src/HOL/Product_Type.thy
author nipkow
Mon Nov 28 11:22:36 2011 +0100 (2011-11-28)
changeset 45662 4f7c05990420
parent 45607 16b4f5774621
child 45694 4a8743618257
permissions -rw-r--r--
Hide Product_Type.Times - too precious an identifier
nipkow@10213
     1
(*  Title:      HOL/Product_Type.thy
nipkow@10213
     2
    Author:     Lawrence C Paulson, Cambridge University Computer Laboratory
nipkow@10213
     3
    Copyright   1992  University of Cambridge
wenzelm@11777
     4
*)
nipkow@10213
     5
wenzelm@11838
     6
header {* Cartesian products *}
nipkow@10213
     7
nipkow@15131
     8
theory Product_Type
haftmann@33959
     9
imports Typedef Inductive Fun
haftmann@24699
    10
uses
haftmann@24699
    11
  ("Tools/split_rule.ML")
haftmann@31723
    12
  ("Tools/inductive_set.ML")
nipkow@15131
    13
begin
wenzelm@11838
    14
haftmann@24699
    15
subsection {* @{typ bool} is a datatype *}
haftmann@24699
    16
haftmann@27104
    17
rep_datatype True False by (auto intro: bool_induct)
haftmann@24699
    18
haftmann@24699
    19
declare case_split [cases type: bool]
haftmann@24699
    20
  -- "prefer plain propositional version"
haftmann@24699
    21
haftmann@28346
    22
lemma
haftmann@38857
    23
  shows [code]: "HOL.equal False P \<longleftrightarrow> \<not> P"
haftmann@38857
    24
    and [code]: "HOL.equal True P \<longleftrightarrow> P" 
haftmann@38857
    25
    and [code]: "HOL.equal P False \<longleftrightarrow> \<not> P" 
haftmann@38857
    26
    and [code]: "HOL.equal P True \<longleftrightarrow> P"
haftmann@38857
    27
    and [code nbe]: "HOL.equal P P \<longleftrightarrow> True"
haftmann@38857
    28
  by (simp_all add: equal)
haftmann@25534
    29
haftmann@43654
    30
lemma If_case_cert:
haftmann@43654
    31
  assumes "CASE \<equiv> (\<lambda>b. If b f g)"
haftmann@43654
    32
  shows "(CASE True \<equiv> f) &&& (CASE False \<equiv> g)"
haftmann@43654
    33
  using assms by simp_all
haftmann@43654
    34
haftmann@43654
    35
setup {*
haftmann@43654
    36
  Code.add_case @{thm If_case_cert}
haftmann@43654
    37
*}
haftmann@43654
    38
haftmann@38857
    39
code_const "HOL.equal \<Colon> bool \<Rightarrow> bool \<Rightarrow> bool"
haftmann@39272
    40
  (Haskell infix 4 "==")
haftmann@25534
    41
haftmann@38857
    42
code_instance bool :: equal
haftmann@25534
    43
  (Haskell -)
haftmann@24699
    44
haftmann@26358
    45
haftmann@37166
    46
subsection {* The @{text unit} type *}
wenzelm@11838
    47
huffman@40590
    48
typedef (open) unit = "{True}"
wenzelm@11838
    49
proof
haftmann@20588
    50
  show "True : ?unit" ..
wenzelm@11838
    51
qed
wenzelm@11838
    52
haftmann@24699
    53
definition
wenzelm@11838
    54
  Unity :: unit    ("'(')")
haftmann@24699
    55
where
haftmann@24699
    56
  "() = Abs_unit True"
wenzelm@11838
    57
blanchet@35828
    58
lemma unit_eq [no_atp]: "u = ()"
huffman@40590
    59
  by (induct u) (simp add: Unity_def)
wenzelm@11838
    60
wenzelm@11838
    61
text {*
wenzelm@11838
    62
  Simplification procedure for @{thm [source] unit_eq}.  Cannot use
wenzelm@11838
    63
  this rule directly --- it loops!
wenzelm@11838
    64
*}
wenzelm@11838
    65
wenzelm@43594
    66
simproc_setup unit_eq ("x::unit") = {*
wenzelm@43594
    67
  fn _ => fn _ => fn ct =>
wenzelm@43594
    68
    if HOLogic.is_unit (term_of ct) then NONE
wenzelm@43594
    69
    else SOME (mk_meta_eq @{thm unit_eq})
wenzelm@11838
    70
*}
wenzelm@11838
    71
haftmann@27104
    72
rep_datatype "()" by simp
haftmann@24699
    73
wenzelm@11838
    74
lemma unit_all_eq1: "(!!x::unit. PROP P x) == PROP P ()"
wenzelm@11838
    75
  by simp
wenzelm@11838
    76
wenzelm@11838
    77
lemma unit_all_eq2: "(!!x::unit. PROP P) == PROP P"
wenzelm@11838
    78
  by (rule triv_forall_equality)
wenzelm@11838
    79
wenzelm@11838
    80
text {*
wenzelm@43594
    81
  This rewrite counters the effect of simproc @{text unit_eq} on @{term
wenzelm@11838
    82
  [source] "%u::unit. f u"}, replacing it by @{term [source]
wenzelm@11838
    83
  f} rather than by @{term [source] "%u. f ()"}.
wenzelm@11838
    84
*}
wenzelm@11838
    85
haftmann@43866
    86
lemma unit_abs_eta_conv [simp, no_atp]: "(%u::unit. f ()) = f"
wenzelm@11838
    87
  by (rule ext) simp
nipkow@10213
    88
haftmann@43866
    89
lemma UNIV_unit [no_atp]:
haftmann@43866
    90
  "UNIV = {()}" by auto
haftmann@43866
    91
haftmann@30924
    92
instantiation unit :: default
haftmann@30924
    93
begin
haftmann@30924
    94
haftmann@30924
    95
definition "default = ()"
haftmann@30924
    96
haftmann@30924
    97
instance ..
haftmann@30924
    98
haftmann@30924
    99
end
nipkow@10213
   100
haftmann@28562
   101
lemma [code]:
haftmann@38857
   102
  "HOL.equal (u\<Colon>unit) v \<longleftrightarrow> True" unfolding equal unit_eq [of u] unit_eq [of v] by rule+
haftmann@26358
   103
haftmann@26358
   104
code_type unit
haftmann@26358
   105
  (SML "unit")
haftmann@26358
   106
  (OCaml "unit")
haftmann@26358
   107
  (Haskell "()")
haftmann@34886
   108
  (Scala "Unit")
haftmann@26358
   109
haftmann@37166
   110
code_const Unity
haftmann@37166
   111
  (SML "()")
haftmann@37166
   112
  (OCaml "()")
haftmann@37166
   113
  (Haskell "()")
haftmann@37166
   114
  (Scala "()")
haftmann@37166
   115
haftmann@38857
   116
code_instance unit :: equal
haftmann@26358
   117
  (Haskell -)
haftmann@26358
   118
haftmann@38857
   119
code_const "HOL.equal \<Colon> unit \<Rightarrow> unit \<Rightarrow> bool"
haftmann@39272
   120
  (Haskell infix 4 "==")
haftmann@26358
   121
haftmann@26358
   122
code_reserved SML
haftmann@26358
   123
  unit
haftmann@26358
   124
haftmann@26358
   125
code_reserved OCaml
haftmann@26358
   126
  unit
haftmann@26358
   127
haftmann@34886
   128
code_reserved Scala
haftmann@34886
   129
  Unit
haftmann@34886
   130
haftmann@26358
   131
haftmann@37166
   132
subsection {* The product type *}
nipkow@10213
   133
haftmann@37166
   134
subsubsection {* Type definition *}
haftmann@37166
   135
haftmann@37166
   136
definition Pair_Rep :: "'a \<Rightarrow> 'b \<Rightarrow> 'a \<Rightarrow> 'b \<Rightarrow> bool" where
haftmann@26358
   137
  "Pair_Rep a b = (\<lambda>x y. x = a \<and> y = b)"
nipkow@10213
   138
haftmann@37678
   139
typedef ('a, 'b) prod (infixr "*" 20)
haftmann@37389
   140
  = "{f. \<exists>a b. f = Pair_Rep (a\<Colon>'a) (b\<Colon>'b)}"
oheimb@11025
   141
proof
haftmann@37389
   142
  fix a b show "Pair_Rep a b \<in> ?prod"
haftmann@26358
   143
    by rule+
oheimb@11025
   144
qed
nipkow@10213
   145
wenzelm@35427
   146
type_notation (xsymbols)
haftmann@37678
   147
  "prod"  ("(_ \<times>/ _)" [21, 20] 20)
wenzelm@35427
   148
type_notation (HTML output)
haftmann@37678
   149
  "prod"  ("(_ \<times>/ _)" [21, 20] 20)
nipkow@10213
   150
haftmann@37389
   151
definition Pair :: "'a \<Rightarrow> 'b \<Rightarrow> 'a \<times> 'b" where
haftmann@37389
   152
  "Pair a b = Abs_prod (Pair_Rep a b)"
haftmann@37166
   153
haftmann@37678
   154
rep_datatype Pair proof -
haftmann@37166
   155
  fix P :: "'a \<times> 'b \<Rightarrow> bool" and p
haftmann@37166
   156
  assume "\<And>a b. P (Pair a b)"
haftmann@37389
   157
  then show "P p" by (cases p) (auto simp add: prod_def Pair_def Pair_Rep_def)
haftmann@37166
   158
next
haftmann@37166
   159
  fix a c :: 'a and b d :: 'b
haftmann@37166
   160
  have "Pair_Rep a b = Pair_Rep c d \<longleftrightarrow> a = c \<and> b = d"
nipkow@39302
   161
    by (auto simp add: Pair_Rep_def fun_eq_iff)
haftmann@37389
   162
  moreover have "Pair_Rep a b \<in> prod" and "Pair_Rep c d \<in> prod"
haftmann@37389
   163
    by (auto simp add: prod_def)
haftmann@37166
   164
  ultimately show "Pair a b = Pair c d \<longleftrightarrow> a = c \<and> b = d"
haftmann@37389
   165
    by (simp add: Pair_def Abs_prod_inject)
haftmann@37166
   166
qed
haftmann@37166
   167
blanchet@37704
   168
declare prod.simps(2) [nitpick_simp del]
blanchet@37704
   169
huffman@40929
   170
declare prod.weak_case_cong [cong del]
haftmann@37411
   171
haftmann@37166
   172
haftmann@37166
   173
subsubsection {* Tuple syntax *}
haftmann@37166
   174
haftmann@37591
   175
abbreviation (input) split :: "('a \<Rightarrow> 'b \<Rightarrow> 'c) \<Rightarrow> 'a \<times> 'b \<Rightarrow> 'c" where
haftmann@37591
   176
  "split \<equiv> prod_case"
wenzelm@19535
   177
wenzelm@11777
   178
text {*
wenzelm@11777
   179
  Patterns -- extends pre-defined type @{typ pttrn} used in
wenzelm@11777
   180
  abstractions.
wenzelm@11777
   181
*}
nipkow@10213
   182
wenzelm@41229
   183
nonterminal tuple_args and patterns
nipkow@10213
   184
nipkow@10213
   185
syntax
nipkow@10213
   186
  "_tuple"      :: "'a => tuple_args => 'a * 'b"        ("(1'(_,/ _'))")
nipkow@10213
   187
  "_tuple_arg"  :: "'a => tuple_args"                   ("_")
nipkow@10213
   188
  "_tuple_args" :: "'a => tuple_args => tuple_args"     ("_,/ _")
oheimb@11025
   189
  "_pattern"    :: "[pttrn, patterns] => pttrn"         ("'(_,/ _')")
oheimb@11025
   190
  ""            :: "pttrn => patterns"                  ("_")
oheimb@11025
   191
  "_patterns"   :: "[pttrn, patterns] => patterns"      ("_,/ _")
nipkow@10213
   192
nipkow@10213
   193
translations
wenzelm@35115
   194
  "(x, y)" == "CONST Pair x y"
nipkow@10213
   195
  "_tuple x (_tuple_args y z)" == "_tuple x (_tuple_arg (_tuple y z))"
haftmann@37591
   196
  "%(x, y, zs). b" == "CONST prod_case (%x (y, zs). b)"
haftmann@37591
   197
  "%(x, y). b" == "CONST prod_case (%x y. b)"
wenzelm@35115
   198
  "_abs (CONST Pair x y) t" => "%(x, y). t"
haftmann@37166
   199
  -- {* The last rule accommodates tuples in `case C ... (x,y) ... => ...'
haftmann@37166
   200
     The (x,y) is parsed as `Pair x y' because it is logic, not pttrn *}
nipkow@10213
   201
wenzelm@35115
   202
(*reconstruct pattern from (nested) splits, avoiding eta-contraction of body;
wenzelm@35115
   203
  works best with enclosing "let", if "let" does not avoid eta-contraction*)
schirmer@14359
   204
print_translation {*
wenzelm@35115
   205
let
wenzelm@35115
   206
  fun split_tr' [Abs (x, T, t as (Abs abs))] =
wenzelm@35115
   207
        (* split (%x y. t) => %(x,y) t *)
wenzelm@35115
   208
        let
wenzelm@42284
   209
          val (y, t') = Syntax_Trans.atomic_abs_tr' abs;
wenzelm@42284
   210
          val (x', t'') = Syntax_Trans.atomic_abs_tr' (x, T, t');
wenzelm@35115
   211
        in
wenzelm@35115
   212
          Syntax.const @{syntax_const "_abs"} $
wenzelm@35115
   213
            (Syntax.const @{syntax_const "_pattern"} $ x' $ y) $ t''
wenzelm@35115
   214
        end
haftmann@37591
   215
    | split_tr' [Abs (x, T, (s as Const (@{const_syntax prod_case}, _) $ t))] =
wenzelm@35115
   216
        (* split (%x. (split (%y z. t))) => %(x,y,z). t *)
wenzelm@35115
   217
        let
wenzelm@35115
   218
          val Const (@{syntax_const "_abs"}, _) $
wenzelm@35115
   219
            (Const (@{syntax_const "_pattern"}, _) $ y $ z) $ t' = split_tr' [t];
wenzelm@42284
   220
          val (x', t'') = Syntax_Trans.atomic_abs_tr' (x, T, t');
wenzelm@35115
   221
        in
wenzelm@35115
   222
          Syntax.const @{syntax_const "_abs"} $
wenzelm@35115
   223
            (Syntax.const @{syntax_const "_pattern"} $ x' $
wenzelm@35115
   224
              (Syntax.const @{syntax_const "_patterns"} $ y $ z)) $ t''
wenzelm@35115
   225
        end
haftmann@37591
   226
    | split_tr' [Const (@{const_syntax prod_case}, _) $ t] =
wenzelm@35115
   227
        (* split (split (%x y z. t)) => %((x, y), z). t *)
wenzelm@35115
   228
        split_tr' [(split_tr' [t])] (* inner split_tr' creates next pattern *)
wenzelm@35115
   229
    | split_tr' [Const (@{syntax_const "_abs"}, _) $ x_y $ Abs abs] =
wenzelm@35115
   230
        (* split (%pttrn z. t) => %(pttrn,z). t *)
wenzelm@42284
   231
        let val (z, t) = Syntax_Trans.atomic_abs_tr' abs in
wenzelm@35115
   232
          Syntax.const @{syntax_const "_abs"} $
wenzelm@35115
   233
            (Syntax.const @{syntax_const "_pattern"} $ x_y $ z) $ t
wenzelm@35115
   234
        end
wenzelm@35115
   235
    | split_tr' _ = raise Match;
haftmann@37591
   236
in [(@{const_syntax prod_case}, split_tr')] end
schirmer@14359
   237
*}
schirmer@14359
   238
schirmer@15422
   239
(* print "split f" as "\<lambda>(x,y). f x y" and "split (\<lambda>x. f x)" as "\<lambda>(x,y). f x y" *) 
schirmer@15422
   240
typed_print_translation {*
schirmer@15422
   241
let
wenzelm@42247
   242
  fun split_guess_names_tr' T [Abs (x, _, Abs _)] = raise Match
wenzelm@42247
   243
    | split_guess_names_tr' T [Abs (x, xT, t)] =
schirmer@15422
   244
        (case (head_of t) of
haftmann@37591
   245
          Const (@{const_syntax prod_case}, _) => raise Match
wenzelm@35115
   246
        | _ =>
wenzelm@35115
   247
          let 
wenzelm@35115
   248
            val (_ :: yT :: _) = binder_types (domain_type T) handle Bind => raise Match;
wenzelm@42284
   249
            val (y, t') = Syntax_Trans.atomic_abs_tr' ("y", yT, incr_boundvars 1 t $ Bound 0);
wenzelm@42284
   250
            val (x', t'') = Syntax_Trans.atomic_abs_tr' (x, xT, t');
wenzelm@35115
   251
          in
wenzelm@35115
   252
            Syntax.const @{syntax_const "_abs"} $
wenzelm@35115
   253
              (Syntax.const @{syntax_const "_pattern"} $ x' $ y) $ t''
wenzelm@35115
   254
          end)
wenzelm@42247
   255
    | split_guess_names_tr' T [t] =
wenzelm@35115
   256
        (case head_of t of
haftmann@37591
   257
          Const (@{const_syntax prod_case}, _) => raise Match
wenzelm@35115
   258
        | _ =>
wenzelm@35115
   259
          let
wenzelm@35115
   260
            val (xT :: yT :: _) = binder_types (domain_type T) handle Bind => raise Match;
wenzelm@42284
   261
            val (y, t') =
wenzelm@42284
   262
              Syntax_Trans.atomic_abs_tr' ("y", yT, incr_boundvars 2 t $ Bound 1 $ Bound 0);
wenzelm@42284
   263
            val (x', t'') = Syntax_Trans.atomic_abs_tr' ("x", xT, t');
wenzelm@35115
   264
          in
wenzelm@35115
   265
            Syntax.const @{syntax_const "_abs"} $
wenzelm@35115
   266
              (Syntax.const @{syntax_const "_pattern"} $ x' $ y) $ t''
wenzelm@35115
   267
          end)
wenzelm@42247
   268
    | split_guess_names_tr' _ _ = raise Match;
haftmann@37591
   269
in [(@{const_syntax prod_case}, split_guess_names_tr')] end
schirmer@15422
   270
*}
schirmer@15422
   271
nipkow@42059
   272
(* Force eta-contraction for terms of the form "Q A (%p. prod_case P p)"
nipkow@42059
   273
   where Q is some bounded quantifier or set operator.
nipkow@42059
   274
   Reason: the above prints as "Q p : A. case p of (x,y) \<Rightarrow> P x y"
nipkow@42059
   275
   whereas we want "Q (x,y):A. P x y".
nipkow@42059
   276
   Otherwise prevent eta-contraction.
nipkow@42059
   277
*)
nipkow@42059
   278
print_translation {*
nipkow@42059
   279
let
nipkow@42059
   280
  fun contract Q f ts =
nipkow@42059
   281
    case ts of
nipkow@42059
   282
      [A, Abs(_, _, (s as Const (@{const_syntax prod_case},_) $ t) $ Bound 0)]
wenzelm@42083
   283
      => if Term.is_dependent t then f ts else Syntax.const Q $ A $ s
nipkow@42059
   284
    | _ => f ts;
nipkow@42059
   285
  fun contract2 (Q,f) = (Q, contract Q f);
nipkow@42059
   286
  val pairs =
wenzelm@42284
   287
    [Syntax_Trans.preserve_binder_abs2_tr' @{const_syntax Ball} @{syntax_const "_Ball"},
wenzelm@42284
   288
     Syntax_Trans.preserve_binder_abs2_tr' @{const_syntax Bex} @{syntax_const "_Bex"},
wenzelm@42284
   289
     Syntax_Trans.preserve_binder_abs2_tr' @{const_syntax INFI} @{syntax_const "_INF"},
wenzelm@42284
   290
     Syntax_Trans.preserve_binder_abs2_tr' @{const_syntax SUPR} @{syntax_const "_SUP"}]
nipkow@42059
   291
in map contract2 pairs end
nipkow@42059
   292
*}
nipkow@10213
   293
haftmann@37166
   294
subsubsection {* Code generator setup *}
haftmann@37166
   295
haftmann@37678
   296
code_type prod
haftmann@37166
   297
  (SML infix 2 "*")
haftmann@37166
   298
  (OCaml infix 2 "*")
haftmann@37166
   299
  (Haskell "!((_),/ (_))")
haftmann@37166
   300
  (Scala "((_),/ (_))")
haftmann@37166
   301
haftmann@37166
   302
code_const Pair
haftmann@37166
   303
  (SML "!((_),/ (_))")
haftmann@37166
   304
  (OCaml "!((_),/ (_))")
haftmann@37166
   305
  (Haskell "!((_),/ (_))")
haftmann@37166
   306
  (Scala "!((_),/ (_))")
haftmann@37166
   307
haftmann@38857
   308
code_instance prod :: equal
haftmann@37166
   309
  (Haskell -)
haftmann@37166
   310
haftmann@38857
   311
code_const "HOL.equal \<Colon> 'a \<times> 'b \<Rightarrow> 'a \<times> 'b \<Rightarrow> bool"
haftmann@39272
   312
  (Haskell infix 4 "==")
haftmann@37166
   313
haftmann@37166
   314
haftmann@37166
   315
subsubsection {* Fundamental operations and properties *}
wenzelm@11838
   316
haftmann@26358
   317
lemma surj_pair [simp]: "EX x y. p = (x, y)"
haftmann@37166
   318
  by (cases p) simp
nipkow@10213
   319
haftmann@37389
   320
definition fst :: "'a \<times> 'b \<Rightarrow> 'a" where
haftmann@37389
   321
  "fst p = (case p of (a, b) \<Rightarrow> a)"
wenzelm@11838
   322
haftmann@37389
   323
definition snd :: "'a \<times> 'b \<Rightarrow> 'b" where
haftmann@37389
   324
  "snd p = (case p of (a, b) \<Rightarrow> b)"
wenzelm@11838
   325
haftmann@22886
   326
lemma fst_conv [simp, code]: "fst (a, b) = a"
haftmann@37166
   327
  unfolding fst_def by simp
wenzelm@11838
   328
haftmann@22886
   329
lemma snd_conv [simp, code]: "snd (a, b) = b"
haftmann@37166
   330
  unfolding snd_def by simp
oheimb@11025
   331
haftmann@37166
   332
code_const fst and snd
haftmann@37166
   333
  (Haskell "fst" and "snd")
haftmann@26358
   334
blanchet@41792
   335
lemma prod_case_unfold [nitpick_unfold]: "prod_case = (%c p. c (fst p) (snd p))"
nipkow@39302
   336
  by (simp add: fun_eq_iff split: prod.split)
haftmann@26358
   337
wenzelm@11838
   338
lemma fst_eqD: "fst (x, y) = a ==> x = a"
wenzelm@11838
   339
  by simp
wenzelm@11838
   340
wenzelm@11838
   341
lemma snd_eqD: "snd (x, y) = a ==> y = a"
wenzelm@11838
   342
  by simp
wenzelm@11838
   343
haftmann@26358
   344
lemma pair_collapse [simp]: "(fst p, snd p) = p"
wenzelm@11838
   345
  by (cases p) simp
wenzelm@11838
   346
haftmann@26358
   347
lemmas surjective_pairing = pair_collapse [symmetric]
wenzelm@11838
   348
huffman@44066
   349
lemma prod_eq_iff: "s = t \<longleftrightarrow> fst s = fst t \<and> snd s = snd t"
haftmann@37166
   350
  by (cases s, cases t) simp
haftmann@37166
   351
haftmann@37166
   352
lemma prod_eqI [intro?]: "fst p = fst q \<Longrightarrow> snd p = snd q \<Longrightarrow> p = q"
huffman@44066
   353
  by (simp add: prod_eq_iff)
haftmann@37166
   354
haftmann@37166
   355
lemma split_conv [simp, code]: "split f (a, b) = f a b"
haftmann@37591
   356
  by (fact prod.cases)
haftmann@37166
   357
haftmann@37166
   358
lemma splitI: "f a b \<Longrightarrow> split f (a, b)"
haftmann@37166
   359
  by (rule split_conv [THEN iffD2])
haftmann@37166
   360
haftmann@37166
   361
lemma splitD: "split f (a, b) \<Longrightarrow> f a b"
haftmann@37166
   362
  by (rule split_conv [THEN iffD1])
haftmann@37166
   363
haftmann@37166
   364
lemma split_Pair [simp]: "(\<lambda>(x, y). (x, y)) = id"
nipkow@39302
   365
  by (simp add: fun_eq_iff split: prod.split)
haftmann@37166
   366
haftmann@37166
   367
lemma split_eta: "(\<lambda>(x, y). f (x, y)) = f"
haftmann@37166
   368
  -- {* Subsumes the old @{text split_Pair} when @{term f} is the identity function. *}
nipkow@39302
   369
  by (simp add: fun_eq_iff split: prod.split)
haftmann@37166
   370
haftmann@37166
   371
lemma split_comp: "split (f \<circ> g) x = f (g (fst x)) (snd x)"
haftmann@37166
   372
  by (cases x) simp
haftmann@37166
   373
haftmann@37166
   374
lemma split_twice: "split f (split g p) = split (\<lambda>x y. split f (g x y)) p"
haftmann@37166
   375
  by (cases p) simp
haftmann@37166
   376
haftmann@37166
   377
lemma The_split: "The (split P) = (THE xy. P (fst xy) (snd xy))"
haftmann@37591
   378
  by (simp add: prod_case_unfold)
haftmann@37166
   379
haftmann@37166
   380
lemma split_weak_cong: "p = q \<Longrightarrow> split c p = split c q"
haftmann@37166
   381
  -- {* Prevents simplification of @{term c}: much faster *}
huffman@40929
   382
  by (fact prod.weak_case_cong)
haftmann@37166
   383
haftmann@37166
   384
lemma cond_split_eta: "(!!x y. f x y = g (x, y)) ==> (%(x, y). f x y) = g"
haftmann@37166
   385
  by (simp add: split_eta)
haftmann@37166
   386
wenzelm@11838
   387
lemma split_paired_all: "(!!x. PROP P x) == (!!a b. PROP P (a, b))"
wenzelm@11820
   388
proof
wenzelm@11820
   389
  fix a b
wenzelm@11820
   390
  assume "!!x. PROP P x"
wenzelm@19535
   391
  then show "PROP P (a, b)" .
wenzelm@11820
   392
next
wenzelm@11820
   393
  fix x
wenzelm@11820
   394
  assume "!!a b. PROP P (a, b)"
wenzelm@19535
   395
  from `PROP P (fst x, snd x)` show "PROP P x" by simp
wenzelm@11820
   396
qed
wenzelm@11820
   397
wenzelm@11838
   398
text {*
wenzelm@11838
   399
  The rule @{thm [source] split_paired_all} does not work with the
wenzelm@11838
   400
  Simplifier because it also affects premises in congrence rules,
wenzelm@11838
   401
  where this can lead to premises of the form @{text "!!a b. ... =
wenzelm@11838
   402
  ?P(a, b)"} which cannot be solved by reflexivity.
wenzelm@11838
   403
*}
wenzelm@11838
   404
haftmann@26358
   405
lemmas split_tupled_all = split_paired_all unit_all_eq2
haftmann@26358
   406
wenzelm@26480
   407
ML {*
wenzelm@11838
   408
  (* replace parameters of product type by individual component parameters *)
wenzelm@11838
   409
  val safe_full_simp_tac = generic_simp_tac true (true, false, false);
wenzelm@11838
   410
  local (* filtering with exists_paired_all is an essential optimization *)
wenzelm@16121
   411
    fun exists_paired_all (Const ("all", _) $ Abs (_, T, t)) =
wenzelm@11838
   412
          can HOLogic.dest_prodT T orelse exists_paired_all t
wenzelm@11838
   413
      | exists_paired_all (t $ u) = exists_paired_all t orelse exists_paired_all u
wenzelm@11838
   414
      | exists_paired_all (Abs (_, _, t)) = exists_paired_all t
wenzelm@11838
   415
      | exists_paired_all _ = false;
wenzelm@11838
   416
    val ss = HOL_basic_ss
wenzelm@26340
   417
      addsimps [@{thm split_paired_all}, @{thm unit_all_eq2}, @{thm unit_abs_eta_conv}]
wenzelm@43594
   418
      addsimprocs [@{simproc unit_eq}];
wenzelm@11838
   419
  in
wenzelm@11838
   420
    val split_all_tac = SUBGOAL (fn (t, i) =>
wenzelm@11838
   421
      if exists_paired_all t then safe_full_simp_tac ss i else no_tac);
wenzelm@11838
   422
    val unsafe_split_all_tac = SUBGOAL (fn (t, i) =>
wenzelm@11838
   423
      if exists_paired_all t then full_simp_tac ss i else no_tac);
wenzelm@11838
   424
    fun split_all th =
wenzelm@26340
   425
   if exists_paired_all (Thm.prop_of th) then full_simplify ss th else th;
wenzelm@11838
   426
  end;
wenzelm@26340
   427
*}
wenzelm@11838
   428
wenzelm@26340
   429
declaration {* fn _ =>
wenzelm@26340
   430
  Classical.map_cs (fn cs => cs addSbefore ("split_all_tac", split_all_tac))
wenzelm@16121
   431
*}
wenzelm@11838
   432
wenzelm@11838
   433
lemma split_paired_All [simp]: "(ALL x. P x) = (ALL a b. P (a, b))"
wenzelm@11838
   434
  -- {* @{text "[iff]"} is not a good idea because it makes @{text blast} loop *}
wenzelm@11838
   435
  by fast
wenzelm@11838
   436
haftmann@26358
   437
lemma split_paired_Ex [simp]: "(EX x. P x) = (EX a b. P (a, b))"
haftmann@26358
   438
  by fast
haftmann@26358
   439
wenzelm@11838
   440
lemma split_paired_The: "(THE x. P x) = (THE (a, b). P (a, b))"
wenzelm@11838
   441
  -- {* Can't be added to simpset: loops! *}
haftmann@26358
   442
  by (simp add: split_eta)
wenzelm@11838
   443
wenzelm@11838
   444
text {*
wenzelm@11838
   445
  Simplification procedure for @{thm [source] cond_split_eta}.  Using
wenzelm@11838
   446
  @{thm [source] split_eta} as a rewrite rule is not general enough,
wenzelm@11838
   447
  and using @{thm [source] cond_split_eta} directly would render some
wenzelm@11838
   448
  existing proofs very inefficient; similarly for @{text
haftmann@26358
   449
  split_beta}.
haftmann@26358
   450
*}
wenzelm@11838
   451
wenzelm@26480
   452
ML {*
wenzelm@11838
   453
local
wenzelm@35364
   454
  val cond_split_eta_ss = HOL_basic_ss addsimps @{thms cond_split_eta};
wenzelm@35364
   455
  fun Pair_pat k 0 (Bound m) = (m = k)
wenzelm@35364
   456
    | Pair_pat k i (Const (@{const_name Pair},  _) $ Bound m $ t) =
wenzelm@35364
   457
        i > 0 andalso m = k + i andalso Pair_pat k (i - 1) t
wenzelm@35364
   458
    | Pair_pat _ _ _ = false;
wenzelm@35364
   459
  fun no_args k i (Abs (_, _, t)) = no_args (k + 1) i t
wenzelm@35364
   460
    | no_args k i (t $ u) = no_args k i t andalso no_args k i u
wenzelm@35364
   461
    | no_args k i (Bound m) = m < k orelse m > k + i
wenzelm@35364
   462
    | no_args _ _ _ = true;
wenzelm@35364
   463
  fun split_pat tp i (Abs  (_, _, t)) = if tp 0 i t then SOME (i, t) else NONE
haftmann@37591
   464
    | split_pat tp i (Const (@{const_name prod_case}, _) $ Abs (_, _, t)) = split_pat tp (i + 1) t
wenzelm@35364
   465
    | split_pat tp i _ = NONE;
wenzelm@20044
   466
  fun metaeq ss lhs rhs = mk_meta_eq (Goal.prove (Simplifier.the_context ss) [] []
wenzelm@35364
   467
        (HOLogic.mk_Trueprop (HOLogic.mk_eq (lhs, rhs)))
wenzelm@18328
   468
        (K (simp_tac (Simplifier.inherit_context ss cond_split_eta_ss) 1)));
wenzelm@11838
   469
wenzelm@35364
   470
  fun beta_term_pat k i (Abs (_, _, t)) = beta_term_pat (k + 1) i t
wenzelm@35364
   471
    | beta_term_pat k i (t $ u) =
wenzelm@35364
   472
        Pair_pat k i (t $ u) orelse (beta_term_pat k i t andalso beta_term_pat k i u)
wenzelm@35364
   473
    | beta_term_pat k i t = no_args k i t;
wenzelm@35364
   474
  fun eta_term_pat k i (f $ arg) = no_args k i f andalso Pair_pat k i arg
wenzelm@35364
   475
    | eta_term_pat _ _ _ = false;
wenzelm@11838
   476
  fun subst arg k i (Abs (x, T, t)) = Abs (x, T, subst arg (k+1) i t)
wenzelm@35364
   477
    | subst arg k i (t $ u) =
wenzelm@35364
   478
        if Pair_pat k i (t $ u) then incr_boundvars k arg
wenzelm@35364
   479
        else (subst arg k i t $ subst arg k i u)
wenzelm@35364
   480
    | subst arg k i t = t;
wenzelm@43595
   481
in
haftmann@37591
   482
  fun beta_proc ss (s as Const (@{const_name prod_case}, _) $ Abs (_, _, t) $ arg) =
wenzelm@11838
   483
        (case split_pat beta_term_pat 1 t of
wenzelm@35364
   484
          SOME (i, f) => SOME (metaeq ss s (subst arg 0 i f))
skalberg@15531
   485
        | NONE => NONE)
wenzelm@35364
   486
    | beta_proc _ _ = NONE;
haftmann@37591
   487
  fun eta_proc ss (s as Const (@{const_name prod_case}, _) $ Abs (_, _, t)) =
wenzelm@11838
   488
        (case split_pat eta_term_pat 1 t of
wenzelm@35364
   489
          SOME (_, ft) => SOME (metaeq ss s (let val (f $ arg) = ft in f end))
skalberg@15531
   490
        | NONE => NONE)
wenzelm@35364
   491
    | eta_proc _ _ = NONE;
wenzelm@11838
   492
end;
wenzelm@11838
   493
*}
wenzelm@43595
   494
simproc_setup split_beta ("split f z") = {* fn _ => fn ss => fn ct => beta_proc ss (term_of ct) *}
wenzelm@43595
   495
simproc_setup split_eta ("split f") = {* fn _ => fn ss => fn ct => eta_proc ss (term_of ct) *}
wenzelm@11838
   496
berghofe@26798
   497
lemma split_beta [mono]: "(%(x, y). P x y) z = P (fst z) (snd z)"
wenzelm@11838
   498
  by (subst surjective_pairing, rule split_conv)
wenzelm@11838
   499
blanchet@35828
   500
lemma split_split [no_atp]: "R(split c p) = (ALL x y. p = (x, y) --> R(c x y))"
wenzelm@11838
   501
  -- {* For use with @{text split} and the Simplifier. *}
paulson@15481
   502
  by (insert surj_pair [of p], clarify, simp)
wenzelm@11838
   503
wenzelm@11838
   504
text {*
wenzelm@11838
   505
  @{thm [source] split_split} could be declared as @{text "[split]"}
wenzelm@11838
   506
  done after the Splitter has been speeded up significantly;
wenzelm@11838
   507
  precompute the constants involved and don't do anything unless the
wenzelm@11838
   508
  current goal contains one of those constants.
wenzelm@11838
   509
*}
wenzelm@11838
   510
blanchet@35828
   511
lemma split_split_asm [no_atp]: "R (split c p) = (~(EX x y. p = (x, y) & (~R (c x y))))"
paulson@14208
   512
by (subst split_split, simp)
wenzelm@11838
   513
wenzelm@11838
   514
text {*
wenzelm@11838
   515
  \medskip @{term split} used as a logical connective or set former.
wenzelm@11838
   516
wenzelm@11838
   517
  \medskip These rules are for use with @{text blast}; could instead
huffman@40929
   518
  call @{text simp} using @{thm [source] prod.split} as rewrite. *}
wenzelm@11838
   519
wenzelm@11838
   520
lemma splitI2: "!!p. [| !!a b. p = (a, b) ==> c a b |] ==> split c p"
wenzelm@11838
   521
  apply (simp only: split_tupled_all)
wenzelm@11838
   522
  apply (simp (no_asm_simp))
wenzelm@11838
   523
  done
wenzelm@11838
   524
wenzelm@11838
   525
lemma splitI2': "!!p. [| !!a b. (a, b) = p ==> c a b x |] ==> split c p x"
wenzelm@11838
   526
  apply (simp only: split_tupled_all)
wenzelm@11838
   527
  apply (simp (no_asm_simp))
wenzelm@11838
   528
  done
wenzelm@11838
   529
wenzelm@11838
   530
lemma splitE: "split c p ==> (!!x y. p = (x, y) ==> c x y ==> Q) ==> Q"
haftmann@37591
   531
  by (induct p) auto
wenzelm@11838
   532
wenzelm@11838
   533
lemma splitE': "split c p z ==> (!!x y. p = (x, y) ==> c x y z ==> Q) ==> Q"
haftmann@37591
   534
  by (induct p) auto
wenzelm@11838
   535
wenzelm@11838
   536
lemma splitE2:
wenzelm@11838
   537
  "[| Q (split P z);  !!x y. [|z = (x, y); Q (P x y)|] ==> R |] ==> R"
wenzelm@11838
   538
proof -
wenzelm@11838
   539
  assume q: "Q (split P z)"
wenzelm@11838
   540
  assume r: "!!x y. [|z = (x, y); Q (P x y)|] ==> R"
wenzelm@11838
   541
  show R
wenzelm@11838
   542
    apply (rule r surjective_pairing)+
wenzelm@11838
   543
    apply (rule split_beta [THEN subst], rule q)
wenzelm@11838
   544
    done
wenzelm@11838
   545
qed
wenzelm@11838
   546
wenzelm@11838
   547
lemma splitD': "split R (a,b) c ==> R a b c"
wenzelm@11838
   548
  by simp
wenzelm@11838
   549
wenzelm@11838
   550
lemma mem_splitI: "z: c a b ==> z: split c (a, b)"
wenzelm@11838
   551
  by simp
wenzelm@11838
   552
wenzelm@11838
   553
lemma mem_splitI2: "!!p. [| !!a b. p = (a, b) ==> z: c a b |] ==> z: split c p"
paulson@14208
   554
by (simp only: split_tupled_all, simp)
wenzelm@11838
   555
wenzelm@18372
   556
lemma mem_splitE:
haftmann@37166
   557
  assumes major: "z \<in> split c p"
haftmann@37166
   558
    and cases: "\<And>x y. p = (x, y) \<Longrightarrow> z \<in> c x y \<Longrightarrow> Q"
wenzelm@18372
   559
  shows Q
haftmann@37591
   560
  by (rule major [unfolded prod_case_unfold] cases surjective_pairing)+
wenzelm@11838
   561
wenzelm@11838
   562
declare mem_splitI2 [intro!] mem_splitI [intro!] splitI2' [intro!] splitI2 [intro!] splitI [intro!]
wenzelm@11838
   563
declare mem_splitE [elim!] splitE' [elim!] splitE [elim!]
wenzelm@11838
   564
wenzelm@26340
   565
ML {*
wenzelm@11838
   566
local (* filtering with exists_p_split is an essential optimization *)
haftmann@37591
   567
  fun exists_p_split (Const (@{const_name prod_case},_) $ _ $ (Const (@{const_name Pair},_)$_$_)) = true
wenzelm@11838
   568
    | exists_p_split (t $ u) = exists_p_split t orelse exists_p_split u
wenzelm@11838
   569
    | exists_p_split (Abs (_, _, t)) = exists_p_split t
wenzelm@11838
   570
    | exists_p_split _ = false;
wenzelm@35364
   571
  val ss = HOL_basic_ss addsimps @{thms split_conv};
wenzelm@11838
   572
in
wenzelm@11838
   573
val split_conv_tac = SUBGOAL (fn (t, i) =>
wenzelm@11838
   574
    if exists_p_split t then safe_full_simp_tac ss i else no_tac);
wenzelm@11838
   575
end;
wenzelm@26340
   576
*}
wenzelm@26340
   577
wenzelm@11838
   578
(* This prevents applications of splitE for already splitted arguments leading
wenzelm@11838
   579
   to quite time-consuming computations (in particular for nested tuples) *)
wenzelm@26340
   580
declaration {* fn _ =>
wenzelm@26340
   581
  Classical.map_cs (fn cs => cs addSbefore ("split_conv_tac", split_conv_tac))
wenzelm@16121
   582
*}
wenzelm@11838
   583
blanchet@35828
   584
lemma split_eta_SetCompr [simp,no_atp]: "(%u. EX x y. u = (x, y) & P (x, y)) = P"
wenzelm@18372
   585
  by (rule ext) fast
wenzelm@11838
   586
blanchet@35828
   587
lemma split_eta_SetCompr2 [simp,no_atp]: "(%u. EX x y. u = (x, y) & P x y) = split P"
wenzelm@18372
   588
  by (rule ext) fast
wenzelm@11838
   589
wenzelm@11838
   590
lemma split_part [simp]: "(%(a,b). P & Q a b) = (%ab. P & split Q ab)"
wenzelm@11838
   591
  -- {* Allows simplifications of nested splits in case of independent predicates. *}
wenzelm@18372
   592
  by (rule ext) blast
wenzelm@11838
   593
nipkow@14337
   594
(* Do NOT make this a simp rule as it
nipkow@14337
   595
   a) only helps in special situations
nipkow@14337
   596
   b) can lead to nontermination in the presence of split_def
nipkow@14337
   597
*)
nipkow@14337
   598
lemma split_comp_eq: 
paulson@20415
   599
  fixes f :: "'a => 'b => 'c" and g :: "'d => 'a"
paulson@20415
   600
  shows "(%u. f (g (fst u)) (snd u)) = (split (%x. f (g x)))"
wenzelm@18372
   601
  by (rule ext) auto
oheimb@14101
   602
haftmann@26358
   603
lemma pair_imageI [intro]: "(a, b) : A ==> f a b : (%(a, b). f a b) ` A"
haftmann@26358
   604
  apply (rule_tac x = "(a, b)" in image_eqI)
haftmann@26358
   605
   apply auto
haftmann@26358
   606
  done
haftmann@26358
   607
wenzelm@11838
   608
lemma The_split_eq [simp]: "(THE (x',y'). x = x' & y = y') = (x, y)"
wenzelm@11838
   609
  by blast
wenzelm@11838
   610
wenzelm@11838
   611
(*
wenzelm@11838
   612
the following  would be slightly more general,
wenzelm@11838
   613
but cannot be used as rewrite rule:
wenzelm@11838
   614
### Cannot add premise as rewrite rule because it contains (type) unknowns:
wenzelm@11838
   615
### ?y = .x
wenzelm@11838
   616
Goal "[| P y; !!x. P x ==> x = y |] ==> (@(x',y). x = x' & P y) = (x,y)"
paulson@14208
   617
by (rtac some_equality 1)
paulson@14208
   618
by ( Simp_tac 1)
paulson@14208
   619
by (split_all_tac 1)
paulson@14208
   620
by (Asm_full_simp_tac 1)
wenzelm@11838
   621
qed "The_split_eq";
wenzelm@11838
   622
*)
wenzelm@11838
   623
wenzelm@11838
   624
text {*
wenzelm@11838
   625
  Setup of internal @{text split_rule}.
wenzelm@11838
   626
*}
wenzelm@11838
   627
wenzelm@45607
   628
lemmas prod_caseI = prod.cases [THEN iffD2]
haftmann@24699
   629
haftmann@24699
   630
lemma prod_caseI2: "!!p. [| !!a b. p = (a, b) ==> c a b |] ==> prod_case c p"
haftmann@37678
   631
  by (fact splitI2)
haftmann@24699
   632
haftmann@24699
   633
lemma prod_caseI2': "!!p. [| !!a b. (a, b) = p ==> c a b x |] ==> prod_case c p x"
haftmann@37678
   634
  by (fact splitI2')
haftmann@24699
   635
haftmann@24699
   636
lemma prod_caseE: "prod_case c p ==> (!!x y. p = (x, y) ==> c x y ==> Q) ==> Q"
haftmann@37678
   637
  by (fact splitE)
haftmann@24699
   638
haftmann@24699
   639
lemma prod_caseE': "prod_case c p z ==> (!!x y. p = (x, y) ==> c x y z ==> Q) ==> Q"
haftmann@37678
   640
  by (fact splitE')
haftmann@24699
   641
haftmann@37678
   642
declare prod_caseI [intro!]
haftmann@24699
   643
bulwahn@26143
   644
lemma prod_case_beta:
bulwahn@26143
   645
  "prod_case f p = f (fst p) (snd p)"
haftmann@37591
   646
  by (fact split_beta)
bulwahn@26143
   647
haftmann@24699
   648
lemma prod_cases3 [cases type]:
haftmann@24699
   649
  obtains (fields) a b c where "y = (a, b, c)"
haftmann@24699
   650
  by (cases y, case_tac b) blast
haftmann@24699
   651
haftmann@24699
   652
lemma prod_induct3 [case_names fields, induct type]:
haftmann@24699
   653
    "(!!a b c. P (a, b, c)) ==> P x"
haftmann@24699
   654
  by (cases x) blast
haftmann@24699
   655
haftmann@24699
   656
lemma prod_cases4 [cases type]:
haftmann@24699
   657
  obtains (fields) a b c d where "y = (a, b, c, d)"
haftmann@24699
   658
  by (cases y, case_tac c) blast
haftmann@24699
   659
haftmann@24699
   660
lemma prod_induct4 [case_names fields, induct type]:
haftmann@24699
   661
    "(!!a b c d. P (a, b, c, d)) ==> P x"
haftmann@24699
   662
  by (cases x) blast
haftmann@24699
   663
haftmann@24699
   664
lemma prod_cases5 [cases type]:
haftmann@24699
   665
  obtains (fields) a b c d e where "y = (a, b, c, d, e)"
haftmann@24699
   666
  by (cases y, case_tac d) blast
haftmann@24699
   667
haftmann@24699
   668
lemma prod_induct5 [case_names fields, induct type]:
haftmann@24699
   669
    "(!!a b c d e. P (a, b, c, d, e)) ==> P x"
haftmann@24699
   670
  by (cases x) blast
haftmann@24699
   671
haftmann@24699
   672
lemma prod_cases6 [cases type]:
haftmann@24699
   673
  obtains (fields) a b c d e f where "y = (a, b, c, d, e, f)"
haftmann@24699
   674
  by (cases y, case_tac e) blast
haftmann@24699
   675
haftmann@24699
   676
lemma prod_induct6 [case_names fields, induct type]:
haftmann@24699
   677
    "(!!a b c d e f. P (a, b, c, d, e, f)) ==> P x"
haftmann@24699
   678
  by (cases x) blast
haftmann@24699
   679
haftmann@24699
   680
lemma prod_cases7 [cases type]:
haftmann@24699
   681
  obtains (fields) a b c d e f g where "y = (a, b, c, d, e, f, g)"
haftmann@24699
   682
  by (cases y, case_tac f) blast
haftmann@24699
   683
haftmann@24699
   684
lemma prod_induct7 [case_names fields, induct type]:
haftmann@24699
   685
    "(!!a b c d e f g. P (a, b, c, d, e, f, g)) ==> P x"
haftmann@24699
   686
  by (cases x) blast
haftmann@24699
   687
haftmann@37166
   688
lemma split_def:
haftmann@37166
   689
  "split = (\<lambda>c p. c (fst p) (snd p))"
haftmann@37591
   690
  by (fact prod_case_unfold)
haftmann@37166
   691
haftmann@37166
   692
definition internal_split :: "('a \<Rightarrow> 'b \<Rightarrow> 'c) \<Rightarrow> 'a \<times> 'b \<Rightarrow> 'c" where
haftmann@37166
   693
  "internal_split == split"
haftmann@37166
   694
haftmann@37166
   695
lemma internal_split_conv: "internal_split c (a, b) = c a b"
haftmann@37166
   696
  by (simp only: internal_split_def split_conv)
haftmann@37166
   697
haftmann@37166
   698
use "Tools/split_rule.ML"
haftmann@37166
   699
setup Split_Rule.setup
haftmann@37166
   700
haftmann@37166
   701
hide_const internal_split
haftmann@37166
   702
haftmann@24699
   703
haftmann@26358
   704
subsubsection {* Derived operations *}
haftmann@26358
   705
haftmann@37387
   706
definition curry    :: "('a \<times> 'b \<Rightarrow> 'c) \<Rightarrow> 'a \<Rightarrow> 'b \<Rightarrow> 'c" where
haftmann@37387
   707
  "curry = (\<lambda>c x y. c (x, y))"
haftmann@37166
   708
haftmann@37166
   709
lemma curry_conv [simp, code]: "curry f a b = f (a, b)"
haftmann@37166
   710
  by (simp add: curry_def)
haftmann@37166
   711
haftmann@37166
   712
lemma curryI [intro!]: "f (a, b) \<Longrightarrow> curry f a b"
haftmann@37166
   713
  by (simp add: curry_def)
haftmann@37166
   714
haftmann@37166
   715
lemma curryD [dest!]: "curry f a b \<Longrightarrow> f (a, b)"
haftmann@37166
   716
  by (simp add: curry_def)
haftmann@37166
   717
haftmann@37166
   718
lemma curryE: "curry f a b \<Longrightarrow> (f (a, b) \<Longrightarrow> Q) \<Longrightarrow> Q"
haftmann@37166
   719
  by (simp add: curry_def)
haftmann@37166
   720
haftmann@37166
   721
lemma curry_split [simp]: "curry (split f) = f"
haftmann@37166
   722
  by (simp add: curry_def split_def)
haftmann@37166
   723
haftmann@37166
   724
lemma split_curry [simp]: "split (curry f) = f"
haftmann@37166
   725
  by (simp add: curry_def split_def)
haftmann@37166
   726
haftmann@26358
   727
text {*
haftmann@26358
   728
  The composition-uncurry combinator.
haftmann@26358
   729
*}
haftmann@26358
   730
haftmann@37751
   731
notation fcomp (infixl "\<circ>>" 60)
haftmann@26358
   732
haftmann@37751
   733
definition scomp :: "('a \<Rightarrow> 'b \<times> 'c) \<Rightarrow> ('b \<Rightarrow> 'c \<Rightarrow> 'd) \<Rightarrow> 'a \<Rightarrow> 'd" (infixl "\<circ>\<rightarrow>" 60) where
haftmann@37751
   734
  "f \<circ>\<rightarrow> g = (\<lambda>x. prod_case g (f x))"
haftmann@26358
   735
haftmann@37678
   736
lemma scomp_unfold: "scomp = (\<lambda>f g x. g (fst (f x)) (snd (f x)))"
nipkow@39302
   737
  by (simp add: fun_eq_iff scomp_def prod_case_unfold)
haftmann@37678
   738
haftmann@37751
   739
lemma scomp_apply [simp]: "(f \<circ>\<rightarrow> g) x = prod_case g (f x)"
haftmann@37751
   740
  by (simp add: scomp_unfold prod_case_unfold)
haftmann@26358
   741
haftmann@37751
   742
lemma Pair_scomp: "Pair x \<circ>\<rightarrow> f = f x"
huffman@44921
   743
  by (simp add: fun_eq_iff)
haftmann@26358
   744
haftmann@37751
   745
lemma scomp_Pair: "x \<circ>\<rightarrow> Pair = x"
huffman@44921
   746
  by (simp add: fun_eq_iff)
haftmann@26358
   747
haftmann@37751
   748
lemma scomp_scomp: "(f \<circ>\<rightarrow> g) \<circ>\<rightarrow> h = f \<circ>\<rightarrow> (\<lambda>x. g x \<circ>\<rightarrow> h)"
nipkow@39302
   749
  by (simp add: fun_eq_iff scomp_unfold)
haftmann@26358
   750
haftmann@37751
   751
lemma scomp_fcomp: "(f \<circ>\<rightarrow> g) \<circ>> h = f \<circ>\<rightarrow> (\<lambda>x. g x \<circ>> h)"
nipkow@39302
   752
  by (simp add: fun_eq_iff scomp_unfold fcomp_def)
haftmann@26358
   753
haftmann@37751
   754
lemma fcomp_scomp: "(f \<circ>> g) \<circ>\<rightarrow> h = f \<circ>> (g \<circ>\<rightarrow> h)"
huffman@44921
   755
  by (simp add: fun_eq_iff scomp_unfold)
haftmann@26358
   756
haftmann@31202
   757
code_const scomp
haftmann@31202
   758
  (Eval infixl 3 "#->")
haftmann@31202
   759
haftmann@37751
   760
no_notation fcomp (infixl "\<circ>>" 60)
haftmann@37751
   761
no_notation scomp (infixl "\<circ>\<rightarrow>" 60)
haftmann@26358
   762
haftmann@26358
   763
text {*
haftmann@40607
   764
  @{term map_pair} --- action of the product functor upon
krauss@36664
   765
  functions.
haftmann@26358
   766
*}
haftmann@21195
   767
haftmann@40607
   768
definition map_pair :: "('a \<Rightarrow> 'c) \<Rightarrow> ('b \<Rightarrow> 'd) \<Rightarrow> 'a \<times> 'b \<Rightarrow> 'c \<times> 'd" where
haftmann@40607
   769
  "map_pair f g = (\<lambda>(x, y). (f x, g y))"
haftmann@26358
   770
haftmann@40607
   771
lemma map_pair_simp [simp, code]:
haftmann@40607
   772
  "map_pair f g (a, b) = (f a, g b)"
haftmann@40607
   773
  by (simp add: map_pair_def)
haftmann@26358
   774
haftmann@41505
   775
enriched_type map_pair: map_pair
huffman@44921
   776
  by (auto simp add: split_paired_all)
nipkow@37278
   777
haftmann@40607
   778
lemma fst_map_pair [simp]:
haftmann@40607
   779
  "fst (map_pair f g x) = f (fst x)"
haftmann@40607
   780
  by (cases x) simp_all
nipkow@37278
   781
haftmann@40607
   782
lemma snd_prod_fun [simp]:
haftmann@40607
   783
  "snd (map_pair f g x) = g (snd x)"
haftmann@40607
   784
  by (cases x) simp_all
nipkow@37278
   785
haftmann@40607
   786
lemma fst_comp_map_pair [simp]:
haftmann@40607
   787
  "fst \<circ> map_pair f g = f \<circ> fst"
haftmann@40607
   788
  by (rule ext) simp_all
nipkow@37278
   789
haftmann@40607
   790
lemma snd_comp_map_pair [simp]:
haftmann@40607
   791
  "snd \<circ> map_pair f g = g \<circ> snd"
haftmann@40607
   792
  by (rule ext) simp_all
haftmann@26358
   793
haftmann@40607
   794
lemma map_pair_compose:
haftmann@40607
   795
  "map_pair (f1 o f2) (g1 o g2) = (map_pair f1 g1 o map_pair f2 g2)"
haftmann@40607
   796
  by (rule ext) (simp add: map_pair.compositionality comp_def)
haftmann@26358
   797
haftmann@40607
   798
lemma map_pair_ident [simp]:
haftmann@40607
   799
  "map_pair (%x. x) (%y. y) = (%z. z)"
haftmann@40607
   800
  by (rule ext) (simp add: map_pair.identity)
haftmann@40607
   801
haftmann@40607
   802
lemma map_pair_imageI [intro]:
haftmann@40607
   803
  "(a, b) \<in> R \<Longrightarrow> (f a, g b) \<in> map_pair f g ` R"
haftmann@40607
   804
  by (rule image_eqI) simp_all
haftmann@21195
   805
haftmann@26358
   806
lemma prod_fun_imageE [elim!]:
haftmann@40607
   807
  assumes major: "c \<in> map_pair f g ` R"
haftmann@40607
   808
    and cases: "\<And>x y. c = (f x, g y) \<Longrightarrow> (x, y) \<in> R \<Longrightarrow> P"
haftmann@26358
   809
  shows P
haftmann@26358
   810
  apply (rule major [THEN imageE])
haftmann@37166
   811
  apply (case_tac x)
haftmann@26358
   812
  apply (rule cases)
haftmann@40607
   813
  apply simp_all
haftmann@26358
   814
  done
haftmann@26358
   815
haftmann@37166
   816
definition apfst :: "('a \<Rightarrow> 'c) \<Rightarrow> 'a \<times> 'b \<Rightarrow> 'c \<times> 'b" where
haftmann@40607
   817
  "apfst f = map_pair f id"
haftmann@26358
   818
haftmann@37166
   819
definition apsnd :: "('b \<Rightarrow> 'c) \<Rightarrow> 'a \<times> 'b \<Rightarrow> 'a \<times> 'c" where
haftmann@40607
   820
  "apsnd f = map_pair id f"
haftmann@26358
   821
haftmann@26358
   822
lemma apfst_conv [simp, code]:
haftmann@26358
   823
  "apfst f (x, y) = (f x, y)" 
haftmann@26358
   824
  by (simp add: apfst_def)
haftmann@26358
   825
hoelzl@33638
   826
lemma apsnd_conv [simp, code]:
haftmann@26358
   827
  "apsnd f (x, y) = (x, f y)" 
haftmann@26358
   828
  by (simp add: apsnd_def)
haftmann@21195
   829
haftmann@33594
   830
lemma fst_apfst [simp]:
haftmann@33594
   831
  "fst (apfst f x) = f (fst x)"
haftmann@33594
   832
  by (cases x) simp
haftmann@33594
   833
haftmann@33594
   834
lemma fst_apsnd [simp]:
haftmann@33594
   835
  "fst (apsnd f x) = fst x"
haftmann@33594
   836
  by (cases x) simp
haftmann@33594
   837
haftmann@33594
   838
lemma snd_apfst [simp]:
haftmann@33594
   839
  "snd (apfst f x) = snd x"
haftmann@33594
   840
  by (cases x) simp
haftmann@33594
   841
haftmann@33594
   842
lemma snd_apsnd [simp]:
haftmann@33594
   843
  "snd (apsnd f x) = f (snd x)"
haftmann@33594
   844
  by (cases x) simp
haftmann@33594
   845
haftmann@33594
   846
lemma apfst_compose:
haftmann@33594
   847
  "apfst f (apfst g x) = apfst (f \<circ> g) x"
haftmann@33594
   848
  by (cases x) simp
haftmann@33594
   849
haftmann@33594
   850
lemma apsnd_compose:
haftmann@33594
   851
  "apsnd f (apsnd g x) = apsnd (f \<circ> g) x"
haftmann@33594
   852
  by (cases x) simp
haftmann@33594
   853
haftmann@33594
   854
lemma apfst_apsnd [simp]:
haftmann@33594
   855
  "apfst f (apsnd g x) = (f (fst x), g (snd x))"
haftmann@33594
   856
  by (cases x) simp
haftmann@33594
   857
haftmann@33594
   858
lemma apsnd_apfst [simp]:
haftmann@33594
   859
  "apsnd f (apfst g x) = (g (fst x), f (snd x))"
haftmann@33594
   860
  by (cases x) simp
haftmann@33594
   861
haftmann@33594
   862
lemma apfst_id [simp] :
haftmann@33594
   863
  "apfst id = id"
nipkow@39302
   864
  by (simp add: fun_eq_iff)
haftmann@33594
   865
haftmann@33594
   866
lemma apsnd_id [simp] :
haftmann@33594
   867
  "apsnd id = id"
nipkow@39302
   868
  by (simp add: fun_eq_iff)
haftmann@33594
   869
haftmann@33594
   870
lemma apfst_eq_conv [simp]:
haftmann@33594
   871
  "apfst f x = apfst g x \<longleftrightarrow> f (fst x) = g (fst x)"
haftmann@33594
   872
  by (cases x) simp
haftmann@33594
   873
haftmann@33594
   874
lemma apsnd_eq_conv [simp]:
haftmann@33594
   875
  "apsnd f x = apsnd g x \<longleftrightarrow> f (snd x) = g (snd x)"
haftmann@33594
   876
  by (cases x) simp
haftmann@33594
   877
hoelzl@33638
   878
lemma apsnd_apfst_commute:
hoelzl@33638
   879
  "apsnd f (apfst g p) = apfst g (apsnd f p)"
hoelzl@33638
   880
  by simp
haftmann@21195
   881
haftmann@26358
   882
text {*
haftmann@26358
   883
  Disjoint union of a family of sets -- Sigma.
haftmann@26358
   884
*}
haftmann@26358
   885
haftmann@40607
   886
definition Sigma :: "['a set, 'a => 'b set] => ('a \<times> 'b) set" where
haftmann@26358
   887
  Sigma_def: "Sigma A B == UN x:A. UN y:B x. {Pair x y}"
haftmann@26358
   888
haftmann@26358
   889
abbreviation
haftmann@26358
   890
  Times :: "['a set, 'b set] => ('a * 'b) set"
haftmann@26358
   891
    (infixr "<*>" 80) where
haftmann@26358
   892
  "A <*> B == Sigma A (%_. B)"
haftmann@26358
   893
haftmann@26358
   894
notation (xsymbols)
haftmann@26358
   895
  Times  (infixr "\<times>" 80)
berghofe@15394
   896
haftmann@26358
   897
notation (HTML output)
haftmann@26358
   898
  Times  (infixr "\<times>" 80)
haftmann@26358
   899
nipkow@45662
   900
hide_const (open) Times
nipkow@45662
   901
haftmann@26358
   902
syntax
wenzelm@35115
   903
  "_Sigma" :: "[pttrn, 'a set, 'b set] => ('a * 'b) set"  ("(3SIGMA _:_./ _)" [0, 0, 10] 10)
haftmann@26358
   904
translations
wenzelm@35115
   905
  "SIGMA x:A. B" == "CONST Sigma A (%x. B)"
haftmann@26358
   906
haftmann@26358
   907
lemma SigmaI [intro!]: "[| a:A;  b:B(a) |] ==> (a,b) : Sigma A B"
haftmann@26358
   908
  by (unfold Sigma_def) blast
haftmann@26358
   909
haftmann@26358
   910
lemma SigmaE [elim!]:
haftmann@26358
   911
    "[| c: Sigma A B;
haftmann@26358
   912
        !!x y.[| x:A;  y:B(x);  c=(x,y) |] ==> P
haftmann@26358
   913
     |] ==> P"
haftmann@26358
   914
  -- {* The general elimination rule. *}
haftmann@26358
   915
  by (unfold Sigma_def) blast
haftmann@20588
   916
haftmann@26358
   917
text {*
haftmann@26358
   918
  Elimination of @{term "(a, b) : A \<times> B"} -- introduces no
haftmann@26358
   919
  eigenvariables.
haftmann@26358
   920
*}
haftmann@26358
   921
haftmann@26358
   922
lemma SigmaD1: "(a, b) : Sigma A B ==> a : A"
haftmann@26358
   923
  by blast
haftmann@26358
   924
haftmann@26358
   925
lemma SigmaD2: "(a, b) : Sigma A B ==> b : B a"
haftmann@26358
   926
  by blast
haftmann@26358
   927
haftmann@26358
   928
lemma SigmaE2:
haftmann@26358
   929
    "[| (a, b) : Sigma A B;
haftmann@26358
   930
        [| a:A;  b:B(a) |] ==> P
haftmann@26358
   931
     |] ==> P"
haftmann@26358
   932
  by blast
haftmann@20588
   933
haftmann@26358
   934
lemma Sigma_cong:
haftmann@26358
   935
     "\<lbrakk>A = B; !!x. x \<in> B \<Longrightarrow> C x = D x\<rbrakk>
haftmann@26358
   936
      \<Longrightarrow> (SIGMA x: A. C x) = (SIGMA x: B. D x)"
haftmann@26358
   937
  by auto
haftmann@26358
   938
haftmann@26358
   939
lemma Sigma_mono: "[| A <= C; !!x. x:A ==> B x <= D x |] ==> Sigma A B <= Sigma C D"
haftmann@26358
   940
  by blast
haftmann@26358
   941
haftmann@26358
   942
lemma Sigma_empty1 [simp]: "Sigma {} B = {}"
haftmann@26358
   943
  by blast
haftmann@26358
   944
haftmann@26358
   945
lemma Sigma_empty2 [simp]: "A <*> {} = {}"
haftmann@26358
   946
  by blast
haftmann@26358
   947
haftmann@26358
   948
lemma UNIV_Times_UNIV [simp]: "UNIV <*> UNIV = UNIV"
haftmann@26358
   949
  by auto
haftmann@21908
   950
haftmann@26358
   951
lemma Compl_Times_UNIV1 [simp]: "- (UNIV <*> A) = UNIV <*> (-A)"
haftmann@26358
   952
  by auto
haftmann@26358
   953
haftmann@26358
   954
lemma Compl_Times_UNIV2 [simp]: "- (A <*> UNIV) = (-A) <*> UNIV"
haftmann@26358
   955
  by auto
haftmann@26358
   956
haftmann@26358
   957
lemma mem_Sigma_iff [iff]: "((a,b): Sigma A B) = (a:A & b:B(a))"
haftmann@26358
   958
  by blast
haftmann@26358
   959
haftmann@26358
   960
lemma Times_subset_cancel2: "x:C ==> (A <*> C <= B <*> C) = (A <= B)"
haftmann@26358
   961
  by blast
haftmann@26358
   962
haftmann@26358
   963
lemma Times_eq_cancel2: "x:C ==> (A <*> C = B <*> C) = (A = B)"
haftmann@26358
   964
  by (blast elim: equalityE)
haftmann@20588
   965
haftmann@26358
   966
lemma SetCompr_Sigma_eq:
haftmann@26358
   967
    "Collect (split (%x y. P x & Q x y)) = (SIGMA x:Collect P. Collect (Q x))"
haftmann@26358
   968
  by blast
haftmann@26358
   969
haftmann@26358
   970
lemma Collect_split [simp]: "{(a,b). P a & Q b} = Collect P <*> Collect Q"
haftmann@26358
   971
  by blast
haftmann@26358
   972
haftmann@26358
   973
lemma UN_Times_distrib:
haftmann@26358
   974
  "(UN (a,b):(A <*> B). E a <*> F b) = (UNION A E) <*> (UNION B F)"
haftmann@26358
   975
  -- {* Suggested by Pierre Chartier *}
haftmann@26358
   976
  by blast
haftmann@26358
   977
blanchet@35828
   978
lemma split_paired_Ball_Sigma [simp,no_atp]:
haftmann@26358
   979
    "(ALL z: Sigma A B. P z) = (ALL x:A. ALL y: B x. P(x,y))"
haftmann@26358
   980
  by blast
haftmann@26358
   981
blanchet@35828
   982
lemma split_paired_Bex_Sigma [simp,no_atp]:
haftmann@26358
   983
    "(EX z: Sigma A B. P z) = (EX x:A. EX y: B x. P(x,y))"
haftmann@26358
   984
  by blast
haftmann@21908
   985
haftmann@26358
   986
lemma Sigma_Un_distrib1: "(SIGMA i:I Un J. C(i)) = (SIGMA i:I. C(i)) Un (SIGMA j:J. C(j))"
haftmann@26358
   987
  by blast
haftmann@26358
   988
haftmann@26358
   989
lemma Sigma_Un_distrib2: "(SIGMA i:I. A(i) Un B(i)) = (SIGMA i:I. A(i)) Un (SIGMA i:I. B(i))"
haftmann@26358
   990
  by blast
haftmann@26358
   991
haftmann@26358
   992
lemma Sigma_Int_distrib1: "(SIGMA i:I Int J. C(i)) = (SIGMA i:I. C(i)) Int (SIGMA j:J. C(j))"
haftmann@26358
   993
  by blast
haftmann@26358
   994
haftmann@26358
   995
lemma Sigma_Int_distrib2: "(SIGMA i:I. A(i) Int B(i)) = (SIGMA i:I. A(i)) Int (SIGMA i:I. B(i))"
haftmann@26358
   996
  by blast
haftmann@26358
   997
haftmann@26358
   998
lemma Sigma_Diff_distrib1: "(SIGMA i:I - J. C(i)) = (SIGMA i:I. C(i)) - (SIGMA j:J. C(j))"
haftmann@26358
   999
  by blast
haftmann@26358
  1000
haftmann@26358
  1001
lemma Sigma_Diff_distrib2: "(SIGMA i:I. A(i) - B(i)) = (SIGMA i:I. A(i)) - (SIGMA i:I. B(i))"
haftmann@26358
  1002
  by blast
haftmann@21908
  1003
haftmann@26358
  1004
lemma Sigma_Union: "Sigma (Union X) B = (UN A:X. Sigma A B)"
haftmann@26358
  1005
  by blast
haftmann@26358
  1006
haftmann@26358
  1007
text {*
haftmann@26358
  1008
  Non-dependent versions are needed to avoid the need for higher-order
haftmann@26358
  1009
  matching, especially when the rules are re-oriented.
haftmann@26358
  1010
*}
haftmann@21908
  1011
haftmann@26358
  1012
lemma Times_Un_distrib1: "(A Un B) <*> C = (A <*> C) Un (B <*> C)"
nipkow@28719
  1013
by blast
haftmann@26358
  1014
haftmann@26358
  1015
lemma Times_Int_distrib1: "(A Int B) <*> C = (A <*> C) Int (B <*> C)"
nipkow@28719
  1016
by blast
haftmann@26358
  1017
haftmann@26358
  1018
lemma Times_Diff_distrib1: "(A - B) <*> C = (A <*> C) - (B <*> C)"
nipkow@28719
  1019
by blast
haftmann@26358
  1020
hoelzl@36622
  1021
lemma Times_empty[simp]: "A \<times> B = {} \<longleftrightarrow> A = {} \<or> B = {}"
hoelzl@36622
  1022
  by auto
hoelzl@36622
  1023
hoelzl@36622
  1024
lemma fst_image_times[simp]: "fst ` (A \<times> B) = (if B = {} then {} else A)"
huffman@44921
  1025
  by force
hoelzl@36622
  1026
hoelzl@36622
  1027
lemma snd_image_times[simp]: "snd ` (A \<times> B) = (if A = {} then {} else B)"
huffman@44921
  1028
  by force
hoelzl@36622
  1029
nipkow@28719
  1030
lemma insert_times_insert[simp]:
nipkow@28719
  1031
  "insert a A \<times> insert b B =
nipkow@28719
  1032
   insert (a,b) (A \<times> insert b B \<union> insert a A \<times> B)"
nipkow@28719
  1033
by blast
haftmann@26358
  1034
paulson@33271
  1035
lemma vimage_Times: "f -` (A \<times> B) = ((fst \<circ> f) -` A) \<inter> ((snd \<circ> f) -` B)"
haftmann@37166
  1036
  by (auto, case_tac "f x", auto)
paulson@33271
  1037
haftmann@35822
  1038
lemma swap_inj_on:
hoelzl@36622
  1039
  "inj_on (\<lambda>(i, j). (j, i)) A"
hoelzl@36622
  1040
  by (auto intro!: inj_onI)
haftmann@35822
  1041
haftmann@35822
  1042
lemma swap_product:
haftmann@35822
  1043
  "(%(i, j). (j, i)) ` (A \<times> B) = B \<times> A"
haftmann@35822
  1044
  by (simp add: split_def image_def) blast
haftmann@35822
  1045
hoelzl@36622
  1046
lemma image_split_eq_Sigma:
hoelzl@36622
  1047
  "(\<lambda>x. (f x, g x)) ` A = Sigma (f ` A) (\<lambda>x. g ` (f -` {x} \<inter> A))"
hoelzl@36622
  1048
proof (safe intro!: imageI vimageI)
hoelzl@36622
  1049
  fix a b assume *: "a \<in> A" "b \<in> A" and eq: "f a = f b"
hoelzl@36622
  1050
  show "(f b, g a) \<in> (\<lambda>x. (f x, g x)) ` A"
hoelzl@36622
  1051
    using * eq[symmetric] by auto
hoelzl@36622
  1052
qed simp_all
haftmann@35822
  1053
haftmann@40607
  1054
text {* The following @{const map_pair} lemmas are due to Joachim Breitner: *}
haftmann@40607
  1055
haftmann@40607
  1056
lemma map_pair_inj_on:
haftmann@40607
  1057
  assumes "inj_on f A" and "inj_on g B"
haftmann@40607
  1058
  shows "inj_on (map_pair f g) (A \<times> B)"
haftmann@40607
  1059
proof (rule inj_onI)
haftmann@40607
  1060
  fix x :: "'a \<times> 'c" and y :: "'a \<times> 'c"
haftmann@40607
  1061
  assume "x \<in> A \<times> B" hence "fst x \<in> A" and "snd x \<in> B" by auto
haftmann@40607
  1062
  assume "y \<in> A \<times> B" hence "fst y \<in> A" and "snd y \<in> B" by auto
haftmann@40607
  1063
  assume "map_pair f g x = map_pair f g y"
haftmann@40607
  1064
  hence "fst (map_pair f g x) = fst (map_pair f g y)" by (auto)
haftmann@40607
  1065
  hence "f (fst x) = f (fst y)" by (cases x,cases y,auto)
haftmann@40607
  1066
  with `inj_on f A` and `fst x \<in> A` and `fst y \<in> A`
haftmann@40607
  1067
  have "fst x = fst y" by (auto dest:dest:inj_onD)
haftmann@40607
  1068
  moreover from `map_pair f g x = map_pair f g y`
haftmann@40607
  1069
  have "snd (map_pair f g x) = snd (map_pair f g y)" by (auto)
haftmann@40607
  1070
  hence "g (snd x) = g (snd y)" by (cases x,cases y,auto)
haftmann@40607
  1071
  with `inj_on g B` and `snd x \<in> B` and `snd y \<in> B`
haftmann@40607
  1072
  have "snd x = snd y" by (auto dest:dest:inj_onD)
haftmann@40607
  1073
  ultimately show "x = y" by(rule prod_eqI)
haftmann@40607
  1074
qed
haftmann@40607
  1075
haftmann@40607
  1076
lemma map_pair_surj:
hoelzl@40702
  1077
  fixes f :: "'a \<Rightarrow> 'b" and g :: "'c \<Rightarrow> 'd"
haftmann@40607
  1078
  assumes "surj f" and "surj g"
haftmann@40607
  1079
  shows "surj (map_pair f g)"
haftmann@40607
  1080
unfolding surj_def
haftmann@40607
  1081
proof
haftmann@40607
  1082
  fix y :: "'b \<times> 'd"
haftmann@40607
  1083
  from `surj f` obtain a where "fst y = f a" by (auto elim:surjE)
haftmann@40607
  1084
  moreover
haftmann@40607
  1085
  from `surj g` obtain b where "snd y = g b" by (auto elim:surjE)
haftmann@40607
  1086
  ultimately have "(fst y, snd y) = map_pair f g (a,b)" by auto
haftmann@40607
  1087
  thus "\<exists>x. y = map_pair f g x" by auto
haftmann@40607
  1088
qed
haftmann@40607
  1089
haftmann@40607
  1090
lemma map_pair_surj_on:
haftmann@40607
  1091
  assumes "f ` A = A'" and "g ` B = B'"
haftmann@40607
  1092
  shows "map_pair f g ` (A \<times> B) = A' \<times> B'"
haftmann@40607
  1093
unfolding image_def
haftmann@40607
  1094
proof(rule set_eqI,rule iffI)
haftmann@40607
  1095
  fix x :: "'a \<times> 'c"
haftmann@40607
  1096
  assume "x \<in> {y\<Colon>'a \<times> 'c. \<exists>x\<Colon>'b \<times> 'd\<in>A \<times> B. y = map_pair f g x}"
haftmann@40607
  1097
  then obtain y where "y \<in> A \<times> B" and "x = map_pair f g y" by blast
haftmann@40607
  1098
  from `image f A = A'` and `y \<in> A \<times> B` have "f (fst y) \<in> A'" by auto
haftmann@40607
  1099
  moreover from `image g B = B'` and `y \<in> A \<times> B` have "g (snd y) \<in> B'" by auto
haftmann@40607
  1100
  ultimately have "(f (fst y), g (snd y)) \<in> (A' \<times> B')" by auto
haftmann@40607
  1101
  with `x = map_pair f g y` show "x \<in> A' \<times> B'" by (cases y, auto)
haftmann@40607
  1102
next
haftmann@40607
  1103
  fix x :: "'a \<times> 'c"
haftmann@40607
  1104
  assume "x \<in> A' \<times> B'" hence "fst x \<in> A'" and "snd x \<in> B'" by auto
haftmann@40607
  1105
  from `image f A = A'` and `fst x \<in> A'` have "fst x \<in> image f A" by auto
haftmann@40607
  1106
  then obtain a where "a \<in> A" and "fst x = f a" by (rule imageE)
haftmann@40607
  1107
  moreover from `image g B = B'` and `snd x \<in> B'`
haftmann@40607
  1108
  obtain b where "b \<in> B" and "snd x = g b" by auto
haftmann@40607
  1109
  ultimately have "(fst x, snd x) = map_pair f g (a,b)" by auto
haftmann@40607
  1110
  moreover from `a \<in> A` and  `b \<in> B` have "(a , b) \<in> A \<times> B" by auto
haftmann@40607
  1111
  ultimately have "\<exists>y \<in> A \<times> B. x = map_pair f g y" by auto
haftmann@40607
  1112
  thus "x \<in> {x. \<exists>y \<in> A \<times> B. x = map_pair f g y}" by auto
haftmann@40607
  1113
qed
haftmann@40607
  1114
haftmann@21908
  1115
haftmann@37166
  1116
subsection {* Inductively defined sets *}
berghofe@15394
  1117
haftmann@31723
  1118
use "Tools/inductive_set.ML"
haftmann@31723
  1119
setup Inductive_Set.setup
haftmann@24699
  1120
haftmann@37166
  1121
haftmann@37166
  1122
subsection {* Legacy theorem bindings and duplicates *}
haftmann@37166
  1123
haftmann@37166
  1124
lemma PairE:
haftmann@37166
  1125
  obtains x y where "p = (x, y)"
haftmann@37166
  1126
  by (fact prod.exhaust)
haftmann@37166
  1127
haftmann@37166
  1128
lemma Pair_inject:
haftmann@37166
  1129
  assumes "(a, b) = (a', b')"
haftmann@37166
  1130
    and "a = a' ==> b = b' ==> R"
haftmann@37166
  1131
  shows R
haftmann@37166
  1132
  using assms by simp
haftmann@37166
  1133
haftmann@37166
  1134
lemmas Pair_eq = prod.inject
haftmann@37166
  1135
haftmann@37166
  1136
lemmas split = split_conv  -- {* for backwards compatibility *}
haftmann@37166
  1137
huffman@44066
  1138
lemmas Pair_fst_snd_eq = prod_eq_iff
huffman@44066
  1139
huffman@45204
  1140
hide_const (open) prod
huffman@45204
  1141
nipkow@10213
  1142
end