src/HOL/List.thy
author nipkow
Tue Aug 28 15:34:15 2007 +0200 (2007-08-28)
changeset 24449 2f05cb7fed85
parent 24349 0dd8782fb02d
child 24461 bbff04c027ec
permissions -rw-r--r--
added (code) lemmas for setsum and foldl
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(*  Title:      HOL/List.thy
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    ID:         $Id$
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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 PreList
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uses "Tools/string_syntax.ML"
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  ("Tools/function_package/lexicographic_order.ML")
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  ("Tools/function_package/fundef_datatype.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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subsection{*Basic list processing functions*}
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consts
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  filter:: "('a => bool) => 'a list => 'a list"
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  concat:: "'a list list => 'a list"
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  foldl :: "('b => 'a => 'b) => 'b => 'a list => 'b"
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  foldr :: "('a => 'b => 'b) => 'a list => 'b => 'b"
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  hd:: "'a list => 'a"
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  tl:: "'a list => 'a list"
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  last:: "'a list => 'a"
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  butlast :: "'a list => 'a list"
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  set :: "'a list => 'a set"
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  map :: "('a=>'b) => ('a list => 'b list)"
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  listsum ::  "'a list => 'a::monoid_add"
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  nth :: "'a list => nat => 'a"    (infixl "!" 100)
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  list_update :: "'a list => nat => 'a => 'a list"
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  take:: "nat => 'a list => 'a list"
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  drop:: "nat => 'a list => 'a list"
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  takeWhile :: "('a => bool) => 'a list => 'a list"
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  dropWhile :: "('a => bool) => 'a list => 'a list"
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  rev :: "'a list => 'a list"
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  zip :: "'a list => 'b list => ('a * 'b) list"
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  upt :: "nat => nat => nat list" ("(1[_..</_'])")
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  remdups :: "'a list => 'a list"
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  remove1 :: "'a => 'a list => 'a list"
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  "distinct":: "'a list => bool"
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  replicate :: "nat => 'a => 'a list"
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  splice :: "'a list \<Rightarrow> 'a list \<Rightarrow> 'a list"
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abbreviation
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  upto:: "nat => nat => nat list"  ("(1[_../_])") where
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  "[i..j] == [i..<(Suc j)]"
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nonterminals lupdbinds lupdbind
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syntax
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  -- {* list Enumeration *}
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  "@list" :: "args => 'a list"    ("[(_)]")
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  -- {* Special syntax for filter *}
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  "@filter" :: "[pttrn, 'a list, bool] => 'a list"    ("(1[_<-_./ _])")
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  -- {* list update *}
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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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  "[x, xs]" == "x#[xs]"
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  "[x]" == "x#[]"
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  "[x<-xs . P]"== "filter (%x. P) xs"
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  "_LUpdate xs (_lupdbinds b bs)"== "_LUpdate (_LUpdate xs b) bs"
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  "xs[i:=x]" == "list_update xs i x"
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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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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 => nat" where
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  "length == size"
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primrec
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  "hd(x#xs) = x"
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primrec
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  "tl([]) = []"
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  "tl(x#xs) = xs"
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primrec
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  "last(x#xs) = (if xs=[] then x else last xs)"
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primrec
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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 [] = {}"
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  "set (x#xs) = insert x (set xs)"
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primrec
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  "map f [] = []"
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  "map f (x#xs) = f(x)#map f xs"
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function (*authentic syntax for append -- revert to primrec
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  as soon as "authentic" primrec is available*)
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  append :: "'a list \<Rightarrow> 'a list \<Rightarrow> 'a list" (infixr "@" 65)
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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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by (auto, case_tac a, auto)
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termination by (relation "measure (size o fst)") auto
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primrec
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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 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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primrec
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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 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([]) = []"
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  "concat(x#xs) = x @ concat(xs)"
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primrec
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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_Nil:"drop n [] = []"
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  drop_Cons: "drop n (x#xs) = (case n of 0 => x#xs | Suc(m) => 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_Nil:"take n [] = []"
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  take_Cons: "take n (x#xs) = (case n of 0 => [] | Suc(m) => 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_Cons:"(x#xs)!n = (case n of 0 => x | (Suc k) => 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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  "[][i:=v] = []"
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  "(x#xs)[i:=v] = (case i of 0 => v # xs | Suc j => x # xs[j:=v])"
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primrec
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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 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 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_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 [] = True"
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  "distinct (x#xs) = (x ~: set xs \<and> distinct xs)"
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primrec
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  "remdups [] = []"
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  "remdups (x#xs) = (if x : set xs then remdups xs else x # remdups xs)"
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primrec
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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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  replicate_0: "replicate 0 x = []"
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  replicate_Suc: "replicate (Suc n) x = x # replicate n x"
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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 [] 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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subsubsection {* List comprehension *}
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text{* Input syntax for Haskell-like list comprehension notation.
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Typical example: @{text"[(x,y). x \<leftarrow> xs, y \<leftarrow> ys, x \<noteq> y]"},
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the list of all pairs of distinct elements from @{text xs} and @{text ys}.
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The syntax is as in Haskell, except that @{text"|"} becomes a dot
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(like in Isabelle's set comprehension): @{text"[e. x \<leftarrow> xs, \<dots>]"} rather than
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\verb![e| x <- xs, ...]!.
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The qualifiers after the dot are
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\begin{description}
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\item[generators] @{text"p \<leftarrow> xs"},
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 where @{text p} is a pattern and @{text xs} an expression of list type,
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\item[guards] @{text"b"}, where @{text b} is a boolean expression, or
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\item[local bindings] @{text"let x = e"}.
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\end{description}
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To avoid misunderstandings, the translation is not reversed upon
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output. You can add the inverse translations in your own theory if you
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desire.
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It is easy to write short list comprehensions which stand for complex
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expressions. During proofs, they may become unreadable (and
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mangled). In such cases it can be advisable to introduce separate
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definitions for the list comprehensions in question.  *}
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(*
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Proper theorem proving support would be nice. For example, if
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@{text"set[f x y. x \<leftarrow> xs, y \<leftarrow> ys, P x y]"}
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produced something like
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@{term"{z. EX x: set xs. EX y:set ys. P x y \<and> z = f x y}"}.
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*)
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nonterminals lc_qual lc_quals
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syntax
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"_listcompr" :: "'a \<Rightarrow> lc_qual \<Rightarrow> lc_quals \<Rightarrow> 'a list"  ("[_ . __")
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"_lc_gen" :: "'a \<Rightarrow> 'a list \<Rightarrow> lc_qual" ("_ <- _")
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"_lc_test" :: "bool \<Rightarrow> lc_qual" ("_")
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"_lc_let" :: "letbinds => lc_qual"  ("let _")
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"_lc_end" :: "lc_quals" ("]")
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"_lc_quals" :: "lc_qual \<Rightarrow> lc_quals \<Rightarrow> lc_quals" (", __")
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"_lc_abs" :: "'a => 'b list => 'b list"
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translations
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"[e. p<-xs]" => "concat(map (_lc_abs p [e]) xs)"
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"_listcompr e (_lc_gen p xs) (_lc_quals Q Qs)"
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 => "concat (map (_lc_abs p (_listcompr e Q Qs)) xs)"
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"[e. P]" => "if P then [e] else []"
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"_listcompr e (_lc_test P) (_lc_quals Q Qs)"
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 => "if P then (_listcompr e Q Qs) else []"
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"_listcompr e (_lc_let b) (_lc_quals Q Qs)"
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 => "_Let b (_listcompr e Q Qs)"
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syntax (xsymbols)
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"_lc_gen" :: "'a \<Rightarrow> 'a list \<Rightarrow> lc_qual" ("_ \<leftarrow> _")
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syntax (HTML output)
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"_lc_gen" :: "'a \<Rightarrow> 'a list \<Rightarrow> lc_qual" ("_ \<leftarrow> _")
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parse_translation (advanced) {*
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let
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   fun abs_tr0 ctxt p es =
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    let
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      val x = Free (Name.variant (add_term_free_names (p$es, [])) "x", dummyT);
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      val case1 = Syntax.const "_case1" $ p $ es;
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      val case2 = Syntax.const "_case1" $ Syntax.const Term.dummy_patternN
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                                        $ Syntax.const @{const_name Nil};
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      val cs = Syntax.const "_case2" $ case1 $ case2
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      val ft = DatatypeCase.case_tr false DatatypePackage.datatype_of_constr
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                 ctxt [x, cs]
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    in lambda x ft end;
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  fun abs_tr ctxt [x as Free (s, T), r] =
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        let val thy = ProofContext.theory_of ctxt;
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            val s' = Sign.intern_const thy s
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        in if Sign.declared_const thy s' then abs_tr0 ctxt x r else lambda x r
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        end
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   | abs_tr ctxt [p,es] = abs_tr0 ctxt p es
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in [("_lc_abs", abs_tr)] end
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*}
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(*
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term "[(x,y,z). b]"
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term "[(x,y). Cons True x \<leftarrow> xs]"
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term "[(x,y,z). Cons x [] \<leftarrow> xs]"
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term "[(x,y,z). x<a, x>b]"
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term "[(x,y,z). x<a, x\<leftarrow>xs]"
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term "[(x,y,z). x\<leftarrow>xs, x>b]"
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term "[(x,y,z). x\<leftarrow>xs, y\<leftarrow>ys]"
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term "[(x,y,z). x<a, x>b, x=d]"
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term "[(x,y,z). x<a, x>b, y\<leftarrow>ys]"
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term "[(x,y,z). x<a, x\<leftarrow>xs,y>b]"
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term "[(x,y,z). x<a, x\<leftarrow>xs, y\<leftarrow>ys]"
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term "[(x,y,z). x\<leftarrow>xs, x>b, y<a]"
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term "[(x,y,z). x\<leftarrow>xs, x>b, y\<leftarrow>ys]"
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term "[(x,y,z). x\<leftarrow>xs, y\<leftarrow>ys,y>x]"
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term "[(x,y,z). x\<leftarrow>xs, y\<leftarrow>ys,z\<leftarrow>zs]"
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term "[(x,y). x\<leftarrow>xs, let xx = x+x, y\<leftarrow>ys, y \<noteq> xx]"
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*)
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subsubsection {* @{const Nil} and @{const Cons} *}
haftmann@21061
   326
haftmann@21061
   327
lemma not_Cons_self [simp]:
haftmann@21061
   328
  "xs \<noteq> x # xs"
nipkow@13145
   329
by (induct xs) auto
wenzelm@13114
   330
wenzelm@13142
   331
lemmas not_Cons_self2 [simp] = not_Cons_self [symmetric]
wenzelm@13114
   332
wenzelm@13142
   333
lemma neq_Nil_conv: "(xs \<noteq> []) = (\<exists>y ys. xs = y # ys)"
nipkow@13145
   334
by (induct xs) auto
wenzelm@13114
   335
wenzelm@13142
   336
lemma length_induct:
haftmann@21061
   337
  "(\<And>xs. \<forall>ys. length ys < length xs \<longrightarrow> P ys \<Longrightarrow> P xs) \<Longrightarrow> P xs"
nipkow@17589
   338
by (rule measure_induct [of length]) iprover
wenzelm@13114
   339
wenzelm@13114
   340
haftmann@21061
   341
subsubsection {* @{const length} *}
wenzelm@13114
   342
wenzelm@13142
   343
text {*
haftmann@21061
   344
  Needs to come before @{text "@"} because of theorem @{text
haftmann@21061
   345
  append_eq_append_conv}.
wenzelm@13142
   346
*}
wenzelm@13114
   347
wenzelm@13142
   348
lemma length_append [simp]: "length (xs @ ys) = length xs + length ys"
nipkow@13145
   349
by (induct xs) auto
wenzelm@13114
   350
wenzelm@13142
   351
lemma length_map [simp]: "length (map f xs) = length xs"
nipkow@13145
   352
by (induct xs) auto
wenzelm@13114
   353
wenzelm@13142
   354
lemma length_rev [simp]: "length (rev xs) = length xs"
nipkow@13145
   355
by (induct xs) auto
wenzelm@13114
   356
wenzelm@13142
   357
lemma length_tl [simp]: "length (tl xs) = length xs - 1"
nipkow@13145
   358
by (cases xs) auto
wenzelm@13114
   359
wenzelm@13142
   360
lemma length_0_conv [iff]: "(length xs = 0) = (xs = [])"
nipkow@13145
   361
by (induct xs) auto
wenzelm@13114
   362
wenzelm@13142
   363
lemma length_greater_0_conv [iff]: "(0 < length xs) = (xs \<noteq> [])"
nipkow@13145
   364
by (induct xs) auto
wenzelm@13114
   365
nipkow@23479
   366
lemma length_pos_if_in_set: "x : set xs \<Longrightarrow> length xs > 0"
nipkow@23479
   367
by auto
nipkow@23479
   368
wenzelm@13114
   369
lemma length_Suc_conv:
nipkow@13145
   370
"(length xs = Suc n) = (\<exists>y ys. xs = y # ys \<and> length ys = n)"
nipkow@13145
   371
by (induct xs) auto
wenzelm@13142
   372
nipkow@14025
   373
lemma Suc_length_conv:
nipkow@14025
   374
"(Suc n = length xs) = (\<exists>y ys. xs = y # ys \<and> length ys = n)"
paulson@14208
   375
apply (induct xs, simp, simp)
nipkow@14025
   376
apply blast
nipkow@14025
   377
done
nipkow@14025
   378
oheimb@14099
   379
lemma impossible_Cons [rule_format]: 
oheimb@14099
   380
  "length xs <= length ys --> xs = x # ys = False"
wenzelm@20503
   381
apply (induct xs)
wenzelm@20503
   382
apply auto
oheimb@14099
   383
done
oheimb@14099
   384
nipkow@14247
   385
lemma list_induct2[consumes 1]: "\<And>ys.
nipkow@14247
   386
 \<lbrakk> length xs = length ys;
nipkow@14247
   387
   P [] [];
nipkow@14247
   388
   \<And>x xs y ys. \<lbrakk> length xs = length ys; P xs ys \<rbrakk> \<Longrightarrow> P (x#xs) (y#ys) \<rbrakk>
nipkow@14247
   389
 \<Longrightarrow> P xs ys"
nipkow@14247
   390
apply(induct xs)
nipkow@14247
   391
 apply simp
nipkow@14247
   392
apply(case_tac ys)
nipkow@14247
   393
 apply simp
nipkow@14247
   394
apply(simp)
nipkow@14247
   395
done
wenzelm@13114
   396
krauss@22493
   397
lemma list_induct2': 
krauss@22493
   398
  "\<lbrakk> P [] [];
krauss@22493
   399
  \<And>x xs. P (x#xs) [];
krauss@22493
   400
  \<And>y ys. P [] (y#ys);
krauss@22493
   401
   \<And>x xs y ys. P xs ys  \<Longrightarrow> P (x#xs) (y#ys) \<rbrakk>
krauss@22493
   402
 \<Longrightarrow> P xs ys"
krauss@22493
   403
by (induct xs arbitrary: ys) (case_tac x, auto)+
krauss@22493
   404
nipkow@22143
   405
lemma neq_if_length_neq: "length xs \<noteq> length ys \<Longrightarrow> (xs = ys) == False"
nipkow@24349
   406
by (rule Eq_FalseI) auto
wenzelm@24037
   407
wenzelm@24037
   408
simproc_setup list_neq ("(xs::'a list) = ys") = {*
nipkow@22143
   409
(*
nipkow@22143
   410
Reduces xs=ys to False if xs and ys cannot be of the same length.
nipkow@22143
   411
This is the case if the atomic sublists of one are a submultiset
nipkow@22143
   412
of those of the other list and there are fewer Cons's in one than the other.
nipkow@22143
   413
*)
wenzelm@24037
   414
wenzelm@24037
   415
let
nipkow@22143
   416
nipkow@22143
   417
fun len (Const("List.list.Nil",_)) acc = acc
nipkow@22143
   418
  | len (Const("List.list.Cons",_) $ _ $ xs) (ts,n) = len xs (ts,n+1)
haftmann@23029
   419
  | len (Const("List.append",_) $ xs $ ys) acc = len xs (len ys acc)
nipkow@22143
   420
  | len (Const("List.rev",_) $ xs) acc = len xs acc
nipkow@22143
   421
  | len (Const("List.map",_) $ _ $ xs) acc = len xs acc
nipkow@22143
   422
  | len t (ts,n) = (t::ts,n);
nipkow@22143
   423
wenzelm@24037
   424
fun list_neq _ ss ct =
nipkow@22143
   425
  let
wenzelm@24037
   426
    val (Const(_,eqT) $ lhs $ rhs) = Thm.term_of ct;
nipkow@22143
   427
    val (ls,m) = len lhs ([],0) and (rs,n) = len rhs ([],0);
nipkow@22143
   428
    fun prove_neq() =
nipkow@22143
   429
      let
nipkow@22143
   430
        val Type(_,listT::_) = eqT;
haftmann@22994
   431
        val size = HOLogic.size_const listT;
nipkow@22143
   432
        val eq_len = HOLogic.mk_eq (size $ lhs, size $ rhs);
nipkow@22143
   433
        val neq_len = HOLogic.mk_Trueprop (HOLogic.Not $ eq_len);
nipkow@22143
   434
        val thm = Goal.prove (Simplifier.the_context ss) [] [] neq_len
haftmann@22633
   435
          (K (simp_tac (Simplifier.inherit_context ss @{simpset}) 1));
haftmann@22633
   436
      in SOME (thm RS @{thm neq_if_length_neq}) end
nipkow@22143
   437
  in
wenzelm@23214
   438
    if m < n andalso submultiset (op aconv) (ls,rs) orelse
wenzelm@23214
   439
       n < m andalso submultiset (op aconv) (rs,ls)
nipkow@22143
   440
    then prove_neq() else NONE
nipkow@22143
   441
  end;
wenzelm@24037
   442
in list_neq end;
nipkow@22143
   443
*}
nipkow@22143
   444
nipkow@22143
   445
nipkow@15392
   446
subsubsection {* @{text "@"} -- append *}
wenzelm@13114
   447
wenzelm@13142
   448
lemma append_assoc [simp]: "(xs @ ys) @ zs = xs @ (ys @ zs)"
nipkow@13145
   449
by (induct xs) auto
wenzelm@13114
   450
wenzelm@13142
   451
lemma append_Nil2 [simp]: "xs @ [] = xs"
nipkow@13145
   452
by (induct xs) auto
nipkow@3507
   453
nipkow@24449
   454
interpretation semigroup_append: semigroup_add ["op @"]
nipkow@24449
   455
by unfold_locales simp
nipkow@24449
   456
interpretation monoid_append: monoid_add ["[]" "op @"]
nipkow@24449
   457
by unfold_locales (simp+)
nipkow@24449
   458
wenzelm@13142
   459
lemma append_is_Nil_conv [iff]: "(xs @ ys = []) = (xs = [] \<and> ys = [])"
nipkow@13145
   460
by (induct xs) auto
wenzelm@13114
   461
wenzelm@13142
   462
lemma Nil_is_append_conv [iff]: "([] = xs @ ys) = (xs = [] \<and> ys = [])"
nipkow@13145
   463
by (induct xs) auto
wenzelm@13114
   464
wenzelm@13142
   465
lemma append_self_conv [iff]: "(xs @ ys = xs) = (ys = [])"
nipkow@13145
   466
by (induct xs) auto
wenzelm@13114
   467
wenzelm@13142
   468
lemma self_append_conv [iff]: "(xs = xs @ ys) = (ys = [])"
nipkow@13145
   469
by (induct xs) auto
wenzelm@13114
   470
paulson@24286
   471
lemma append_eq_append_conv [simp,noatp]:
berghofe@13883
   472
 "!!ys. length xs = length ys \<or> length us = length vs
berghofe@13883
   473
 ==> (xs@us = ys@vs) = (xs=ys \<and> us=vs)"
berghofe@13883
   474
apply (induct xs)
paulson@14208
   475
 apply (case_tac ys, simp, force)
paulson@14208
   476
apply (case_tac ys, force, simp)
nipkow@13145
   477
done
wenzelm@13142
   478
nipkow@14495
   479
lemma append_eq_append_conv2: "!!ys zs ts.
nipkow@14495
   480
 (xs @ ys = zs @ ts) =
nipkow@14495
   481
 (EX us. xs = zs @ us & us @ ys = ts | xs @ us = zs & ys = us@ ts)"
nipkow@14495
   482
apply (induct xs)
nipkow@14495
   483
 apply fastsimp
nipkow@14495
   484
apply(case_tac zs)
nipkow@14495
   485
 apply simp
nipkow@14495
   486
apply fastsimp
nipkow@14495
   487
done
nipkow@14495
   488
wenzelm@13142
   489
lemma same_append_eq [iff]: "(xs @ ys = xs @ zs) = (ys = zs)"
nipkow@13145
   490
by simp
wenzelm@13142
   491
wenzelm@13142
   492
lemma append1_eq_conv [iff]: "(xs @ [x] = ys @ [y]) = (xs = ys \<and> x = y)"
nipkow@13145
   493
by simp
wenzelm@13114
   494
wenzelm@13142
   495
lemma append_same_eq [iff]: "(ys @ xs = zs @ xs) = (ys = zs)"
nipkow@13145
   496
by simp
wenzelm@13114
   497
wenzelm@13142
   498
lemma append_self_conv2 [iff]: "(xs @ ys = ys) = (xs = [])"
nipkow@13145
   499
using append_same_eq [of _ _ "[]"] by auto
nipkow@3507
   500
wenzelm@13142
   501
lemma self_append_conv2 [iff]: "(ys = xs @ ys) = (xs = [])"
nipkow@13145
   502
using append_same_eq [of "[]"] by auto
wenzelm@13114
   503
paulson@24286
   504
lemma hd_Cons_tl [simp,noatp]: "xs \<noteq> [] ==> hd xs # tl xs = xs"
nipkow@13145
   505
by (induct xs) auto
wenzelm@13114
   506
wenzelm@13142
   507
lemma hd_append: "hd (xs @ ys) = (if xs = [] then hd ys else hd xs)"
nipkow@13145
   508
by (induct xs) auto
wenzelm@13114
   509
wenzelm@13142
   510
lemma hd_append2 [simp]: "xs \<noteq> [] ==> hd (xs @ ys) = hd xs"
nipkow@13145
   511
by (simp add: hd_append split: list.split)
wenzelm@13114
   512
wenzelm@13142
   513
lemma tl_append: "tl (xs @ ys) = (case xs of [] => tl ys | z#zs => zs @ ys)"
nipkow@13145
   514
by (simp split: list.split)
wenzelm@13114
   515
wenzelm@13142
   516
lemma tl_append2 [simp]: "xs \<noteq> [] ==> tl (xs @ ys) = tl xs @ ys"
nipkow@13145
   517
by (simp add: tl_append split: list.split)
wenzelm@13114
   518
wenzelm@13114
   519
nipkow@14300
   520
lemma Cons_eq_append_conv: "x#xs = ys@zs =
nipkow@14300
   521
 (ys = [] & x#xs = zs | (EX ys'. x#ys' = ys & xs = ys'@zs))"
nipkow@14300
   522
by(cases ys) auto
nipkow@14300
   523
nipkow@15281
   524
lemma append_eq_Cons_conv: "(ys@zs = x#xs) =
nipkow@15281
   525
 (ys = [] & zs = x#xs | (EX ys'. ys = x#ys' & ys'@zs = xs))"
nipkow@15281
   526
by(cases ys) auto
nipkow@15281
   527
nipkow@14300
   528
wenzelm@13142
   529
text {* Trivial rules for solving @{text "@"}-equations automatically. *}
wenzelm@13114
   530
wenzelm@13114
   531
lemma eq_Nil_appendI: "xs = ys ==> xs = [] @ ys"
nipkow@13145
   532
by simp
wenzelm@13114
   533
wenzelm@13142
   534
lemma Cons_eq_appendI:
nipkow@13145
   535
"[| x # xs1 = ys; xs = xs1 @ zs |] ==> x # xs = ys @ zs"
nipkow@13145
   536
by (drule sym) simp
wenzelm@13114
   537
wenzelm@13142
   538
lemma append_eq_appendI:
nipkow@13145
   539
"[| xs @ xs1 = zs; ys = xs1 @ us |] ==> xs @ ys = zs @ us"
nipkow@13145
   540
by (drule sym) simp
wenzelm@13114
   541
wenzelm@13114
   542
wenzelm@13142
   543
text {*
nipkow@13145
   544
Simplification procedure for all list equalities.
nipkow@13145
   545
Currently only tries to rearrange @{text "@"} to see if
nipkow@13145
   546
- both lists end in a singleton list,
nipkow@13145
   547
- or both lists end in the same list.
wenzelm@13142
   548
*}
wenzelm@13142
   549
wenzelm@13142
   550
ML_setup {*
nipkow@3507
   551
local
nipkow@3507
   552
wenzelm@13114
   553
fun last (cons as Const("List.list.Cons",_) $ _ $ xs) =
wenzelm@13462
   554
  (case xs of Const("List.list.Nil",_) => cons | _ => last xs)
haftmann@23029
   555
  | last (Const("List.append",_) $ _ $ ys) = last ys
wenzelm@13462
   556
  | last t = t;
wenzelm@13114
   557
wenzelm@13114
   558
fun list1 (Const("List.list.Cons",_) $ _ $ Const("List.list.Nil",_)) = true
wenzelm@13462
   559
  | list1 _ = false;
wenzelm@13114
   560
wenzelm@13114
   561
fun butlast ((cons as Const("List.list.Cons",_) $ x) $ xs) =
wenzelm@13462
   562
  (case xs of Const("List.list.Nil",_) => xs | _ => cons $ butlast xs)
haftmann@23029
   563
  | butlast ((app as Const("List.append",_) $ xs) $ ys) = app $ butlast ys
wenzelm@13462
   564
  | butlast xs = Const("List.list.Nil",fastype_of xs);
wenzelm@13114
   565
haftmann@22633
   566
val rearr_ss = HOL_basic_ss addsimps [@{thm append_assoc},
haftmann@22633
   567
  @{thm append_Nil}, @{thm append_Cons}];
wenzelm@16973
   568
wenzelm@20044
   569
fun list_eq ss (F as (eq as Const(_,eqT)) $ lhs $ rhs) =
wenzelm@13462
   570
  let
wenzelm@13462
   571
    val lastl = last lhs and lastr = last rhs;
wenzelm@13462
   572
    fun rearr conv =
wenzelm@13462
   573
      let
wenzelm@13462
   574
        val lhs1 = butlast lhs and rhs1 = butlast rhs;
wenzelm@13462
   575
        val Type(_,listT::_) = eqT
wenzelm@13462
   576
        val appT = [listT,listT] ---> listT
haftmann@23029
   577
        val app = Const("List.append",appT)
wenzelm@13462
   578
        val F2 = eq $ (app$lhs1$lastl) $ (app$rhs1$lastr)
wenzelm@13480
   579
        val eq = HOLogic.mk_Trueprop (HOLogic.mk_eq (F,F2));
wenzelm@20044
   580
        val thm = Goal.prove (Simplifier.the_context ss) [] [] eq
wenzelm@17877
   581
          (K (simp_tac (Simplifier.inherit_context ss rearr_ss) 1));
skalberg@15531
   582
      in SOME ((conv RS (thm RS trans)) RS eq_reflection) end;
wenzelm@13114
   583
wenzelm@13462
   584
  in
haftmann@22633
   585
    if list1 lastl andalso list1 lastr then rearr @{thm append1_eq_conv}
haftmann@22633
   586
    else if lastl aconv lastr then rearr @{thm append_same_eq}
skalberg@15531
   587
    else NONE
wenzelm@13462
   588
  end;
wenzelm@13462
   589
wenzelm@13114
   590
in
wenzelm@13462
   591
wenzelm@13462
   592
val list_eq_simproc =
haftmann@22633
   593
  Simplifier.simproc @{theory} "list_eq" ["(xs::'a list) = ys"] (K list_eq);
wenzelm@13462
   594
wenzelm@13114
   595
end;
wenzelm@13114
   596
wenzelm@13114
   597
Addsimprocs [list_eq_simproc];
wenzelm@13114
   598
*}
wenzelm@13114
   599
wenzelm@13114
   600
nipkow@15392
   601
subsubsection {* @{text map} *}
wenzelm@13114
   602
wenzelm@13142
   603
lemma map_ext: "(!!x. x : set xs --> f x = g x) ==> map f xs = map g xs"
nipkow@13145
   604
by (induct xs) simp_all
wenzelm@13114
   605
wenzelm@13142
   606
lemma map_ident [simp]: "map (\<lambda>x. x) = (\<lambda>xs. xs)"
nipkow@13145
   607
by (rule ext, induct_tac xs) auto
wenzelm@13114
   608
wenzelm@13142
   609
lemma map_append [simp]: "map f (xs @ ys) = map f xs @ map f ys"
nipkow@13145
   610
by (induct xs) auto
wenzelm@13114
   611
wenzelm@13142
   612
lemma map_compose: "map (f o g) xs = map f (map g xs)"
nipkow@13145
   613
by (induct xs) (auto simp add: o_def)
wenzelm@13114
   614
wenzelm@13142
   615
lemma rev_map: "rev (map f xs) = map f (rev xs)"
nipkow@13145
   616
by (induct xs) auto
wenzelm@13114
   617
nipkow@13737
   618
lemma map_eq_conv[simp]: "(map f xs = map g xs) = (!x : set xs. f x = g x)"
nipkow@13737
   619
by (induct xs) auto
nipkow@13737
   620
krauss@19770
   621
lemma map_cong [fundef_cong, recdef_cong]:
nipkow@13145
   622
"xs = ys ==> (!!x. x : set ys ==> f x = g x) ==> map f xs = map g ys"
nipkow@13145
   623
-- {* a congruence rule for @{text map} *}
nipkow@13737
   624
by simp
wenzelm@13114
   625
wenzelm@13142
   626
lemma map_is_Nil_conv [iff]: "(map f xs = []) = (xs = [])"
nipkow@13145
   627
by (cases xs) auto
wenzelm@13114
   628
wenzelm@13142
   629
lemma Nil_is_map_conv [iff]: "([] = map f xs) = (xs = [])"
nipkow@13145
   630
by (cases xs) auto
wenzelm@13114
   631
paulson@18447
   632
lemma map_eq_Cons_conv:
nipkow@14025
   633
 "(map f xs = y#ys) = (\<exists>z zs. xs = z#zs \<and> f z = y \<and> map f zs = ys)"
nipkow@13145
   634
by (cases xs) auto
wenzelm@13114
   635
paulson@18447
   636
lemma Cons_eq_map_conv:
nipkow@14025
   637
 "(x#xs = map f ys) = (\<exists>z zs. ys = z#zs \<and> x = f z \<and> xs = map f zs)"
nipkow@14025
   638
by (cases ys) auto
nipkow@14025
   639
paulson@18447
   640
lemmas map_eq_Cons_D = map_eq_Cons_conv [THEN iffD1]
paulson@18447
   641
lemmas Cons_eq_map_D = Cons_eq_map_conv [THEN iffD1]
paulson@18447
   642
declare map_eq_Cons_D [dest!]  Cons_eq_map_D [dest!]
paulson@18447
   643
nipkow@14111
   644
lemma ex_map_conv:
nipkow@14111
   645
  "(EX xs. ys = map f xs) = (ALL y : set ys. EX x. y = f x)"
paulson@18447
   646
by(induct ys, auto simp add: Cons_eq_map_conv)
nipkow@14111
   647
nipkow@15110
   648
lemma map_eq_imp_length_eq:
nipkow@15110
   649
  "!!xs. map f xs = map f ys ==> length xs = length ys"
nipkow@15110
   650
apply (induct ys)
nipkow@15110
   651
 apply simp
nipkow@15110
   652
apply(simp (no_asm_use))
nipkow@15110
   653
apply clarify
nipkow@15110
   654
apply(simp (no_asm_use))
nipkow@15110
   655
apply fast
nipkow@15110
   656
done
nipkow@15110
   657
nipkow@15110
   658
lemma map_inj_on:
nipkow@15110
   659
 "[| map f xs = map f ys; inj_on f (set xs Un set ys) |]
nipkow@15110
   660
  ==> xs = ys"
nipkow@15110
   661
apply(frule map_eq_imp_length_eq)
nipkow@15110
   662
apply(rotate_tac -1)
nipkow@15110
   663
apply(induct rule:list_induct2)
nipkow@15110
   664
 apply simp
nipkow@15110
   665
apply(simp)
nipkow@15110
   666
apply (blast intro:sym)
nipkow@15110
   667
done
nipkow@15110
   668
nipkow@15110
   669
lemma inj_on_map_eq_map:
nipkow@15110
   670
 "inj_on f (set xs Un set ys) \<Longrightarrow> (map f xs = map f ys) = (xs = ys)"
nipkow@15110
   671
by(blast dest:map_inj_on)
nipkow@15110
   672
wenzelm@13114
   673
lemma map_injective:
nipkow@14338
   674
 "!!xs. map f xs = map f ys ==> inj f ==> xs = ys"
nipkow@14338
   675
by (induct ys) (auto dest!:injD)
wenzelm@13114
   676
nipkow@14339
   677
lemma inj_map_eq_map[simp]: "inj f \<Longrightarrow> (map f xs = map f ys) = (xs = ys)"
nipkow@14339
   678
by(blast dest:map_injective)
nipkow@14339
   679
wenzelm@13114
   680
lemma inj_mapI: "inj f ==> inj (map f)"
nipkow@17589
   681
by (iprover dest: map_injective injD intro: inj_onI)
wenzelm@13114
   682
wenzelm@13114
   683
lemma inj_mapD: "inj (map f) ==> inj f"
paulson@14208
   684
apply (unfold inj_on_def, clarify)
nipkow@13145
   685
apply (erule_tac x = "[x]" in ballE)
paulson@14208
   686
 apply (erule_tac x = "[y]" in ballE, simp, blast)
nipkow@13145
   687
apply blast
nipkow@13145
   688
done
wenzelm@13114
   689
nipkow@14339
   690
lemma inj_map[iff]: "inj (map f) = inj f"
nipkow@13145
   691
by (blast dest: inj_mapD intro: inj_mapI)
wenzelm@13114
   692
nipkow@15303
   693
lemma inj_on_mapI: "inj_on f (\<Union>(set ` A)) \<Longrightarrow> inj_on (map f) A"
nipkow@15303
   694
apply(rule inj_onI)
nipkow@15303
   695
apply(erule map_inj_on)
nipkow@15303
   696
apply(blast intro:inj_onI dest:inj_onD)
nipkow@15303
   697
done
nipkow@15303
   698
kleing@14343
   699
lemma map_idI: "(\<And>x. x \<in> set xs \<Longrightarrow> f x = x) \<Longrightarrow> map f xs = xs"
kleing@14343
   700
by (induct xs, auto)
wenzelm@13114
   701
nipkow@14402
   702
lemma map_fun_upd [simp]: "y \<notin> set xs \<Longrightarrow> map (f(y:=v)) xs = map f xs"
nipkow@14402
   703
by (induct xs) auto
nipkow@14402
   704
nipkow@15110
   705
lemma map_fst_zip[simp]:
nipkow@15110
   706
  "length xs = length ys \<Longrightarrow> map fst (zip xs ys) = xs"
nipkow@15110
   707
by (induct rule:list_induct2, simp_all)
nipkow@15110
   708
nipkow@15110
   709
lemma map_snd_zip[simp]:
nipkow@15110
   710
  "length xs = length ys \<Longrightarrow> map snd (zip xs ys) = ys"
nipkow@15110
   711
by (induct rule:list_induct2, simp_all)
nipkow@15110
   712
nipkow@15110
   713
nipkow@15392
   714
subsubsection {* @{text rev} *}
wenzelm@13114
   715
wenzelm@13142
   716
lemma rev_append [simp]: "rev (xs @ ys) = rev ys @ rev xs"
nipkow@13145
   717
by (induct xs) auto
wenzelm@13114
   718
wenzelm@13142
   719
lemma rev_rev_ident [simp]: "rev (rev xs) = xs"
nipkow@13145
   720
by (induct xs) auto
wenzelm@13114
   721
kleing@15870
   722
lemma rev_swap: "(rev xs = ys) = (xs = rev ys)"
kleing@15870
   723
by auto
kleing@15870
   724
wenzelm@13142
   725
lemma rev_is_Nil_conv [iff]: "(rev xs = []) = (xs = [])"
nipkow@13145
   726
by (induct xs) auto
wenzelm@13114
   727
wenzelm@13142
   728
lemma Nil_is_rev_conv [iff]: "([] = rev xs) = (xs = [])"
nipkow@13145
   729
by (induct xs) auto
wenzelm@13114
   730
kleing@15870
   731
lemma rev_singleton_conv [simp]: "(rev xs = [x]) = (xs = [x])"
kleing@15870
   732
by (cases xs) auto
kleing@15870
   733
kleing@15870
   734
lemma singleton_rev_conv [simp]: "([x] = rev xs) = (xs = [x])"
kleing@15870
   735
by (cases xs) auto
kleing@15870
   736
haftmann@21061
   737
lemma rev_is_rev_conv [iff]: "(rev xs = rev ys) = (xs = ys)"
haftmann@21061
   738
apply (induct xs arbitrary: ys, force)
paulson@14208
   739
apply (case_tac ys, simp, force)
nipkow@13145
   740
done
wenzelm@13114
   741
nipkow@15439
   742
lemma inj_on_rev[iff]: "inj_on rev A"
nipkow@15439
   743
by(simp add:inj_on_def)
nipkow@15439
   744
wenzelm@13366
   745
lemma rev_induct [case_names Nil snoc]:
wenzelm@13366
   746
  "[| P []; !!x xs. P xs ==> P (xs @ [x]) |] ==> P xs"
berghofe@15489
   747
apply(simplesubst rev_rev_ident[symmetric])
nipkow@13145
   748
apply(rule_tac list = "rev xs" in list.induct, simp_all)
nipkow@13145
   749
done
wenzelm@13114
   750
nipkow@13145
   751
ML {* val rev_induct_tac = induct_thm_tac (thm "rev_induct") *}-- "compatibility"
wenzelm@13114
   752
wenzelm@13366
   753
lemma rev_exhaust [case_names Nil snoc]:
wenzelm@13366
   754
  "(xs = [] ==> P) ==>(!!ys y. xs = ys @ [y] ==> P) ==> P"
nipkow@13145
   755
by (induct xs rule: rev_induct) auto
wenzelm@13114
   756
wenzelm@13366
   757
lemmas rev_cases = rev_exhaust
wenzelm@13366
   758
nipkow@18423
   759
lemma rev_eq_Cons_iff[iff]: "(rev xs = y#ys) = (xs = rev ys @ [y])"
nipkow@18423
   760
by(rule rev_cases[of xs]) auto
nipkow@18423
   761
wenzelm@13114
   762
nipkow@15392
   763
subsubsection {* @{text set} *}
wenzelm@13114
   764
wenzelm@13142
   765
lemma finite_set [iff]: "finite (set xs)"
nipkow@13145
   766
by (induct xs) auto
wenzelm@13114
   767
wenzelm@13142
   768
lemma set_append [simp]: "set (xs @ ys) = (set xs \<union> set ys)"
nipkow@13145
   769
by (induct xs) auto
wenzelm@13114
   770
nipkow@17830
   771
lemma hd_in_set[simp]: "xs \<noteq> [] \<Longrightarrow> hd xs : set xs"
nipkow@17830
   772
by(cases xs) auto
oheimb@14099
   773
wenzelm@13142
   774
lemma set_subset_Cons: "set xs \<subseteq> set (x # xs)"
nipkow@13145
   775
by auto
wenzelm@13114
   776
oheimb@14099
   777
lemma set_ConsD: "y \<in> set (x # xs) \<Longrightarrow> y=x \<or> y \<in> set xs" 
oheimb@14099
   778
by auto
oheimb@14099
   779
wenzelm@13142
   780
lemma set_empty [iff]: "(set xs = {}) = (xs = [])"
nipkow@13145
   781
by (induct xs) auto
wenzelm@13114
   782
nipkow@15245
   783
lemma set_empty2[iff]: "({} = set xs) = (xs = [])"
nipkow@15245
   784
by(induct xs) auto
nipkow@15245
   785
wenzelm@13142
   786
lemma set_rev [simp]: "set (rev xs) = set xs"
nipkow@13145
   787
by (induct xs) auto
wenzelm@13114
   788
wenzelm@13142
   789
lemma set_map [simp]: "set (map f xs) = f`(set xs)"
nipkow@13145
   790
by (induct xs) auto
wenzelm@13114
   791
wenzelm@13142
   792
lemma set_filter [simp]: "set (filter P xs) = {x. x : set xs \<and> P x}"
nipkow@13145
   793
by (induct xs) auto
wenzelm@13114
   794
nipkow@15425
   795
lemma set_upt [simp]: "set[i..<j] = {k. i \<le> k \<and> k < j}"
paulson@14208
   796
apply (induct j, simp_all)
paulson@14208
   797
apply (erule ssubst, auto)
nipkow@13145
   798
done
wenzelm@13114
   799
wenzelm@13142
   800
lemma in_set_conv_decomp: "(x : set xs) = (\<exists>ys zs. xs = ys @ x # zs)"
paulson@15113
   801
proof (induct xs)
paulson@15113
   802
  case Nil show ?case by simp
paulson@15113
   803
  case (Cons a xs)
paulson@15113
   804
  show ?case
paulson@15113
   805
  proof 
paulson@15113
   806
    assume "x \<in> set (a # xs)"
paulson@15113
   807
    with prems show "\<exists>ys zs. a # xs = ys @ x # zs"
paulson@15113
   808
      by (simp, blast intro: Cons_eq_appendI)
paulson@15113
   809
  next
paulson@15113
   810
    assume "\<exists>ys zs. a # xs = ys @ x # zs"
paulson@15113
   811
    then obtain ys zs where eq: "a # xs = ys @ x # zs" by blast
paulson@15113
   812
    show "x \<in> set (a # xs)" 
paulson@15113
   813
      by (cases ys, auto simp add: eq)
paulson@15113
   814
  qed
paulson@15113
   815
qed
wenzelm@13142
   816
nipkow@18049
   817
lemma in_set_conv_decomp_first:
nipkow@18049
   818
 "(x : set xs) = (\<exists>ys zs. xs = ys @ x # zs \<and> x \<notin> set ys)"
nipkow@18049
   819
proof (induct xs)
nipkow@18049
   820
  case Nil show ?case by simp
nipkow@18049
   821
next
nipkow@18049
   822
  case (Cons a xs)
nipkow@18049
   823
  show ?case
nipkow@18049
   824
  proof cases
nipkow@18049
   825
    assume "x = a" thus ?case using Cons by force
nipkow@18049
   826
  next
nipkow@18049
   827
    assume "x \<noteq> a"
nipkow@18049
   828
    show ?case
nipkow@18049
   829
    proof
nipkow@18049
   830
      assume "x \<in> set (a # xs)"
nipkow@18049
   831
      from prems show "\<exists>ys zs. a # xs = ys @ x # zs \<and> x \<notin> set ys"
nipkow@18049
   832
	by(fastsimp intro!: Cons_eq_appendI)
nipkow@18049
   833
    next
nipkow@18049
   834
      assume "\<exists>ys zs. a # xs = ys @ x # zs \<and> x \<notin> set ys"
nipkow@18049
   835
      then obtain ys zs where eq: "a # xs = ys @ x # zs" by blast
nipkow@18049
   836
      show "x \<in> set (a # xs)" by (cases ys, auto simp add: eq)
nipkow@18049
   837
    qed
nipkow@18049
   838
  qed
nipkow@18049
   839
qed
nipkow@18049
   840
nipkow@18049
   841
lemmas split_list       = in_set_conv_decomp[THEN iffD1, standard]
nipkow@18049
   842
lemmas split_list_first = in_set_conv_decomp_first[THEN iffD1, standard]
nipkow@18049
   843
nipkow@18049
   844
paulson@13508
   845
lemma finite_list: "finite A ==> EX l. set l = A"
paulson@13508
   846
apply (erule finite_induct, auto)
paulson@13508
   847
apply (rule_tac x="x#l" in exI, auto)
paulson@13508
   848
done
paulson@13508
   849
kleing@14388
   850
lemma card_length: "card (set xs) \<le> length xs"
kleing@14388
   851
by (induct xs) (auto simp add: card_insert_if)
wenzelm@13114
   852
paulson@15168
   853
nipkow@15392
   854
subsubsection {* @{text filter} *}
wenzelm@13114
   855
wenzelm@13142
   856
lemma filter_append [simp]: "filter P (xs @ ys) = filter P xs @ filter P ys"
nipkow@13145
   857
by (induct xs) auto
wenzelm@13114
   858
nipkow@15305
   859
lemma rev_filter: "rev (filter P xs) = filter P (rev xs)"
nipkow@15305
   860
by (induct xs) simp_all
nipkow@15305
   861
wenzelm@13142
   862
lemma filter_filter [simp]: "filter P (filter Q xs) = filter (\<lambda>x. Q x \<and> P x) xs"
nipkow@13145
   863
by (induct xs) auto
wenzelm@13114
   864
nipkow@16998
   865
lemma length_filter_le [simp]: "length (filter P xs) \<le> length xs"
nipkow@16998
   866
by (induct xs) (auto simp add: le_SucI)
nipkow@16998
   867
nipkow@18423
   868
lemma sum_length_filter_compl:
nipkow@18423
   869
  "length(filter P xs) + length(filter (%x. ~P x) xs) = length xs"
nipkow@18423
   870
by(induct xs) simp_all
nipkow@18423
   871
wenzelm@13142
   872
lemma filter_True [simp]: "\<forall>x \<in> set xs. P x ==> filter P xs = xs"
nipkow@13145
   873
by (induct xs) auto
wenzelm@13114
   874
wenzelm@13142
   875
lemma filter_False [simp]: "\<forall>x \<in> set xs. \<not> P x ==> filter P xs = []"
nipkow@13145
   876
by (induct xs) auto
wenzelm@13114
   877
nipkow@16998
   878
lemma filter_empty_conv: "(filter P xs = []) = (\<forall>x\<in>set xs. \<not> P x)" 
nipkow@24349
   879
by (induct xs) simp_all
nipkow@16998
   880
nipkow@16998
   881
lemma filter_id_conv: "(filter P xs = xs) = (\<forall>x\<in>set xs. P x)"
nipkow@16998
   882
apply (induct xs)
nipkow@16998
   883
 apply auto
nipkow@16998
   884
apply(cut_tac P=P and xs=xs in length_filter_le)
nipkow@16998
   885
apply simp
nipkow@16998
   886
done
wenzelm@13114
   887
nipkow@16965
   888
lemma filter_map:
nipkow@16965
   889
  "filter P (map f xs) = map f (filter (P o f) xs)"
nipkow@16965
   890
by (induct xs) simp_all
nipkow@16965
   891
nipkow@16965
   892
lemma length_filter_map[simp]:
nipkow@16965
   893
  "length (filter P (map f xs)) = length(filter (P o f) xs)"
nipkow@16965
   894
by (simp add:filter_map)
nipkow@16965
   895
wenzelm@13142
   896
lemma filter_is_subset [simp]: "set (filter P xs) \<le> set xs"
nipkow@13145
   897
by auto
wenzelm@13114
   898
nipkow@15246
   899
lemma length_filter_less:
nipkow@15246
   900
  "\<lbrakk> x : set xs; ~ P x \<rbrakk> \<Longrightarrow> length(filter P xs) < length xs"
nipkow@15246
   901
proof (induct xs)
nipkow@15246
   902
  case Nil thus ?case by simp
nipkow@15246
   903
next
nipkow@15246
   904
  case (Cons x xs) thus ?case
nipkow@15246
   905
    apply (auto split:split_if_asm)
nipkow@15246
   906
    using length_filter_le[of P xs] apply arith
nipkow@15246
   907
  done
nipkow@15246
   908
qed
wenzelm@13114
   909
nipkow@15281
   910
lemma length_filter_conv_card:
nipkow@15281
   911
 "length(filter p xs) = card{i. i < length xs & p(xs!i)}"
nipkow@15281
   912
proof (induct xs)
nipkow@15281
   913
  case Nil thus ?case by simp
nipkow@15281
   914
next
nipkow@15281
   915
  case (Cons x xs)
nipkow@15281
   916
  let ?S = "{i. i < length xs & p(xs!i)}"
nipkow@15281
   917
  have fin: "finite ?S" by(fast intro: bounded_nat_set_is_finite)
nipkow@15281
   918
  show ?case (is "?l = card ?S'")
nipkow@15281
   919
  proof (cases)
nipkow@15281
   920
    assume "p x"
nipkow@15281
   921
    hence eq: "?S' = insert 0 (Suc ` ?S)"
nipkow@15281
   922
      by(auto simp add: nth_Cons image_def split:nat.split elim:lessE)
nipkow@15281
   923
    have "length (filter p (x # xs)) = Suc(card ?S)"
wenzelm@23388
   924
      using Cons `p x` by simp
nipkow@15281
   925
    also have "\<dots> = Suc(card(Suc ` ?S))" using fin
nipkow@15281
   926
      by (simp add: card_image inj_Suc)
nipkow@15281
   927
    also have "\<dots> = card ?S'" using eq fin
nipkow@15281
   928
      by (simp add:card_insert_if) (simp add:image_def)
nipkow@15281
   929
    finally show ?thesis .
nipkow@15281
   930
  next
nipkow@15281
   931
    assume "\<not> p x"
nipkow@15281
   932
    hence eq: "?S' = Suc ` ?S"
nipkow@15281
   933
      by(auto simp add: nth_Cons image_def split:nat.split elim:lessE)
nipkow@15281
   934
    have "length (filter p (x # xs)) = card ?S"
wenzelm@23388
   935
      using Cons `\<not> p x` by simp
nipkow@15281
   936
    also have "\<dots> = card(Suc ` ?S)" using fin
nipkow@15281
   937
      by (simp add: card_image inj_Suc)
nipkow@15281
   938
    also have "\<dots> = card ?S'" using eq fin
nipkow@15281
   939
      by (simp add:card_insert_if)
nipkow@15281
   940
    finally show ?thesis .
nipkow@15281
   941
  qed
nipkow@15281
   942
qed
nipkow@15281
   943
nipkow@17629
   944
lemma Cons_eq_filterD:
nipkow@17629
   945
 "x#xs = filter P ys \<Longrightarrow>
nipkow@17629
   946
  \<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
   947
  (is "_ \<Longrightarrow> \<exists>us vs. ?P ys us vs")
nipkow@17629
   948
proof(induct ys)
nipkow@17629
   949
  case Nil thus ?case by simp
nipkow@17629
   950
next
nipkow@17629
   951
  case (Cons y ys)
nipkow@17629
   952
  show ?case (is "\<exists>x. ?Q x")
nipkow@17629
   953
  proof cases
nipkow@17629
   954
    assume Py: "P y"
nipkow@17629
   955
    show ?thesis
nipkow@17629
   956
    proof cases
nipkow@17629
   957
      assume xy: "x = y"
nipkow@17629
   958
      show ?thesis
nipkow@17629
   959
      proof from Py xy Cons(2) show "?Q []" by simp qed
nipkow@17629
   960
    next
nipkow@17629
   961
      assume "x \<noteq> y" with Py Cons(2) show ?thesis by simp
nipkow@17629
   962
    qed
nipkow@17629
   963
  next
nipkow@17629
   964
    assume Py: "\<not> P y"
nipkow@17629
   965
    with Cons obtain us vs where 1 : "?P (y#ys) (y#us) vs" by fastsimp
nipkow@17629
   966
    show ?thesis (is "? us. ?Q us")
nipkow@17629
   967
    proof show "?Q (y#us)" using 1 by simp qed
nipkow@17629
   968
  qed
nipkow@17629
   969
qed
nipkow@17629
   970
nipkow@17629
   971
lemma filter_eq_ConsD:
nipkow@17629
   972
 "filter P ys = x#xs \<Longrightarrow>
nipkow@17629
   973
  \<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
   974
by(rule Cons_eq_filterD) simp
nipkow@17629
   975
nipkow@17629
   976
lemma filter_eq_Cons_iff:
nipkow@17629
   977
 "(filter P ys = x#xs) =
nipkow@17629
   978
  (\<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
   979
by(auto dest:filter_eq_ConsD)
nipkow@17629
   980
nipkow@17629
   981
lemma Cons_eq_filter_iff:
nipkow@17629
   982
 "(x#xs = filter P ys) =
nipkow@17629
   983
  (\<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
   984
by(auto dest:Cons_eq_filterD)
nipkow@17629
   985
krauss@19770
   986
lemma filter_cong[fundef_cong, recdef_cong]:
nipkow@17501
   987
 "xs = ys \<Longrightarrow> (\<And>x. x \<in> set ys \<Longrightarrow> P x = Q x) \<Longrightarrow> filter P xs = filter Q ys"
nipkow@17501
   988
apply simp
nipkow@17501
   989
apply(erule thin_rl)
nipkow@17501
   990
by (induct ys) simp_all
nipkow@17501
   991
nipkow@15281
   992
nipkow@15392
   993
subsubsection {* @{text concat} *}
wenzelm@13114
   994
wenzelm@13142
   995
lemma concat_append [simp]: "concat (xs @ ys) = concat xs @ concat ys"
nipkow@13145
   996
by (induct xs) auto
wenzelm@13114
   997
paulson@18447
   998
lemma concat_eq_Nil_conv [simp]: "(concat xss = []) = (\<forall>xs \<in> set xss. xs = [])"
nipkow@13145
   999
by (induct xss) auto
wenzelm@13114
  1000
paulson@18447
  1001
lemma Nil_eq_concat_conv [simp]: "([] = concat xss) = (\<forall>xs \<in> set xss. xs = [])"
nipkow@13145
  1002
by (induct xss) auto
wenzelm@13114
  1003
nipkow@24308
  1004
lemma set_concat [simp]: "set (concat xs) = (UN x:set xs. set x)"
nipkow@13145
  1005
by (induct xs) auto
wenzelm@13114
  1006
nipkow@24349
  1007
lemma concat_map_singleton[simp, code]: "concat(map (%x. [f x]) xs) = map f xs"
nipkow@24349
  1008
by (induct xs) auto
nipkow@24349
  1009
wenzelm@13142
  1010
lemma map_concat: "map f (concat xs) = concat (map (map f) xs)"
nipkow@13145
  1011
by (induct xs) auto
wenzelm@13114
  1012
wenzelm@13142
  1013
lemma filter_concat: "filter p (concat xs) = concat (map (filter p) xs)"
nipkow@13145
  1014
by (induct xs) auto
wenzelm@13114
  1015
wenzelm@13142
  1016
lemma rev_concat: "rev (concat xs) = concat (map rev (rev xs))"
nipkow@13145
  1017
by (induct xs) auto
wenzelm@13114
  1018
wenzelm@13114
  1019
nipkow@15392
  1020
subsubsection {* @{text nth} *}
wenzelm@13114
  1021
wenzelm@13142
  1022
lemma nth_Cons_0 [simp]: "(x # xs)!0 = x"
nipkow@13145
  1023
by auto
wenzelm@13114
  1024
wenzelm@13142
  1025
lemma nth_Cons_Suc [simp]: "(x # xs)!(Suc n) = xs!n"
nipkow@13145
  1026
by auto
wenzelm@13114
  1027
wenzelm@13142
  1028
declare nth.simps [simp del]
wenzelm@13114
  1029
wenzelm@13114
  1030
lemma nth_append:
nipkow@13145
  1031
"!!n. (xs @ ys)!n = (if n < length xs then xs!n else ys!(n - length xs))"
paulson@14208
  1032
apply (induct "xs", simp)
paulson@14208
  1033
apply (case_tac n, auto)
nipkow@13145
  1034
done
wenzelm@13114
  1035
nipkow@14402
  1036
lemma nth_append_length [simp]: "(xs @ x # ys) ! length xs = x"
nipkow@14402
  1037
by (induct "xs") auto
nipkow@14402
  1038
nipkow@14402
  1039
lemma nth_append_length_plus[simp]: "(xs @ ys) ! (length xs + n) = ys ! n"
nipkow@14402
  1040
by (induct "xs") auto
nipkow@14402
  1041
wenzelm@13142
  1042
lemma nth_map [simp]: "!!n. n < length xs ==> (map f xs)!n = f(xs!n)"
paulson@14208
  1043
apply (induct xs, simp)
paulson@14208
  1044
apply (case_tac n, auto)
nipkow@13145
  1045
done
wenzelm@13114
  1046
nipkow@18423
  1047
lemma hd_conv_nth: "xs \<noteq> [] \<Longrightarrow> hd xs = xs!0"
nipkow@18423
  1048
by(cases xs) simp_all
nipkow@18423
  1049
nipkow@18049
  1050
nipkow@18049
  1051
lemma list_eq_iff_nth_eq:
nipkow@18049
  1052
 "!!ys. (xs = ys) = (length xs = length ys \<and> (ALL i<length xs. xs!i = ys!i))"
nipkow@18049
  1053
apply(induct xs)
nipkow@18049
  1054
 apply simp apply blast
nipkow@18049
  1055
apply(case_tac ys)
nipkow@18049
  1056
 apply simp
nipkow@18049
  1057
apply(simp add:nth_Cons split:nat.split)apply blast
nipkow@18049
  1058
done
nipkow@18049
  1059
wenzelm@13142
  1060
lemma set_conv_nth: "set xs = {xs!i | i. i < length xs}"
paulson@15251
  1061
apply (induct xs, simp, simp)
nipkow@13145
  1062
apply safe
paulson@14208
  1063
apply (rule_tac x = 0 in exI, simp)
paulson@14208
  1064
 apply (rule_tac x = "Suc i" in exI, simp)
paulson@14208
  1065
apply (case_tac i, simp)
nipkow@13145
  1066
apply (rename_tac j)
paulson@14208
  1067
apply (rule_tac x = j in exI, simp)
nipkow@13145
  1068
done
wenzelm@13114
  1069
nipkow@17501
  1070
lemma in_set_conv_nth: "(x \<in> set xs) = (\<exists>i < length xs. xs!i = x)"
nipkow@17501
  1071
by(auto simp:set_conv_nth)
nipkow@17501
  1072
nipkow@13145
  1073
lemma list_ball_nth: "[| n < length xs; !x : set xs. P x|] ==> P(xs!n)"
nipkow@13145
  1074
by (auto simp add: set_conv_nth)
wenzelm@13114
  1075
wenzelm@13142
  1076
lemma nth_mem [simp]: "n < length xs ==> xs!n : set xs"
nipkow@13145
  1077
by (auto simp add: set_conv_nth)
wenzelm@13114
  1078
wenzelm@13114
  1079
lemma all_nth_imp_all_set:
nipkow@13145
  1080
"[| !i < length xs. P(xs!i); x : set xs|] ==> P x"
nipkow@13145
  1081
by (auto simp add: set_conv_nth)
wenzelm@13114
  1082
wenzelm@13114
  1083
lemma all_set_conv_all_nth:
nipkow@13145
  1084
"(\<forall>x \<in> set xs. P x) = (\<forall>i. i < length xs --> P (xs ! i))"
nipkow@13145
  1085
by (auto simp add: set_conv_nth)
wenzelm@13114
  1086
wenzelm@13114
  1087
nipkow@15392
  1088
subsubsection {* @{text list_update} *}
wenzelm@13114
  1089
wenzelm@13142
  1090
lemma length_list_update [simp]: "!!i. length(xs[i:=x]) = length xs"
nipkow@13145
  1091
by (induct xs) (auto split: nat.split)
wenzelm@13114
  1092
wenzelm@13114
  1093
lemma nth_list_update:
nipkow@13145
  1094
"!!i j. i < length xs==> (xs[i:=x])!j = (if i = j then x else xs!j)"
nipkow@13145
  1095
by (induct xs) (auto simp add: nth_Cons split: nat.split)
wenzelm@13114
  1096
wenzelm@13142
  1097
lemma nth_list_update_eq [simp]: "i < length xs ==> (xs[i:=x])!i = x"
nipkow@13145
  1098
by (simp add: nth_list_update)
wenzelm@13114
  1099
wenzelm@13142
  1100
lemma nth_list_update_neq [simp]: "!!i j. i \<noteq> j ==> xs[i:=x]!j = xs!j"
nipkow@13145
  1101
by (induct xs) (auto simp add: nth_Cons split: nat.split)
wenzelm@13114
  1102
wenzelm@13142
  1103
lemma list_update_overwrite [simp]:
nipkow@13145
  1104
"!!i. i < size xs ==> xs[i:=x, i:=y] = xs[i:=y]"
nipkow@13145
  1105
by (induct xs) (auto split: nat.split)
wenzelm@13114
  1106
nipkow@14402
  1107
lemma list_update_id[simp]: "!!i. i < length xs ==> xs[i := xs!i] = xs"
paulson@14208
  1108
apply (induct xs, simp)
nipkow@14187
  1109
apply(simp split:nat.splits)
nipkow@14187
  1110
done
nipkow@14187
  1111
nipkow@17501
  1112
lemma list_update_beyond[simp]: "\<And>i. length xs \<le> i \<Longrightarrow> xs[i:=x] = xs"
nipkow@17501
  1113
apply (induct xs)
nipkow@17501
  1114
 apply simp
nipkow@17501
  1115
apply (case_tac i)
nipkow@17501
  1116
apply simp_all
nipkow@17501
  1117
done
nipkow@17501
  1118
wenzelm@13114
  1119
lemma list_update_same_conv:
nipkow@13145
  1120
"!!i. i < length xs ==> (xs[i := x] = xs) = (xs!i = x)"
nipkow@13145
  1121
by (induct xs) (auto split: nat.split)
wenzelm@13114
  1122
nipkow@14187
  1123
lemma list_update_append1:
nipkow@14187
  1124
 "!!i. i < size xs \<Longrightarrow> (xs @ ys)[i:=x] = xs[i:=x] @ ys"
paulson@14208
  1125
apply (induct xs, simp)
nipkow@14187
  1126
apply(simp split:nat.split)
nipkow@14187
  1127
done
nipkow@14187
  1128
kleing@15868
  1129
lemma list_update_append:
kleing@15868
  1130
  "!!n. (xs @ ys) [n:= x] = 
kleing@15868
  1131
  (if n < length xs then xs[n:= x] @ ys else xs @ (ys [n-length xs:= x]))"
kleing@15868
  1132
by (induct xs) (auto split:nat.splits)
kleing@15868
  1133
nipkow@14402
  1134
lemma list_update_length [simp]:
nipkow@14402
  1135
 "(xs @ x # ys)[length xs := y] = (xs @ y # ys)"
nipkow@14402
  1136
by (induct xs, auto)
nipkow@14402
  1137
wenzelm@13114
  1138
lemma update_zip:
nipkow@13145
  1139
"!!i xy xs. length xs = length ys ==>
nipkow@13145
  1140
(zip xs ys)[i:=xy] = zip (xs[i:=fst xy]) (ys[i:=snd xy])"
nipkow@13145
  1141
by (induct ys) (auto, case_tac xs, auto split: nat.split)
wenzelm@13114
  1142
wenzelm@13114
  1143
lemma set_update_subset_insert: "!!i. set(xs[i:=x]) <= insert x (set xs)"
nipkow@13145
  1144
by (induct xs) (auto split: nat.split)
wenzelm@13114
  1145
wenzelm@13114
  1146
lemma set_update_subsetI: "[| set xs <= A; x:A |] ==> set(xs[i := x]) <= A"
nipkow@13145
  1147
by (blast dest!: set_update_subset_insert [THEN subsetD])
wenzelm@13114
  1148
kleing@15868
  1149
lemma set_update_memI: "!!n. n < length xs \<Longrightarrow> x \<in> set (xs[n := x])"
kleing@15868
  1150
by (induct xs) (auto split:nat.splits)
kleing@15868
  1151
wenzelm@13114
  1152
nipkow@15392
  1153
subsubsection {* @{text last} and @{text butlast} *}
wenzelm@13114
  1154
wenzelm@13142
  1155
lemma last_snoc [simp]: "last (xs @ [x]) = x"
nipkow@13145
  1156
by (induct xs) auto
wenzelm@13114
  1157
wenzelm@13142
  1158
lemma butlast_snoc [simp]: "butlast (xs @ [x]) = xs"
nipkow@13145
  1159
by (induct xs) auto
wenzelm@13114
  1160
nipkow@14302
  1161
lemma last_ConsL: "xs = [] \<Longrightarrow> last(x#xs) = x"
nipkow@14302
  1162
by(simp add:last.simps)
nipkow@14302
  1163
nipkow@14302
  1164
lemma last_ConsR: "xs \<noteq> [] \<Longrightarrow> last(x#xs) = last xs"
nipkow@14302
  1165
by(simp add:last.simps)
nipkow@14302
  1166
nipkow@14302
  1167
lemma last_append: "last(xs @ ys) = (if ys = [] then last xs else last ys)"
nipkow@14302
  1168
by (induct xs) (auto)
nipkow@14302
  1169
nipkow@14302
  1170
lemma last_appendL[simp]: "ys = [] \<Longrightarrow> last(xs @ ys) = last xs"
nipkow@14302
  1171
by(simp add:last_append)
nipkow@14302
  1172
nipkow@14302
  1173
lemma last_appendR[simp]: "ys \<noteq> [] \<Longrightarrow> last(xs @ ys) = last ys"
nipkow@14302
  1174
by(simp add:last_append)
nipkow@14302
  1175
nipkow@17762
  1176
lemma hd_rev: "xs \<noteq> [] \<Longrightarrow> hd(rev xs) = last xs"
nipkow@17762
  1177
by(rule rev_exhaust[of xs]) simp_all
nipkow@17762
  1178
nipkow@17762
  1179
lemma last_rev: "xs \<noteq> [] \<Longrightarrow> last(rev xs) = hd xs"
nipkow@17762
  1180
by(cases xs) simp_all
nipkow@17762
  1181
nipkow@17765
  1182
lemma last_in_set[simp]: "as \<noteq> [] \<Longrightarrow> last as \<in> set as"
nipkow@17765
  1183
by (induct as) auto
nipkow@17762
  1184
wenzelm@13142
  1185
lemma length_butlast [simp]: "length (butlast xs) = length xs - 1"
nipkow@13145
  1186
by (induct xs rule: rev_induct) auto
wenzelm@13114
  1187
wenzelm@13114
  1188
lemma butlast_append:
nipkow@13145
  1189
"!!ys. butlast (xs @ ys) = (if ys = [] then butlast xs else xs @ butlast ys)"
nipkow@13145
  1190
by (induct xs) auto
wenzelm@13114
  1191
wenzelm@13142
  1192
lemma append_butlast_last_id [simp]:
nipkow@13145
  1193
"xs \<noteq> [] ==> butlast xs @ [last xs] = xs"
nipkow@13145
  1194
by (induct xs) auto
wenzelm@13114
  1195
wenzelm@13142
  1196
lemma in_set_butlastD: "x : set (butlast xs) ==> x : set xs"
nipkow@13145
  1197
by (induct xs) (auto split: split_if_asm)
wenzelm@13114
  1198
wenzelm@13114
  1199
lemma in_set_butlast_appendI:
nipkow@13145
  1200
"x : set (butlast xs) | x : set (butlast ys) ==> x : set (butlast (xs @ ys))"
nipkow@13145
  1201
by (auto dest: in_set_butlastD simp add: butlast_append)
wenzelm@13114
  1202
nipkow@17501
  1203
lemma last_drop[simp]: "!!n. n < length xs \<Longrightarrow> last (drop n xs) = last xs"
nipkow@17501
  1204
apply (induct xs)
nipkow@17501
  1205
 apply simp
nipkow@17501
  1206
apply (auto split:nat.split)
nipkow@17501
  1207
done
nipkow@17501
  1208
nipkow@17589
  1209
lemma last_conv_nth: "xs\<noteq>[] \<Longrightarrow> last xs = xs!(length xs - 1)"
nipkow@17589
  1210
by(induct xs)(auto simp:neq_Nil_conv)
nipkow@17589
  1211
nipkow@15392
  1212
subsubsection {* @{text take} and @{text drop} *}
wenzelm@13114
  1213
wenzelm@13142
  1214
lemma take_0 [simp]: "take 0 xs = []"
nipkow@13145
  1215
by (induct xs) auto
wenzelm@13114
  1216
wenzelm@13142
  1217
lemma drop_0 [simp]: "drop 0 xs = xs"
nipkow@13145
  1218
by (induct xs) auto
wenzelm@13114
  1219
wenzelm@13142
  1220
lemma take_Suc_Cons [simp]: "take (Suc n) (x # xs) = x # take n xs"
nipkow@13145
  1221
by simp
wenzelm@13114
  1222
wenzelm@13142
  1223
lemma drop_Suc_Cons [simp]: "drop (Suc n) (x # xs) = drop n xs"
nipkow@13145
  1224
by simp
wenzelm@13114
  1225
wenzelm@13142
  1226
declare take_Cons [simp del] and drop_Cons [simp del]
wenzelm@13114
  1227
nipkow@15110
  1228
lemma take_Suc: "xs ~= [] ==> take (Suc n) xs = hd xs # take n (tl xs)"
nipkow@15110
  1229
by(clarsimp simp add:neq_Nil_conv)
nipkow@15110
  1230
nipkow@14187
  1231
lemma drop_Suc: "drop (Suc n) xs = drop n (tl xs)"
nipkow@14187
  1232
by(cases xs, simp_all)
nipkow@14187
  1233
nipkow@14187
  1234
lemma drop_tl: "!!n. drop n (tl xs) = tl(drop n xs)"
nipkow@14187
  1235
by(induct xs, simp_all add:drop_Cons drop_Suc split:nat.split)
nipkow@14187
  1236
nipkow@14187
  1237
lemma nth_via_drop: "!!n. drop n xs = y#ys \<Longrightarrow> xs!n = y"
paulson@14208
  1238
apply (induct xs, simp)
nipkow@14187
  1239
apply(simp add:drop_Cons nth_Cons split:nat.splits)
nipkow@14187
  1240
done
nipkow@14187
  1241
nipkow@13913
  1242
lemma take_Suc_conv_app_nth:
nipkow@13913
  1243
 "!!i. i < length xs \<Longrightarrow> take (Suc i) xs = take i xs @ [xs!i]"
paulson@14208
  1244
apply (induct xs, simp)
paulson@14208
  1245
apply (case_tac i, auto)
nipkow@13913
  1246
done
nipkow@13913
  1247
mehta@14591
  1248
lemma drop_Suc_conv_tl:
mehta@14591
  1249
  "!!i. i < length xs \<Longrightarrow> (xs!i) # (drop (Suc i) xs) = drop i xs"
mehta@14591
  1250
apply (induct xs, simp)
mehta@14591
  1251
apply (case_tac i, auto)
mehta@14591
  1252
done
mehta@14591
  1253
wenzelm@13142
  1254
lemma length_take [simp]: "!!xs. length (take n xs) = min (length xs) n"
nipkow@13145
  1255
by (induct n) (auto, case_tac xs, auto)
wenzelm@13114
  1256
wenzelm@13142
  1257
lemma length_drop [simp]: "!!xs. length (drop n xs) = (length xs - n)"
nipkow@13145
  1258
by (induct n) (auto, case_tac xs, auto)
wenzelm@13114
  1259
wenzelm@13142
  1260
lemma take_all [simp]: "!!xs. length xs <= n ==> take n xs = xs"
nipkow@13145
  1261
by (induct n) (auto, case_tac xs, auto)
wenzelm@13114
  1262
wenzelm@13142
  1263
lemma drop_all [simp]: "!!xs. length xs <= n ==> drop n xs = []"
nipkow@13145
  1264
by (induct n) (auto, case_tac xs, auto)
wenzelm@13114
  1265
wenzelm@13142
  1266
lemma take_append [simp]:
nipkow@13145
  1267
"!!xs. take n (xs @ ys) = (take n xs @ take (n - length xs) ys)"
nipkow@13145
  1268
by (induct n) (auto, case_tac xs, auto)
wenzelm@13114
  1269
wenzelm@13142
  1270
lemma drop_append [simp]:
nipkow@13145
  1271
"!!xs. drop n (xs @ ys) = drop n xs @ drop (n - length xs) ys"
nipkow@13145
  1272
by (induct n) (auto, case_tac xs, auto)
wenzelm@13114
  1273
wenzelm@13142
  1274
lemma take_take [simp]: "!!xs n. take n (take m xs) = take (min n m) xs"
paulson@14208
  1275
apply (induct m, auto)
paulson@14208
  1276
apply (case_tac xs, auto)
nipkow@15236
  1277
apply (case_tac n, auto)
nipkow@13145
  1278
done
wenzelm@13114
  1279
wenzelm@13142
  1280
lemma drop_drop [simp]: "!!xs. drop n (drop m xs) = drop (n + m) xs"
paulson@14208
  1281
apply (induct m, auto)
paulson@14208
  1282
apply (case_tac xs, auto)
nipkow@13145
  1283
done
wenzelm@13114
  1284
wenzelm@13114
  1285
lemma take_drop: "!!xs n. take n (drop m xs) = drop m (take (n + m) xs)"
paulson@14208
  1286
apply (induct m, auto)
paulson@14208
  1287
apply (case_tac xs, auto)
nipkow@13145
  1288
done
wenzelm@13114
  1289
nipkow@14802
  1290
lemma drop_take: "!!m n. drop n (take m xs) = take (m-n) (drop n xs)"
nipkow@14802
  1291
apply(induct xs)
nipkow@14802
  1292
 apply simp
nipkow@14802
  1293
apply(simp add: take_Cons drop_Cons split:nat.split)
nipkow@14802
  1294
done
nipkow@14802
  1295
wenzelm@13142
  1296
lemma append_take_drop_id [simp]: "!!xs. take n xs @ drop n xs = xs"
paulson@14208
  1297
apply (induct n, auto)
paulson@14208
  1298
apply (case_tac xs, auto)
nipkow@13145
  1299
done
wenzelm@13114
  1300
nipkow@15110
  1301
lemma take_eq_Nil[simp]: "!!n. (take n xs = []) = (n = 0 \<or> xs = [])"
nipkow@15110
  1302
apply(induct xs)
nipkow@15110
  1303
 apply simp
nipkow@15110
  1304
apply(simp add:take_Cons split:nat.split)
nipkow@15110
  1305
done
nipkow@15110
  1306
nipkow@15110
  1307
lemma drop_eq_Nil[simp]: "!!n. (drop n xs = []) = (length xs <= n)"
nipkow@15110
  1308
apply(induct xs)
nipkow@15110
  1309
apply simp
nipkow@15110
  1310
apply(simp add:drop_Cons split:nat.split)
nipkow@15110
  1311
done
nipkow@15110
  1312
wenzelm@13114
  1313
lemma take_map: "!!xs. take n (map f xs) = map f (take n xs)"
paulson@14208
  1314
apply (induct n, auto)
paulson@14208
  1315
apply (case_tac xs, auto)
nipkow@13145
  1316
done
wenzelm@13114
  1317
wenzelm@13142
  1318
lemma drop_map: "!!xs. drop n (map f xs) = map f (drop n xs)"
paulson@14208
  1319
apply (induct n, auto)
paulson@14208
  1320
apply (case_tac xs, auto)
nipkow@13145
  1321
done
wenzelm@13114
  1322
wenzelm@13114
  1323
lemma rev_take: "!!i. rev (take i xs) = drop (length xs - i) (rev xs)"
paulson@14208
  1324
apply (induct xs, auto)
paulson@14208
  1325
apply (case_tac i, auto)
nipkow@13145
  1326
done
wenzelm@13114
  1327
wenzelm@13114
  1328
lemma rev_drop: "!!i. rev (drop i xs) = take (length xs - i) (rev xs)"
paulson@14208
  1329
apply (induct xs, auto)
paulson@14208
  1330
apply (case_tac i, auto)
nipkow@13145
  1331
done
wenzelm@13114
  1332
wenzelm@13142
  1333
lemma nth_take [simp]: "!!n i. i < n ==> (take n xs)!i = xs!i"
paulson@14208
  1334
apply (induct xs, auto)
paulson@14208
  1335
apply (case_tac n, blast)
paulson@14208
  1336
apply (case_tac i, auto)
nipkow@13145
  1337
done
wenzelm@13114
  1338
wenzelm@13142
  1339
lemma nth_drop [simp]:
nipkow@13145
  1340
"!!xs i. n + i <= length xs ==> (drop n xs)!i = xs!(n + i)"
paulson@14208
  1341
apply (induct n, auto)
paulson@14208
  1342
apply (case_tac xs, auto)
nipkow@13145
  1343
done
nipkow@3507
  1344
nipkow@18423
  1345
lemma hd_drop_conv_nth: "\<lbrakk> xs \<noteq> []; n < length xs \<rbrakk> \<Longrightarrow> hd(drop n xs) = xs!n"
nipkow@18423
  1346
by(simp add: hd_conv_nth)
nipkow@18423
  1347
nipkow@14025
  1348
lemma set_take_subset: "\<And>n. set(take n xs) \<subseteq> set xs"
nipkow@14025
  1349
by(induct xs)(auto simp:take_Cons split:nat.split)
nipkow@14025
  1350
nipkow@14025
  1351
lemma set_drop_subset: "\<And>n. set(drop n xs) \<subseteq> set xs"
nipkow@14025
  1352
by(induct xs)(auto simp:drop_Cons split:nat.split)
nipkow@14025
  1353
nipkow@14187
  1354
lemma in_set_takeD: "x : set(take n xs) \<Longrightarrow> x : set xs"
nipkow@14187
  1355
using set_take_subset by fast
nipkow@14187
  1356
nipkow@14187
  1357
lemma in_set_dropD: "x : set(drop n xs) \<Longrightarrow> x : set xs"
nipkow@14187
  1358
using set_drop_subset by fast
nipkow@14187
  1359
wenzelm@13114
  1360
lemma append_eq_conv_conj:
nipkow@13145
  1361
"!!zs. (xs @ ys = zs) = (xs = take (length xs) zs \<and> ys = drop (length xs) zs)"
paulson@14208
  1362
apply (induct xs, simp, clarsimp)
paulson@14208
  1363
apply (case_tac zs, auto)
nipkow@13145
  1364
done
wenzelm@13142
  1365
paulson@14050
  1366
lemma take_add [rule_format]: 
paulson@14050
  1367
    "\<forall>i. i+j \<le> length(xs) --> take (i+j) xs = take i xs @ take j (drop i xs)"
paulson@14050
  1368
apply (induct xs, auto) 
paulson@14050
  1369
apply (case_tac i, simp_all) 
paulson@14050
  1370
done
paulson@14050
  1371
nipkow@14300
  1372
lemma append_eq_append_conv_if:
nipkow@14300
  1373
 "!! ys\<^isub>1. (xs\<^isub>1 @ xs\<^isub>2 = ys\<^isub>1 @ ys\<^isub>2) =
nipkow@14300
  1374
  (if size xs\<^isub>1 \<le> size ys\<^isub>1
nipkow@14300
  1375
   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
  1376
   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@14300
  1377
apply(induct xs\<^isub>1)
nipkow@14300
  1378
 apply simp
nipkow@14300
  1379
apply(case_tac ys\<^isub>1)
nipkow@14300
  1380
apply simp_all
nipkow@14300
  1381
done
nipkow@14300
  1382
nipkow@15110
  1383
lemma take_hd_drop:
nipkow@15110
  1384
  "!!n. n < length xs \<Longrightarrow> take n xs @ [hd (drop n xs)] = take (n+1) xs"
nipkow@15110
  1385
apply(induct xs)
nipkow@15110
  1386
apply simp
nipkow@15110
  1387
apply(simp add:drop_Cons split:nat.split)
nipkow@15110
  1388
done
nipkow@15110
  1389
nipkow@17501
  1390
lemma id_take_nth_drop:
nipkow@17501
  1391
 "i < length xs \<Longrightarrow> xs = take i xs @ xs!i # drop (Suc i) xs" 
nipkow@17501
  1392
proof -
nipkow@17501
  1393
  assume si: "i < length xs"
nipkow@17501
  1394
  hence "xs = take (Suc i) xs @ drop (Suc i) xs" by auto
nipkow@17501
  1395
  moreover
nipkow@17501
  1396
  from si have "take (Suc i) xs = take i xs @ [xs!i]"
nipkow@17501
  1397
    apply (rule_tac take_Suc_conv_app_nth) by arith
nipkow@17501
  1398
  ultimately show ?thesis by auto
nipkow@17501
  1399
qed
nipkow@17501
  1400
  
nipkow@17501
  1401
lemma upd_conv_take_nth_drop:
nipkow@17501
  1402
 "i < length xs \<Longrightarrow> xs[i:=a] = take i xs @ a # drop (Suc i) xs"
nipkow@17501
  1403
proof -
nipkow@17501
  1404
  assume i: "i < length xs"
nipkow@17501
  1405
  have "xs[i:=a] = (take i xs @ xs!i # drop (Suc i) xs)[i:=a]"
nipkow@17501
  1406
    by(rule arg_cong[OF id_take_nth_drop[OF i]])
nipkow@17501
  1407
  also have "\<dots> = take i xs @ a # drop (Suc i) xs"
nipkow@17501
  1408
    using i by (simp add: list_update_append)
nipkow@17501
  1409
  finally show ?thesis .
nipkow@17501
  1410
qed
nipkow@17501
  1411
wenzelm@13114
  1412
nipkow@15392
  1413
subsubsection {* @{text takeWhile} and @{text dropWhile} *}
wenzelm@13114
  1414
wenzelm@13142
  1415
lemma takeWhile_dropWhile_id [simp]: "takeWhile P xs @ dropWhile P xs = xs"
nipkow@13145
  1416
by (induct xs) auto
wenzelm@13114
  1417
wenzelm@13142
  1418
lemma takeWhile_append1 [simp]:
nipkow@13145
  1419
"[| x:set xs; ~P(x)|] ==> takeWhile P (xs @ ys) = takeWhile P xs"
nipkow@13145
  1420
by (induct xs) auto
wenzelm@13114
  1421
wenzelm@13142
  1422
lemma takeWhile_append2 [simp]:
nipkow@13145
  1423
"(!!x. x : set xs ==> P x) ==> takeWhile P (xs @ ys) = xs @ takeWhile P ys"
nipkow@13145
  1424
by (induct xs) auto
wenzelm@13114
  1425
wenzelm@13142
  1426
lemma takeWhile_tail: "\<not> P x ==> takeWhile P (xs @ (x#l)) = takeWhile P xs"
nipkow@13145
  1427
by (induct xs) auto
wenzelm@13114
  1428
wenzelm@13142
  1429
lemma dropWhile_append1 [simp]:
nipkow@13145
  1430
"[| x : set xs; ~P(x)|] ==> dropWhile P (xs @ ys) = (dropWhile P xs)@ys"
nipkow@13145
  1431
by (induct xs) auto
wenzelm@13114
  1432
wenzelm@13142
  1433
lemma dropWhile_append2 [simp]:
nipkow@13145
  1434
"(!!x. x:set xs ==> P(x)) ==> dropWhile P (xs @ ys) = dropWhile P ys"
nipkow@13145
  1435
by (induct xs) auto
wenzelm@13114
  1436
krauss@23971
  1437
lemma set_takeWhileD: "x : set (takeWhile P xs) ==> x : set xs \<and> P x"
nipkow@13145
  1438
by (induct xs) (auto split: split_if_asm)
wenzelm@13114
  1439
nipkow@13913
  1440
lemma takeWhile_eq_all_conv[simp]:
nipkow@13913
  1441
 "(takeWhile P xs = xs) = (\<forall>x \<in> set xs. P x)"
nipkow@13913
  1442
by(induct xs, auto)
nipkow@13913
  1443
nipkow@13913
  1444
lemma dropWhile_eq_Nil_conv[simp]:
nipkow@13913
  1445
 "(dropWhile P xs = []) = (\<forall>x \<in> set xs. P x)"
nipkow@13913
  1446
by(induct xs, auto)
nipkow@13913
  1447
nipkow@13913
  1448
lemma dropWhile_eq_Cons_conv:
nipkow@13913
  1449
 "(dropWhile P xs = y#ys) = (xs = takeWhile P xs @ y # ys & \<not> P y)"
nipkow@13913
  1450
by(induct xs, auto)
nipkow@13913
  1451
nipkow@17501
  1452
text{* The following two lemmmas could be generalized to an arbitrary
nipkow@17501
  1453
property. *}
nipkow@17501
  1454
nipkow@17501
  1455
lemma takeWhile_neq_rev: "\<lbrakk>distinct xs; x \<in> set xs\<rbrakk> \<Longrightarrow>
nipkow@17501
  1456
 takeWhile (\<lambda>y. y \<noteq> x) (rev xs) = rev (tl (dropWhile (\<lambda>y. y \<noteq> x) xs))"
nipkow@17501
  1457
by(induct xs) (auto simp: takeWhile_tail[where l="[]"])
nipkow@17501
  1458
nipkow@17501
  1459
lemma dropWhile_neq_rev: "\<lbrakk>distinct xs; x \<in> set xs\<rbrakk> \<Longrightarrow>
nipkow@17501
  1460
  dropWhile (\<lambda>y. y \<noteq> x) (rev xs) = x # rev (takeWhile (\<lambda>y. y \<noteq> x) xs)"
nipkow@17501
  1461
apply(induct xs)
nipkow@17501
  1462
 apply simp
nipkow@17501
  1463
apply auto
nipkow@17501
  1464
apply(subst dropWhile_append2)
nipkow@17501
  1465
apply auto
nipkow@17501
  1466
done
nipkow@17501
  1467
nipkow@18423
  1468
lemma takeWhile_not_last:
nipkow@18423
  1469
 "\<lbrakk> xs \<noteq> []; distinct xs\<rbrakk> \<Longrightarrow> takeWhile (\<lambda>y. y \<noteq> last xs) xs = butlast xs"
nipkow@18423
  1470
apply(induct xs)
nipkow@18423
  1471
 apply simp
nipkow@18423
  1472
apply(case_tac xs)
nipkow@18423
  1473
apply(auto)
nipkow@18423
  1474
done
nipkow@18423
  1475
krauss@19770
  1476
lemma takeWhile_cong [fundef_cong, recdef_cong]:
krauss@18336
  1477
  "[| l = k; !!x. x : set l ==> P x = Q x |] 
krauss@18336
  1478
  ==> takeWhile P l = takeWhile Q k"
nipkow@24349
  1479
by (induct k arbitrary: l) (simp_all)
krauss@18336
  1480
krauss@19770
  1481
lemma dropWhile_cong [fundef_cong, recdef_cong]:
krauss@18336
  1482
  "[| l = k; !!x. x : set l ==> P x = Q x |] 
krauss@18336
  1483
  ==> dropWhile P l = dropWhile Q k"
nipkow@24349
  1484
by (induct k arbitrary: l, simp_all)
krauss@18336
  1485
wenzelm@13114
  1486
nipkow@15392
  1487
subsubsection {* @{text zip} *}
wenzelm@13114
  1488
wenzelm@13142
  1489
lemma zip_Nil [simp]: "zip [] ys = []"
nipkow@13145
  1490
by (induct ys) auto
wenzelm@13114
  1491
wenzelm@13142
  1492
lemma zip_Cons_Cons [simp]: "zip (x # xs) (y # ys) = (x, y) # zip xs ys"
nipkow@13145
  1493
by simp
wenzelm@13114
  1494
wenzelm@13142
  1495
declare zip_Cons [simp del]
wenzelm@13114
  1496
nipkow@15281
  1497
lemma zip_Cons1:
nipkow@15281
  1498
 "zip (x#xs) ys = (case ys of [] \<Rightarrow> [] | y#ys \<Rightarrow> (x,y)#zip xs ys)"
nipkow@15281
  1499
by(auto split:list.split)
nipkow@15281
  1500
wenzelm@13142
  1501
lemma length_zip [simp]:
krauss@22493
  1502
"length (zip xs ys) = min (length xs) (length ys)"
krauss@22493
  1503
by (induct xs ys rule:list_induct2') auto
wenzelm@13114
  1504
wenzelm@13114
  1505
lemma zip_append1:
krauss@22493
  1506
"zip (xs @ ys) zs =
nipkow@13145
  1507
zip xs (take (length xs) zs) @ zip ys (drop (length xs) zs)"
krauss@22493
  1508
by (induct xs zs rule:list_induct2') auto
wenzelm@13114
  1509
wenzelm@13114
  1510
lemma zip_append2:
krauss@22493
  1511
"zip xs (ys @ zs) =
nipkow@13145
  1512
zip (take (length ys) xs) ys @ zip (drop (length ys) xs) zs"
krauss@22493
  1513
by (induct xs ys rule:list_induct2') auto
wenzelm@13114
  1514
wenzelm@13142
  1515
lemma zip_append [simp]:
wenzelm@13142
  1516
 "[| length xs = length us; length ys = length vs |] ==>
nipkow@13145
  1517
zip (xs@ys) (us@vs) = zip xs us @ zip ys vs"
nipkow@13145
  1518
by (simp add: zip_append1)
wenzelm@13114
  1519
wenzelm@13114
  1520
lemma zip_rev:
nipkow@14247
  1521
"length xs = length ys ==> zip (rev xs) (rev ys) = rev (zip xs ys)"
nipkow@14247
  1522
by (induct rule:list_induct2, simp_all)
wenzelm@13114
  1523
nipkow@23096
  1524
lemma map_zip_map:
nipkow@23096
  1525
 "map f (zip (map g xs) ys) = map (%(x,y). f(g x, y)) (zip xs ys)"
nipkow@23096
  1526
apply(induct xs arbitrary:ys) apply simp
nipkow@23096
  1527
apply(case_tac ys)
nipkow@23096
  1528
apply simp_all
nipkow@23096
  1529
done
nipkow@23096
  1530
nipkow@23096
  1531
lemma map_zip_map2:
nipkow@23096
  1532
 "map f (zip xs (map g ys)) = map (%(x,y). f(x, g y)) (zip xs ys)"
nipkow@23096
  1533
apply(induct xs arbitrary:ys) apply simp
nipkow@23096
  1534
apply(case_tac ys)
nipkow@23096
  1535
apply simp_all
nipkow@23096
  1536
done
nipkow@23096
  1537
wenzelm@13142
  1538
lemma nth_zip [simp]:
nipkow@13145
  1539
"!!i xs. [| i < length xs; i < length ys|] ==> (zip xs ys)!i = (xs!i, ys!i)"
paulson@14208
  1540
apply (induct ys, simp)
nipkow@13145
  1541
apply (case_tac xs)
nipkow@13145
  1542
 apply (simp_all add: nth.simps split: nat.split)
nipkow@13145
  1543
done
wenzelm@13114
  1544
wenzelm@13114
  1545
lemma set_zip:
nipkow@13145
  1546
"set (zip xs ys) = {(xs!i, ys!i) | i. i < min (length xs) (length ys)}"
nipkow@13145
  1547
by (simp add: set_conv_nth cong: rev_conj_cong)
wenzelm@13114
  1548
wenzelm@13114
  1549
lemma zip_update:
nipkow@13145
  1550
"length xs = length ys ==> zip (xs[i:=x]) (ys[i:=y]) = (zip xs ys)[i:=(x,y)]"
nipkow@13145
  1551
by (rule sym, simp add: update_zip)
wenzelm@13114
  1552
wenzelm@13142
  1553
lemma zip_replicate [simp]:
nipkow@13145
  1554
"!!j. zip (replicate i x) (replicate j y) = replicate (min i j) (x,y)"
paulson@14208
  1555
apply (induct i, auto)
paulson@14208
  1556
apply (case_tac j, auto)
nipkow@13145
  1557
done
wenzelm@13114
  1558
nipkow@19487
  1559
lemma take_zip:
nipkow@19487
  1560
 "!!xs ys. take n (zip xs ys) = zip (take n xs) (take n ys)"
nipkow@19487
  1561
apply (induct n)
nipkow@19487
  1562
 apply simp
nipkow@19487
  1563
apply (case_tac xs, simp)
nipkow@19487
  1564
apply (case_tac ys, simp_all)
nipkow@19487
  1565
done
nipkow@19487
  1566
nipkow@19487
  1567
lemma drop_zip:
nipkow@19487
  1568
 "!!xs ys. drop n (zip xs ys) = zip (drop n xs) (drop n ys)"
nipkow@19487
  1569
apply (induct n)
nipkow@19487
  1570
 apply simp
nipkow@19487
  1571
apply (case_tac xs, simp)
nipkow@19487
  1572
apply (case_tac ys, simp_all)
nipkow@19487
  1573
done
nipkow@19487
  1574
krauss@22493
  1575
lemma set_zip_leftD:
krauss@22493
  1576
  "(x,y)\<in> set (zip xs ys) \<Longrightarrow> x \<in> set xs"
krauss@22493
  1577
by (induct xs ys rule:list_induct2') auto
krauss@22493
  1578
krauss@22493
  1579
lemma set_zip_rightD:
krauss@22493
  1580
  "(x,y)\<in> set (zip xs ys) \<Longrightarrow> y \<in> set ys"
krauss@22493
  1581
by (induct xs ys rule:list_induct2') auto
wenzelm@13142
  1582
nipkow@23983
  1583
lemma in_set_zipE:
nipkow@23983
  1584
  "(x,y) : set(zip xs ys) \<Longrightarrow> (\<lbrakk> x : set xs; y : set ys \<rbrakk> \<Longrightarrow> R) \<Longrightarrow> R"
nipkow@23983
  1585
by(blast dest: set_zip_leftD set_zip_rightD)
nipkow@23983
  1586
nipkow@15392
  1587
subsubsection {* @{text list_all2} *}
wenzelm@13114
  1588
kleing@14316
  1589
lemma list_all2_lengthD [intro?]: 
kleing@14316
  1590
  "list_all2 P xs ys ==> length xs = length ys"
nipkow@24349
  1591
by (simp add: list_all2_def)
haftmann@19607
  1592
haftmann@19787
  1593
lemma list_all2_Nil [iff, code]: "list_all2 P [] ys = (ys = [])"
nipkow@24349
  1594
by (simp add: list_all2_def)
haftmann@19607
  1595
haftmann@19787
  1596
lemma list_all2_Nil2 [iff, code]: "list_all2 P xs [] = (xs = [])"
nipkow@24349
  1597
by (simp add: list_all2_def)
haftmann@19607
  1598
haftmann@19607
  1599
lemma list_all2_Cons [iff, code]:
haftmann@19607
  1600
  "list_all2 P (x # xs) (y # ys) = (P x y \<and> list_all2 P xs ys)"
nipkow@24349
  1601
by (auto simp add: list_all2_def)
wenzelm@13114
  1602
wenzelm@13114
  1603
lemma list_all2_Cons1:
nipkow@13145
  1604
"list_all2 P (x # xs) ys = (\<exists>z zs. ys = z # zs \<and> P x z \<and> list_all2 P xs zs)"
nipkow@13145
  1605
by (cases ys) auto
wenzelm@13114
  1606
wenzelm@13114
  1607
lemma list_all2_Cons2:
nipkow@13145
  1608
"list_all2 P xs (y # ys) = (\<exists>z zs. xs = z # zs \<and> P z y \<and> list_all2 P zs ys)"
nipkow@13145
  1609
by (cases xs) auto
wenzelm@13114
  1610
wenzelm@13142
  1611
lemma list_all2_rev [iff]:
nipkow@13145
  1612
"list_all2 P (rev xs) (rev ys) = list_all2 P xs ys"
nipkow@13145
  1613
by (simp add: list_all2_def zip_rev cong: conj_cong)
wenzelm@13114
  1614
kleing@13863
  1615
lemma list_all2_rev1:
kleing@13863
  1616
"list_all2 P (rev xs) ys = list_all2 P xs (rev ys)"
kleing@13863
  1617
by (subst list_all2_rev [symmetric]) simp
kleing@13863
  1618
wenzelm@13114
  1619
lemma list_all2_append1:
nipkow@13145
  1620
"list_all2 P (xs @ ys) zs =
nipkow@13145
  1621
(EX us vs. zs = us @ vs \<and> length us = length xs \<and> length vs = length ys \<and>
nipkow@13145
  1622
list_all2 P xs us \<and> list_all2 P ys vs)"
nipkow@13145
  1623
apply (simp add: list_all2_def zip_append1)
nipkow@13145
  1624
apply (rule iffI)
nipkow@13145
  1625
 apply (rule_tac x = "take (length xs) zs" in exI)
nipkow@13145
  1626
 apply (rule_tac x = "drop (length xs) zs" in exI)
paulson@14208
  1627
 apply (force split: nat_diff_split simp add: min_def, clarify)
nipkow@13145
  1628
apply (simp add: ball_Un)
nipkow@13145
  1629
done
wenzelm@13114
  1630
wenzelm@13114
  1631
lemma list_all2_append2:
nipkow@13145
  1632
"list_all2 P xs (ys @ zs) =
nipkow@13145
  1633
(EX us vs. xs = us @ vs \<and> length us = length ys \<and> length vs = length zs \<and>
nipkow@13145
  1634
list_all2 P us ys \<and> list_all2 P vs zs)"
nipkow@13145
  1635
apply (simp add: list_all2_def zip_append2)
nipkow@13145
  1636
apply (rule iffI)
nipkow@13145
  1637
 apply (rule_tac x = "take (length ys) xs" in exI)
nipkow@13145
  1638
 apply (rule_tac x = "drop (length ys) xs" in exI)
paulson@14208
  1639
 apply (force split: nat_diff_split simp add: min_def, clarify)
nipkow@13145
  1640
apply (simp add: ball_Un)
nipkow@13145
  1641
done
wenzelm@13114
  1642
kleing@13863
  1643
lemma list_all2_append:
nipkow@14247
  1644
  "length xs = length ys \<Longrightarrow>
nipkow@14247
  1645
  list_all2 P (xs@us) (ys@vs) = (list_all2 P xs ys \<and> list_all2 P us vs)"
nipkow@14247
  1646
by (induct rule:list_induct2, simp_all)
kleing@13863
  1647
kleing@13863
  1648
lemma list_all2_appendI [intro?, trans]:
kleing@13863
  1649
  "\<lbrakk> list_all2 P a b; list_all2 P c d \<rbrakk> \<Longrightarrow> list_all2 P (a@c) (b@d)"
nipkow@24349
  1650
by (simp add: list_all2_append list_all2_lengthD)
kleing@13863
  1651
wenzelm@13114
  1652
lemma list_all2_conv_all_nth:
nipkow@13145
  1653
"list_all2 P xs ys =
nipkow@13145
  1654
(length xs = length ys \<and> (\<forall>i < length xs. P (xs!i) (ys!i)))"
nipkow@13145
  1655
by (force simp add: list_all2_def set_zip)
wenzelm@13114
  1656
berghofe@13883
  1657
lemma list_all2_trans:
berghofe@13883
  1658
  assumes tr: "!!a b c. P1 a b ==> P2 b c ==> P3 a c"
berghofe@13883
  1659
  shows "!!bs cs. list_all2 P1 as bs ==> list_all2 P2 bs cs ==> list_all2 P3 as cs"
berghofe@13883
  1660
        (is "!!bs cs. PROP ?Q as bs cs")
berghofe@13883
  1661
proof (induct as)
berghofe@13883
  1662
  fix x xs bs assume I1: "!!bs cs. PROP ?Q xs bs cs"
berghofe@13883
  1663
  show "!!cs. PROP ?Q (x # xs) bs cs"
berghofe@13883
  1664
  proof (induct bs)
berghofe@13883
  1665
    fix y ys cs assume I2: "!!cs. PROP ?Q (x # xs) ys cs"
berghofe@13883
  1666
    show "PROP ?Q (x # xs) (y # ys) cs"
berghofe@13883
  1667
      by (induct cs) (auto intro: tr I1 I2)
berghofe@13883
  1668
  qed simp
berghofe@13883
  1669
qed simp
berghofe@13883
  1670
kleing@13863
  1671
lemma list_all2_all_nthI [intro?]:
kleing@13863
  1672
  "length a = length b \<Longrightarrow> (\<And>n. n < length a \<Longrightarrow> P (a!n) (b!n)) \<Longrightarrow> list_all2 P a b"
nipkow@24349
  1673
by (simp add: list_all2_conv_all_nth)
kleing@13863
  1674
paulson@14395
  1675
lemma list_all2I:
paulson@14395
  1676
  "\<forall>x \<in> set (zip a b). split P x \<Longrightarrow> length a = length b \<Longrightarrow> list_all2 P a b"
nipkow@24349
  1677
by (simp add: list_all2_def)
paulson@14395
  1678
kleing@14328
  1679
lemma list_all2_nthD:
kleing@13863
  1680
  "\<lbrakk> list_all2 P xs ys; p < size xs \<rbrakk> \<Longrightarrow> P (xs!p) (ys!p)"
nipkow@24349
  1681
by (simp add: list_all2_conv_all_nth)
kleing@13863
  1682
nipkow@14302
  1683
lemma list_all2_nthD2:
nipkow@14302
  1684
  "\<lbrakk>list_all2 P xs ys; p < size ys\<rbrakk> \<Longrightarrow> P (xs!p) (ys!p)"
nipkow@24349
  1685
by (frule list_all2_lengthD) (auto intro: list_all2_nthD)
nipkow@14302
  1686
kleing@13863
  1687
lemma list_all2_map1: 
kleing@13863
  1688
  "list_all2 P (map f as) bs = list_all2 (\<lambda>x y. P (f x) y) as bs"
nipkow@24349
  1689
by (simp add: list_all2_conv_all_nth)
kleing@13863
  1690
kleing@13863
  1691
lemma list_all2_map2: 
kleing@13863
  1692
  "list_all2 P as (map f bs) = list_all2 (\<lambda>x y. P x (f y)) as bs"
nipkow@24349
  1693
by (auto simp add: list_all2_conv_all_nth)
kleing@13863
  1694
kleing@14316
  1695
lemma list_all2_refl [intro?]:
kleing@13863
  1696
  "(\<And>x. P x x) \<Longrightarrow> list_all2 P xs xs"
nipkow@24349
  1697
by (simp add: list_all2_conv_all_nth)
kleing@13863
  1698
kleing@13863
  1699
lemma list_all2_update_cong:
kleing@13863
  1700
  "\<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
  1701
by (simp add: list_all2_conv_all_nth nth_list_update)
kleing@13863
  1702
kleing@13863
  1703
lemma list_all2_update_cong2:
kleing@13863
  1704
  "\<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
  1705
by (simp add: list_all2_lengthD list_all2_update_cong)
kleing@13863
  1706
nipkow@14302
  1707
lemma list_all2_takeI [simp,intro?]:
nipkow@14302
  1708
  "\<And>n ys. list_all2 P xs ys \<Longrightarrow> list_all2 P (take n xs) (take n ys)"
nipkow@14302
  1709
  apply (induct xs)
nipkow@14302
  1710
   apply simp
nipkow@14302
  1711
  apply (clarsimp simp add: list_all2_Cons1)
nipkow@14302
  1712
  apply (case_tac n)
nipkow@14302
  1713
  apply auto
nipkow@14302
  1714
  done
nipkow@14302
  1715
nipkow@14302
  1716
lemma list_all2_dropI [simp,intro?]:
kleing@13863
  1717
  "\<And>n bs. list_all2 P as bs \<Longrightarrow> list_all2 P (drop n as) (drop n bs)"
paulson@14208
  1718
  apply (induct as, simp)
kleing@13863
  1719
  apply (clarsimp simp add: list_all2_Cons1)
paulson@14208
  1720
  apply (case_tac n, simp, simp)
kleing@13863
  1721
  done
kleing@13863
  1722
kleing@14327
  1723
lemma list_all2_mono [intro?]:
kleing@13863
  1724
  "\<And>y. list_all2 P x y \<Longrightarrow> (\<And>x y. P x y \<Longrightarrow> Q x y) \<Longrightarrow> list_all2 Q x y"
paulson@14208
  1725
  apply (induct x, simp)
paulson@14208
  1726
  apply (case_tac y, auto)
kleing@13863
  1727
  done
kleing@13863
  1728
haftmann@22551
  1729
lemma list_all2_eq:
haftmann@22551
  1730
  "xs = ys \<longleftrightarrow> list_all2 (op =) xs ys"
nipkow@24349
  1731
by (induct xs ys rule: list_induct2') auto
haftmann@22551
  1732
wenzelm@13142
  1733
nipkow@15392
  1734
subsubsection {* @{text foldl} and @{text foldr} *}
wenzelm@13142
  1735
wenzelm@13142
  1736
lemma foldl_append [simp]:
nipkow@13145
  1737
"!!a. foldl f a (xs @ ys) = foldl f (foldl f a xs) ys"
nipkow@13145
  1738
by (induct xs) auto
wenzelm@13142
  1739
nipkow@14402
  1740
lemma foldr_append[simp]: "foldr f (xs @ ys) a = foldr f xs (foldr f ys a)"
nipkow@14402
  1741
by (induct xs) auto
nipkow@14402
  1742
nipkow@23096
  1743
lemma foldr_map: "foldr g (map f xs) a = foldr (g o f) xs a"
nipkow@23096
  1744
by(induct xs) simp_all
nipkow@23096
  1745
nipkow@24449
  1746
text{* For efficient code generation: avoid intermediate list. *}
nipkow@24449
  1747
lemma foldl_map[code unfold]:
nipkow@24449
  1748
  "foldl g a (map f xs) = foldl (%a x. g a (f x)) a xs"
nipkow@23096
  1749
by(induct xs arbitrary:a) simp_all
nipkow@23096
  1750
krauss@19770
  1751
lemma foldl_cong [fundef_cong, recdef_cong]:
krauss@18336
  1752
  "[| a = b; l = k; !!a x. x : set l ==> f a x = g a x |] 
krauss@18336
  1753
  ==> foldl f a l = foldl g b k"
nipkow@24349
  1754
by (induct k arbitrary: a b l) simp_all
krauss@18336
  1755
krauss@19770
  1756
lemma foldr_cong [fundef_cong, recdef_cong]:
krauss@18336
  1757
  "[| a = b; l = k; !!a x. x : set l ==> f x a = g x a |] 
krauss@18336
  1758
  ==> foldr f l a = foldr g k b"
nipkow@24349
  1759
by (induct k arbitrary: a b l) simp_all
krauss@18336
  1760
nipkow@24449
  1761
lemma (in semigroup_add) foldl_assoc:
nipkow@24449
  1762
shows "foldl op\<^loc>+ (x\<^loc>+y) zs = x \<^loc>+ (foldl op\<^loc>+ y zs)"
nipkow@24449
  1763
by (induct zs arbitrary: y) (simp_all add:add_assoc)
nipkow@24449
  1764
nipkow@24449
  1765
lemma (in monoid_add) foldl_absorb0:
nipkow@24449
  1766
shows "x \<^loc>+ (foldl op\<^loc>+ \<^loc>0 zs) = foldl op\<^loc>+ x zs"
nipkow@24449
  1767
by (induct zs) (simp_all add:foldl_assoc)
nipkow@24449
  1768
nipkow@24449
  1769
nipkow@23096
  1770
text{* The ``First Duality Theorem'' in Bird \& Wadler: *}
nipkow@23096
  1771
nipkow@23096
  1772
lemma foldl_foldr1_lemma:
nipkow@23096
  1773
 "foldl op + a xs = a + foldr op + xs (0\<Colon>'a::monoid_add)"
nipkow@23096
  1774
by (induct xs arbitrary: a) (auto simp:add_assoc)
nipkow@23096
  1775
nipkow@23096
  1776
corollary foldl_foldr1:
nipkow@23096
  1777
 "foldl op + 0 xs = foldr op + xs (0\<Colon>'a::monoid_add)"
nipkow@23096
  1778
by (simp add:foldl_foldr1_lemma)
nipkow@23096
  1779
nipkow@23096
  1780
nipkow@23096
  1781
text{* The ``Third Duality Theorem'' in Bird \& Wadler: *}
nipkow@23096
  1782
nipkow@14402
  1783
lemma foldr_foldl: "foldr f xs a = foldl (%x y. f y x) a (rev xs)"
nipkow@14402
  1784
by (induct xs) auto
nipkow@14402
  1785
nipkow@14402
  1786
lemma foldl_foldr: "foldl f a xs = foldr (%x y. f y x) (rev xs) a"
nipkow@14402
  1787
by (simp add: foldr_foldl [of "%x y. f y x" "rev xs"])
nipkow@14402
  1788
wenzelm@13142
  1789
text {*
nipkow@13145
  1790
Note: @{text "n \<le> foldl (op +) n ns"} looks simpler, but is more
nipkow@13145
  1791
difficult to use because it requires an additional transitivity step.
wenzelm@13142
  1792
*}
wenzelm@13142
  1793
wenzelm@13142
  1794
lemma start_le_sum: "!!n::nat. m <= n ==> m <= foldl (op +) n ns"
nipkow@13145
  1795
by (induct ns) auto
wenzelm@13142
  1796
wenzelm@13142
  1797
lemma elem_le_sum: "!!n::nat. n : set ns ==> n <= foldl (op +) 0 ns"
nipkow@13145
  1798
by (force intro: start_le_sum simp add: in_set_conv_decomp)
wenzelm@13142
  1799
wenzelm@13142
  1800
lemma sum_eq_0_conv [iff]:
nipkow@13145
  1801
"!!m::nat. (foldl (op +) m ns = 0) = (m = 0 \<and> (\<forall>n \<in> set ns. n = 0))"
nipkow@13145
  1802
by (induct ns) auto
wenzelm@13114
  1803
nipkow@24449
  1804
text{* @{const foldl} and @{text concat} *}
nipkow@24449
  1805
nipkow@24449
  1806
lemma concat_conv_foldl: "concat xss = foldl op@ [] xss"
nipkow@24449
  1807
by (induct xss) (simp_all add:monoid_append.foldl_absorb0)
nipkow@24449
  1808
nipkow@24449
  1809
lemma foldl_conv_concat:
nipkow@24449
  1810
  "foldl (op @) xs xxs = xs @ (concat xxs)"
nipkow@24449
  1811
by(simp add:concat_conv_foldl monoid_append.foldl_absorb0)
nipkow@24449
  1812
nipkow@23096
  1813
subsubsection {* List summation: @{const listsum} and @{text"\<Sum>"}*}
nipkow@23096
  1814
nipkow@24449
  1815
lemma listsum_append[simp]: "listsum (xs @ ys) = listsum xs + listsum ys"
nipkow@24449
  1816
by (induct xs) (simp_all add:add_assoc)
nipkow@24449
  1817
nipkow@24449
  1818
lemma listsum_rev[simp]:
nipkow@24449
  1819
fixes xs :: "'a::comm_monoid_add list"
nipkow@24449
  1820
shows "listsum (rev xs) = listsum xs"
nipkow@24449
  1821
by (induct xs) (simp_all add:add_ac)
nipkow@24449
  1822
nipkow@23096
  1823
lemma listsum_foldr:
nipkow@23096
  1824
 "listsum xs = foldr (op +) xs 0"
nipkow@23096
  1825
by(induct xs) auto
nipkow@23096
  1826
nipkow@24449
  1827
text{* For efficient code generation ---
nipkow@24449
  1828
       @{const listsum} is not tail recursive but @{const foldl} is. *}
nipkow@24449
  1829
lemma listsum[code unfold]: "listsum xs = foldl (op +) 0 xs"
nipkow@23096
  1830
by(simp add:listsum_foldr foldl_foldr1)
nipkow@23096
  1831
nipkow@24449
  1832
nipkow@23096
  1833
text{* Some syntactic sugar for summing a function over a list: *}
nipkow@23096
  1834
nipkow@23096
  1835
syntax
nipkow@23096
  1836
  "_listsum" :: "pttrn => 'a list => 'b => 'b"    ("(3SUM _<-_. _)" [0, 51, 10] 10)
nipkow@23096
  1837
syntax (xsymbols)
nipkow@23096
  1838
  "_listsum" :: "pttrn => 'a list => 'b => 'b"    ("(3\<Sum>_\<leftarrow>_. _)" [0, 51, 10] 10)
nipkow@23096
  1839
syntax (HTML output)
nipkow@23096
  1840
  "_listsum" :: "pttrn => 'a list => 'b => 'b"    ("(3\<Sum>_\<leftarrow>_. _)" [0, 51, 10] 10)
nipkow@23096
  1841
nipkow@23096
  1842
translations -- {* Beware of argument permutation! *}
nipkow@23096
  1843
  "SUM x<-xs. b" == "CONST listsum (map (%x. b) xs)"
nipkow@23096
  1844
  "\<Sum>x\<leftarrow>xs. b" == "CONST listsum (map (%x. b) xs)"
nipkow@23096
  1845
nipkow@23096
  1846
lemma listsum_0 [simp]: "(\<Sum>x\<leftarrow>xs. 0) = 0"
nipkow@23096
  1847
by (induct xs) simp_all
nipkow@23096
  1848
nipkow@23096
  1849
text{* For non-Abelian groups @{text xs} needs to be reversed on one side: *}
nipkow@23096
  1850
lemma uminus_listsum_map:
nipkow@23096
  1851
 "- listsum (map f xs) = (listsum (map (uminus o f) xs) :: 'a::ab_group_add)"
nipkow@23096
  1852
by(induct xs) simp_all
nipkow@23096
  1853
wenzelm@13114
  1854
nipkow@15392
  1855
subsubsection {* @{text upto} *}
wenzelm@13114
  1856
nipkow@17090
  1857
lemma upt_rec[code]: "[i..<j] = (if i<j then i#[Suc i..<j] else [])"
nipkow@17090
  1858
-- {* simp does not terminate! *}
nipkow@13145
  1859
by (induct j) auto
wenzelm@13142
  1860
nipkow@15425
  1861
lemma upt_conv_Nil [simp]: "j <= i ==> [i..<j] = []"
nipkow@13145
  1862
by (subst upt_rec) simp
wenzelm@13114
  1863
nipkow@15425
  1864
lemma upt_eq_Nil_conv[simp]: "([i..<j] = []) = (j = 0 \<or> j <= i)"
nipkow@15281
  1865
by(induct j)simp_all
nipkow@15281
  1866
nipkow@15281
  1867
lemma upt_eq_Cons_conv:
nipkow@15425
  1868
 "!!x xs. ([i..<j] = x#xs) = (i < j & i = x & [i+1..<j] = xs)"
nipkow@15281
  1869
apply(induct j)
nipkow@15281
  1870
 apply simp
nipkow@15281
  1871
apply(clarsimp simp add: append_eq_Cons_conv)
nipkow@15281
  1872
apply arith
nipkow@15281
  1873
done
nipkow@15281
  1874
nipkow@15425
  1875
lemma upt_Suc_append: "i <= j ==> [i..<(Suc j)] = [i..<j]@[j]"
nipkow@13145
  1876
-- {* Only needed if @{text upt_Suc} is deleted from the simpset. *}
nipkow@13145
  1877
by simp
wenzelm@13114
  1878
nipkow@15425
  1879
lemma upt_conv_Cons: "i < j ==> [i..<j] = i # [Suc i..<j]"
nipkow@13145
  1880
apply(rule trans)
nipkow@13145
  1881
apply(subst upt_rec)
paulson@14208
  1882
 prefer 2 apply (rule refl, simp)
nipkow@13145
  1883
done
wenzelm@13114
  1884
nipkow@15425
  1885
lemma upt_add_eq_append: "i<=j ==> [i..<j+k] = [i..<j]@[j..<j+k]"
nipkow@13145
  1886
-- {* LOOPS as a simprule, since @{text "j <= j"}. *}
nipkow@13145
  1887
by (induct k) auto
wenzelm@13114
  1888
nipkow@15425
  1889
lemma length_upt [simp]: "length [i..<j] = j - i"
nipkow@13145
  1890
by (induct j) (auto simp add: Suc_diff_le)
wenzelm@13114
  1891
nipkow@15425
  1892
lemma nth_upt [simp]: "i + k < j ==> [i..<j] ! k = i + k"
nipkow@13145
  1893
apply (induct j)
nipkow@13145
  1894
apply (auto simp add: less_Suc_eq nth_append split: nat_diff_split)
nipkow@13145
  1895
done
wenzelm@13114
  1896
nipkow@17906
  1897
nipkow@17906
  1898
lemma hd_upt[simp]: "i < j \<Longrightarrow> hd[i..<j] = i"
nipkow@17906
  1899
by(simp add:upt_conv_Cons)
nipkow@17906
  1900
nipkow@17906
  1901
lemma last_upt[simp]: "i < j \<Longrightarrow> last[i..<j] = j - 1"
nipkow@17906
  1902
apply(cases j)
nipkow@17906
  1903
 apply simp
nipkow@17906
  1904
by(simp add:upt_Suc_append)
nipkow@17906
  1905
nipkow@15425
  1906
lemma take_upt [simp]: "!!i. i+m <= n ==> take m [i..<n] = [i..<i+m]"
paulson@14208
  1907
apply (induct m, simp)
nipkow@13145
  1908
apply (subst upt_rec)
nipkow@13145
  1909
apply (rule sym)
nipkow@13145
  1910
apply (subst upt_rec)
nipkow@13145
  1911
apply (simp del: upt.simps)
nipkow@13145
  1912
done
nipkow@3507
  1913
nipkow@17501
  1914
lemma drop_upt[simp]: "drop m [i..<j] = [i+m..<j]"
nipkow@17501
  1915
apply(induct j)
nipkow@17501
  1916
apply auto
nipkow@17501
  1917
done
nipkow@17501
  1918
nipkow@15425
  1919
lemma map_Suc_upt: "map Suc [m..<n] = [Suc m..n]"
nipkow@13145
  1920
by (induct n) auto
wenzelm@13114
  1921
nipkow@15425
  1922
lemma nth_map_upt: "!!i. i < n-m ==> (map f [m..<n]) ! i = f(m+i)"
nipkow@13145
  1923
apply (induct n m rule: diff_induct)
nipkow@13145
  1924
prefer 3 apply (subst map_Suc_upt[symmetric])
nipkow@13145
  1925
apply (auto simp add: less_diff_conv nth_upt)
nipkow@13145
  1926
done
wenzelm@13114
  1927
berghofe@13883
  1928
lemma nth_take_lemma:
berghofe@13883
  1929
  "!!xs ys. k <= length xs ==> k <= length ys ==>
berghofe@13883
  1930
     (!!i. i < k --> xs!i = ys!i) ==> take k xs = take k ys"
berghofe@13883
  1931
apply (atomize, induct k)
paulson@14208
  1932
apply (simp_all add: less_Suc_eq_0_disj all_conj_distrib, clarify)
nipkow@13145
  1933
txt {* Both lists must be non-empty *}
paulson@14208
  1934
apply (case_tac xs, simp)
paulson@14208
  1935
apply (case_tac ys, clarify)
nipkow@13145
  1936
 apply (simp (no_asm_use))
nipkow@13145
  1937
apply clarify
nipkow@13145
  1938
txt {* prenexing's needed, not miniscoping *}
nipkow@13145
  1939
apply (simp (no_asm_use) add: all_simps [symmetric] del: all_simps)
nipkow@13145
  1940
apply blast
nipkow@13145
  1941
done
wenzelm@13114
  1942
wenzelm@13114
  1943
lemma nth_equalityI:
wenzelm@13114
  1944
 "[| length xs = length ys; ALL i < length xs. xs!i = ys!i |] ==> xs = ys"
nipkow@13145
  1945
apply (frule nth_take_lemma [OF le_refl eq_imp_le])
nipkow@13145
  1946
apply (simp_all add: take_all)
nipkow@13145
  1947
done
wenzelm@13142
  1948
kleing@13863
  1949
(* needs nth_equalityI *)
kleing@13863
  1950
lemma list_all2_antisym:
kleing@13863
  1951
  "\<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
  1952
  \<Longrightarrow> xs = ys"
kleing@13863
  1953
  apply (simp add: list_all2_conv_all_nth) 
paulson@14208
  1954
  apply (rule nth_equalityI, blast, simp)
kleing@13863
  1955
  done
kleing@13863
  1956
wenzelm@13142
  1957
lemma take_equalityI: "(\<forall>i. take i xs = take i ys) ==> xs = ys"
nipkow@13145
  1958
-- {* The famous take-lemma. *}
nipkow@13145
  1959
apply (drule_tac x = "max (length xs) (length ys)" in spec)
nipkow@13145
  1960
apply (simp add: le_max_iff_disj take_all)
nipkow@13145
  1961
done
wenzelm@13142
  1962
wenzelm@13142
  1963
nipkow@15302
  1964
lemma take_Cons':
nipkow@15302
  1965
     "take n (x # xs) = (if n = 0 then [] else x # take (n - 1) xs)"
nipkow@15302
  1966
by (cases n) simp_all
nipkow@15302
  1967
nipkow@15302
  1968
lemma drop_Cons':
nipkow@15302
  1969
     "drop n (x # xs) = (if n = 0 then x # xs else drop (n - 1) xs)"
nipkow@15302
  1970
by (cases n) simp_all
nipkow@15302
  1971
nipkow@15302
  1972
lemma nth_Cons': "(x # xs)!n = (if n = 0 then x else xs!(n - 1))"
nipkow@15302
  1973
by (cases n) simp_all
nipkow@15302
  1974
paulson@18622
  1975
lemmas take_Cons_number_of = take_Cons'[of "number_of v",standard]
paulson@18622
  1976
lemmas drop_Cons_number_of = drop_Cons'[of "number_of v",standard]
paulson@18622
  1977
lemmas nth_Cons_number_of = nth_Cons'[of _ _ "number_of v",standard]
paulson@18622
  1978
paulson@18622
  1979
declare take_Cons_number_of [simp] 
paulson@18622
  1980
        drop_Cons_number_of [simp] 
paulson@18622
  1981
        nth_Cons_number_of [simp] 
nipkow@15302
  1982
nipkow@15302
  1983
nipkow@15392
  1984
subsubsection {* @{text "distinct"} and @{text remdups} *}
wenzelm@13142
  1985
wenzelm@13142
  1986
lemma distinct_append [simp]:
nipkow@13145
  1987
"distinct (xs @ ys) = (distinct xs \<and> distinct ys \<and> set xs \<inter> set ys = {})"
nipkow@13145
  1988
by (induct xs) auto
wenzelm@13142
  1989
nipkow@15305
  1990
lemma distinct_rev[simp]: "distinct(rev xs) = distinct xs"
nipkow@15305
  1991
by(induct xs) auto
nipkow@15305
  1992
wenzelm@13142
  1993
lemma set_remdups [simp]: "set (remdups xs) = set xs"
nipkow@13145
  1994
by (induct xs) (auto simp add: insert_absorb)
wenzelm@13142
  1995
wenzelm@13142
  1996
lemma distinct_remdups [iff]: "distinct (remdups xs)"
nipkow@13145
  1997
by (induct xs) auto
wenzelm@13142
  1998
paulson@15072
  1999
lemma remdups_eq_nil_iff [simp]: "(remdups x = []) = (x = [])"
nipkow@24349
  2000
by (induct x, auto) 
paulson@15072
  2001
paulson@15072
  2002
lemma remdups_eq_nil_right_iff [simp]: "([] = remdups x) = (x = [])"
nipkow@24349
  2003
by (induct x, auto)
paulson@15072
  2004
nipkow@15245
  2005
lemma length_remdups_leq[iff]: "length(remdups xs) <= length xs"
nipkow@15245
  2006
by (induct xs) auto
nipkow@15245
  2007
nipkow@15245
  2008
lemma length_remdups_eq[iff]:
nipkow@15245
  2009
  "(length (remdups xs) = length xs) = (remdups xs = xs)"
nipkow@15245
  2010
apply(induct xs)
nipkow@15245
  2011
 apply auto
nipkow@15245
  2012
apply(subgoal_tac "length (remdups xs) <= length xs")
nipkow@15245
  2013
 apply arith
nipkow@15245
  2014
apply(rule length_remdups_leq)
nipkow@15245
  2015
done
nipkow@15245
  2016
nipkow@18490
  2017
nipkow@18490
  2018
lemma distinct_map:
nipkow@18490
  2019
  "distinct(map f xs) = (distinct xs & inj_on f (set xs))"
nipkow@18490
  2020
by (induct xs) auto
nipkow@18490
  2021
nipkow@18490
  2022
wenzelm@13142
  2023
lemma distinct_filter [simp]: "distinct xs ==> distinct (filter P xs)"
nipkow@13145
  2024
by (induct xs) auto
wenzelm@13114
  2025
nipkow@17501
  2026
lemma distinct_upt[simp]: "distinct[i..<j]"
nipkow@17501
  2027
by (induct j) auto
nipkow@17501
  2028
nipkow@17501
  2029
lemma distinct_take[simp]: "\<And>i. distinct xs \<Longrightarrow> distinct (take i xs)"
nipkow@17501
  2030
apply(induct xs)
nipkow@17501
  2031
 apply simp
nipkow@17501
  2032
apply (case_tac i)
nipkow@17501
  2033
 apply simp_all
nipkow@17501
  2034
apply(blast dest:in_set_takeD)
nipkow@17501
  2035
done
nipkow@17501
  2036
nipkow@17501
  2037
lemma distinct_drop[simp]: "\<And>i. distinct xs \<Longrightarrow> distinct (drop i xs)"
nipkow@17501
  2038
apply(induct xs)
nipkow@17501
  2039
 apply simp
nipkow@17501
  2040
apply (case_tac i)
nipkow@17501
  2041
 apply simp_all
nipkow@17501
  2042
done
nipkow@17501
  2043
nipkow@17501
  2044
lemma distinct_list_update:
nipkow@17501
  2045
assumes d: "distinct xs" and a: "a \<notin> set xs - {xs!i}"
nipkow@17501
  2046
shows "distinct (xs[i:=a])"
nipkow@17501
  2047
proof (cases "i < length xs")
nipkow@17501
  2048
  case True
nipkow@17501
  2049
  with a have "a \<notin> set (take i xs @ xs ! i # drop (Suc i) xs) - {xs!i}"
nipkow@17501
  2050
    apply (drule_tac id_take_nth_drop) by simp
nipkow@17501
  2051
  with d True show ?thesis
nipkow@17501
  2052
    apply (simp add: upd_conv_take_nth_drop)
nipkow@17501
  2053
    apply (drule subst [OF id_take_nth_drop]) apply assumption
nipkow@17501
  2054
    apply simp apply (cases "a = xs!i") apply simp by blast
nipkow@17501
  2055
next
nipkow@17501
  2056
  case False with d show ?thesis by auto
nipkow@17501
  2057
qed
nipkow@17501
  2058
nipkow@17501
  2059
nipkow@17501
  2060
text {* It is best to avoid this indexed version of distinct, but
nipkow@17501
  2061
sometimes it is useful. *}
nipkow@17501
  2062
wenzelm@13142
  2063
lemma distinct_conv_nth:
nipkow@17501
  2064
"distinct xs = (\<forall>i < size xs. \<forall>j < size xs. i \<noteq> j --> xs!i \<noteq> xs!j)"
paulson@15251
  2065
apply (induct xs, simp, simp)
paulson@14208
  2066
apply (rule iffI, clarsimp)
nipkow@13145
  2067
 apply (case_tac i)
paulson@14208
  2068
apply (case_tac j, simp)
nipkow@13145
  2069
apply (simp add: set_conv_nth)
nipkow@13145
  2070
 apply (case_tac j)
paulson@14208
  2071
apply (clarsimp simp add: set_conv_nth, simp)
nipkow@13145
  2072
apply (rule conjI)
nipkow@13145
  2073
 apply (clarsimp simp add: set_conv_nth)
nipkow@17501
  2074
 apply (erule_tac x = 0 in allE, simp)
paulson@14208
  2075
 apply (erule_tac x = "Suc i" in allE, simp, clarsimp)
nipkow@17501
  2076
apply (erule_tac x = "Suc i" in allE, simp)
paulson@14208
  2077
apply (erule_tac x = "Suc j" in allE, simp)
nipkow@13145
  2078
done
wenzelm@13114
  2079
nipkow@18490
  2080
lemma nth_eq_iff_index_eq:
nipkow@18490
  2081
 "\<lbrakk> distinct xs; i < length xs; j < length xs \<rbrakk> \<Longrightarrow> (xs!i = xs!j) = (i = j)"
nipkow@18490
  2082
by(auto simp: distinct_conv_nth)
nipkow@18490
  2083
nipkow@15110
  2084
lemma distinct_card: "distinct xs ==> card (set xs) = size xs"
nipkow@24349
  2085
by (induct xs) auto
kleing@14388
  2086
nipkow@15110
  2087
lemma card_distinct: "card (set xs) = size xs ==> distinct xs"
kleing@14388
  2088
proof (induct xs)
kleing@14388
  2089
  case Nil thus ?case by simp
kleing@14388
  2090
next
kleing@14388
  2091
  case (Cons x xs)
kleing@14388
  2092
  show ?case
kleing@14388
  2093
  proof (cases "x \<in> set xs")
kleing@14388
  2094
    case False with Cons show ?thesis by simp
kleing@14388
  2095
  next
kleing@14388
  2096
    case True with Cons.prems
kleing@14388
  2097
    have "card (set xs) = Suc (length xs)" 
kleing@14388
  2098
      by (simp add: card_insert_if split: split_if_asm)
kleing@14388
  2099
    moreover have "card (set xs) \<le> length xs" by (rule card_length)
kleing@14388
  2100
    ultimately have False by simp
kleing@14388
  2101
    thus ?thesis ..
kleing@14388
  2102
  qed
kleing@14388
  2103
qed
kleing@14388
  2104
nipkow@18490
  2105
nipkow@18490
  2106
lemma length_remdups_concat:
nipkow@18490
  2107
 "length(remdups(concat xss)) = card(\<Union>xs \<in> set xss. set xs)"
nipkow@24308
  2108
by(simp add: set_concat distinct_card[symmetric])
nipkow@17906
  2109
nipkow@17906
  2110
nipkow@15392
  2111
subsubsection {* @{text remove1} *}
nipkow@15110
  2112
nipkow@18049
  2113
lemma remove1_append:
nipkow@18049
  2114
  "remove1 x (xs @ ys) =
nipkow@18049
  2115
  (if x \<in> set xs then remove1 x xs @ ys else xs @ remove1 x ys)"
nipkow@18049
  2116
by (induct xs) auto
nipkow@18049
  2117
nipkow@23479
  2118
lemma in_set_remove1[simp]:
nipkow@23479
  2119
  "a \<noteq> b \<Longrightarrow> a : set(remove1 b xs) = (a : set xs)"
nipkow@23479
  2120
apply (induct xs)
nipkow@23479
  2121
apply auto
nipkow@23479
  2122
done
nipkow@23479
  2123
nipkow@15110
  2124
lemma set_remove1_subset: "set(remove1 x xs) <= set xs"
nipkow@15110
  2125
apply(induct xs)
nipkow@15110
  2126
 apply simp
nipkow@15110
  2127
apply simp
nipkow@15110
  2128
apply blast
nipkow@15110
  2129
done
nipkow@15110
  2130
paulson@17724
  2131
lemma set_remove1_eq [simp]: "distinct xs ==> set(remove1 x xs) = set xs - {x}"
nipkow@15110
  2132
apply(induct xs)
nipkow@15110
  2133
 apply simp
nipkow@15110
  2134
apply simp
nipkow@15110
  2135
apply blast
nipkow@15110
  2136
done
nipkow@15110
  2137
nipkow@23479
  2138
lemma length_remove1:
nipkow@23479
  2139
  "length(remove1 x xs) = (if x : set xs then length xs - 1 else length xs)"
nipkow@23479
  2140
apply (induct xs)
nipkow@23479
  2141
 apply (auto dest!:length_pos_if_in_set)
nipkow@23479
  2142
done
nipkow@23479
  2143
nipkow@18049
  2144
lemma remove1_filter_not[simp]:
nipkow@18049
  2145
  "\<not> P x \<Longrightarrow> remove1 x (filter P xs) = filter P xs"
nipkow@18049
  2146
by(induct xs) auto
nipkow@18049
  2147
nipkow@15110
  2148
lemma notin_set_remove1[simp]: "x ~: set xs ==> x ~: set(remove1 y xs)"
nipkow@15110
  2149
apply(insert set_remove1_subset)
nipkow@15110
  2150
apply fast
nipkow@15110
  2151
done
nipkow@15110
  2152
nipkow@15110
  2153
lemma distinct_remove1[simp]: "distinct xs ==> distinct(remove1 x xs)"
nipkow@15110
  2154
by (induct xs) simp_all
nipkow@15110
  2155
wenzelm@13114
  2156
nipkow@15392
  2157
subsubsection {* @{text replicate} *}
wenzelm@13114
  2158
wenzelm@13142
  2159
lemma length_replicate [simp]: "length (replicate n x) = n"
nipkow@13145
  2160
by (induct n) auto
nipkow@13124
  2161
wenzelm@13142
  2162
lemma map_replicate [simp]: "map f (replicate n x) = replicate n (f x)"
nipkow@13145
  2163
by (induct n) auto
wenzelm@13114
  2164
wenzelm@13114
  2165
lemma replicate_app_Cons_same:
nipkow@13145
  2166
"(replicate n x) @ (x # xs) = x # replicate n x @ xs"
nipkow@13145
  2167
by (induct n) auto
wenzelm@13114
  2168
wenzelm@13142
  2169
lemma rev_replicate [simp]: "rev (replicate n x) = replicate n x"
paulson@14208
  2170
apply (induct n, simp)
nipkow@13145
  2171
apply (simp add: replicate_app_Cons_same)
nipkow@13145
  2172
done
wenzelm@13114
  2173
wenzelm@13142
  2174
lemma replicate_add: "replicate (n + m) x = replicate n x @ replicate m x"
nipkow@13145
  2175
by (induct n) auto
wenzelm@13114
  2176
nipkow@16397
  2177
text{* Courtesy of Matthias Daum: *}
nipkow@16397
  2178
lemma append_replicate_commute:
nipkow@16397
  2179
  "replicate n x @ replicate k x = replicate k x @ replicate n x"
nipkow@16397
  2180
apply (simp add: replicate_add [THEN sym])
nipkow@16397
  2181
apply (simp add: add_commute)
nipkow@16397
  2182
done
nipkow@16397
  2183
wenzelm@13142
  2184
lemma hd_replicate [simp]: "n \<noteq> 0 ==> hd (replicate n x) = x"
nipkow@13145
  2185
by (induct n) auto
wenzelm@13114
  2186
wenzelm@13142
  2187
lemma tl_replicate [simp]: "n \<noteq> 0 ==> tl (replicate n x) = replicate (n - 1) x"
nipkow@13145
  2188
by (induct n) auto
wenzelm@13114
  2189
wenzelm@13142
  2190
lemma last_replicate [simp]: "n \<noteq> 0 ==> last (replicate n x) = x"
nipkow@13145
  2191
by (atomize (full), induct n) auto
wenzelm@13114
  2192
wenzelm@13142
  2193
lemma nth_replicate[simp]: "!!i. i < n ==> (replicate n x)!i = x"
paulson@14208
  2194
apply (induct n, simp)
nipkow@13145
  2195
apply (simp add: nth_Cons split: nat.split)
nipkow@13145
  2196
done
wenzelm@13114
  2197
nipkow@16397
  2198
text{* Courtesy of Matthias Daum (2 lemmas): *}
nipkow@16397
  2199
lemma take_replicate[simp]: "take i (replicate k x) = replicate (min i k) x"
nipkow@16397
  2200
apply (case_tac "k \<le> i")
nipkow@16397
  2201
 apply  (simp add: min_def)
nipkow@16397
  2202
apply (drule not_leE)
nipkow@16397
  2203
apply (simp add: min_def)
nipkow@16397
  2204
apply (subgoal_tac "replicate k x = replicate i x @ replicate (k - i) x")
nipkow@16397
  2205
 apply  simp
nipkow@16397
  2206
apply (simp add: replicate_add [symmetric])
nipkow@16397
  2207
done
nipkow@16397
  2208
nipkow@16397
  2209
lemma drop_replicate[simp]: "!!i. drop i (replicate k x) = replicate (k-i) x"
nipkow@16397
  2210
apply (induct k)
nipkow@16397
  2211
 apply simp
nipkow@16397
  2212
apply clarsimp
nipkow@16397
  2213
apply (case_tac i)
nipkow@16397
  2214
 apply simp
nipkow@16397
  2215
apply clarsimp
nipkow@16397
  2216
done
nipkow@16397
  2217
nipkow@16397
  2218
wenzelm@13142
  2219
lemma set_replicate_Suc: "set (replicate (Suc n) x) = {x}"
nipkow@13145
  2220
by (induct n) auto
wenzelm@13114
  2221
wenzelm@13142
  2222
lemma set_replicate [simp]: "n \<noteq> 0 ==> set (replicate n x) = {x}"
nipkow@13145
  2223
by (fast dest!: not0_implies_Suc intro!: set_replicate_Suc)
wenzelm@13114
  2224
wenzelm@13142
  2225
lemma set_replicate_conv_if: "set (replicate n x) = (if n = 0 then {} else {x})"
nipkow@13145
  2226
by auto
wenzelm@13114
  2227
wenzelm@13142
  2228
lemma in_set_replicateD: "x : set (replicate n y) ==> x = y"
nipkow@13145
  2229
by (simp add: set_replicate_conv_if split: split_if_asm)
wenzelm@13114
  2230
wenzelm@13114
  2231
nipkow@15392
  2232
subsubsection{*@{text rotate1} and @{text rotate}*}
nipkow@15302
  2233
nipkow@15302
  2234
lemma rotate_simps[simp]: "rotate1 [] = [] \<and> rotate1 (x#xs) = xs @ [x]"
nipkow@15302
  2235
by(simp add:rotate1_def)
nipkow@15302
  2236
nipkow@15302
  2237
lemma rotate0[simp]: "rotate 0 = id"
nipkow@15302
  2238
by(simp add:rotate_def)
nipkow@15302
  2239
nipkow@15302
  2240
lemma rotate_Suc[simp]: "rotate (Suc n) xs = rotate1(rotate n xs)"
nipkow@15302
  2241
by(simp add:rotate_def)
nipkow@15302
  2242
nipkow@15302
  2243
lemma rotate_add:
nipkow@15302
  2244
  "rotate (m+n) = rotate m o rotate n"
nipkow@15302
  2245
by(simp add:rotate_def funpow_add)
nipkow@15302
  2246
nipkow@15302
  2247
lemma rotate_rotate: "rotate m (rotate n xs) = rotate (m+n) xs"
nipkow@15302
  2248
by(simp add:rotate_add)
nipkow@15302
  2249
nipkow@18049
  2250
lemma rotate1_rotate_swap: "rotate1 (rotate n xs) = rotate n (rotate1 xs)"
nipkow@18049
  2251
by(simp add:rotate_def funpow_swap1)
nipkow@18049
  2252
nipkow@15302
  2253
lemma rotate1_length01[simp]: "length xs <= 1 \<Longrightarrow> rotate1 xs = xs"
nipkow@15302
  2254
by(cases xs) simp_all
nipkow@15302
  2255
nipkow@15302
  2256
lemma rotate_length01[simp]: "length xs <= 1 \<Longrightarrow> rotate n xs = xs"
nipkow@15302
  2257
apply(induct n)
nipkow@15302
  2258
 apply simp
nipkow@15302
  2259
apply (simp add:rotate_def)
nipkow@13145
  2260
done
wenzelm@13114
  2261
nipkow@15302
  2262
lemma rotate1_hd_tl: "xs \<noteq> [] \<Longrightarrow> rotate1 xs = tl xs @ [hd xs]"
nipkow@15302
  2263
by(simp add:rotate1_def split:list.split)
nipkow@15302
  2264
nipkow@15302
  2265
lemma rotate_drop_take:
nipkow@15302
  2266
  "rotate n xs = drop (n mod length xs) xs @ take (n mod length xs) xs"
nipkow@15302
  2267
apply(induct n)
nipkow@15302
  2268
 apply simp
nipkow@15302
  2269
apply(simp add:rotate_def)
nipkow@15302
  2270
apply(cases "xs = []")
nipkow@15302
  2271
 apply (simp)
nipkow@15302
  2272
apply(case_tac "n mod length xs = 0")
nipkow@15302
  2273
 apply(simp add:mod_Suc)
nipkow@15302
  2274
 apply(simp add: rotate1_hd_tl drop_Suc take_Suc)
nipkow@15302
  2275
apply(simp add:mod_Suc rotate1_hd_tl drop_Suc[symmetric] drop_tl[symmetric]
nipkow@15302
  2276
                take_hd_drop linorder_not_le)
nipkow@13145
  2277
done
wenzelm@13114
  2278
nipkow@15302
  2279
lemma rotate_conv_mod: "rotate n xs = rotate (n mod length xs) xs"
nipkow@15302
  2280
by(simp add:rotate_drop_take)
nipkow@15302
  2281
nipkow@15302
  2282
lemma rotate_id[simp]: "n mod length xs = 0 \<Longrightarrow> rotate n xs = xs"
nipkow@15302
  2283
by(simp add:rotate_drop_take)
nipkow@15302
  2284
nipkow@15302
  2285
lemma length_rotate1[simp]: "length(rotate1 xs) = length xs"
nipkow@15302
  2286
by(simp add:rotate1_def split:list.split)
nipkow@15302
  2287
nipkow@15302
  2288
lemma length_rotate[simp]: "!!xs. length(rotate n xs) = length xs"
nipkow@15302
  2289
by (induct n) (simp_all add:rotate_def)
nipkow@15302
  2290
nipkow@15302
  2291
lemma distinct1_rotate[simp]: "distinct(rotate1 xs) = distinct xs"
nipkow@15302
  2292
by(simp add:rotate1_def split:list.split) blast
nipkow@15302
  2293
nipkow@15302
  2294
lemma distinct_rotate[simp]: "distinct(rotate n xs) = distinct xs"
nipkow@15302
  2295
by (induct n) (simp_all add:rotate_def)
nipkow@15302
  2296
nipkow@15302
  2297
lemma rotate_map: "rotate n (map f xs) = map f (rotate n xs)"
nipkow@15302
  2298
by(simp add:rotate_drop_take take_map drop_map)
nipkow@15302
  2299
nipkow@15302
  2300
lemma set_rotate1[simp]: "set(rotate1 xs) = set xs"
nipkow@15302
  2301
by(simp add:rotate1_def split:list.split)
nipkow@15302
  2302
nipkow@15302
  2303
lemma set_rotate[simp]: "set(rotate n xs) = set xs"
nipkow@15302
  2304
by (induct n) (simp_all add:rotate_def)
nipkow@15302
  2305
nipkow@15302
  2306
lemma rotate1_is_Nil_conv[simp]: "(rotate1 xs = []) = (xs = [])"
nipkow@15302
  2307
by(simp add:rotate1_def split:list.split)
nipkow@15302
  2308
nipkow@15302
  2309
lemma rotate_is_Nil_conv[simp]: "(rotate n xs = []) = (xs = [])"
nipkow@15302
  2310
by (induct n) (simp_all add:rotate_def)
wenzelm@13114
  2311
nipkow@15439
  2312
lemma rotate_rev:
nipkow@15439
  2313
  "rotate n (rev xs) = rev(rotate (length xs - (n mod length xs)) xs)"
nipkow@15439
  2314
apply(simp add:rotate_drop_take rev_drop rev_take)
nipkow@15439
  2315
apply(cases "length xs = 0")
nipkow@15439
  2316
 apply simp
nipkow@15439
  2317
apply(cases "n mod length xs = 0")
nipkow@15439
  2318
 apply simp
nipkow@15439
  2319
apply(simp add:rotate_drop_take rev_drop rev_take)
nipkow@15439
  2320
done
nipkow@15439
  2321
nipkow@18423
  2322
lemma hd_rotate_conv_nth: "xs \<noteq> [] \<Longrightarrow> hd(rotate n xs) = xs!(n mod length xs)"
nipkow@18423
  2323
apply(simp add:rotate_drop_take hd_append hd_drop_conv_nth hd_conv_nth)
nipkow@18423
  2324
apply(subgoal_tac "length xs \<noteq> 0")
nipkow@18423
  2325
 prefer 2 apply simp
nipkow@18423
  2326
using mod_less_divisor[of "length xs" n] by arith
nipkow@18423
  2327
wenzelm@13114
  2328
nipkow@15392
  2329
subsubsection {* @{text sublist} --- a generalization of @{text nth} to sets *}
wenzelm@13114
  2330
wenzelm@13142
  2331
lemma sublist_empty [simp]: "sublist xs {} = []"
nipkow@13145
  2332
by (auto simp add: sublist_def)
wenzelm@13114
  2333
wenzelm@13142
  2334
lemma sublist_nil [simp]: "sublist [] A = []"
nipkow@13145
  2335
by (auto simp add: sublist_def)
wenzelm@13114
  2336
nipkow@15281
  2337
lemma length_sublist:
nipkow@15281
  2338
  "length(sublist xs I) = card{i. i < length xs \<and> i : I}"
nipkow@15281
  2339
by(simp add: sublist_def length_filter_conv_card cong:conj_cong)
nipkow@15281
  2340
nipkow@15281
  2341
lemma sublist_shift_lemma_Suc:
nipkow@15281
  2342
  "!!is. map fst (filter (%p. P(Suc(snd p))) (zip xs is)) =
nipkow@15281
  2343
         map fst (filter (%p. P(snd p)) (zip xs (map Suc is)))"
nipkow@15281
  2344
apply(induct xs)
nipkow@15281
  2345
 apply simp
nipkow@15281
  2346
apply (case_tac "is")
nipkow@15281
  2347
 apply simp
nipkow@15281
  2348
apply simp
nipkow@15281
  2349
done
nipkow@15281
  2350
wenzelm@13114
  2351
lemma sublist_shift_lemma:
nipkow@23279
  2352
     "map fst [p<-zip xs [i..<i + length xs] . snd p : A] =
nipkow@23279
  2353
      map fst [p<-zip xs [0..<length xs] . snd p + i : A]"
nipkow@13145
  2354
by (induct xs rule: rev_induct) (simp_all add: add_commute)
wenzelm@13114
  2355
wenzelm@13114
  2356
lemma sublist_append:
paulson@15168
  2357
     "sublist (l @ l') A = sublist l A @ sublist l' {j. j + length l : A}"
nipkow@13145
  2358
apply (unfold sublist_def)
paulson@14208
  2359
apply (induct l' rule: rev_induct, simp)
nipkow@13145
  2360
apply (simp add: upt_add_eq_append[of 0] zip_append sublist_shift_lemma)
nipkow@13145
  2361
apply (simp add: add_commute)
nipkow@13145
  2362
done
wenzelm@13114
  2363
wenzelm@13114
  2364
lemma sublist_Cons:
nipkow@13145
  2365
"sublist (x # l) A = (if 0:A then [x] else []) @ sublist l {j. Suc j : A}"
nipkow@13145
  2366
apply (induct l rule: rev_induct)
nipkow@13145
  2367
 apply (simp add: sublist_def)
nipkow@13145
  2368
apply (simp del: append_Cons add: append_Cons[symmetric] sublist_append)
nipkow@13145
  2369
done
wenzelm@13114
  2370
nipkow@15281
  2371
lemma set_sublist: "!!I. set(sublist xs I) = {xs!i|i. i<size xs \<and> i \<in> I}"
nipkow@15281
  2372
apply(induct xs)
nipkow@15281
  2373
 apply simp
nipkow@15281
  2374
apply(auto simp add:sublist_Cons nth_Cons split:nat.split elim: lessE)
nipkow@15281
  2375
 apply(erule lessE)
nipkow@15281
  2376
  apply auto
nipkow@15281
  2377
apply(erule lessE)
nipkow@15281
  2378
apply auto
nipkow@15281
  2379
done
nipkow@15281
  2380
nipkow@15281
  2381
lemma set_sublist_subset: "set(sublist xs I) \<subseteq> set xs"
nipkow@15281
  2382
by(auto simp add:set_sublist)
nipkow@15281
  2383
nipkow@15281
  2384
lemma notin_set_sublistI[simp]: "x \<notin> set xs \<Longrightarrow> x \<notin> set(sublist xs I)"
nipkow@15281
  2385
by(auto simp add:set_sublist)
nipkow@15281
  2386
nipkow@15281
  2387
lemma in_set_sublistD: "x \<in> set(sublist xs I) \<Longrightarrow> x \<in> set xs"
nipkow@15281
  2388
by(auto simp add:set_sublist)
nipkow@15281
  2389
wenzelm@13142
  2390
lemma sublist_singleton [simp]: "sublist [x] A = (if 0 : A then [x] else [])"
nipkow@13145
  2391
by (simp add: sublist_Cons)
wenzelm@13114
  2392
nipkow@15281
  2393
nipkow@15281
  2394
lemma distinct_sublistI[simp]: "!!I. distinct xs \<Longrightarrow> distinct(sublist xs I)"
nipkow@15281
  2395
apply(induct xs)
nipkow@15281
  2396
 apply simp
nipkow@15281
  2397
apply(auto simp add:sublist_Cons)
nipkow@15281
  2398
done
nipkow@15281
  2399
nipkow@15281
  2400
nipkow@15045
  2401
lemma sublist_upt_eq_take [simp]: "sublist l {..<n} = take n l"
paulson@14208
  2402
apply (induct l rule: rev_induct, simp)
nipkow@13145
  2403
apply (simp split: nat_diff_split add: sublist_append)
nipkow@13145
  2404
done
wenzelm@13114
  2405
nipkow@17501
  2406
lemma filter_in_sublist: "\<And>s. distinct xs \<Longrightarrow>
nipkow@17501
  2407
  filter (%x. x \<in> set(sublist xs s)) xs = sublist xs s"
nipkow@17501
  2408
proof (induct xs)
nipkow@17501
  2409
  case Nil thus ?case by simp
nipkow@17501
  2410
next
nipkow@17501
  2411
  case (Cons a xs)
nipkow@17501
  2412
  moreover hence "!x. x: set xs \<longrightarrow> x \<noteq> a" by auto
nipkow@17501
  2413
  ultimately show ?case by(simp add: sublist_Cons cong:filter_cong)
nipkow@17501
  2414
qed
nipkow@17501
  2415
wenzelm@13114
  2416
nipkow@19390
  2417
subsubsection {* @{const splice} *}
nipkow@19390
  2418
haftmann@19607
  2419
lemma splice_Nil2 [simp, code]:
nipkow@19390
  2420
 "splice xs [] = xs"
nipkow@19390
  2421
by (cases xs) simp_all
nipkow@19390
  2422
haftmann@19607
  2423
lemma splice_Cons_Cons [simp, code]:
nipkow@19390
  2424
 "splice (x#xs) (y#ys) = x # y # splice xs ys"
nipkow@19390
  2425
by simp
nipkow@19390
  2426
haftmann@19607
  2427
declare splice.simps(2) [simp del, code del]
nipkow@19390
  2428
nipkow@22793
  2429
lemma length_splice[simp]: "!!ys. length(splice xs ys) = length xs + length ys"
nipkow@22793
  2430
apply(induct xs) apply simp
nipkow@22793
  2431
apply(case_tac ys)
nipkow@22793
  2432
 apply auto
nipkow@22793
  2433
done
nipkow@22793
  2434
nipkow@15392
  2435
subsubsection {* @{text lists}: the list-forming operator over sets *}
nipkow@15302
  2436
berghofe@23740
  2437
inductive_set
berghofe@22262
  2438
  lists :: "'a set => 'a list set"
berghofe@23740
  2439
  for A :: "'a set"
berghofe@23740
  2440
where
berghofe@23740
  2441
    Nil [intro!]: "[]: lists A"
paulson@24286
  2442
  | Cons [intro!,noatp]: "[| a: A;l: lists A|] ==> a#l : lists A"
paulson@24286
  2443
paulson@24286
  2444
inductive_cases listsE [elim!,noatp]: "x#l : lists A"
paulson@24286
  2445
inductive_cases listspE [elim!,noatp]: "listsp A (x # l)"
berghofe@23740
  2446
berghofe@23740
  2447
lemma listsp_mono [mono]: "A \<le> B ==> listsp A \<le> listsp B"
nipkow@24349
  2448
by (clarify, erule listsp.induct, blast+)
berghofe@22262
  2449
berghofe@23740
  2450
lemmas lists_mono = listsp_mono [to_set]
berghofe@22262
  2451
haftmann@22422
  2452
lemma listsp_infI:
haftmann@22422
  2453
  assumes l: "listsp A l" shows "listsp B l ==> listsp (inf A B) l" using l
nipkow@24349
  2454
by induct blast+
nipkow@15302
  2455
haftmann@22422
  2456
lemmas lists_IntI = listsp_infI [to_set]
haftmann@22422
  2457
haftmann@22422
  2458
lemma listsp_inf_eq [simp]: "listsp (inf A B) = inf (listsp A) (listsp B)"
haftmann@22422
  2459
proof (rule mono_inf [where f=listsp, THEN order_antisym])
berghofe@22262
  2460
  show "mono listsp" by (simp add: mono_def listsp_mono)
haftmann@22422
  2461
  show "inf (listsp A) (listsp B) \<le> listsp (inf A B)" by (blast intro: listsp_infI)
kleing@14388
  2462
qed
kleing@14388
  2463
haftmann@22422
  2464
lemmas listsp_conj_eq [simp] = listsp_inf_eq [simplified inf_fun_eq inf_bool_eq]
haftmann@22422
  2465
haftmann@22422
  2466
lemmas lists_Int_eq [simp] = listsp_inf_eq [to_set]
berghofe@22262
  2467
berghofe@22262
  2468
lemma append_in_listsp_conv [iff]:
berghofe@22262
  2469
     "(listsp A (xs @ ys)) = (listsp A xs \<and> listsp A ys)"
nipkow@15302
  2470
by (induct xs) auto
nipkow@15302
  2471
berghofe@22262
  2472
lemmas append_in_lists_conv [iff] = append_in_listsp_conv [to_set]
berghofe@22262
  2473
berghofe@22262
  2474
lemma in_listsp_conv_set: "(listsp A xs) = (\<forall>x \<in> set xs. A x)"
berghofe@22262
  2475
-- {* eliminate @{text listsp} in favour of @{text set} *}
nipkow@15302
  2476
by (induct xs) auto
nipkow@15302
  2477
berghofe@22262
  2478
lemmas in_lists_conv_set = in_listsp_conv_set [to_set]
berghofe@22262
  2479
paulson@24286
  2480
lemma in_listspD [dest!,noatp]: "listsp A xs ==> \<forall>x\<in>set xs. A x"
berghofe@22262
  2481
by (rule in_listsp_conv_set [THEN iffD1])
berghofe@22262
  2482
paulson@24286
  2483
lemmas in_listsD [dest!,noatp] = in_listspD [to_set]
paulson@24286
  2484
paulson@24286
  2485
lemma in_listspI [intro!,noatp]: "\<forall>x\<in>set xs. A x ==> listsp A xs"
berghofe@22262
  2486
by (rule in_listsp_conv_set [THEN iffD2])
berghofe@22262
  2487
paulson@24286
  2488
lemmas in_listsI [intro!,noatp] = in_listspI [to_set]
nipkow@15302
  2489
nipkow@15302
  2490
lemma lists_UNIV [simp]: "lists UNIV = UNIV"
nipkow@15302
  2491
by auto
nipkow@15302
  2492
nipkow@17086
  2493
nipkow@17086
  2494
nipkow@17086
  2495
subsubsection{* Inductive definition for membership *}
nipkow@17086
  2496
berghofe@23740
  2497
inductive ListMem :: "'a \<Rightarrow> 'a list \<Rightarrow> bool"
berghofe@22262
  2498
where
berghofe@22262
  2499
    elem:  "ListMem x (x # xs)"
berghofe@22262
  2500
  | insert:  "ListMem x xs \<Longrightarrow> ListMem x (y # xs)"
berghofe@22262
  2501
berghofe@22262
  2502
lemma ListMem_iff: "(ListMem x xs) = (x \<in> set xs)"
nipkow@17086
  2503
apply (rule iffI)
nipkow@17086
  2504
 apply (induct set: ListMem)
nipkow@17086
  2505
  apply auto
nipkow@17086
  2506
apply (induct xs)
nipkow@17086
  2507
 apply (auto intro: ListMem.intros)
nipkow@17086
  2508
done
nipkow@17086
  2509
nipkow@17086
  2510
nipkow@17086
  2511
nipkow@15392
  2512
subsubsection{*Lists as Cartesian products*}
nipkow@15302
  2513
nipkow@15302
  2514
text{*@{text"set_Cons A Xs"}: the set of lists with head drawn from
nipkow@15302
  2515
@{term A} and tail drawn from @{term Xs}.*}
nipkow@15302
  2516
nipkow@15302
  2517
constdefs
nipkow@15302
  2518
  set_Cons :: "'a set \<Rightarrow> 'a list set \<Rightarrow> 'a list set"
nipkow@15302
  2519
  "set_Cons A XS == {z. \<exists>x xs. z = x#xs & x \<in> A & xs \<in> XS}"
nipkow@15302
  2520
paulson@17724
  2521
lemma set_Cons_sing_Nil [simp]: "set_Cons A {[]} = (%x. [x])`A"
nipkow@15302
  2522
by (auto simp add: set_Cons_def)
nipkow@15302
  2523
nipkow@15302
  2524
text{*Yields the set of lists, all of the same length as the argument and
nipkow@15302
  2525
with elements drawn from the corresponding element of the argument.*}
nipkow@15302
  2526
nipkow@15302
  2527
consts  listset :: "'a set list \<Rightarrow> 'a list set"
nipkow@15302
  2528
primrec
nipkow@15302
  2529
   "listset []    = {[]}"
nipkow@15302
  2530
   "listset(A#As) = set_Cons A (listset As)"
nipkow@15302
  2531
nipkow@15302
  2532
paulson@15656
  2533
subsection{*Relations on Lists*}
paulson@15656
  2534
paulson@15656
  2535
subsubsection {* Length Lexicographic Ordering *}
paulson@15656
  2536
paulson@15656
  2537
text{*These orderings preserve well-foundedness: shorter lists 
paulson@15656
  2538
  precede longer lists. These ordering are not used in dictionaries.*}
paulson@15656
  2539
paulson@15656
  2540
consts lexn :: "('a * 'a)set => nat => ('a list * 'a list)set"
paulson@15656
  2541
        --{*The lexicographic ordering for lists of the specified length*}
nipkow@15302
  2542
primrec
paulson@15656
  2543
  "lexn r 0 = {}"
paulson@15656
  2544
  "lexn r (Suc n) =
paulson@15656
  2545
    (prod_fun (%(x,xs). x#xs) (%(x,xs). x#xs) ` (r <*lex*> lexn r n)) Int
paulson@15656
  2546
    {(xs,ys). length xs = Suc n \<and> length ys = Suc n}"
nipkow@15302
  2547
nipkow@15302
  2548
constdefs
paulson@15656
  2549
  lex :: "('a \<times> 'a) set => ('a list \<times> 'a list) set"
paulson@15656
  2550
    "lex r == \<Union>n. lexn r n"
paulson@15656
  2551
        --{*Holds only between lists of the same length*}
paulson@15656
  2552
nipkow@15693
  2553
  lenlex :: "('a \<times> 'a) set => ('a list \<times> 'a list) set"
nipkow@15693
  2554
    "lenlex r == inv_image (less_than <*lex*> lex r) (%xs. (length xs, xs))"
paulson@15656
  2555
        --{*Compares lists by their length and then lexicographically*}
nipkow@15302
  2556
nipkow@15302
  2557
nipkow@15302
  2558
lemma wf_lexn: "wf r ==> wf (lexn r n)"
nipkow@15302
  2559
apply (induct n, simp, simp)
nipkow@15302
  2560
apply(rule wf_subset)
nipkow@15302
  2561
 prefer 2 apply (rule Int_lower1)
nipkow@15302
  2562
apply(rule wf_prod_fun_image)
nipkow@15302
  2563
 prefer 2 apply (rule inj_onI, auto)
nipkow@15302
  2564
done
nipkow@15302
  2565
nipkow@15302
  2566
lemma lexn_length:
nipkow@15302
  2567
     "!!xs ys. (xs, ys) : lexn r n ==> length xs = n \<and> length ys = n"
nipkow@15302
  2568
by (induct n) auto
nipkow@15302
  2569
nipkow@15302
  2570
lemma wf_lex [intro!]: "wf r ==> wf (lex r)"
nipkow@15302
  2571
apply (unfold lex_def)
nipkow@15302
  2572
apply (rule wf_UN)
nipkow@15302
  2573
apply (blast intro: wf_lexn, clarify)
nipkow@15302
  2574
apply (rename_tac m n)
nipkow@15302
  2575
apply (subgoal_tac "m \<noteq> n")
nipkow@15302
  2576
 prefer 2 apply blast
nipkow@15302
  2577
apply (blast dest: lexn_length not_sym)
nipkow@15302
  2578
done
nipkow@15302
  2579
nipkow@15302
  2580
lemma lexn_conv:
paulson@15656
  2581
  "lexn r n =
paulson@15656
  2582
    {(xs,ys). length xs = n \<and> length ys = n \<and>
paulson@15656
  2583
    (\<exists>xys x y xs' ys'. xs= xys @ x#xs' \<and> ys= xys @ y # ys' \<and> (x, y):r)}"
nipkow@18423
  2584
apply (induct n, simp)
nipkow@15302
  2585
apply (simp add: image_Collect lex_prod_def, safe, blast)
nipkow@15302
  2586
 apply (rule_tac x = "ab # xys" in exI, simp)
nipkow@15302
  2587
apply (case_tac xys, simp_all, blast)
nipkow@15302
  2588
done
nipkow@15302
  2589
nipkow@15302
  2590
lemma lex_conv:
paulson@15656
  2591
  "lex r =
paulson@15656
  2592
    {(xs,ys). length xs = length ys \<and>
paulson@15656
  2593
    (\<exists>xys x y xs' ys'. xs = xys @ x # xs' \<and> ys = xys @ y # ys' \<and> (x, y):r)}"
nipkow@15302
  2594
by (force simp add: lex_def lexn_conv)
nipkow@15302
  2595
nipkow@15693
  2596
lemma wf_lenlex [intro!]: "wf r ==> wf (lenlex r)"
nipkow@15693
  2597
by (unfold lenlex_def) blast
nipkow@15693
  2598
nipkow@15693
  2599
lemma lenlex_conv:
nipkow@15693
  2600
    "lenlex r = {(xs,ys). length xs < length ys |
paulson@15656
  2601
                 length xs = length ys \<and> (xs, ys) : lex r}"
nipkow@19623
  2602
by (simp add: lenlex_def diag_def lex_prod_def inv_image_def)
nipkow@15302
  2603
nipkow@15302
  2604
lemma Nil_notin_lex [iff]: "([], ys) \<notin> lex r"
nipkow@15302
  2605
by (simp add: lex_conv)
nipkow@15302
  2606
nipkow@15302
  2607
lemma Nil2_notin_lex [iff]: "(xs, []) \<notin> lex r"
nipkow@15302
  2608
by (simp add:lex_conv)
nipkow@15302
  2609
paulson@18447
  2610
lemma Cons_in_lex [simp]:
paulson@15656
  2611
    "((x # xs, y # ys) : lex r) =
paulson@15656
  2612
      ((x, y) : r \<and> length xs = length ys | x = y \<and> (xs, ys) : lex r)"
nipkow@15302
  2613
apply (simp add: lex_conv)
nipkow@15302
  2614
apply (rule iffI)
nipkow@15302
  2615
 prefer 2 apply (blast intro: Cons_eq_appendI, clarify)
nipkow@15302
  2616
apply (case_tac xys, simp, simp)
nipkow@15302
  2617
apply blast
nipkow@15302
  2618
done
nipkow@15302
  2619
nipkow@15302
  2620
paulson@15656
  2621
subsubsection {* Lexicographic Ordering *}
paulson@15656
  2622
paulson@15656
  2623
text {* Classical lexicographic ordering on lists, ie. "a" < "ab" < "b".
paulson@15656
  2624
    This ordering does \emph{not} preserve well-foundedness.
nipkow@17090
  2625
     Author: N. Voelker, March 2005. *} 
paulson@15656
  2626
paulson@15656
  2627
constdefs 
paulson@15656
  2628
  lexord :: "('a * 'a)set \<Rightarrow> ('a list * 'a list) set" 
paulson@15656
  2629
  "lexord  r == {(x,y). \<exists> a v. y = x @ a # v \<or> 
paulson@15656
  2630
            (\<exists> u a b v w. (a,b) \<in> r \<and> x = u @ (a # v) \<and> y = u @ (b # w))}"
paulson@15656
  2631
paulson@15656
  2632
lemma lexord_Nil_left[simp]:  "([],y) \<in> lexord r = (\<exists> a x. y = a # x)"
nipkow@24349
  2633
by (unfold lexord_def, induct_tac y, auto) 
paulson@15656
  2634
paulson@15656
  2635
lemma lexord_Nil_right[simp]: "(x,[]) \<notin> lexord r"
nipkow@24349
  2636
by (unfold lexord_def, induct_tac x, auto)
paulson@15656
  2637
paulson@15656
  2638
lemma lexord_cons_cons[simp]:
paulson@15656
  2639
     "((a # x, b # y) \<in> lexord r) = ((a,b)\<in> r | (a = b & (x,y)\<in> lexord r))"
paulson@15656
  2640
  apply (unfold lexord_def, safe, simp_all)
paulson@15656
  2641
  apply (case_tac u, simp, simp)
paulson@15656
  2642
  apply (case_tac u, simp, clarsimp, blast, blast, clarsimp)
paulson@15656
  2643
  apply (erule_tac x="b # u" in allE)
paulson@15656
  2644
  by force
paulson@15656
  2645
paulson@15656
  2646
lemmas lexord_simps = lexord_Nil_left lexord_Nil_right lexord_cons_cons
paulson@15656
  2647
paulson@15656
  2648
lemma lexord_append_rightI: "\<exists> b z. y = b # z \<Longrightarrow> (x, x @ y) \<in> lexord r"
nipkow@24349
  2649
by (induct_tac x, auto)  
paulson@15656
  2650
paulson@15656
  2651
lemma lexord_append_left_rightI:
paulson@15656
  2652
     "(a,b) \<in> r \<Longrightarrow> (u @ a # x, u @ b # y) \<in> lexord r"
nipkow@24349
  2653
by (induct_tac u, auto)
paulson@15656
  2654
paulson@15656
  2655
lemma lexord_append_leftI: " (u,v) \<in> lexord r \<Longrightarrow> (x @ u, x @ v) \<in> lexord r"
nipkow@24349
  2656
by (induct x, auto)
paulson@15656
  2657
paulson@15656
  2658
lemma lexord_append_leftD:
paulson@15656
  2659
     "\<lbrakk> (x @ u, x @ v) \<in> lexord r; (! a. (a,a) \<notin> r) \<rbrakk> \<Longrightarrow> (u,v) \<in> lexord r"
nipkow@24349
  2660
by (erule rev_mp, induct_tac x, auto)
paulson@15656
  2661
paulson@15656
  2662
lemma lexord_take_index_conv: 
paulson@15656
  2663
   "((x,y) : lexord r) = 
paulson@15656
  2664
    ((length x < length y \<and> take (length x) y = x) \<or> 
paulson@15656
  2665
     (\<exists>i. i < min(length x)(length y) & take i x = take i y & (x!i,y!i) \<in> r))"
paulson@15656
  2666
  apply (unfold lexord_def Let_def, clarsimp) 
paulson@15656
  2667
  apply (rule_tac f = "(% a b. a \<or> b)" in arg_cong2)
paulson@15656
  2668
  apply auto 
paulson@15656
  2669
  apply (rule_tac x="hd (drop (length x) y)" in exI)
paulson@15656
  2670
  apply (rule_tac x="tl (drop (length x) y)" in exI)
paulson@15656
  2671
  apply (erule subst, simp add: min_def) 
paulson@15656
  2672
  apply (rule_tac x ="length u" in exI, simp) 
paulson@15656
  2673
  apply (rule_tac x ="take i x" in exI) 
paulson@15656
  2674
  apply (rule_tac x ="x ! i" in exI) 
paulson@15656
  2675
  apply (rule_tac x ="y ! i" in exI, safe) 
paulson@15656
  2676
  apply (rule_tac x="drop (Suc i) x" in exI)
paulson@15656
  2677
  apply (drule sym, simp add: drop_Suc_conv_tl) 
paulson@15656
  2678
  apply (rule_tac x="drop (Suc i) y" in exI)
paulson@15656
  2679
  by (simp add: drop_Suc_conv_tl) 
paulson@15656
  2680
paulson@15656
  2681
-- {* lexord is extension of partial ordering List.lex *} 
paulson@15656
  2682
lemma lexord_lex: " (x,y) \<in> lex r = ((x,y) \<in> lexord r \<and> length x = length y)"
paulson@15656
  2683
  apply (rule_tac x = y in spec) 
paulson@15656
  2684
  apply (induct_tac x, clarsimp) 
paulson@15656
  2685
  by (clarify, case_tac x, simp, force)
paulson@15656
  2686
paulson@15656
  2687
lemma lexord_irreflexive: "(! x. (x,x) \<notin> r) \<Longrightarrow> (y,y) \<notin> lexord r"
paulson@15656
  2688
  by (induct y, auto)
paulson@15656
  2689
paulson@15656
  2690
lemma lexord_trans: 
paulson@15656
  2691
    "\<lbrakk> (x, y) \<in> lexord r; (y, z) \<in> lexord r; trans r \<rbrakk> \<Longrightarrow> (x, z) \<in> lexord r"
paulson@15656
  2692
   apply (erule rev_mp)+
paulson@15656
  2693
   apply (rule_tac x = x in spec) 
paulson@15656
  2694
  apply (rule_tac x = z in spec) 
paulson@15656
  2695
  apply ( induct_tac y, simp, clarify)
paulson@15656
  2696
  apply (case_tac xa, erule ssubst) 
paulson@15656
  2697
  apply (erule allE, erule allE) -- {* avoid simp recursion *} 
paulson@15656
  2698
  apply (case_tac x, simp, simp) 
paulson@15656
  2699
  apply (case_tac x, erule allE, erule allE, simp) 
paulson@15656
  2700
  apply (erule_tac x = listb in allE) 
paulson@15656
  2701
  apply (erule_tac x = lista in allE, simp)
paulson@15656
  2702
  apply (unfold trans_def)
paulson@15656
  2703
  by blast
paulson@15656
  2704
paulson@15656
  2705
lemma lexord_transI:  "trans r \<Longrightarrow> trans (lexord r)"
nipkow@24349
  2706
by (rule transI, drule lexord_trans, blast) 
paulson@15656
  2707
paulson@15656
  2708
lemma lexord_linear: "(! a b. (a,b)\<in> r | a = b | (b,a) \<in> r) \<Longrightarrow> (x,y) : lexord r | x = y | (y,x) : lexord r"
paulson@15656
  2709
  apply (rule_tac x = y in spec) 
paulson@15656
  2710
  apply (induct_tac x, rule allI) 
paulson@15656
  2711
  apply (case_tac x, simp, simp) 
paulson@15656
  2712
  apply (rule allI, case_tac x, simp, simp) 
paulson@15656
  2713
  by blast
paulson@15656
  2714
paulson@15656
  2715
krauss@21103
  2716
subsection {* Lexicographic combination of measure functions *}
krauss@21103
  2717
krauss@21103
  2718
text {* These are useful for termination proofs *}
krauss@21103
  2719
krauss@21103
  2720
definition
krauss@21103
  2721
  "measures fs = inv_image (lex less_than) (%a. map (%f. f a) fs)"
krauss@21103
  2722
krauss@21106
  2723
lemma wf_measures[recdef_wf, simp]: "wf (measures fs)"
nipkow@24349
  2724
unfolding measures_def
nipkow@24349
  2725
by blast
krauss@21103
  2726
krauss@21103
  2727
lemma in_measures[simp]: 
krauss@21103
  2728
  "(x, y) \<in> measures [] = False"
krauss@21103
  2729
  "(x, y) \<in> measures (f # fs)
krauss@21103
  2730
         = (f x < f y \<or> (f x = f y \<and> (x, y) \<in> measures fs))"  
nipkow@24349
  2731
unfolding measures_def
nipkow@24349
  2732
by auto
krauss@21103
  2733
krauss@21103
  2734
lemma measures_less: "f x < f y ==> (x, y) \<in> measures (f#fs)"
nipkow@24349
  2735
by simp
krauss@21103
  2736
krauss@21103
  2737
lemma measures_lesseq: "f x <= f y ==> (x, y) \<in> measures fs ==> (x, y) \<in> measures (f#fs)"
nipkow@24349
  2738
by auto
krauss@21103
  2739
krauss@21211
  2740
(* install the lexicographic_order method and the "fun" command *)
bulwahn@21131
  2741
use "Tools/function_package/lexicographic_order.ML"
krauss@21211
  2742
use "Tools/function_package/fundef_datatype.ML"
krauss@21211
  2743
setup LexicographicOrder.setup
krauss@21211
  2744
setup FundefDatatype.setup
krauss@21211
  2745
krauss@21103
  2746
nipkow@15392
  2747
subsubsection{*Lifting a Relation on List Elements to the Lists*}
nipkow@15302
  2748
berghofe@23740
  2749
inductive_set
berghofe@23740
  2750
  listrel :: "('a * 'a)set => ('a list * 'a list)set"
berghofe@23740
  2751
  for r :: "('a * 'a)set"
berghofe@22262
  2752
where
berghofe@23740
  2753
    Nil:  "([],[]) \<in> listrel r"
berghofe@23740
  2754
  | Cons: "[| (x,y) \<in> r; (xs,ys) \<in> listrel r |] ==> (x#xs, y#ys) \<in> listrel r"
berghofe@23740
  2755
berghofe@23740
  2756
inductive_cases listrel_Nil1 [elim!]: "([],xs) \<in> listrel r"
berghofe@23740
  2757
inductive_cases listrel_Nil2 [elim!]: "(xs,[]) \<in> listrel r"
berghofe@23740
  2758
inductive_cases listrel_Cons1 [elim!]: "(y#ys,xs) \<in> listrel r"
berghofe@23740
  2759
inductive_cases listrel_Cons2 [elim!]: "(xs,y#ys) \<in> listrel r"
nipkow@15302