule:list_induct2') auto
wenzelm@13142
  2109
nipkow@23983
  2110
lemma in_set_zipE:
nipkow@23983
  2111
  "(x,y) : set(zip xs ys) \<Longrightarrow> (\<lbrakk> x : set xs; y : set ys \<rbrakk> \<Longrightarrow> R) \<Longrightarrow> R"
nipkow@23983
  2112
by(blast dest: set_zip_leftD set_zip_rightD)
nipkow@23983
  2113
haftmann@29829
  2114
lemma zip_map_fst_snd:
haftmann@29829
  2115
  "zip (map fst zs) (map snd zs) = zs"
haftmann@29829
  2116
  by (induct zs) simp_all
haftmann@29829
  2117
haftmann@29829
  2118
lemma zip_eq_conv:
haftmann@29829
  2119
  "length xs = length ys \<Longrightarrow> zip xs ys = zs \<longleftrightarrow> map fst zs = xs \<and> map snd zs = ys"
haftmann@29829
  2120
  by (auto simp add: zip_map_fst_snd)
haftmann@29829
  2121
hoelzl@33639
  2122
lemma distinct_zipI1:
hoelzl@33639
  2123
  "distinct xs \<Longrightarrow> distinct (zip xs ys)"
hoelzl@33639
  2124
proof (induct xs arbitrary: ys)
hoelzl@33639
  2125
  case (Cons x xs)
hoelzl@33639
  2126
  show ?case
hoelzl@33639
  2127
  proof (cases ys)
hoelzl@33639
  2128
    case (Cons y ys')
hoelzl@33639
  2129
    have "(x, y) \<notin> set (zip xs ys')"
hoelzl@33639
  2130
      using Cons.prems by (auto simp: set_zip)
hoelzl@33639
  2131
    thus ?thesis
hoelzl@33639
  2132
      unfolding Cons zip_Cons_Cons distinct.simps
hoelzl@33639
  2133
      using Cons.hyps Cons.prems by simp
hoelzl@33639
  2134
  qed simp
hoelzl@33639
  2135
qed simp
hoelzl@33639
  2136
hoelzl@33639
  2137
lemma distinct_zipI2:
hoelzl@33639
  2138
  "distinct xs \<Longrightarrow> distinct (zip xs ys)"
hoelzl@33639
  2139
proof (induct xs arbitrary: ys)
hoelzl@33639
  2140
  case (Cons x xs)
hoelzl@33639
  2141
  show ?case
hoelzl@33639
  2142
  proof (cases ys)
hoelzl@33639
  2143
    case (Cons y ys')
hoelzl@33639
  2144
     have "(x, y) \<notin> set (zip xs ys')"
hoelzl@33639
  2145
      using Cons.prems by (auto simp: set_zip)
hoelzl@33639
  2146
    thus ?thesis
hoelzl@33639
  2147
      unfolding Cons zip_Cons_Cons distinct.simps
hoelzl@33639
  2148
      using Cons.hyps Cons.prems by simp
hoelzl@33639
  2149
  qed simp
hoelzl@33639
  2150
qed simp
haftmann@29829
  2151
wenzelm@35115
  2152
nipkow@15392
  2153
subsubsection {* @{text list_all2} *}
wenzelm@13114
  2154
kleing@14316
  2155
lemma list_all2_lengthD [intro?]: 
kleing@14316
  2156
  "list_all2 P xs ys ==> length xs = length ys"
nipkow@24349
  2157
by (simp add: list_all2_def)
haftmann@19607
  2158
haftmann@19787
  2159
lemma list_all2_Nil [iff, code]: "list_all2 P [] ys = (ys = [])"
nipkow@24349
  2160
by (simp add: list_all2_def)
haftmann@19607
  2161
haftmann@19787
  2162
lemma list_all2_Nil2 [iff, code]: "list_all2 P xs [] = (xs = [])"
nipkow@24349
  2163
by (simp add: list_all2_def)
haftmann@19607
  2164
haftmann@19607
  2165
lemma list_all2_Cons [iff, code]:
haftmann@19607
  2166
  "list_all2 P (x # xs) (y # ys) = (P x y \<and> list_all2 P xs ys)"
nipkow@24349
  2167
by (auto simp add: list_all2_def)
wenzelm@13114
  2168
wenzelm@13114
  2169
lemma list_all2_Cons1:
nipkow@13145
  2170
"list_all2 P (x # xs) ys = (\<exists>z zs. ys = z # zs \<and> P x z \<and> list_all2 P xs zs)"
nipkow@13145
  2171
by (cases ys) auto
wenzelm@13114
  2172
wenzelm@13114
  2173
lemma list_all2_Cons2:
nipkow@13145
  2174
"list_all2 P xs (y # ys) = (\<exists>z zs. xs = z # zs \<and> P z y \<and> list_all2 P zs ys)"
nipkow@13145
  2175
by (cases xs) auto
wenzelm@13114
  2176
wenzelm@13142
  2177
lemma list_all2_rev [iff]:
nipkow@13145
  2178
"list_all2 P (rev xs) (rev ys) = list_all2 P xs ys"
nipkow@13145
  2179
by (simp add: list_all2_def zip_rev cong: conj_cong)
wenzelm@13114
  2180
kleing@13863
  2181
lemma list_all2_rev1:
kleing@13863
  2182
"list_all2 P (rev xs) ys = list_all2 P xs (rev ys)"
kleing@13863
  2183
by (subst list_all2_rev [symmetric]) simp
kleing@13863
  2184
wenzelm@13114
  2185
lemma list_all2_append1:
nipkow@13145
  2186
"list_all2 P (xs @ ys) zs =
nipkow@13145
  2187
(EX us vs. zs = us @ vs \<and> length us = length xs \<and> length vs = length ys \<and>
nipkow@13145
  2188
list_all2 P xs us \<and> list_all2 P ys vs)"
nipkow@13145
  2189
apply (simp add: list_all2_def zip_append1)
nipkow@13145
  2190
apply (rule iffI)
nipkow@13145
  2191
 apply (rule_tac x = "take (length xs) zs" in exI)
nipkow@13145
  2192
 apply (rule_tac x = "drop (length xs) zs" in exI)
paulson@14208
  2193
 apply (force split: nat_diff_split simp add: min_def, clarify)
nipkow@13145
  2194
apply (simp add: ball_Un)
nipkow@13145
  2195
done
wenzelm@13114
  2196
wenzelm@13114
  2197
lemma list_all2_append2:
nipkow@13145
  2198
"list_all2 P xs (ys @ zs) =
nipkow@13145
  2199
(EX us vs. xs = us @ vs \<and> length us = length ys \<and> length vs = length zs \<and>
nipkow@13145
  2200
list_all2 P us ys \<and> list_all2 P vs zs)"
nipkow@13145
  2201
apply (simp add: list_all2_def zip_append2)
nipkow@13145
  2202
apply (rule iffI)
nipkow@13145
  2203
 apply (rule_tac x = "take (length ys) xs" in exI)
nipkow@13145
  2204
 apply (rule_tac x = "drop (length ys) xs" in exI)
paulson@14208
  2205
 apply (force split: nat_diff_split simp add: min_def, clarify)
nipkow@13145
  2206
apply (simp add: ball_Un)
nipkow@13145
  2207
done
wenzelm@13114
  2208
kleing@13863
  2209
lemma list_all2_append:
nipkow@14247
  2210
  "length xs = length ys \<Longrightarrow>
nipkow@14247
  2211
  list_all2 P (xs@us) (ys@vs) = (list_all2 P xs ys \<and> list_all2 P us vs)"
nipkow@14247
  2212
by (induct rule:list_induct2, simp_all)
kleing@13863
  2213
kleing@13863
  2214
lemma list_all2_appendI [intro?, trans]:
kleing@13863
  2215
  "\<lbrakk> list_all2 P a b; list_all2 P c d \<rbrakk> \<Longrightarrow> list_all2 P (a@c) (b@d)"
nipkow@24349
  2216
by (simp add: list_all2_append list_all2_lengthD)
kleing@13863
  2217
wenzelm@13114
  2218
lemma list_all2_conv_all_nth:
nipkow@13145
  2219
"list_all2 P xs ys =
nipkow@13145
  2220
(length xs = length ys \<and> (\<forall>i < length xs. P (xs!i) (ys!i)))"
nipkow@13145
  2221
by (force simp add: list_all2_def set_zip)
wenzelm@13114
  2222
berghofe@13883
  2223
lemma list_all2_trans:
berghofe@13883
  2224
  assumes tr: "!!a b c. P1 a b ==> P2 b c ==> P3 a c"
berghofe@13883
  2225
  shows "!!bs cs. list_all2 P1 as bs ==> list_all2 P2 bs cs ==> list_all2 P3 as cs"
berghofe@13883
  2226
        (is "!!bs cs. PROP ?Q as bs cs")
berghofe@13883
  2227
proof (induct as)
berghofe@13883
  2228
  fix x xs bs assume I1: "!!bs cs. PROP ?Q xs bs cs"
berghofe@13883
  2229
  show "!!cs. PROP ?Q (x # xs) bs cs"
berghofe@13883
  2230
  proof (induct bs)
berghofe@13883
  2231
    fix y ys cs assume I2: "!!cs. PROP ?Q (x # xs) ys cs"
berghofe@13883
  2232
    show "PROP ?Q (x # xs) (y # ys) cs"
berghofe@13883
  2233
      by (induct cs) (auto intro: tr I1 I2)
berghofe@13883
  2234
  qed simp
berghofe@13883
  2235
qed simp
berghofe@13883
  2236
kleing@13863
  2237
lemma list_all2_all_nthI [intro?]:
kleing@13863
  2238
  "length a = length b \<Longrightarrow> (\<And>n. n < length a \<Longrightarrow> P (a!n) (b!n)) \<Longrightarrow> list_all2 P a b"
nipkow@24349
  2239
by (simp add: list_all2_conv_all_nth)
kleing@13863
  2240
paulson@14395
  2241
lemma list_all2I:
paulson@14395
  2242
  "\<forall>x \<in> set (zip a b). split P x \<Longrightarrow> length a = length b \<Longrightarrow> list_all2 P a b"
nipkow@24349
  2243
by (simp add: list_all2_def)
paulson@14395
  2244
kleing@14328
  2245
lemma list_all2_nthD:
kleing@13863
  2246
  "\<lbrakk> list_all2 P xs ys; p < size xs \<rbrakk> \<Longrightarrow> P (xs!p) (ys!p)"
nipkow@24349
  2247
by (simp add: list_all2_conv_all_nth)
kleing@13863
  2248
nipkow@14302
  2249
lemma list_all2_nthD2:
nipkow@14302
  2250
  "\<lbrakk>list_all2 P xs ys; p < size ys\<rbrakk> \<Longrightarrow> P (xs!p) (ys!p)"
nipkow@24349
  2251
by (frule list_all2_lengthD) (auto intro: list_all2_nthD)
nipkow@14302
  2252
kleing@13863
  2253
lemma list_all2_map1: 
kleing@13863
  2254
  "list_all2 P (map f as) bs = list_all2 (\<lambda>x y. P (f x) y) as bs"
nipkow@24349
  2255
by (simp add: list_all2_conv_all_nth)
kleing@13863
  2256
kleing@13863
  2257
lemma list_all2_map2: 
kleing@13863
  2258
  "list_all2 P as (map f bs) = list_all2 (\<lambda>x y. P x (f y)) as bs"
nipkow@24349
  2259
by (auto simp add: list_all2_conv_all_nth)
kleing@13863
  2260
kleing@14316
  2261
lemma list_all2_refl [intro?]:
kleing@13863
  2262
  "(\<And>x. P x x) \<Longrightarrow> list_all2 P xs xs"
nipkow@24349
  2263
by (simp add: list_all2_conv_all_nth)
kleing@13863
  2264
kleing@13863
  2265
lemma list_all2_update_cong:
kleing@13863
  2266
  "\<lbrakk> i<size xs; list_all2 P xs ys; P x y \<rbrakk> \<Longrightarrow> list_all2 P (xs[i:=x]) (ys[i:=y])"
nipkow@24349
  2267
by (simp add: list_all2_conv_all_nth nth_list_update)
kleing@13863
  2268
kleing@13863
  2269
lemma list_all2_update_cong2:
kleing@13863
  2270
  "\<lbrakk>list_all2 P xs ys; P x y; i < length ys\<rbrakk> \<Longrightarrow> list_all2 P (xs[i:=x]) (ys[i:=y])"
nipkow@24349
  2271
by (simp add: list_all2_lengthD list_all2_update_cong)
kleing@13863
  2272
nipkow@14302
  2273
lemma list_all2_takeI [simp,intro?]:
nipkow@24526
  2274
  "list_all2 P xs ys \<Longrightarrow> list_all2 P (take n xs) (take n ys)"
nipkow@24526
  2275
apply (induct xs arbitrary: n ys)
nipkow@24526
  2276
 apply simp
nipkow@24526
  2277
apply (clarsimp simp add: list_all2_Cons1)
nipkow@24526
  2278
apply (case_tac n)
nipkow@24526
  2279
apply auto
nipkow@24526
  2280
done
nipkow@14302
  2281
nipkow@14302
  2282
lemma list_all2_dropI [simp,intro?]:
nipkow@24526
  2283
  "list_all2 P as bs \<Longrightarrow> list_all2 P (drop n as) (drop n bs)"
nipkow@24526
  2284
apply (induct as arbitrary: n bs, simp)
nipkow@24526
  2285
apply (clarsimp simp add: list_all2_Cons1)
nipkow@24526
  2286
apply (case_tac n, simp, simp)
nipkow@24526
  2287
done
kleing@13863
  2288
kleing@14327
  2289
lemma list_all2_mono [intro?]:
nipkow@24526
  2290
  "list_all2 P xs ys \<Longrightarrow> (\<And>xs ys. P xs ys \<Longrightarrow> Q xs ys) \<Longrightarrow> list_all2 Q xs ys"
nipkow@24526
  2291
apply (induct xs arbitrary: ys, simp)
nipkow@24526
  2292
apply (case_tac ys, auto)
nipkow@24526
  2293
done
kleing@13863
  2294
haftmann@22551
  2295
lemma list_all2_eq:
haftmann@22551
  2296
  "xs = ys \<longleftrightarrow> list_all2 (op =) xs ys"
nipkow@24349
  2297
by (induct xs ys rule: list_induct2') auto
haftmann@22551
  2298
wenzelm@13142
  2299
nipkow@15392
  2300
subsubsection {* @{text foldl} and @{text foldr} *}
wenzelm@13142
  2301
wenzelm@13142
  2302
lemma foldl_append [simp]:
nipkow@24526
  2303
  "foldl f a (xs @ ys) = foldl f (foldl f a xs) ys"
nipkow@24526
  2304
by (induct xs arbitrary: a) auto
wenzelm@13142
  2305
nipkow@14402
  2306
lemma foldr_append[simp]: "foldr f (xs @ ys) a = foldr f xs (foldr f ys a)"
nipkow@14402
  2307
by (induct xs) auto
nipkow@14402
  2308
nipkow@23096
  2309
lemma foldr_map: "foldr g (map f xs) a = foldr (g o f) xs a"
nipkow@23096
  2310
by(induct xs) simp_all
nipkow@23096
  2311
nipkow@24449
  2312
text{* For efficient code generation: avoid intermediate list. *}
haftmann@31998
  2313
lemma foldl_map[code_unfold]:
nipkow@24449
  2314
  "foldl g a (map f xs) = foldl (%a x. g a (f x)) a xs"
nipkow@23096
  2315
by(induct xs arbitrary:a) simp_all
nipkow@23096
  2316
haftmann@34978
  2317
lemma foldl_apply:
haftmann@34978
  2318
  assumes "\<And>x. x \<in> set xs \<Longrightarrow> f x \<circ> h = h \<circ> g x"
haftmann@34978
  2319
  shows "foldl (\<lambda>s x. f x s) (h s) xs = h (foldl (\<lambda>s x. g x s) s xs)"
haftmann@34978
  2320
  by (rule sym, insert assms, induct xs arbitrary: s) (simp_all add: expand_fun_eq)
haftmann@31930
  2321
krauss@19770
  2322
lemma foldl_cong [fundef_cong, recdef_cong]:
krauss@18336
  2323
  "[| a = b; l = k; !!a x. x : set l ==> f a x = g a x |] 
krauss@18336
  2324
  ==> foldl f a l = foldl g b k"
nipkow@24349
  2325
by (induct k arbitrary: a b l) simp_all
krauss@18336
  2326
krauss@19770
  2327
lemma foldr_cong [fundef_cong, recdef_cong]:
krauss@18336
  2328
  "[| a = b; l = k; !!a x. x : set l ==> f x a = g x a |] 
krauss@18336
  2329
  ==> foldr f l a = foldr g k b"
nipkow@24349
  2330
by (induct k arbitrary: a b l) simp_all
krauss@18336
  2331
haftmann@35195
  2332
lemma foldl_fun_comm:
haftmann@35195
  2333
  assumes "\<And>x y s. f (f s x) y = f (f s y) x"
haftmann@35195
  2334
  shows "f (foldl f s xs) x = foldl f (f s x) xs"
haftmann@35195
  2335
  by (induct xs arbitrary: s)
haftmann@35195
  2336
    (simp_all add: assms)
haftmann@35195
  2337
nipkow@24449
  2338
lemma (in semigroup_add) foldl_assoc:
haftmann@25062
  2339
shows "foldl op+ (x+y) zs = x + (foldl op+ y zs)"
nipkow@24449
  2340
by (induct zs arbitrary: y) (simp_all add:add_assoc)
nipkow@24449
  2341
nipkow@24449
  2342
lemma (in monoid_add) foldl_absorb0:
haftmann@25062
  2343
shows "x + (foldl op+ 0 zs) = foldl op+ x zs"
nipkow@24449
  2344
by (induct zs) (simp_all add:foldl_assoc)
nipkow@24449
  2345
haftmann@35195
  2346
lemma foldl_rev:
haftmann@35195
  2347
  assumes "\<And>x y s. f (f s x) y = f (f s y) x"
haftmann@35195
  2348
  shows "foldl f s (rev xs) = foldl f s xs"
haftmann@35195
  2349
proof (induct xs arbitrary: s)
haftmann@35195
  2350
  case Nil then show ?case by simp
haftmann@35195
  2351
next
haftmann@35195
  2352
  case (Cons x xs) with assms show ?case by (simp add: foldl_fun_comm)
haftmann@35195
  2353
qed
haftmann@35195
  2354
haftmann@37605
  2355
lemma rev_foldl_cons [code]:
haftmann@37605
  2356
  "rev xs = foldl (\<lambda>xs x. x # xs) [] xs"
haftmann@37605
  2357
proof (induct xs)
haftmann@37605
  2358
  case Nil then show ?case by simp
haftmann@37605
  2359
next
haftmann@37605
  2360
  case Cons
haftmann@37605
  2361
  {
haftmann@37605
  2362
    fix x xs ys
haftmann@37605
  2363
    have "foldl (\<lambda>xs x. x # xs) ys xs @ [x]
haftmann@37605
  2364
      = foldl (\<lambda>xs x. x # xs) (ys @ [x]) xs"
haftmann@37605
  2365
    by (induct xs arbitrary: ys) auto
haftmann@37605
  2366
  }
haftmann@37605
  2367
  note aux = this
haftmann@37605
  2368
  show ?case by (induct xs) (auto simp add: Cons aux)
haftmann@37605
  2369
qed
haftmann@37605
  2370
nipkow@24449
  2371
nipkow@23096
  2372
text{* The ``First Duality Theorem'' in Bird \& Wadler: *}
nipkow@23096
  2373
nipkow@23096
  2374
lemma foldl_foldr1_lemma:
nipkow@23096
  2375
 "foldl op + a xs = a + foldr op + xs (0\<Colon>'a::monoid_add)"
nipkow@23096
  2376
by (induct xs arbitrary: a) (auto simp:add_assoc)
nipkow@23096
  2377
nipkow@23096
  2378
corollary foldl_foldr1:
nipkow@23096
  2379
 "foldl op + 0 xs = foldr op + xs (0\<Colon>'a::monoid_add)"
nipkow@23096
  2380
by (simp add:foldl_foldr1_lemma)
nipkow@23096
  2381
nipkow@23096
  2382
nipkow@23096
  2383
text{* The ``Third Duality Theorem'' in Bird \& Wadler: *}
nipkow@23096
  2384
nipkow@14402
  2385
lemma foldr_foldl: "foldr f xs a = foldl (%x y. f y x) a (rev xs)"
nipkow@14402
  2386
by (induct xs) auto
nipkow@14402
  2387
nipkow@14402
  2388
lemma foldl_foldr: "foldl f a xs = foldr (%x y. f y x) (rev xs) a"
nipkow@14402
  2389
by (simp add: foldr_foldl [of "%x y. f y x" "rev xs"])
nipkow@14402
  2390
haftmann@25062
  2391
lemma (in ab_semigroup_add) foldr_conv_foldl: "foldr op + xs a = foldl op + a xs"
chaieb@24471
  2392
  by (induct xs, auto simp add: foldl_assoc add_commute)
chaieb@24471
  2393
wenzelm@13142
  2394
text {*
nipkow@13145
  2395
Note: @{text "n \<le> foldl (op +) n ns"} looks simpler, but is more
nipkow@13145
  2396
difficult to use because it requires an additional transitivity step.
wenzelm@13142
  2397
*}
wenzelm@13142
  2398
nipkow@24526
  2399
lemma start_le_sum: "(m::nat) <= n ==> m <= foldl (op +) n ns"
nipkow@24526
  2400
by (induct ns arbitrary: n) auto
nipkow@24526
  2401
nipkow@24526
  2402
lemma elem_le_sum: "(n::nat) : set ns ==> n <= foldl (op +) 0 ns"
nipkow@13145
  2403
by (force intro: start_le_sum simp add: in_set_conv_decomp)
wenzelm@13142
  2404
wenzelm@13142
  2405
lemma sum_eq_0_conv [iff]:
nipkow@24526
  2406
  "(foldl (op +) (m::nat) ns = 0) = (m = 0 \<and> (\<forall>n \<in> set ns. n = 0))"
nipkow@24526
  2407
by (induct ns arbitrary: m) auto
wenzelm@13114
  2408
chaieb@24471
  2409
lemma foldr_invariant: 
chaieb@24471
  2410
  "\<lbrakk>Q x ; \<forall> x\<in> set xs. P x; \<forall> x y. P x \<and> Q y \<longrightarrow> Q (f x y) \<rbrakk> \<Longrightarrow> Q (foldr f xs x)"
chaieb@24471
  2411
  by (induct xs, simp_all)
chaieb@24471
  2412
chaieb@24471
  2413
lemma foldl_invariant: 
chaieb@24471
  2414
  "\<lbrakk>Q x ; \<forall> x\<in> set xs. P x; \<forall> x y. P x \<and> Q y \<longrightarrow> Q (f y x) \<rbrakk> \<Longrightarrow> Q (foldl f x xs)"
chaieb@24471
  2415
  by (induct xs arbitrary: x, simp_all)
chaieb@24471
  2416
haftmann@34978
  2417
lemma foldl_weak_invariant:
haftmann@34978
  2418
  assumes "P s"
haftmann@34978
  2419
    and "\<And>s x. x \<in> set xs \<Longrightarrow> P s \<Longrightarrow> P (f s x)"
haftmann@34978
  2420
  shows "P (foldl f s xs)"
haftmann@34978
  2421
  using assms by (induct xs arbitrary: s) simp_all
haftmann@34978
  2422
haftmann@31455
  2423
text {* @{const foldl} and @{const concat} *}
nipkow@24449
  2424
nipkow@24449
  2425
lemma foldl_conv_concat:
haftmann@29782
  2426
  "foldl (op @) xs xss = xs @ concat xss"
haftmann@29782
  2427
proof (induct xss arbitrary: xs)
haftmann@29782
  2428
  case Nil show ?case by simp
haftmann@29782
  2429
next
haftmann@35267
  2430
  interpret monoid_add "op @" "[]" proof qed simp_all
haftmann@29782
  2431
  case Cons then show ?case by (simp add: foldl_absorb0)
haftmann@29782
  2432
qed
haftmann@29782
  2433
haftmann@29782
  2434
lemma concat_conv_foldl: "concat xss = foldl (op @) [] xss"
haftmann@29782
  2435
  by (simp add: foldl_conv_concat)
haftmann@29782
  2436
haftmann@31455
  2437
text {* @{const Finite_Set.fold} and @{const foldl} *}
haftmann@31455
  2438
haftmann@35195
  2439
lemma (in fun_left_comm) fold_set_remdups:
haftmann@35195
  2440
  "fold f y (set xs) = foldl (\<lambda>y x. f x y) y (remdups xs)"
haftmann@35195
  2441
  by (rule sym, induct xs arbitrary: y) (simp_all add: fold_fun_comm insert_absorb)
haftmann@35195
  2442
haftmann@31455
  2443
lemma (in fun_left_comm_idem) fold_set:
haftmann@31455
  2444
  "fold f y (set xs) = foldl (\<lambda>y x. f x y) y xs"
haftmann@31455
  2445
  by (rule sym, induct xs arbitrary: y) (simp_all add: fold_fun_comm)
haftmann@31455
  2446
haftmann@32681
  2447
lemma (in ab_semigroup_idem_mult) fold1_set:
haftmann@32681
  2448
  assumes "xs \<noteq> []"
haftmann@32681
  2449
  shows "fold1 times (set xs) = foldl times (hd xs) (tl xs)"
haftmann@32681
  2450
proof -
haftmann@32681
  2451
  interpret fun_left_comm_idem times by (fact fun_left_comm_idem)
haftmann@32681
  2452
  from assms obtain y ys where xs: "xs = y # ys"
haftmann@32681
  2453
    by (cases xs) auto
haftmann@32681
  2454
  show ?thesis
haftmann@32681
  2455
  proof (cases "set ys = {}")
haftmann@32681
  2456
    case True with xs show ?thesis by simp
haftmann@32681
  2457
  next
haftmann@32681
  2458
    case False
haftmann@32681
  2459
    then have "fold1 times (insert y (set ys)) = fold times y (set ys)"
haftmann@32681
  2460
      by (simp only: finite_set fold1_eq_fold_idem)
haftmann@32681
  2461
    with xs show ?thesis by (simp add: fold_set mult_commute)
haftmann@32681
  2462
  qed
haftmann@32681
  2463
qed
haftmann@32681
  2464
haftmann@32681
  2465
lemma (in lattice) Inf_fin_set_fold [code_unfold]:
haftmann@32681
  2466
  "Inf_fin (set (x # xs)) = foldl inf x xs"
haftmann@32681
  2467
proof -
haftmann@32681
  2468
  interpret ab_semigroup_idem_mult "inf :: 'a \<Rightarrow> 'a \<Rightarrow> 'a"
haftmann@32681
  2469
    by (fact ab_semigroup_idem_mult_inf)
haftmann@32681
  2470
  show ?thesis
haftmann@32681
  2471
    by (simp add: Inf_fin_def fold1_set del: set.simps)
haftmann@32681
  2472
qed
haftmann@32681
  2473
haftmann@32681
  2474
lemma (in lattice) Sup_fin_set_fold [code_unfold]:
haftmann@32681
  2475
  "Sup_fin (set (x # xs)) = foldl sup x xs"
haftmann@32681
  2476
proof -
haftmann@32681
  2477
  interpret ab_semigroup_idem_mult "sup :: 'a \<Rightarrow> 'a \<Rightarrow> 'a"
haftmann@32681
  2478
    by (fact ab_semigroup_idem_mult_sup)
haftmann@32681
  2479
  show ?thesis
haftmann@32681
  2480
    by (simp add: Sup_fin_def fold1_set del: set.simps)
haftmann@32681
  2481
qed
haftmann@32681
  2482
haftmann@32681
  2483
lemma (in linorder) Min_fin_set_fold [code_unfold]:
haftmann@32681
  2484
  "Min (set (x # xs)) = foldl min x xs"
haftmann@32681
  2485
proof -
haftmann@32681
  2486
  interpret ab_semigroup_idem_mult "min :: 'a \<Rightarrow> 'a \<Rightarrow> 'a"
haftmann@32681
  2487
    by (fact ab_semigroup_idem_mult_min)
haftmann@32681
  2488
  show ?thesis
haftmann@32681
  2489
    by (simp add: Min_def fold1_set del: set.simps)
haftmann@32681
  2490
qed
haftmann@32681
  2491
haftmann@32681
  2492
lemma (in linorder) Max_fin_set_fold [code_unfold]:
haftmann@32681
  2493
  "Max (set (x # xs)) = foldl max x xs"
haftmann@32681
  2494
proof -
haftmann@32681
  2495
  interpret ab_semigroup_idem_mult "max :: 'a \<Rightarrow> 'a \<Rightarrow> 'a"
haftmann@32681
  2496
    by (fact ab_semigroup_idem_mult_max)
haftmann@32681
  2497
  show ?thesis
haftmann@32681
  2498
    by (simp add: Max_def fold1_set del: set.simps)
haftmann@32681
  2499
qed
haftmann@32681
  2500
haftmann@32681
  2501
lemma (in complete_lattice) Inf_set_fold [code_unfold]:
haftmann@32681
  2502
  "Inf (set xs) = foldl inf top xs"
haftmann@34007
  2503
proof -
haftmann@34007
  2504
  interpret fun_left_comm_idem "inf :: 'a \<Rightarrow> 'a \<Rightarrow> 'a"
haftmann@34007
  2505
    by (fact fun_left_comm_idem_inf)
haftmann@34007
  2506
  show ?thesis by (simp add: Inf_fold_inf fold_set inf_commute)
haftmann@34007
  2507
qed
haftmann@32681
  2508
haftmann@32681
  2509
lemma (in complete_lattice) Sup_set_fold [code_unfold]:
haftmann@32681
  2510
  "Sup (set xs) = foldl sup bot xs"
haftmann@34007
  2511
proof -
haftmann@34007
  2512
  interpret fun_left_comm_idem "sup :: 'a \<Rightarrow> 'a \<Rightarrow> 'a"
haftmann@34007
  2513
    by (fact fun_left_comm_idem_sup)
haftmann@34007
  2514
  show ?thesis by (simp add: Sup_fold_sup fold_set sup_commute)
haftmann@34007
  2515
qed
haftmann@34007
  2516
haftmann@34007
  2517
lemma (in complete_lattice) INFI_set_fold:
haftmann@34007
  2518
  "INFI (set xs) f = foldl (\<lambda>y x. inf (f x) y) top xs"
haftmann@34007
  2519
  unfolding INFI_def set_map [symmetric] Inf_set_fold foldl_map
haftmann@34007
  2520
    by (simp add: inf_commute)
haftmann@34007
  2521
haftmann@34007
  2522
lemma (in complete_lattice) SUPR_set_fold:
haftmann@34007
  2523
  "SUPR (set xs) f = foldl (\<lambda>y x. sup (f x) y) bot xs"
haftmann@34007
  2524
  unfolding SUPR_def set_map [symmetric] Sup_set_fold foldl_map
haftmann@34007
  2525
    by (simp add: sup_commute)
haftmann@31455
  2526
wenzelm@35115
  2527
nipkow@24645
  2528
subsubsection {* @{text upt} *}
wenzelm@13114
  2529
nipkow@17090
  2530
lemma upt_rec[code]: "[i..<j] = (if i<j then i#[Suc i..<j] else [])"
nipkow@17090
  2531
-- {* simp does not terminate! *}
nipkow@13145
  2532
by (induct j) auto
wenzelm@13142
  2533
nipkow@32005
  2534
lemmas upt_rec_number_of[simp] = upt_rec[of "number_of m" "number_of n", standard]
nipkow@32005
  2535
nipkow@15425
  2536
lemma upt_conv_Nil [simp]: "j <= i ==> [i..<j] = []"
nipkow@13145
  2537
by (subst upt_rec) simp
wenzelm@13114
  2538
nipkow@15425
  2539
lemma upt_eq_Nil_conv[simp]: "([i..<j] = []) = (j = 0 \<or> j <= i)"
nipkow@15281
  2540
by(induct j)simp_all
nipkow@15281
  2541
nipkow@15281
  2542
lemma upt_eq_Cons_conv:
nipkow@24526
  2543
 "([i..<j] = x#xs) = (i < j & i = x & [i+1..<j] = xs)"
nipkow@24526
  2544
apply(induct j arbitrary: x xs)
nipkow@15281
  2545
 apply simp
nipkow@15281
  2546
apply(clarsimp simp add: append_eq_Cons_conv)
nipkow@15281
  2547
apply arith
nipkow@15281
  2548
done
nipkow@15281
  2549
nipkow@15425
  2550
lemma upt_Suc_append: "i <= j ==> [i..<(Suc j)] = [i..<j]@[j]"
nipkow@13145
  2551
-- {* Only needed if @{text upt_Suc} is deleted from the simpset. *}
nipkow@13145
  2552
by simp
wenzelm@13114
  2553
nipkow@15425
  2554
lemma upt_conv_Cons: "i < j ==> [i..<j] = i # [Suc i..<j]"
haftmann@26734
  2555
  by (simp add: upt_rec)
wenzelm@13114
  2556
nipkow@15425
  2557
lemma upt_add_eq_append: "i<=j ==> [i..<j+k] = [i..<j]@[j..<j+k]"
nipkow@13145
  2558
-- {* LOOPS as a simprule, since @{text "j <= j"}. *}
nipkow@13145
  2559
by (induct k) auto
wenzelm@13114
  2560
nipkow@15425
  2561
lemma length_upt [simp]: "length [i..<j] = j - i"
nipkow@13145
  2562
by (induct j) (auto simp add: Suc_diff_le)
wenzelm@13114
  2563
nipkow@15425
  2564
lemma nth_upt [simp]: "i + k < j ==> [i..<j] ! k = i + k"
nipkow@13145
  2565
apply (induct j)
nipkow@13145
  2566
apply (auto simp add: less_Suc_eq nth_append split: nat_diff_split)
nipkow@13145
  2567
done
wenzelm@13114
  2568
nipkow@17906
  2569
nipkow@17906
  2570
lemma hd_upt[simp]: "i < j \<Longrightarrow> hd[i..<j] = i"
nipkow@17906
  2571
by(simp add:upt_conv_Cons)
nipkow@17906
  2572
nipkow@17906
  2573
lemma last_upt[simp]: "i < j \<Longrightarrow> last[i..<j] = j - 1"
nipkow@17906
  2574
apply(cases j)
nipkow@17906
  2575
 apply simp
nipkow@17906
  2576
by(simp add:upt_Suc_append)
nipkow@17906
  2577
nipkow@24526
  2578
lemma take_upt [simp]: "i+m <= n ==> take m [i..<n] = [i..<i+m]"
nipkow@24526
  2579
apply (induct m arbitrary: i, simp)
nipkow@13145
  2580
apply (subst upt_rec)
nipkow@13145
  2581
apply (rule sym)
nipkow@13145
  2582
apply (subst upt_rec)
nipkow@13145
  2583
apply (simp del: upt.simps)
nipkow@13145
  2584
done
nipkow@3507
  2585
nipkow@17501
  2586
lemma drop_upt[simp]: "drop m [i..<j] = [i+m..<j]"
nipkow@17501
  2587
apply(induct j)
nipkow@17501
  2588
apply auto
nipkow@17501
  2589
done
nipkow@17501
  2590
nipkow@24645
  2591
lemma map_Suc_upt: "map Suc [m..<n] = [Suc m..<Suc n]"
nipkow@13145
  2592
by (induct n) auto
wenzelm@13114
  2593
nipkow@24526
  2594
lemma nth_map_upt: "i < n-m ==> (map f [m..<n]) ! i = f(m+i)"
nipkow@24526
  2595
apply (induct n m  arbitrary: i rule: diff_induct)
nipkow@13145
  2596
prefer 3 apply (subst map_Suc_upt[symmetric])
nipkow@13145
  2597
apply (auto simp add: less_diff_conv nth_upt)
nipkow@13145
  2598
done
wenzelm@13114
  2599
berghofe@13883
  2600
lemma nth_take_lemma:
nipkow@24526
  2601
  "k <= length xs ==> k <= length ys ==>
berghofe@13883
  2602
     (!!i. i < k --> xs!i = ys!i) ==> take k xs = take k ys"
nipkow@24526
  2603
apply (atomize, induct k arbitrary: xs ys)
paulson@14208
  2604
apply (simp_all add: less_Suc_eq_0_disj all_conj_distrib, clarify)
nipkow@13145
  2605
txt {* Both lists must be non-empty *}
paulson@14208
  2606
apply (case_tac xs, simp)
paulson@14208
  2607
apply (case_tac ys, clarify)
nipkow@13145
  2608
 apply (simp (no_asm_use))
nipkow@13145
  2609
apply clarify
nipkow@13145
  2610
txt {* prenexing's needed, not miniscoping *}
nipkow@13145
  2611
apply (simp (no_asm_use) add: all_simps [symmetric] del: all_simps)
nipkow@13145
  2612
apply blast
nipkow@13145
  2613
done
wenzelm@13114
  2614
wenzelm@13114
  2615
lemma nth_equalityI:
wenzelm@13114
  2616
 "[| length xs = length ys; ALL i < length xs. xs!i = ys!i |] ==> xs = ys"
nipkow@13145
  2617
apply (frule nth_take_lemma [OF le_refl eq_imp_le])
nipkow@13145
  2618
apply (simp_all add: take_all)
nipkow@13145
  2619
done
wenzelm@13142
  2620
haftmann@24796
  2621
lemma map_nth:
haftmann@24796
  2622
  "map (\<lambda>i. xs ! i) [0..<length xs] = xs"
haftmann@24796
  2623
  by (rule nth_equalityI, auto)
haftmann@24796
  2624
kleing@13863
  2625
(* needs nth_equalityI *)
kleing@13863
  2626
lemma list_all2_antisym:
kleing@13863
  2627
  "\<lbrakk> (\<And>x y. \<lbrakk>P x y; Q y x\<rbrakk> \<Longrightarrow> x = y); list_all2 P xs ys; list_all2 Q ys xs \<rbrakk> 
kleing@13863
  2628
  \<Longrightarrow> xs = ys"
kleing@13863
  2629
  apply (simp add: list_all2_conv_all_nth) 
paulson@14208
  2630
  apply (rule nth_equalityI, blast, simp)
kleing@13863
  2631
  done
kleing@13863
  2632
wenzelm@13142
  2633
lemma take_equalityI: "(\<forall>i. take i xs = take i ys) ==> xs = ys"
nipkow@13145
  2634
-- {* The famous take-lemma. *}
nipkow@13145
  2635
apply (drule_tac x = "max (length xs) (length ys)" in spec)
nipkow@13145
  2636
apply (simp add: le_max_iff_disj take_all)
nipkow@13145
  2637
done
wenzelm@13142
  2638
wenzelm@13142
  2639
nipkow@15302
  2640
lemma take_Cons':
nipkow@15302
  2641
     "take n (x # xs) = (if n = 0 then [] else x # take (n - 1) xs)"
nipkow@15302
  2642
by (cases n) simp_all
nipkow@15302
  2643
nipkow@15302
  2644
lemma drop_Cons':
nipkow@15302
  2645
     "drop n (x # xs) = (if n = 0 then x # xs else drop (n - 1) xs)"
nipkow@15302
  2646
by (cases n) simp_all
nipkow@15302
  2647
nipkow@15302
  2648
lemma nth_Cons': "(x # xs)!n = (if n = 0 then x else xs!(n - 1))"
nipkow@15302
  2649
by (cases n) simp_all
nipkow@15302
  2650
paulson@18622
  2651
lemmas take_Cons_number_of = take_Cons'[of "number_of v",standard]
paulson@18622
  2652
lemmas drop_Cons_number_of = drop_Cons'[of "number_of v",standard]
paulson@18622
  2653
lemmas nth_Cons_number_of = nth_Cons'[of _ _ "number_of v",standard]
paulson@18622
  2654
paulson@18622
  2655
declare take_Cons_number_of [simp] 
paulson@18622
  2656
        drop_Cons_number_of [simp] 
paulson@18622
  2657
        nth_Cons_number_of [simp] 
nipkow@15302
  2658
nipkow@15302
  2659
nipkow@32415
  2660
subsubsection {* @{text upto}: interval-list on @{typ int} *}
nipkow@32415
  2661
nipkow@32415
  2662
(* FIXME make upto tail recursive? *)
nipkow@32415
  2663
nipkow@32415
  2664
function upto :: "int \<Rightarrow> int \<Rightarrow> int list" ("(1[_../_])") where
nipkow@32415
  2665
"upto i j = (if i \<le> j then i # [i+1..j] else [])"
nipkow@32415
  2666
by auto
nipkow@32415
  2667
termination
nipkow@32415
  2668
by(relation "measure(%(i::int,j). nat(j - i + 1))") auto
nipkow@32415
  2669
nipkow@32415
  2670
declare upto.simps[code, simp del]
nipkow@32415
  2671
nipkow@32415
  2672
lemmas upto_rec_number_of[simp] =
nipkow@32415
  2673
  upto.simps[of "number_of m" "number_of n", standard]
nipkow@32415
  2674
nipkow@32415
  2675
lemma upto_empty[simp]: "j < i \<Longrightarrow> [i..j] = []"