src/HOL/List.thy
author berghofe
Tue Mar 25 09:58:51 2003 +0100 (2003-03-25)
changeset 13883 0451e0fb3f22
parent 13863 ec901a432ea1
child 13913 b3ed67af04b8
permissions -rw-r--r--
Re-structured some proofs in order to get rid of rule_format attribute.
     1 (*  Title:      HOL/List.thy
     2     ID:         $Id$
     3     Author:     Tobias Nipkow
     4     License:    GPL (GNU GENERAL PUBLIC LICENSE)
     5 *)
     6 
     7 header {* The datatype of finite lists *}
     8 
     9 theory List = PreList:
    10 
    11 datatype 'a list =
    12     Nil    ("[]")
    13   | Cons 'a  "'a list"    (infixr "#" 65)
    14 
    15 consts
    16   "@" :: "'a list => 'a list => 'a list"    (infixr 65)
    17   filter:: "('a => bool) => 'a list => 'a list"
    18   concat:: "'a list list => 'a list"
    19   foldl :: "('b => 'a => 'b) => 'b => 'a list => 'b"
    20   foldr :: "('a => 'b => 'b) => 'a list => 'b => 'b"
    21   hd:: "'a list => 'a"
    22   tl:: "'a list => 'a list"
    23   last:: "'a list => 'a"
    24   butlast :: "'a list => 'a list"
    25   set :: "'a list => 'a set"
    26   list_all:: "('a => bool) => ('a list => bool)"
    27   list_all2 :: "('a => 'b => bool) => 'a list => 'b list => bool"
    28   map :: "('a=>'b) => ('a list => 'b list)"
    29   mem :: "'a => 'a list => bool"    (infixl 55)
    30   nth :: "'a list => nat => 'a"    (infixl "!" 100)
    31   list_update :: "'a list => nat => 'a => 'a list"
    32   take:: "nat => 'a list => 'a list"
    33   drop:: "nat => 'a list => 'a list"
    34   takeWhile :: "('a => bool) => 'a list => 'a list"
    35   dropWhile :: "('a => bool) => 'a list => 'a list"
    36   rev :: "'a list => 'a list"
    37   zip :: "'a list => 'b list => ('a * 'b) list"
    38   upt :: "nat => nat => nat list" ("(1[_../_'(])")
    39   remdups :: "'a list => 'a list"
    40   null:: "'a list => bool"
    41   "distinct":: "'a list => bool"
    42   replicate :: "nat => 'a => 'a list"
    43 
    44 nonterminals lupdbinds lupdbind
    45 
    46 syntax
    47   -- {* list Enumeration *}
    48   "@list" :: "args => 'a list"    ("[(_)]")
    49 
    50   -- {* Special syntax for filter *}
    51   "@filter" :: "[pttrn, 'a list, bool] => 'a list"    ("(1[_:_./ _])")
    52 
    53   -- {* list update *}
    54   "_lupdbind":: "['a, 'a] => lupdbind"    ("(2_ :=/ _)")
    55   "" :: "lupdbind => lupdbinds"    ("_")
    56   "_lupdbinds" :: "[lupdbind, lupdbinds] => lupdbinds"    ("_,/ _")
    57   "_LUpdate" :: "['a, lupdbinds] => 'a"    ("_/[(_)]" [900,0] 900)
    58 
    59   upto:: "nat => nat => nat list"    ("(1[_../_])")
    60 
    61 translations
    62   "[x, xs]" == "x#[xs]"
    63   "[x]" == "x#[]"
    64   "[x:xs . P]"== "filter (%x. P) xs"
    65 
    66   "_LUpdate xs (_lupdbinds b bs)"== "_LUpdate (_LUpdate xs b) bs"
    67   "xs[i:=x]" == "list_update xs i x"
    68 
    69   "[i..j]" == "[i..(Suc j)(]"
    70 
    71 
    72 syntax (xsymbols)
    73   "@filter" :: "[pttrn, 'a list, bool] => 'a list"("(1[_\<in>_ ./ _])")
    74 
    75 
    76 text {*
    77   Function @{text size} is overloaded for all datatypes.Users may
    78   refer to the list version as @{text length}. *}
    79 
    80 syntax length :: "'a list => nat"
    81 translations "length" => "size :: _ list => nat"
    82 
    83 typed_print_translation {*
    84   let
    85     fun size_tr' _ (Type ("fun", (Type ("list", _) :: _))) [t] =
    86           Syntax.const "length" $ t
    87       | size_tr' _ _ _ = raise Match;
    88   in [("size", size_tr')] end
    89 *}
    90 
    91 primrec
    92 "hd(x#xs) = x"
    93 primrec
    94 "tl([]) = []"
    95 "tl(x#xs) = xs"
    96 primrec
    97 "null([]) = True"
    98 "null(x#xs) = False"
    99 primrec
   100 "last(x#xs) = (if xs=[] then x else last xs)"
   101 primrec
   102 "butlast []= []"
   103 "butlast(x#xs) = (if xs=[] then [] else x#butlast xs)"
   104 primrec
   105 "x mem [] = False"
   106 "x mem (y#ys) = (if y=x then True else x mem ys)"
   107 primrec
   108 "set [] = {}"
   109 "set (x#xs) = insert x (set xs)"
   110 primrec
   111 list_all_Nil:"list_all P [] = True"
   112 list_all_Cons: "list_all P (x#xs) = (P(x) \<and> list_all P xs)"
   113 primrec
   114 "map f [] = []"
   115 "map f (x#xs) = f(x)#map f xs"
   116 primrec
   117 append_Nil:"[]@ys = ys"
   118 append_Cons: "(x#xs)@ys = x#(xs@ys)"
   119 primrec
   120 "rev([]) = []"
   121 "rev(x#xs) = rev(xs) @ [x]"
   122 primrec
   123 "filter P [] = []"
   124 "filter P (x#xs) = (if P x then x#filter P xs else filter P xs)"
   125 primrec
   126 foldl_Nil:"foldl f a [] = a"
   127 foldl_Cons: "foldl f a (x#xs) = foldl f (f a x) xs"
   128 primrec
   129 "foldr f [] a = a"
   130 "foldr f (x#xs) a = f x (foldr f xs a)"
   131 primrec
   132 "concat([]) = []"
   133 "concat(x#xs) = x @ concat(xs)"
   134 primrec
   135 drop_Nil:"drop n [] = []"
   136 drop_Cons: "drop n (x#xs) = (case n of 0 => x#xs | Suc(m) => drop m xs)"
   137 -- {* Warning: simpset does not contain this definition *}
   138 -- {* but separate theorems for @{text "n = 0"} and @{text "n = Suc k"} *}
   139 primrec
   140 take_Nil:"take n [] = []"
   141 take_Cons: "take n (x#xs) = (case n of 0 => [] | Suc(m) => x # take m xs)"
   142 -- {* Warning: simpset does not contain this definition *}
   143 -- {* but separate theorems for @{text "n = 0"} and @{text "n = Suc k"} *}
   144 primrec
   145 nth_Cons:"(x#xs)!n = (case n of 0 => x | (Suc k) => xs!k)"
   146 -- {* Warning: simpset does not contain this definition *}
   147 -- {* but separate theorems for @{text "n = 0"} and @{text "n = Suc k"} *}
   148 primrec
   149 "[][i:=v] = []"
   150 "(x#xs)[i:=v] =
   151 (case i of 0 => v # xs
   152 | Suc j => x # xs[j:=v])"
   153 primrec
   154 "takeWhile P [] = []"
   155 "takeWhile P (x#xs) = (if P x then x#takeWhile P xs else [])"
   156 primrec
   157 "dropWhile P [] = []"
   158 "dropWhile P (x#xs) = (if P x then dropWhile P xs else x#xs)"
   159 primrec
   160 "zip xs [] = []"
   161 zip_Cons: "zip xs (y#ys) = (case xs of [] => [] | z#zs => (z,y)#zip zs ys)"
   162 -- {* Warning: simpset does not contain this definition *}
   163 -- {* but separate theorems for @{text "xs = []"} and @{text "xs = z # zs"} *}
   164 primrec
   165 upt_0: "[i..0(] = []"
   166 upt_Suc: "[i..(Suc j)(] = (if i <= j then [i..j(] @ [j] else [])"
   167 primrec
   168 "distinct [] = True"
   169 "distinct (x#xs) = (x ~: set xs \<and> distinct xs)"
   170 primrec
   171 "remdups [] = []"
   172 "remdups (x#xs) = (if x : set xs then remdups xs else x # remdups xs)"
   173 primrec
   174 replicate_0: "replicate 0 x = []"
   175 replicate_Suc: "replicate (Suc n) x = x # replicate n x"
   176 defs
   177  list_all2_def:
   178  "list_all2 P xs ys == length xs = length ys \<and> (\<forall>(x, y) \<in> set (zip xs ys). P x y)"
   179 
   180 
   181 subsection {* Lexicographic orderings on lists *}
   182 
   183 consts
   184 lexn :: "('a * 'a)set => nat => ('a list * 'a list)set"
   185 primrec
   186 "lexn r 0 = {}"
   187 "lexn r (Suc n) =
   188 (prod_fun (%(x,xs). x#xs) (%(x,xs). x#xs) ` (r <*lex*> lexn r n)) Int
   189 {(xs,ys). length xs = Suc n \<and> length ys = Suc n}"
   190 
   191 constdefs
   192 lex :: "('a \<times> 'a) set => ('a list \<times> 'a list) set"
   193 "lex r == \<Union>n. lexn r n"
   194 
   195 lexico :: "('a \<times> 'a) set => ('a list \<times> 'a list) set"
   196 "lexico r == inv_image (less_than <*lex*> lex r) (%xs. (length xs, xs))"
   197 
   198 sublist :: "'a list => nat set => 'a list"
   199 "sublist xs A == map fst (filter (%p. snd p : A) (zip xs [0..size xs(]))"
   200 
   201 
   202 lemma not_Cons_self [simp]: "xs \<noteq> x # xs"
   203 by (induct xs) auto
   204 
   205 lemmas not_Cons_self2 [simp] = not_Cons_self [symmetric]
   206 
   207 lemma neq_Nil_conv: "(xs \<noteq> []) = (\<exists>y ys. xs = y # ys)"
   208 by (induct xs) auto
   209 
   210 lemma length_induct:
   211 "(!!xs. \<forall>ys. length ys < length xs --> P ys ==> P xs) ==> P xs"
   212 by (rule measure_induct [of length]) rules
   213 
   214 
   215 subsection {* @{text lists}: the list-forming operator over sets *}
   216 
   217 consts lists :: "'a set => 'a list set"
   218 inductive "lists A"
   219 intros
   220 Nil [intro!]: "[]: lists A"
   221 Cons [intro!]: "[| a: A;l: lists A|] ==> a#l : lists A"
   222 
   223 inductive_cases listsE [elim!]: "x#l : lists A"
   224 
   225 lemma lists_mono [mono]: "A \<subseteq> B ==> lists A \<subseteq> lists B"
   226 by (unfold lists.defs) (blast intro!: lfp_mono)
   227 
   228 lemma lists_IntI:
   229   assumes l: "l: lists A" shows "l: lists B ==> l: lists (A Int B)" using l
   230   by induct blast+
   231 
   232 lemma lists_Int_eq [simp]: "lists (A \<inter> B) = lists A \<inter> lists B"
   233 apply (rule mono_Int [THEN equalityI])
   234 apply (simp add: mono_def lists_mono)
   235 apply (blast intro!: lists_IntI)
   236 done
   237 
   238 lemma append_in_lists_conv [iff]:
   239 "(xs @ ys : lists A) = (xs : lists A \<and> ys : lists A)"
   240 by (induct xs) auto
   241 
   242 
   243 subsection {* @{text length} *}
   244 
   245 text {*
   246 Needs to come before @{text "@"} because of theorem @{text
   247 append_eq_append_conv}.
   248 *}
   249 
   250 lemma length_append [simp]: "length (xs @ ys) = length xs + length ys"
   251 by (induct xs) auto
   252 
   253 lemma length_map [simp]: "length (map f xs) = length xs"
   254 by (induct xs) auto
   255 
   256 lemma length_rev [simp]: "length (rev xs) = length xs"
   257 by (induct xs) auto
   258 
   259 lemma length_tl [simp]: "length (tl xs) = length xs - 1"
   260 by (cases xs) auto
   261 
   262 lemma length_0_conv [iff]: "(length xs = 0) = (xs = [])"
   263 by (induct xs) auto
   264 
   265 lemma length_greater_0_conv [iff]: "(0 < length xs) = (xs \<noteq> [])"
   266 by (induct xs) auto
   267 
   268 lemma length_Suc_conv:
   269 "(length xs = Suc n) = (\<exists>y ys. xs = y # ys \<and> length ys = n)"
   270 by (induct xs) auto
   271 
   272 
   273 subsection {* @{text "@"} -- append *}
   274 
   275 lemma append_assoc [simp]: "(xs @ ys) @ zs = xs @ (ys @ zs)"
   276 by (induct xs) auto
   277 
   278 lemma append_Nil2 [simp]: "xs @ [] = xs"
   279 by (induct xs) auto
   280 
   281 lemma append_is_Nil_conv [iff]: "(xs @ ys = []) = (xs = [] \<and> ys = [])"
   282 by (induct xs) auto
   283 
   284 lemma Nil_is_append_conv [iff]: "([] = xs @ ys) = (xs = [] \<and> ys = [])"
   285 by (induct xs) auto
   286 
   287 lemma append_self_conv [iff]: "(xs @ ys = xs) = (ys = [])"
   288 by (induct xs) auto
   289 
   290 lemma self_append_conv [iff]: "(xs = xs @ ys) = (ys = [])"
   291 by (induct xs) auto
   292 
   293 lemma append_eq_append_conv [simp]:
   294  "!!ys. length xs = length ys \<or> length us = length vs
   295  ==> (xs@us = ys@vs) = (xs=ys \<and> us=vs)"
   296 apply (induct xs)
   297  apply (case_tac ys)
   298 apply simp
   299  apply force
   300 apply (case_tac ys)
   301  apply force
   302 apply simp
   303 done
   304 
   305 lemma same_append_eq [iff]: "(xs @ ys = xs @ zs) = (ys = zs)"
   306 by simp
   307 
   308 lemma append1_eq_conv [iff]: "(xs @ [x] = ys @ [y]) = (xs = ys \<and> x = y)"
   309 by simp
   310 
   311 lemma append_same_eq [iff]: "(ys @ xs = zs @ xs) = (ys = zs)"
   312 by simp
   313 
   314 lemma append_self_conv2 [iff]: "(xs @ ys = ys) = (xs = [])"
   315 using append_same_eq [of _ _ "[]"] by auto
   316 
   317 lemma self_append_conv2 [iff]: "(ys = xs @ ys) = (xs = [])"
   318 using append_same_eq [of "[]"] by auto
   319 
   320 lemma hd_Cons_tl [simp]: "xs \<noteq> [] ==> hd xs # tl xs = xs"
   321 by (induct xs) auto
   322 
   323 lemma hd_append: "hd (xs @ ys) = (if xs = [] then hd ys else hd xs)"
   324 by (induct xs) auto
   325 
   326 lemma hd_append2 [simp]: "xs \<noteq> [] ==> hd (xs @ ys) = hd xs"
   327 by (simp add: hd_append split: list.split)
   328 
   329 lemma tl_append: "tl (xs @ ys) = (case xs of [] => tl ys | z#zs => zs @ ys)"
   330 by (simp split: list.split)
   331 
   332 lemma tl_append2 [simp]: "xs \<noteq> [] ==> tl (xs @ ys) = tl xs @ ys"
   333 by (simp add: tl_append split: list.split)
   334 
   335 
   336 text {* Trivial rules for solving @{text "@"}-equations automatically. *}
   337 
   338 lemma eq_Nil_appendI: "xs = ys ==> xs = [] @ ys"
   339 by simp
   340 
   341 lemma Cons_eq_appendI:
   342 "[| x # xs1 = ys; xs = xs1 @ zs |] ==> x # xs = ys @ zs"
   343 by (drule sym) simp
   344 
   345 lemma append_eq_appendI:
   346 "[| xs @ xs1 = zs; ys = xs1 @ us |] ==> xs @ ys = zs @ us"
   347 by (drule sym) simp
   348 
   349 
   350 text {*
   351 Simplification procedure for all list equalities.
   352 Currently only tries to rearrange @{text "@"} to see if
   353 - both lists end in a singleton list,
   354 - or both lists end in the same list.
   355 *}
   356 
   357 ML_setup {*
   358 local
   359 
   360 val append_assoc = thm "append_assoc";
   361 val append_Nil = thm "append_Nil";
   362 val append_Cons = thm "append_Cons";
   363 val append1_eq_conv = thm "append1_eq_conv";
   364 val append_same_eq = thm "append_same_eq";
   365 
   366 fun last (cons as Const("List.list.Cons",_) $ _ $ xs) =
   367   (case xs of Const("List.list.Nil",_) => cons | _ => last xs)
   368   | last (Const("List.op @",_) $ _ $ ys) = last ys
   369   | last t = t;
   370 
   371 fun list1 (Const("List.list.Cons",_) $ _ $ Const("List.list.Nil",_)) = true
   372   | list1 _ = false;
   373 
   374 fun butlast ((cons as Const("List.list.Cons",_) $ x) $ xs) =
   375   (case xs of Const("List.list.Nil",_) => xs | _ => cons $ butlast xs)
   376   | butlast ((app as Const("List.op @",_) $ xs) $ ys) = app $ butlast ys
   377   | butlast xs = Const("List.list.Nil",fastype_of xs);
   378 
   379 val rearr_tac =
   380   simp_tac (HOL_basic_ss addsimps [append_assoc, append_Nil, append_Cons]);
   381 
   382 fun list_eq sg _ (F as (eq as Const(_,eqT)) $ lhs $ rhs) =
   383   let
   384     val lastl = last lhs and lastr = last rhs;
   385     fun rearr conv =
   386       let
   387         val lhs1 = butlast lhs and rhs1 = butlast rhs;
   388         val Type(_,listT::_) = eqT
   389         val appT = [listT,listT] ---> listT
   390         val app = Const("List.op @",appT)
   391         val F2 = eq $ (app$lhs1$lastl) $ (app$rhs1$lastr)
   392         val eq = HOLogic.mk_Trueprop (HOLogic.mk_eq (F,F2));
   393         val thm = Tactic.prove sg [] [] eq (K (rearr_tac 1));
   394       in Some ((conv RS (thm RS trans)) RS eq_reflection) end;
   395 
   396   in
   397     if list1 lastl andalso list1 lastr then rearr append1_eq_conv
   398     else if lastl aconv lastr then rearr append_same_eq
   399     else None
   400   end;
   401 
   402 in
   403 
   404 val list_eq_simproc =
   405   Simplifier.simproc (Theory.sign_of (the_context ())) "list_eq" ["(xs::'a list) = ys"] list_eq;
   406 
   407 end;
   408 
   409 Addsimprocs [list_eq_simproc];
   410 *}
   411 
   412 
   413 subsection {* @{text map} *}
   414 
   415 lemma map_ext: "(!!x. x : set xs --> f x = g x) ==> map f xs = map g xs"
   416 by (induct xs) simp_all
   417 
   418 lemma map_ident [simp]: "map (\<lambda>x. x) = (\<lambda>xs. xs)"
   419 by (rule ext, induct_tac xs) auto
   420 
   421 lemma map_append [simp]: "map f (xs @ ys) = map f xs @ map f ys"
   422 by (induct xs) auto
   423 
   424 lemma map_compose: "map (f o g) xs = map f (map g xs)"
   425 by (induct xs) (auto simp add: o_def)
   426 
   427 lemma rev_map: "rev (map f xs) = map f (rev xs)"
   428 by (induct xs) auto
   429 
   430 lemma map_eq_conv[simp]: "(map f xs = map g xs) = (!x : set xs. f x = g x)"
   431 by (induct xs) auto
   432 
   433 lemma map_cong [recdef_cong]:
   434 "xs = ys ==> (!!x. x : set ys ==> f x = g x) ==> map f xs = map g ys"
   435 -- {* a congruence rule for @{text map} *}
   436 by simp
   437 
   438 lemma map_is_Nil_conv [iff]: "(map f xs = []) = (xs = [])"
   439 by (cases xs) auto
   440 
   441 lemma Nil_is_map_conv [iff]: "([] = map f xs) = (xs = [])"
   442 by (cases xs) auto
   443 
   444 lemma map_eq_Cons:
   445 "(map f xs = y # ys) = (\<exists>x xs'. xs = x # xs' \<and> f x = y \<and> map f xs' = ys)"
   446 by (cases xs) auto
   447 
   448 lemma map_injective:
   449 "!!xs. map f xs = map f ys ==> (\<forall>x y. f x = f y --> x = y) ==> xs = ys"
   450 by (induct ys) (auto simp add: map_eq_Cons)
   451 
   452 lemma inj_mapI: "inj f ==> inj (map f)"
   453 by (rules dest: map_injective injD intro: inj_onI)
   454 
   455 lemma inj_mapD: "inj (map f) ==> inj f"
   456 apply (unfold inj_on_def)
   457 apply clarify
   458 apply (erule_tac x = "[x]" in ballE)
   459  apply (erule_tac x = "[y]" in ballE)
   460 apply simp
   461  apply blast
   462 apply blast
   463 done
   464 
   465 lemma inj_map: "inj (map f) = inj f"
   466 by (blast dest: inj_mapD intro: inj_mapI)
   467 
   468 
   469 subsection {* @{text rev} *}
   470 
   471 lemma rev_append [simp]: "rev (xs @ ys) = rev ys @ rev xs"
   472 by (induct xs) auto
   473 
   474 lemma rev_rev_ident [simp]: "rev (rev xs) = xs"
   475 by (induct xs) auto
   476 
   477 lemma rev_is_Nil_conv [iff]: "(rev xs = []) = (xs = [])"
   478 by (induct xs) auto
   479 
   480 lemma Nil_is_rev_conv [iff]: "([] = rev xs) = (xs = [])"
   481 by (induct xs) auto
   482 
   483 lemma rev_is_rev_conv [iff]: "!!ys. (rev xs = rev ys) = (xs = ys)"
   484 apply (induct xs)
   485  apply force
   486 apply (case_tac ys)
   487  apply simp
   488 apply force
   489 done
   490 
   491 lemma rev_induct [case_names Nil snoc]:
   492   "[| P []; !!x xs. P xs ==> P (xs @ [x]) |] ==> P xs"
   493 apply(subst rev_rev_ident[symmetric])
   494 apply(rule_tac list = "rev xs" in list.induct, simp_all)
   495 done
   496 
   497 ML {* val rev_induct_tac = induct_thm_tac (thm "rev_induct") *}-- "compatibility"
   498 
   499 lemma rev_exhaust [case_names Nil snoc]:
   500   "(xs = [] ==> P) ==>(!!ys y. xs = ys @ [y] ==> P) ==> P"
   501 by (induct xs rule: rev_induct) auto
   502 
   503 lemmas rev_cases = rev_exhaust
   504 
   505 
   506 subsection {* @{text set} *}
   507 
   508 lemma finite_set [iff]: "finite (set xs)"
   509 by (induct xs) auto
   510 
   511 lemma set_append [simp]: "set (xs @ ys) = (set xs \<union> set ys)"
   512 by (induct xs) auto
   513 
   514 lemma set_subset_Cons: "set xs \<subseteq> set (x # xs)"
   515 by auto
   516 
   517 lemma set_empty [iff]: "(set xs = {}) = (xs = [])"
   518 by (induct xs) auto
   519 
   520 lemma set_rev [simp]: "set (rev xs) = set xs"
   521 by (induct xs) auto
   522 
   523 lemma set_map [simp]: "set (map f xs) = f`(set xs)"
   524 by (induct xs) auto
   525 
   526 lemma set_filter [simp]: "set (filter P xs) = {x. x : set xs \<and> P x}"
   527 by (induct xs) auto
   528 
   529 lemma set_upt [simp]: "set[i..j(] = {k. i \<le> k \<and> k < j}"
   530 apply (induct j)
   531  apply simp_all
   532 apply(erule ssubst)
   533 apply auto
   534 done
   535 
   536 lemma in_set_conv_decomp: "(x : set xs) = (\<exists>ys zs. xs = ys @ x # zs)"
   537 apply (induct xs)
   538  apply simp
   539 apply simp
   540 apply (rule iffI)
   541  apply (blast intro: eq_Nil_appendI Cons_eq_appendI)
   542 apply (erule exE)+
   543 apply (case_tac ys)
   544 apply auto
   545 done
   546 
   547 lemma in_lists_conv_set: "(xs : lists A) = (\<forall>x \<in> set xs. x : A)"
   548 -- {* eliminate @{text lists} in favour of @{text set} *}
   549 by (induct xs) auto
   550 
   551 lemma in_listsD [dest!]: "xs \<in> lists A ==> \<forall>x\<in>set xs. x \<in> A"
   552 by (rule in_lists_conv_set [THEN iffD1])
   553 
   554 lemma in_listsI [intro!]: "\<forall>x\<in>set xs. x \<in> A ==> xs \<in> lists A"
   555 by (rule in_lists_conv_set [THEN iffD2])
   556 
   557 lemma finite_list: "finite A ==> EX l. set l = A"
   558 apply (erule finite_induct, auto)
   559 apply (rule_tac x="x#l" in exI, auto)
   560 done
   561 
   562 
   563 subsection {* @{text mem} *}
   564 
   565 lemma set_mem_eq: "(x mem xs) = (x : set xs)"
   566 by (induct xs) auto
   567 
   568 
   569 subsection {* @{text list_all} *}
   570 
   571 lemma list_all_conv: "list_all P xs = (\<forall>x \<in> set xs. P x)"
   572 by (induct xs) auto
   573 
   574 lemma list_all_append [simp]:
   575 "list_all P (xs @ ys) = (list_all P xs \<and> list_all P ys)"
   576 by (induct xs) auto
   577 
   578 
   579 subsection {* @{text filter} *}
   580 
   581 lemma filter_append [simp]: "filter P (xs @ ys) = filter P xs @ filter P ys"
   582 by (induct xs) auto
   583 
   584 lemma filter_filter [simp]: "filter P (filter Q xs) = filter (\<lambda>x. Q x \<and> P x) xs"
   585 by (induct xs) auto
   586 
   587 lemma filter_True [simp]: "\<forall>x \<in> set xs. P x ==> filter P xs = xs"
   588 by (induct xs) auto
   589 
   590 lemma filter_False [simp]: "\<forall>x \<in> set xs. \<not> P x ==> filter P xs = []"
   591 by (induct xs) auto
   592 
   593 lemma length_filter [simp]: "length (filter P xs) \<le> length xs"
   594 by (induct xs) (auto simp add: le_SucI)
   595 
   596 lemma filter_is_subset [simp]: "set (filter P xs) \<le> set xs"
   597 by auto
   598 
   599 
   600 subsection {* @{text concat} *}
   601 
   602 lemma concat_append [simp]: "concat (xs @ ys) = concat xs @ concat ys"
   603 by (induct xs) auto
   604 
   605 lemma concat_eq_Nil_conv [iff]: "(concat xss = []) = (\<forall>xs \<in> set xss. xs = [])"
   606 by (induct xss) auto
   607 
   608 lemma Nil_eq_concat_conv [iff]: "([] = concat xss) = (\<forall>xs \<in> set xss. xs = [])"
   609 by (induct xss) auto
   610 
   611 lemma set_concat [simp]: "set (concat xs) = \<Union>(set ` set xs)"
   612 by (induct xs) auto
   613 
   614 lemma map_concat: "map f (concat xs) = concat (map (map f) xs)"
   615 by (induct xs) auto
   616 
   617 lemma filter_concat: "filter p (concat xs) = concat (map (filter p) xs)"
   618 by (induct xs) auto
   619 
   620 lemma rev_concat: "rev (concat xs) = concat (map rev (rev xs))"
   621 by (induct xs) auto
   622 
   623 
   624 subsection {* @{text nth} *}
   625 
   626 lemma nth_Cons_0 [simp]: "(x # xs)!0 = x"
   627 by auto
   628 
   629 lemma nth_Cons_Suc [simp]: "(x # xs)!(Suc n) = xs!n"
   630 by auto
   631 
   632 declare nth.simps [simp del]
   633 
   634 lemma nth_append:
   635 "!!n. (xs @ ys)!n = (if n < length xs then xs!n else ys!(n - length xs))"
   636 apply(induct "xs")
   637  apply simp
   638 apply (case_tac n)
   639  apply auto
   640 done
   641 
   642 lemma nth_map [simp]: "!!n. n < length xs ==> (map f xs)!n = f(xs!n)"
   643 apply(induct xs)
   644  apply simp
   645 apply (case_tac n)
   646  apply auto
   647 done
   648 
   649 lemma set_conv_nth: "set xs = {xs!i | i. i < length xs}"
   650 apply (induct_tac xs)
   651  apply simp
   652 apply simp
   653 apply safe
   654 apply (rule_tac x = 0 in exI)
   655 apply simp
   656  apply (rule_tac x = "Suc i" in exI)
   657  apply simp
   658 apply (case_tac i)
   659  apply simp
   660 apply (rename_tac j)
   661 apply (rule_tac x = j in exI)
   662 apply simp
   663 done
   664 
   665 lemma list_ball_nth: "[| n < length xs; !x : set xs. P x|] ==> P(xs!n)"
   666 by (auto simp add: set_conv_nth)
   667 
   668 lemma nth_mem [simp]: "n < length xs ==> xs!n : set xs"
   669 by (auto simp add: set_conv_nth)
   670 
   671 lemma all_nth_imp_all_set:
   672 "[| !i < length xs. P(xs!i); x : set xs|] ==> P x"
   673 by (auto simp add: set_conv_nth)
   674 
   675 lemma all_set_conv_all_nth:
   676 "(\<forall>x \<in> set xs. P x) = (\<forall>i. i < length xs --> P (xs ! i))"
   677 by (auto simp add: set_conv_nth)
   678 
   679 
   680 subsection {* @{text list_update} *}
   681 
   682 lemma length_list_update [simp]: "!!i. length(xs[i:=x]) = length xs"
   683 by (induct xs) (auto split: nat.split)
   684 
   685 lemma nth_list_update:
   686 "!!i j. i < length xs==> (xs[i:=x])!j = (if i = j then x else xs!j)"
   687 by (induct xs) (auto simp add: nth_Cons split: nat.split)
   688 
   689 lemma nth_list_update_eq [simp]: "i < length xs ==> (xs[i:=x])!i = x"
   690 by (simp add: nth_list_update)
   691 
   692 lemma nth_list_update_neq [simp]: "!!i j. i \<noteq> j ==> xs[i:=x]!j = xs!j"
   693 by (induct xs) (auto simp add: nth_Cons split: nat.split)
   694 
   695 lemma list_update_overwrite [simp]:
   696 "!!i. i < size xs ==> xs[i:=x, i:=y] = xs[i:=y]"
   697 by (induct xs) (auto split: nat.split)
   698 
   699 lemma list_update_same_conv:
   700 "!!i. i < length xs ==> (xs[i := x] = xs) = (xs!i = x)"
   701 by (induct xs) (auto split: nat.split)
   702 
   703 lemma update_zip:
   704 "!!i xy xs. length xs = length ys ==>
   705 (zip xs ys)[i:=xy] = zip (xs[i:=fst xy]) (ys[i:=snd xy])"
   706 by (induct ys) (auto, case_tac xs, auto split: nat.split)
   707 
   708 lemma set_update_subset_insert: "!!i. set(xs[i:=x]) <= insert x (set xs)"
   709 by (induct xs) (auto split: nat.split)
   710 
   711 lemma set_update_subsetI: "[| set xs <= A; x:A |] ==> set(xs[i := x]) <= A"
   712 by (blast dest!: set_update_subset_insert [THEN subsetD])
   713 
   714 
   715 subsection {* @{text last} and @{text butlast} *}
   716 
   717 lemma last_snoc [simp]: "last (xs @ [x]) = x"
   718 by (induct xs) auto
   719 
   720 lemma butlast_snoc [simp]: "butlast (xs @ [x]) = xs"
   721 by (induct xs) auto
   722 
   723 lemma length_butlast [simp]: "length (butlast xs) = length xs - 1"
   724 by (induct xs rule: rev_induct) auto
   725 
   726 lemma butlast_append:
   727 "!!ys. butlast (xs @ ys) = (if ys = [] then butlast xs else xs @ butlast ys)"
   728 by (induct xs) auto
   729 
   730 lemma append_butlast_last_id [simp]:
   731 "xs \<noteq> [] ==> butlast xs @ [last xs] = xs"
   732 by (induct xs) auto
   733 
   734 lemma in_set_butlastD: "x : set (butlast xs) ==> x : set xs"
   735 by (induct xs) (auto split: split_if_asm)
   736 
   737 lemma in_set_butlast_appendI:
   738 "x : set (butlast xs) | x : set (butlast ys) ==> x : set (butlast (xs @ ys))"
   739 by (auto dest: in_set_butlastD simp add: butlast_append)
   740 
   741 
   742 subsection {* @{text take} and @{text drop} *}
   743 
   744 lemma take_0 [simp]: "take 0 xs = []"
   745 by (induct xs) auto
   746 
   747 lemma drop_0 [simp]: "drop 0 xs = xs"
   748 by (induct xs) auto
   749 
   750 lemma take_Suc_Cons [simp]: "take (Suc n) (x # xs) = x # take n xs"
   751 by simp
   752 
   753 lemma drop_Suc_Cons [simp]: "drop (Suc n) (x # xs) = drop n xs"
   754 by simp
   755 
   756 declare take_Cons [simp del] and drop_Cons [simp del]
   757 
   758 lemma length_take [simp]: "!!xs. length (take n xs) = min (length xs) n"
   759 by (induct n) (auto, case_tac xs, auto)
   760 
   761 lemma length_drop [simp]: "!!xs. length (drop n xs) = (length xs - n)"
   762 by (induct n) (auto, case_tac xs, auto)
   763 
   764 lemma take_all [simp]: "!!xs. length xs <= n ==> take n xs = xs"
   765 by (induct n) (auto, case_tac xs, auto)
   766 
   767 lemma drop_all [simp]: "!!xs. length xs <= n ==> drop n xs = []"
   768 by (induct n) (auto, case_tac xs, auto)
   769 
   770 lemma take_append [simp]:
   771 "!!xs. take n (xs @ ys) = (take n xs @ take (n - length xs) ys)"
   772 by (induct n) (auto, case_tac xs, auto)
   773 
   774 lemma drop_append [simp]:
   775 "!!xs. drop n (xs @ ys) = drop n xs @ drop (n - length xs) ys"
   776 by (induct n) (auto, case_tac xs, auto)
   777 
   778 lemma take_take [simp]: "!!xs n. take n (take m xs) = take (min n m) xs"
   779 apply (induct m)
   780  apply auto
   781 apply (case_tac xs)
   782  apply auto
   783 apply (case_tac na)
   784  apply auto
   785 done
   786 
   787 lemma drop_drop [simp]: "!!xs. drop n (drop m xs) = drop (n + m) xs"
   788 apply (induct m)
   789  apply auto
   790 apply (case_tac xs)
   791  apply auto
   792 done
   793 
   794 lemma take_drop: "!!xs n. take n (drop m xs) = drop m (take (n + m) xs)"
   795 apply (induct m)
   796  apply auto
   797 apply (case_tac xs)
   798  apply auto
   799 done
   800 
   801 lemma append_take_drop_id [simp]: "!!xs. take n xs @ drop n xs = xs"
   802 apply (induct n)
   803  apply auto
   804 apply (case_tac xs)
   805  apply auto
   806 done
   807 
   808 lemma take_map: "!!xs. take n (map f xs) = map f (take n xs)"
   809 apply (induct n)
   810  apply auto
   811 apply (case_tac xs)
   812  apply auto
   813 done
   814 
   815 lemma drop_map: "!!xs. drop n (map f xs) = map f (drop n xs)"
   816 apply (induct n)
   817  apply auto
   818 apply (case_tac xs)
   819  apply auto
   820 done
   821 
   822 lemma rev_take: "!!i. rev (take i xs) = drop (length xs - i) (rev xs)"
   823 apply (induct xs)
   824  apply auto
   825 apply (case_tac i)
   826  apply auto
   827 done
   828 
   829 lemma rev_drop: "!!i. rev (drop i xs) = take (length xs - i) (rev xs)"
   830 apply (induct xs)
   831  apply auto
   832 apply (case_tac i)
   833  apply auto
   834 done
   835 
   836 lemma nth_take [simp]: "!!n i. i < n ==> (take n xs)!i = xs!i"
   837 apply (induct xs)
   838  apply auto
   839 apply (case_tac n)
   840  apply(blast )
   841 apply (case_tac i)
   842  apply auto
   843 done
   844 
   845 lemma nth_drop [simp]:
   846 "!!xs i. n + i <= length xs ==> (drop n xs)!i = xs!(n + i)"
   847 apply (induct n)
   848  apply auto
   849 apply (case_tac xs)
   850  apply auto
   851 done
   852 
   853 lemma append_eq_conv_conj:
   854 "!!zs. (xs @ ys = zs) = (xs = take (length xs) zs \<and> ys = drop (length xs) zs)"
   855 apply(induct xs)
   856  apply simp
   857 apply clarsimp
   858 apply (case_tac zs)
   859 apply auto
   860 done
   861 
   862 
   863 subsection {* @{text takeWhile} and @{text dropWhile} *}
   864 
   865 lemma takeWhile_dropWhile_id [simp]: "takeWhile P xs @ dropWhile P xs = xs"
   866 by (induct xs) auto
   867 
   868 lemma takeWhile_append1 [simp]:
   869 "[| x:set xs; ~P(x)|] ==> takeWhile P (xs @ ys) = takeWhile P xs"
   870 by (induct xs) auto
   871 
   872 lemma takeWhile_append2 [simp]:
   873 "(!!x. x : set xs ==> P x) ==> takeWhile P (xs @ ys) = xs @ takeWhile P ys"
   874 by (induct xs) auto
   875 
   876 lemma takeWhile_tail: "\<not> P x ==> takeWhile P (xs @ (x#l)) = takeWhile P xs"
   877 by (induct xs) auto
   878 
   879 lemma dropWhile_append1 [simp]:
   880 "[| x : set xs; ~P(x)|] ==> dropWhile P (xs @ ys) = (dropWhile P xs)@ys"
   881 by (induct xs) auto
   882 
   883 lemma dropWhile_append2 [simp]:
   884 "(!!x. x:set xs ==> P(x)) ==> dropWhile P (xs @ ys) = dropWhile P ys"
   885 by (induct xs) auto
   886 
   887 lemma set_take_whileD: "x : set (takeWhile P xs) ==> x : set xs \<and> P x"
   888 by (induct xs) (auto split: split_if_asm)
   889 
   890 
   891 subsection {* @{text zip} *}
   892 
   893 lemma zip_Nil [simp]: "zip [] ys = []"
   894 by (induct ys) auto
   895 
   896 lemma zip_Cons_Cons [simp]: "zip (x # xs) (y # ys) = (x, y) # zip xs ys"
   897 by simp
   898 
   899 declare zip_Cons [simp del]
   900 
   901 lemma length_zip [simp]:
   902 "!!xs. length (zip xs ys) = min (length xs) (length ys)"
   903 apply(induct ys)
   904  apply simp
   905 apply (case_tac xs)
   906  apply auto
   907 done
   908 
   909 lemma zip_append1:
   910 "!!xs. zip (xs @ ys) zs =
   911 zip xs (take (length xs) zs) @ zip ys (drop (length xs) zs)"
   912 apply (induct zs)
   913  apply simp
   914 apply (case_tac xs)
   915  apply simp_all
   916 done
   917 
   918 lemma zip_append2:
   919 "!!ys. zip xs (ys @ zs) =
   920 zip (take (length ys) xs) ys @ zip (drop (length ys) xs) zs"
   921 apply (induct xs)
   922  apply simp
   923 apply (case_tac ys)
   924  apply simp_all
   925 done
   926 
   927 lemma zip_append [simp]:
   928  "[| length xs = length us; length ys = length vs |] ==>
   929 zip (xs@ys) (us@vs) = zip xs us @ zip ys vs"
   930 by (simp add: zip_append1)
   931 
   932 lemma zip_rev:
   933 "!!xs. length xs = length ys ==> zip (rev xs) (rev ys) = rev (zip xs ys)"
   934 apply(induct ys)
   935  apply simp
   936 apply (case_tac xs)
   937  apply simp_all
   938 done
   939 
   940 lemma nth_zip [simp]:
   941 "!!i xs. [| i < length xs; i < length ys|] ==> (zip xs ys)!i = (xs!i, ys!i)"
   942 apply (induct ys)
   943  apply simp
   944 apply (case_tac xs)
   945  apply (simp_all add: nth.simps split: nat.split)
   946 done
   947 
   948 lemma set_zip:
   949 "set (zip xs ys) = {(xs!i, ys!i) | i. i < min (length xs) (length ys)}"
   950 by (simp add: set_conv_nth cong: rev_conj_cong)
   951 
   952 lemma zip_update:
   953 "length xs = length ys ==> zip (xs[i:=x]) (ys[i:=y]) = (zip xs ys)[i:=(x,y)]"
   954 by (rule sym, simp add: update_zip)
   955 
   956 lemma zip_replicate [simp]:
   957 "!!j. zip (replicate i x) (replicate j y) = replicate (min i j) (x,y)"
   958 apply (induct i)
   959  apply auto
   960 apply (case_tac j)
   961  apply auto
   962 done
   963 
   964 
   965 subsection {* @{text list_all2} *}
   966 
   967 lemma list_all2_lengthD: "list_all2 P xs ys ==> length xs = length ys"
   968 by (simp add: list_all2_def)
   969 
   970 lemma list_all2_Nil [iff]: "list_all2 P [] ys = (ys = [])"
   971 by (simp add: list_all2_def)
   972 
   973 lemma list_all2_Nil2[iff]: "list_all2 P xs [] = (xs = [])"
   974 by (simp add: list_all2_def)
   975 
   976 lemma list_all2_Cons [iff]:
   977 "list_all2 P (x # xs) (y # ys) = (P x y \<and> list_all2 P xs ys)"
   978 by (auto simp add: list_all2_def)
   979 
   980 lemma list_all2_Cons1:
   981 "list_all2 P (x # xs) ys = (\<exists>z zs. ys = z # zs \<and> P x z \<and> list_all2 P xs zs)"
   982 by (cases ys) auto
   983 
   984 lemma list_all2_Cons2:
   985 "list_all2 P xs (y # ys) = (\<exists>z zs. xs = z # zs \<and> P z y \<and> list_all2 P zs ys)"
   986 by (cases xs) auto
   987 
   988 lemma list_all2_rev [iff]:
   989 "list_all2 P (rev xs) (rev ys) = list_all2 P xs ys"
   990 by (simp add: list_all2_def zip_rev cong: conj_cong)
   991 
   992 lemma list_all2_rev1:
   993 "list_all2 P (rev xs) ys = list_all2 P xs (rev ys)"
   994 by (subst list_all2_rev [symmetric]) simp
   995 
   996 lemma list_all2_append1:
   997 "list_all2 P (xs @ ys) zs =
   998 (EX us vs. zs = us @ vs \<and> length us = length xs \<and> length vs = length ys \<and>
   999 list_all2 P xs us \<and> list_all2 P ys vs)"
  1000 apply (simp add: list_all2_def zip_append1)
  1001 apply (rule iffI)
  1002  apply (rule_tac x = "take (length xs) zs" in exI)
  1003  apply (rule_tac x = "drop (length xs) zs" in exI)
  1004  apply (force split: nat_diff_split simp add: min_def)
  1005 apply clarify
  1006 apply (simp add: ball_Un)
  1007 done
  1008 
  1009 lemma list_all2_append2:
  1010 "list_all2 P xs (ys @ zs) =
  1011 (EX us vs. xs = us @ vs \<and> length us = length ys \<and> length vs = length zs \<and>
  1012 list_all2 P us ys \<and> list_all2 P vs zs)"
  1013 apply (simp add: list_all2_def zip_append2)
  1014 apply (rule iffI)
  1015  apply (rule_tac x = "take (length ys) xs" in exI)
  1016  apply (rule_tac x = "drop (length ys) xs" in exI)
  1017  apply (force split: nat_diff_split simp add: min_def)
  1018 apply clarify
  1019 apply (simp add: ball_Un)
  1020 done
  1021 
  1022 lemma list_all2_append:
  1023   "\<And>b. length a = length b \<Longrightarrow>
  1024   list_all2 P (a@c) (b@d) = (list_all2 P a b \<and> list_all2 P c d)"
  1025   apply (induct a)
  1026    apply simp
  1027   apply (case_tac b)
  1028   apply auto
  1029   done
  1030 
  1031 lemma list_all2_appendI [intro?, trans]:
  1032   "\<lbrakk> list_all2 P a b; list_all2 P c d \<rbrakk> \<Longrightarrow> list_all2 P (a@c) (b@d)"
  1033   by (simp add: list_all2_append list_all2_lengthD)
  1034 
  1035 lemma list_all2_conv_all_nth:
  1036 "list_all2 P xs ys =
  1037 (length xs = length ys \<and> (\<forall>i < length xs. P (xs!i) (ys!i)))"
  1038 by (force simp add: list_all2_def set_zip)
  1039 
  1040 lemma list_all2_trans:
  1041   assumes tr: "!!a b c. P1 a b ==> P2 b c ==> P3 a c"
  1042   shows "!!bs cs. list_all2 P1 as bs ==> list_all2 P2 bs cs ==> list_all2 P3 as cs"
  1043         (is "!!bs cs. PROP ?Q as bs cs")
  1044 proof (induct as)
  1045   fix x xs bs assume I1: "!!bs cs. PROP ?Q xs bs cs"
  1046   show "!!cs. PROP ?Q (x # xs) bs cs"
  1047   proof (induct bs)
  1048     fix y ys cs assume I2: "!!cs. PROP ?Q (x # xs) ys cs"
  1049     show "PROP ?Q (x # xs) (y # ys) cs"
  1050       by (induct cs) (auto intro: tr I1 I2)
  1051   qed simp
  1052 qed simp
  1053 
  1054 lemma list_all2_all_nthI [intro?]:
  1055   "length a = length b \<Longrightarrow> (\<And>n. n < length a \<Longrightarrow> P (a!n) (b!n)) \<Longrightarrow> list_all2 P a b"
  1056   by (simp add: list_all2_conv_all_nth)
  1057 
  1058 lemma list_all2_nthD [dest?]:
  1059   "\<lbrakk> list_all2 P xs ys; p < size xs \<rbrakk> \<Longrightarrow> P (xs!p) (ys!p)"
  1060   by (simp add: list_all2_conv_all_nth)
  1061 
  1062 lemma list_all2_map1: 
  1063   "list_all2 P (map f as) bs = list_all2 (\<lambda>x y. P (f x) y) as bs"
  1064   by (simp add: list_all2_conv_all_nth)
  1065 
  1066 lemma list_all2_map2: 
  1067   "list_all2 P as (map f bs) = list_all2 (\<lambda>x y. P x (f y)) as bs"
  1068   by (auto simp add: list_all2_conv_all_nth)
  1069 
  1070 lemma list_all2_refl:
  1071   "(\<And>x. P x x) \<Longrightarrow> list_all2 P xs xs"
  1072   by (simp add: list_all2_conv_all_nth)
  1073 
  1074 lemma list_all2_update_cong:
  1075   "\<lbrakk> i<size xs; list_all2 P xs ys; P x y \<rbrakk> \<Longrightarrow> list_all2 P (xs[i:=x]) (ys[i:=y])"
  1076   by (simp add: list_all2_conv_all_nth nth_list_update)
  1077 
  1078 lemma list_all2_update_cong2:
  1079   "\<lbrakk>list_all2 P xs ys; P x y; i < length ys\<rbrakk> \<Longrightarrow> list_all2 P (xs[i:=x]) (ys[i:=y])"
  1080   by (simp add: list_all2_lengthD list_all2_update_cong)
  1081 
  1082 lemma list_all2_dropI [intro?]:
  1083   "\<And>n bs. list_all2 P as bs \<Longrightarrow> list_all2 P (drop n as) (drop n bs)"
  1084   apply (induct as)
  1085    apply simp
  1086   apply (clarsimp simp add: list_all2_Cons1)
  1087   apply (case_tac n)
  1088    apply simp
  1089   apply simp
  1090   done
  1091 
  1092 lemma list_all2_mono [intro?]:
  1093   "\<And>y. list_all2 P x y \<Longrightarrow> (\<And>x y. P x y \<Longrightarrow> Q x y) \<Longrightarrow> list_all2 Q x y"
  1094   apply (induct x)
  1095    apply simp
  1096   apply (case_tac y)
  1097   apply auto
  1098   done
  1099 
  1100 
  1101 subsection {* @{text foldl} *}
  1102 
  1103 lemma foldl_append [simp]:
  1104 "!!a. foldl f a (xs @ ys) = foldl f (foldl f a xs) ys"
  1105 by (induct xs) auto
  1106 
  1107 text {*
  1108 Note: @{text "n \<le> foldl (op +) n ns"} looks simpler, but is more
  1109 difficult to use because it requires an additional transitivity step.
  1110 *}
  1111 
  1112 lemma start_le_sum: "!!n::nat. m <= n ==> m <= foldl (op +) n ns"
  1113 by (induct ns) auto
  1114 
  1115 lemma elem_le_sum: "!!n::nat. n : set ns ==> n <= foldl (op +) 0 ns"
  1116 by (force intro: start_le_sum simp add: in_set_conv_decomp)
  1117 
  1118 lemma sum_eq_0_conv [iff]:
  1119 "!!m::nat. (foldl (op +) m ns = 0) = (m = 0 \<and> (\<forall>n \<in> set ns. n = 0))"
  1120 by (induct ns) auto
  1121 
  1122 
  1123 subsection {* @{text upto} *}
  1124 
  1125 lemma upt_rec: "[i..j(] = (if i<j then i#[Suc i..j(] else [])"
  1126 -- {* Does not terminate! *}
  1127 by (induct j) auto
  1128 
  1129 lemma upt_conv_Nil [simp]: "j <= i ==> [i..j(] = []"
  1130 by (subst upt_rec) simp
  1131 
  1132 lemma upt_Suc_append: "i <= j ==> [i..(Suc j)(] = [i..j(]@[j]"
  1133 -- {* Only needed if @{text upt_Suc} is deleted from the simpset. *}
  1134 by simp
  1135 
  1136 lemma upt_conv_Cons: "i < j ==> [i..j(] = i # [Suc i..j(]"
  1137 apply(rule trans)
  1138 apply(subst upt_rec)
  1139  prefer 2 apply(rule refl)
  1140 apply simp
  1141 done
  1142 
  1143 lemma upt_add_eq_append: "i<=j ==> [i..j+k(] = [i..j(]@[j..j+k(]"
  1144 -- {* LOOPS as a simprule, since @{text "j <= j"}. *}
  1145 by (induct k) auto
  1146 
  1147 lemma length_upt [simp]: "length [i..j(] = j - i"
  1148 by (induct j) (auto simp add: Suc_diff_le)
  1149 
  1150 lemma nth_upt [simp]: "i + k < j ==> [i..j(] ! k = i + k"
  1151 apply (induct j)
  1152 apply (auto simp add: less_Suc_eq nth_append split: nat_diff_split)
  1153 done
  1154 
  1155 lemma take_upt [simp]: "!!i. i+m <= n ==> take m [i..n(] = [i..i+m(]"
  1156 apply (induct m)
  1157  apply simp
  1158 apply (subst upt_rec)
  1159 apply (rule sym)
  1160 apply (subst upt_rec)
  1161 apply (simp del: upt.simps)
  1162 done
  1163 
  1164 lemma map_Suc_upt: "map Suc [m..n(] = [Suc m..n]"
  1165 by (induct n) auto
  1166 
  1167 lemma nth_map_upt: "!!i. i < n-m ==> (map f [m..n(]) ! i = f(m+i)"
  1168 apply (induct n m rule: diff_induct)
  1169 prefer 3 apply (subst map_Suc_upt[symmetric])
  1170 apply (auto simp add: less_diff_conv nth_upt)
  1171 done
  1172 
  1173 lemma nth_take_lemma:
  1174   "!!xs ys. k <= length xs ==> k <= length ys ==>
  1175      (!!i. i < k --> xs!i = ys!i) ==> take k xs = take k ys"
  1176 apply (atomize, induct k)
  1177 apply (simp_all add: less_Suc_eq_0_disj all_conj_distrib)
  1178 apply clarify
  1179 txt {* Both lists must be non-empty *}
  1180 apply (case_tac xs)
  1181  apply simp
  1182 apply (case_tac ys)
  1183  apply clarify
  1184  apply (simp (no_asm_use))
  1185 apply clarify
  1186 txt {* prenexing's needed, not miniscoping *}
  1187 apply (simp (no_asm_use) add: all_simps [symmetric] del: all_simps)
  1188 apply blast
  1189 done
  1190 
  1191 lemma nth_equalityI:
  1192  "[| length xs = length ys; ALL i < length xs. xs!i = ys!i |] ==> xs = ys"
  1193 apply (frule nth_take_lemma [OF le_refl eq_imp_le])
  1194 apply (simp_all add: take_all)
  1195 done
  1196 
  1197 (* needs nth_equalityI *)
  1198 lemma list_all2_antisym:
  1199   "\<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> 
  1200   \<Longrightarrow> xs = ys"
  1201   apply (simp add: list_all2_conv_all_nth) 
  1202   apply (rule nth_equalityI)
  1203    apply blast
  1204   apply simp
  1205   done
  1206 
  1207 lemma take_equalityI: "(\<forall>i. take i xs = take i ys) ==> xs = ys"
  1208 -- {* The famous take-lemma. *}
  1209 apply (drule_tac x = "max (length xs) (length ys)" in spec)
  1210 apply (simp add: le_max_iff_disj take_all)
  1211 done
  1212 
  1213 
  1214 subsection {* @{text "distinct"} and @{text remdups} *}
  1215 
  1216 lemma distinct_append [simp]:
  1217 "distinct (xs @ ys) = (distinct xs \<and> distinct ys \<and> set xs \<inter> set ys = {})"
  1218 by (induct xs) auto
  1219 
  1220 lemma set_remdups [simp]: "set (remdups xs) = set xs"
  1221 by (induct xs) (auto simp add: insert_absorb)
  1222 
  1223 lemma distinct_remdups [iff]: "distinct (remdups xs)"
  1224 by (induct xs) auto
  1225 
  1226 lemma distinct_filter [simp]: "distinct xs ==> distinct (filter P xs)"
  1227 by (induct xs) auto
  1228 
  1229 text {*
  1230 It is best to avoid this indexed version of distinct, but sometimes
  1231 it is useful. *}
  1232 lemma distinct_conv_nth:
  1233 "distinct xs = (\<forall>i j. i < size xs \<and> j < size xs \<and> i \<noteq> j --> xs!i \<noteq> xs!j)"
  1234 apply (induct_tac xs)
  1235  apply simp
  1236 apply simp
  1237 apply (rule iffI)
  1238  apply clarsimp
  1239  apply (case_tac i)
  1240 apply (case_tac j)
  1241  apply simp
  1242 apply (simp add: set_conv_nth)
  1243  apply (case_tac j)
  1244 apply (clarsimp simp add: set_conv_nth)
  1245  apply simp
  1246 apply (rule conjI)
  1247  apply (clarsimp simp add: set_conv_nth)
  1248  apply (erule_tac x = 0 in allE)
  1249  apply (erule_tac x = "Suc i" in allE)
  1250  apply simp
  1251 apply clarsimp
  1252 apply (erule_tac x = "Suc i" in allE)
  1253 apply (erule_tac x = "Suc j" in allE)
  1254 apply simp
  1255 done
  1256 
  1257 
  1258 subsection {* @{text replicate} *}
  1259 
  1260 lemma length_replicate [simp]: "length (replicate n x) = n"
  1261 by (induct n) auto
  1262 
  1263 lemma map_replicate [simp]: "map f (replicate n x) = replicate n (f x)"
  1264 by (induct n) auto
  1265 
  1266 lemma replicate_app_Cons_same:
  1267 "(replicate n x) @ (x # xs) = x # replicate n x @ xs"
  1268 by (induct n) auto
  1269 
  1270 lemma rev_replicate [simp]: "rev (replicate n x) = replicate n x"
  1271 apply(induct n)
  1272  apply simp
  1273 apply (simp add: replicate_app_Cons_same)
  1274 done
  1275 
  1276 lemma replicate_add: "replicate (n + m) x = replicate n x @ replicate m x"
  1277 by (induct n) auto
  1278 
  1279 lemma hd_replicate [simp]: "n \<noteq> 0 ==> hd (replicate n x) = x"
  1280 by (induct n) auto
  1281 
  1282 lemma tl_replicate [simp]: "n \<noteq> 0 ==> tl (replicate n x) = replicate (n - 1) x"
  1283 by (induct n) auto
  1284 
  1285 lemma last_replicate [simp]: "n \<noteq> 0 ==> last (replicate n x) = x"
  1286 by (atomize (full), induct n) auto
  1287 
  1288 lemma nth_replicate[simp]: "!!i. i < n ==> (replicate n x)!i = x"
  1289 apply(induct n)
  1290  apply simp
  1291 apply (simp add: nth_Cons split: nat.split)
  1292 done
  1293 
  1294 lemma set_replicate_Suc: "set (replicate (Suc n) x) = {x}"
  1295 by (induct n) auto
  1296 
  1297 lemma set_replicate [simp]: "n \<noteq> 0 ==> set (replicate n x) = {x}"
  1298 by (fast dest!: not0_implies_Suc intro!: set_replicate_Suc)
  1299 
  1300 lemma set_replicate_conv_if: "set (replicate n x) = (if n = 0 then {} else {x})"
  1301 by auto
  1302 
  1303 lemma in_set_replicateD: "x : set (replicate n y) ==> x = y"
  1304 by (simp add: set_replicate_conv_if split: split_if_asm)
  1305 
  1306 
  1307 subsection {* Lexcicographic orderings on lists *}
  1308 
  1309 lemma wf_lexn: "wf r ==> wf (lexn r n)"
  1310 apply (induct_tac n)
  1311  apply simp
  1312 apply simp
  1313 apply(rule wf_subset)
  1314  prefer 2 apply (rule Int_lower1)
  1315 apply(rule wf_prod_fun_image)
  1316  prefer 2 apply (rule inj_onI)
  1317 apply auto
  1318 done
  1319 
  1320 lemma lexn_length:
  1321 "!!xs ys. (xs, ys) : lexn r n ==> length xs = n \<and> length ys = n"
  1322 by (induct n) auto
  1323 
  1324 lemma wf_lex [intro!]: "wf r ==> wf (lex r)"
  1325 apply (unfold lex_def)
  1326 apply (rule wf_UN)
  1327 apply (blast intro: wf_lexn)
  1328 apply clarify
  1329 apply (rename_tac m n)
  1330 apply (subgoal_tac "m \<noteq> n")
  1331  prefer 2 apply blast
  1332 apply (blast dest: lexn_length not_sym)
  1333 done
  1334 
  1335 lemma lexn_conv:
  1336 "lexn r n =
  1337 {(xs,ys). length xs = n \<and> length ys = n \<and>
  1338 (\<exists>xys x y xs' ys'. xs= xys @ x#xs' \<and> ys= xys @ y # ys' \<and> (x, y):r)}"
  1339 apply (induct_tac n)
  1340  apply simp
  1341  apply blast
  1342 apply (simp add: image_Collect lex_prod_def)
  1343 apply safe
  1344 apply blast
  1345  apply (rule_tac x = "ab # xys" in exI)
  1346  apply simp
  1347 apply (case_tac xys)
  1348  apply simp_all
  1349 apply blast
  1350 done
  1351 
  1352 lemma lex_conv:
  1353 "lex r =
  1354 {(xs,ys). length xs = length ys \<and>
  1355 (\<exists>xys x y xs' ys'. xs = xys @ x # xs' \<and> ys = xys @ y # ys' \<and> (x, y):r)}"
  1356 by (force simp add: lex_def lexn_conv)
  1357 
  1358 lemma wf_lexico [intro!]: "wf r ==> wf (lexico r)"
  1359 by (unfold lexico_def) blast
  1360 
  1361 lemma lexico_conv:
  1362 "lexico r = {(xs,ys). length xs < length ys |
  1363 length xs = length ys \<and> (xs, ys) : lex r}"
  1364 by (simp add: lexico_def diag_def lex_prod_def measure_def inv_image_def)
  1365 
  1366 lemma Nil_notin_lex [iff]: "([], ys) \<notin> lex r"
  1367 by (simp add: lex_conv)
  1368 
  1369 lemma Nil2_notin_lex [iff]: "(xs, []) \<notin> lex r"
  1370 by (simp add:lex_conv)
  1371 
  1372 lemma Cons_in_lex [iff]:
  1373 "((x # xs, y # ys) : lex r) =
  1374 ((x, y) : r \<and> length xs = length ys | x = y \<and> (xs, ys) : lex r)"
  1375 apply (simp add: lex_conv)
  1376 apply (rule iffI)
  1377  prefer 2 apply (blast intro: Cons_eq_appendI)
  1378 apply clarify
  1379 apply (case_tac xys)
  1380  apply simp
  1381 apply simp
  1382 apply blast
  1383 done
  1384 
  1385 
  1386 subsection {* @{text sublist} --- a generalization of @{text nth} to sets *}
  1387 
  1388 lemma sublist_empty [simp]: "sublist xs {} = []"
  1389 by (auto simp add: sublist_def)
  1390 
  1391 lemma sublist_nil [simp]: "sublist [] A = []"
  1392 by (auto simp add: sublist_def)
  1393 
  1394 lemma sublist_shift_lemma:
  1395 "map fst [p:zip xs [i..i + length xs(] . snd p : A] =
  1396 map fst [p:zip xs [0..length xs(] . snd p + i : A]"
  1397 by (induct xs rule: rev_induct) (simp_all add: add_commute)
  1398 
  1399 lemma sublist_append:
  1400 "sublist (l @ l') A = sublist l A @ sublist l' {j. j + length l : A}"
  1401 apply (unfold sublist_def)
  1402 apply (induct l' rule: rev_induct)
  1403  apply simp
  1404 apply (simp add: upt_add_eq_append[of 0] zip_append sublist_shift_lemma)
  1405 apply (simp add: add_commute)
  1406 done
  1407 
  1408 lemma sublist_Cons:
  1409 "sublist (x # l) A = (if 0:A then [x] else []) @ sublist l {j. Suc j : A}"
  1410 apply (induct l rule: rev_induct)
  1411  apply (simp add: sublist_def)
  1412 apply (simp del: append_Cons add: append_Cons[symmetric] sublist_append)
  1413 done
  1414 
  1415 lemma sublist_singleton [simp]: "sublist [x] A = (if 0 : A then [x] else [])"
  1416 by (simp add: sublist_Cons)
  1417 
  1418 lemma sublist_upt_eq_take [simp]: "sublist l {..n(} = take n l"
  1419 apply (induct l rule: rev_induct)
  1420  apply simp
  1421 apply (simp split: nat_diff_split add: sublist_append)
  1422 done
  1423 
  1424 
  1425 lemma take_Cons':
  1426 "take n (x # xs) = (if n = 0 then [] else x # take (n - 1) xs)"
  1427 by (cases n) simp_all
  1428 
  1429 lemma drop_Cons':
  1430 "drop n (x # xs) = (if n = 0 then x # xs else drop (n - 1) xs)"
  1431 by (cases n) simp_all
  1432 
  1433 lemma nth_Cons': "(x # xs)!n = (if n = 0 then x else xs!(n - 1))"
  1434 by (cases n) simp_all
  1435 
  1436 lemmas [simp] = take_Cons'[of "number_of v",standard]
  1437                 drop_Cons'[of "number_of v",standard]
  1438                 nth_Cons'[of _ _ "number_of v",standard]
  1439 
  1440 
  1441 subsection {* Characters and strings *}
  1442 
  1443 datatype nibble =
  1444     Nibble0 | Nibble1 | Nibble2 | Nibble3 | Nibble4 | Nibble5 | Nibble6 | Nibble7
  1445   | Nibble8 | Nibble9 | NibbleA | NibbleB | NibbleC | NibbleD | NibbleE | NibbleF
  1446 
  1447 datatype char = Char nibble nibble
  1448   -- "Note: canonical order of character encoding coincides with standard term ordering"
  1449 
  1450 types string = "char list"
  1451 
  1452 syntax
  1453   "_Char" :: "xstr => char"    ("CHR _")
  1454   "_String" :: "xstr => string"    ("_")
  1455 
  1456 parse_ast_translation {*
  1457   let
  1458     val constants = Syntax.Appl o map Syntax.Constant;
  1459 
  1460     fun mk_nib n = "Nibble" ^ chr (n + (if n <= 9 then ord "0" else ord "A" - 10));
  1461     fun mk_char c =
  1462       if Symbol.is_ascii c andalso Symbol.is_printable c then
  1463         constants ["Char", mk_nib (ord c div 16), mk_nib (ord c mod 16)]
  1464       else error ("Printable ASCII character expected: " ^ quote c);
  1465 
  1466     fun mk_string [] = Syntax.Constant "Nil"
  1467       | mk_string (c :: cs) = Syntax.Appl [Syntax.Constant "Cons", mk_char c, mk_string cs];
  1468 
  1469     fun char_ast_tr [Syntax.Variable xstr] =
  1470         (case Syntax.explode_xstr xstr of
  1471           [c] => mk_char c
  1472         | _ => error ("Single character expected: " ^ xstr))
  1473       | char_ast_tr asts = raise AST ("char_ast_tr", asts);
  1474 
  1475     fun string_ast_tr [Syntax.Variable xstr] =
  1476         (case Syntax.explode_xstr xstr of
  1477           [] => constants [Syntax.constrainC, "Nil", "string"]
  1478         | cs => mk_string cs)
  1479       | string_ast_tr asts = raise AST ("string_tr", asts);
  1480   in [("_Char", char_ast_tr), ("_String", string_ast_tr)] end;
  1481 *}
  1482 
  1483 print_ast_translation {*
  1484   let
  1485     fun dest_nib (Syntax.Constant c) =
  1486         (case explode c of
  1487           ["N", "i", "b", "b", "l", "e", h] =>
  1488             if "0" <= h andalso h <= "9" then ord h - ord "0"
  1489             else if "A" <= h andalso h <= "F" then ord h - ord "A" + 10
  1490             else raise Match
  1491         | _ => raise Match)
  1492       | dest_nib _ = raise Match;
  1493 
  1494     fun dest_chr c1 c2 =
  1495       let val c = chr (dest_nib c1 * 16 + dest_nib c2)
  1496       in if Symbol.is_printable c then c else raise Match end;
  1497 
  1498     fun dest_char (Syntax.Appl [Syntax.Constant "Char", c1, c2]) = dest_chr c1 c2
  1499       | dest_char _ = raise Match;
  1500 
  1501     fun xstr cs = Syntax.Appl [Syntax.Constant "_xstr", Syntax.Variable (Syntax.implode_xstr cs)];
  1502 
  1503     fun char_ast_tr' [c1, c2] = Syntax.Appl [Syntax.Constant "_Char", xstr [dest_chr c1 c2]]
  1504       | char_ast_tr' _ = raise Match;
  1505 
  1506     fun list_ast_tr' [args] = Syntax.Appl [Syntax.Constant "_String",
  1507             xstr (map dest_char (Syntax.unfold_ast "_args" args))]
  1508       | list_ast_tr' ts = raise Match;
  1509   in [("Char", char_ast_tr'), ("@list", list_ast_tr')] end;
  1510 *}
  1511 
  1512 end