src/HOL/Product_Type.thy
author blanchet
Wed Feb 12 08:35:56 2014 +0100 (2014-02-12)
changeset 55403 677569668824
parent 55393 ce5cebfaedda
child 55414 eab03e9cee8a
permissions -rw-r--r--
avoid duplicate 'case' definitions by first looking up 'Ctr_Sugar'
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(*  Title:      HOL/Product_Type.thy
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    Author:     Lawrence C Paulson, Cambridge University Computer Laboratory
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    Copyright   1992  University of Cambridge
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*)
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header {* Cartesian products *}
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theory Product_Type
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imports Typedef Inductive Fun
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keywords "inductive_set" "coinductive_set" :: thy_decl
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begin
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subsection {* @{typ bool} is a datatype *}
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wrap_free_constructors [True, False] bool_case [=]
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by auto
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-- {* Avoid name clashes by prefixing the output of @{text rep_datatype} with @{text old}. *}
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setup {* Sign.mandatory_path "old" *}
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rep_datatype True False by (auto intro: bool_induct)
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setup {* Sign.parent_path *}
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-- {* But erase the prefix for properties that are not generated by @{text wrap_free_constructors}. *}
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setup {* Sign.mandatory_path "bool" *}
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lemmas induct = old.bool.induct
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lemmas inducts = old.bool.inducts
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lemmas recs = old.bool.recs
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lemmas cases = bool.case
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lemmas simps = bool.distinct bool.case old.bool.recs
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setup {* Sign.parent_path *}
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declare case_split [cases type: bool]
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  -- "prefer plain propositional version"
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lemma
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  shows [code]: "HOL.equal False P \<longleftrightarrow> \<not> P"
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    and [code]: "HOL.equal True P \<longleftrightarrow> P" 
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    and [code]: "HOL.equal P False \<longleftrightarrow> \<not> P"
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    and [code]: "HOL.equal P True \<longleftrightarrow> P"
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    and [code nbe]: "HOL.equal P P \<longleftrightarrow> True"
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  by (simp_all add: equal)
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lemma If_case_cert:
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  assumes "CASE \<equiv> (\<lambda>b. If b f g)"
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  shows "(CASE True \<equiv> f) &&& (CASE False \<equiv> g)"
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  using assms by simp_all
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setup {*
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  Code.add_case @{thm If_case_cert}
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*}
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code_printing
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  constant "HOL.equal :: bool \<Rightarrow> bool \<Rightarrow> bool" \<rightharpoonup> (Haskell) infix 4 "=="
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| class_instance "bool" :: "equal" \<rightharpoonup> (Haskell) -
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subsection {* The @{text unit} type *}
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typedef unit = "{True}"
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  by auto
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definition Unity :: unit  ("'(')")
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  where "() = Abs_unit True"
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lemma unit_eq [no_atp]: "u = ()"
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  by (induct u) (simp add: Unity_def)
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text {*
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  Simplification procedure for @{thm [source] unit_eq}.  Cannot use
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  this rule directly --- it loops!
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*}
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simproc_setup unit_eq ("x::unit") = {*
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  fn _ => fn _ => fn ct =>
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    if HOLogic.is_unit (term_of ct) then NONE
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    else SOME (mk_meta_eq @{thm unit_eq})
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*}
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wrap_free_constructors ["()"] unit_case
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by auto
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-- {* Avoid name clashes by prefixing the output of @{text rep_datatype} with @{text old}. *}
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setup {* Sign.mandatory_path "old" *}
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rep_datatype "()" by simp
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setup {* Sign.parent_path *}
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-- {* But erase the prefix for properties that are not generated by @{text wrap_free_constructors}. *}
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setup {* Sign.mandatory_path "unit" *}
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lemmas induct = old.unit.induct
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lemmas inducts = old.unit.inducts
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lemmas recs = old.unit.recs
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lemmas cases = unit.case
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lemmas simps = unit.case old.unit.recs
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setup {* Sign.parent_path *}
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lemma unit_all_eq1: "(!!x::unit. PROP P x) == PROP P ()"
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  by simp
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lemma unit_all_eq2: "(!!x::unit. PROP P) == PROP P"
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  by (rule triv_forall_equality)
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text {*
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  This rewrite counters the effect of simproc @{text unit_eq} on @{term
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  [source] "%u::unit. f u"}, replacing it by @{term [source]
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  f} rather than by @{term [source] "%u. f ()"}.
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*}
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lemma unit_abs_eta_conv [simp]: "(%u::unit. f ()) = f"
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  by (rule ext) simp
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lemma UNIV_unit:
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  "UNIV = {()}" by auto
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instantiation unit :: default
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begin
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definition "default = ()"
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instance ..
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end
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lemma [code]:
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  "HOL.equal (u\<Colon>unit) v \<longleftrightarrow> True" unfolding equal unit_eq [of u] unit_eq [of v] by rule+
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code_printing
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  type_constructor unit \<rightharpoonup>
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    (SML) "unit"
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    and (OCaml) "unit"
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    and (Haskell) "()"
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    and (Scala) "Unit"
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| constant Unity \<rightharpoonup>
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    (SML) "()"
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    and (OCaml) "()"
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    and (Haskell) "()"
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    and (Scala) "()"
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| class_instance unit :: equal \<rightharpoonup>
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    (Haskell) -
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| constant "HOL.equal :: unit \<Rightarrow> unit \<Rightarrow> bool" \<rightharpoonup>
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    (Haskell) infix 4 "=="
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code_reserved SML
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  unit
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code_reserved OCaml
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  unit
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code_reserved Scala
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  Unit
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subsection {* The product type *}
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subsubsection {* Type definition *}
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definition Pair_Rep :: "'a \<Rightarrow> 'b \<Rightarrow> 'a \<Rightarrow> 'b \<Rightarrow> bool" where
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  "Pair_Rep a b = (\<lambda>x y. x = a \<and> y = b)"
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definition "prod = {f. \<exists>a b. f = Pair_Rep (a\<Colon>'a) (b\<Colon>'b)}"
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typedef ('a, 'b) prod (infixr "*" 20) = "prod :: ('a \<Rightarrow> 'b \<Rightarrow> bool) set"
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  unfolding prod_def by auto
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type_notation (xsymbols)
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  "prod"  ("(_ \<times>/ _)" [21, 20] 20)
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type_notation (HTML output)
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  "prod"  ("(_ \<times>/ _)" [21, 20] 20)
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definition Pair :: "'a \<Rightarrow> 'b \<Rightarrow> 'a \<times> 'b" where
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  "Pair a b = Abs_prod (Pair_Rep a b)"
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lemma prod_cases: "(\<And>a b. P (Pair a b)) \<Longrightarrow> P p"
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  by (cases p) (auto simp add: prod_def Pair_def Pair_Rep_def)
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wrap_free_constructors [Pair] prod_case [] [[fst, snd]]
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proof -
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  fix P :: bool and p :: "'a \<times> 'b"
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  show "(\<And>x1 x2. p = Pair x1 x2 \<Longrightarrow> P) \<Longrightarrow> P"
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    by (cases p) (auto simp add: prod_def Pair_def Pair_Rep_def)
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next
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  fix a c :: 'a and b d :: 'b
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  have "Pair_Rep a b = Pair_Rep c d \<longleftrightarrow> a = c \<and> b = d"
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    by (auto simp add: Pair_Rep_def fun_eq_iff)
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  moreover have "Pair_Rep a b \<in> prod" and "Pair_Rep c d \<in> prod"
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    by (auto simp add: prod_def)
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  ultimately show "Pair a b = Pair c d \<longleftrightarrow> a = c \<and> b = d"
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    by (simp add: Pair_def Abs_prod_inject)
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qed
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-- {* Avoid name clashes by prefixing the output of @{text rep_datatype} with @{text old}. *}
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setup {* Sign.mandatory_path "old" *}
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rep_datatype Pair
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by (erule prod_cases) (rule prod.inject)
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setup {* Sign.parent_path *}
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-- {* But erase the prefix for properties that are not generated by @{text wrap_free_constructors}. *}
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setup {* Sign.mandatory_path "prod" *}
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declare
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  old.prod.inject[iff del]
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lemmas induct = old.prod.induct
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lemmas inducts = old.prod.inducts
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lemmas recs = old.prod.recs
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lemmas cases = prod.case
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lemmas simps = prod.inject prod.case old.prod.recs
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setup {* Sign.parent_path *}
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declare prod.case [nitpick_simp del]
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declare prod.weak_case_cong [cong del]
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subsubsection {* Tuple syntax *}
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abbreviation (input) split :: "('a \<Rightarrow> 'b \<Rightarrow> 'c) \<Rightarrow> 'a \<times> 'b \<Rightarrow> 'c" where
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  "split \<equiv> prod_case"
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text {*
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  Patterns -- extends pre-defined type @{typ pttrn} used in
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  abstractions.
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*}
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nonterminal tuple_args and patterns
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syntax
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  "_tuple"      :: "'a => tuple_args => 'a * 'b"        ("(1'(_,/ _'))")
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  "_tuple_arg"  :: "'a => tuple_args"                   ("_")
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  "_tuple_args" :: "'a => tuple_args => tuple_args"     ("_,/ _")
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  "_pattern"    :: "[pttrn, patterns] => pttrn"         ("'(_,/ _')")
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  ""            :: "pttrn => patterns"                  ("_")
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  "_patterns"   :: "[pttrn, patterns] => patterns"      ("_,/ _")
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translations
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  "(x, y)" == "CONST Pair x y"
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  "_pattern x y" => "CONST Pair x y"
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  "_patterns x y" => "CONST Pair x y"
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  "_tuple x (_tuple_args y z)" == "_tuple x (_tuple_arg (_tuple y z))"
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  "%(x, y, zs). b" == "CONST prod_case (%x (y, zs). b)"
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  "%(x, y). b" == "CONST prod_case (%x y. b)"
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  "_abs (CONST Pair x y) t" => "%(x, y). t"
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  -- {* The last rule accommodates tuples in `case C ... (x,y) ... => ...'
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     The (x,y) is parsed as `Pair x y' because it is logic, not pttrn *}
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(*reconstruct pattern from (nested) splits, avoiding eta-contraction of body;
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  works best with enclosing "let", if "let" does not avoid eta-contraction*)
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print_translation {*
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  let
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    fun split_tr' [Abs (x, T, t as (Abs abs))] =
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          (* split (%x y. t) => %(x,y) t *)
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          let
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            val (y, t') = Syntax_Trans.atomic_abs_tr' abs;
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            val (x', t'') = Syntax_Trans.atomic_abs_tr' (x, T, t');
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          in
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            Syntax.const @{syntax_const "_abs"} $
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              (Syntax.const @{syntax_const "_pattern"} $ x' $ y) $ t''
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          end
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      | split_tr' [Abs (x, T, (s as Const (@{const_syntax prod_case}, _) $ t))] =
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          (* split (%x. (split (%y z. t))) => %(x,y,z). t *)
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          let
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            val Const (@{syntax_const "_abs"}, _) $
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              (Const (@{syntax_const "_pattern"}, _) $ y $ z) $ t' = split_tr' [t];
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            val (x', t'') = Syntax_Trans.atomic_abs_tr' (x, T, t');
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          in
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            Syntax.const @{syntax_const "_abs"} $
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              (Syntax.const @{syntax_const "_pattern"} $ x' $
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                (Syntax.const @{syntax_const "_patterns"} $ y $ z)) $ t''
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          end
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      | split_tr' [Const (@{const_syntax prod_case}, _) $ t] =
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          (* split (split (%x y z. t)) => %((x, y), z). t *)
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          split_tr' [(split_tr' [t])] (* inner split_tr' creates next pattern *)
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      | split_tr' [Const (@{syntax_const "_abs"}, _) $ x_y $ Abs abs] =
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          (* split (%pttrn z. t) => %(pttrn,z). t *)
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          let val (z, t) = Syntax_Trans.atomic_abs_tr' abs in
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            Syntax.const @{syntax_const "_abs"} $
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              (Syntax.const @{syntax_const "_pattern"} $ x_y $ z) $ t
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          end
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      | split_tr' _ = raise Match;
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  in [(@{const_syntax prod_case}, K split_tr')] end
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*}
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(* print "split f" as "\<lambda>(x,y). f x y" and "split (\<lambda>x. f x)" as "\<lambda>(x,y). f x y" *) 
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typed_print_translation {*
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  let
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    fun split_guess_names_tr' T [Abs (x, _, Abs _)] = raise Match
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      | split_guess_names_tr' T [Abs (x, xT, t)] =
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          (case (head_of t) of
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            Const (@{const_syntax prod_case}, _) => raise Match
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          | _ =>
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            let 
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              val (_ :: yT :: _) = binder_types (domain_type T) handle Bind => raise Match;
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              val (y, t') = Syntax_Trans.atomic_abs_tr' ("y", yT, incr_boundvars 1 t $ Bound 0);
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              val (x', t'') = Syntax_Trans.atomic_abs_tr' (x, xT, t');
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            in
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              Syntax.const @{syntax_const "_abs"} $
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                (Syntax.const @{syntax_const "_pattern"} $ x' $ y) $ t''
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            end)
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      | split_guess_names_tr' T [t] =
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          (case head_of t of
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            Const (@{const_syntax prod_case}, _) => raise Match
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          | _ =>
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            let
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              val (xT :: yT :: _) = binder_types (domain_type T) handle Bind => raise Match;
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              val (y, t') =
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                Syntax_Trans.atomic_abs_tr' ("y", yT, incr_boundvars 2 t $ Bound 1 $ Bound 0);
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              val (x', t'') = Syntax_Trans.atomic_abs_tr' ("x", xT, t');
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            in
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              Syntax.const @{syntax_const "_abs"} $
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                (Syntax.const @{syntax_const "_pattern"} $ x' $ y) $ t''
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            end)
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      | split_guess_names_tr' _ _ = raise Match;
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  in [(@{const_syntax prod_case}, K split_guess_names_tr')] end
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*}
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(* Force eta-contraction for terms of the form "Q A (%p. prod_case P p)"
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   where Q is some bounded quantifier or set operator.
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   Reason: the above prints as "Q p : A. case p of (x,y) \<Rightarrow> P x y"
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   whereas we want "Q (x,y):A. P x y".
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   Otherwise prevent eta-contraction.
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*)
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print_translation {*
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  let
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   333
    fun contract Q tr ctxt ts =
wenzelm@52143
   334
      (case ts of
wenzelm@52143
   335
        [A, Abs (_, _, (s as Const (@{const_syntax prod_case},_) $ t) $ Bound 0)] =>
wenzelm@52143
   336
          if Term.is_dependent t then tr ctxt ts
wenzelm@52143
   337
          else Syntax.const Q $ A $ s
wenzelm@52143
   338
      | _ => tr ctxt ts);
wenzelm@52143
   339
  in
wenzelm@42284
   340
    [Syntax_Trans.preserve_binder_abs2_tr' @{const_syntax Ball} @{syntax_const "_Ball"},
wenzelm@42284
   341
     Syntax_Trans.preserve_binder_abs2_tr' @{const_syntax Bex} @{syntax_const "_Bex"},
wenzelm@42284
   342
     Syntax_Trans.preserve_binder_abs2_tr' @{const_syntax INFI} @{syntax_const "_INF"},
wenzelm@42284
   343
     Syntax_Trans.preserve_binder_abs2_tr' @{const_syntax SUPR} @{syntax_const "_SUP"}]
wenzelm@52143
   344
    |> map (fn (Q, tr) => (Q, contract Q tr))
wenzelm@52143
   345
  end
nipkow@42059
   346
*}
nipkow@10213
   347
haftmann@37166
   348
subsubsection {* Code generator setup *}
haftmann@37166
   349
haftmann@52435
   350
code_printing
haftmann@52435
   351
  type_constructor prod \<rightharpoonup>
haftmann@52435
   352
    (SML) infix 2 "*"
haftmann@52435
   353
    and (OCaml) infix 2 "*"
haftmann@52435
   354
    and (Haskell) "!((_),/ (_))"
haftmann@52435
   355
    and (Scala) "((_),/ (_))"
haftmann@52435
   356
| constant Pair \<rightharpoonup>
haftmann@52435
   357
    (SML) "!((_),/ (_))"
haftmann@52435
   358
    and (OCaml) "!((_),/ (_))"
haftmann@52435
   359
    and (Haskell) "!((_),/ (_))"
haftmann@52435
   360
    and (Scala) "!((_),/ (_))"
haftmann@52435
   361
| class_instance  prod :: equal \<rightharpoonup>
haftmann@52435
   362
    (Haskell) -
haftmann@52435
   363
| constant "HOL.equal :: 'a \<times> 'b \<Rightarrow> 'a \<times> 'b \<Rightarrow> bool" \<rightharpoonup>
haftmann@52435
   364
    (Haskell) infix 4 "=="
haftmann@37166
   365
haftmann@37166
   366
haftmann@37166
   367
subsubsection {* Fundamental operations and properties *}
wenzelm@11838
   368
bulwahn@49897
   369
lemma Pair_inject:
bulwahn@49897
   370
  assumes "(a, b) = (a', b')"
bulwahn@49897
   371
    and "a = a' ==> b = b' ==> R"
bulwahn@49897
   372
  shows R
bulwahn@49897
   373
  using assms by simp
bulwahn@49897
   374
haftmann@26358
   375
lemma surj_pair [simp]: "EX x y. p = (x, y)"
haftmann@37166
   376
  by (cases p) simp
nipkow@10213
   377
haftmann@52435
   378
code_printing
haftmann@52435
   379
  constant fst \<rightharpoonup> (Haskell) "fst"
haftmann@52435
   380
| constant snd \<rightharpoonup> (Haskell) "snd"
haftmann@26358
   381
blanchet@41792
   382
lemma prod_case_unfold [nitpick_unfold]: "prod_case = (%c p. c (fst p) (snd p))"
nipkow@39302
   383
  by (simp add: fun_eq_iff split: prod.split)
haftmann@26358
   384
wenzelm@11838
   385
lemma fst_eqD: "fst (x, y) = a ==> x = a"
wenzelm@11838
   386
  by simp
wenzelm@11838
   387
wenzelm@11838
   388
lemma snd_eqD: "snd (x, y) = a ==> y = a"
wenzelm@11838
   389
  by simp
wenzelm@11838
   390
blanchet@55393
   391
lemmas surjective_pairing = prod.collapse [symmetric]
wenzelm@11838
   392
huffman@44066
   393
lemma prod_eq_iff: "s = t \<longleftrightarrow> fst s = fst t \<and> snd s = snd t"
haftmann@37166
   394
  by (cases s, cases t) simp
haftmann@37166
   395
haftmann@37166
   396
lemma prod_eqI [intro?]: "fst p = fst q \<Longrightarrow> snd p = snd q \<Longrightarrow> p = q"
huffman@44066
   397
  by (simp add: prod_eq_iff)
haftmann@37166
   398
haftmann@37166
   399
lemma split_conv [simp, code]: "split f (a, b) = f a b"
haftmann@37591
   400
  by (fact prod.cases)
haftmann@37166
   401
haftmann@37166
   402
lemma splitI: "f a b \<Longrightarrow> split f (a, b)"
haftmann@37166
   403
  by (rule split_conv [THEN iffD2])
haftmann@37166
   404
haftmann@37166
   405
lemma splitD: "split f (a, b) \<Longrightarrow> f a b"
haftmann@37166
   406
  by (rule split_conv [THEN iffD1])
haftmann@37166
   407
haftmann@37166
   408
lemma split_Pair [simp]: "(\<lambda>(x, y). (x, y)) = id"
nipkow@39302
   409
  by (simp add: fun_eq_iff split: prod.split)
haftmann@37166
   410
haftmann@37166
   411
lemma split_eta: "(\<lambda>(x, y). f (x, y)) = f"
haftmann@37166
   412
  -- {* Subsumes the old @{text split_Pair} when @{term f} is the identity function. *}
nipkow@39302
   413
  by (simp add: fun_eq_iff split: prod.split)
haftmann@37166
   414
haftmann@37166
   415
lemma split_comp: "split (f \<circ> g) x = f (g (fst x)) (snd x)"
haftmann@37166
   416
  by (cases x) simp
haftmann@37166
   417
haftmann@37166
   418
lemma split_twice: "split f (split g p) = split (\<lambda>x y. split f (g x y)) p"
haftmann@37166
   419
  by (cases p) simp
haftmann@37166
   420
haftmann@37166
   421
lemma The_split: "The (split P) = (THE xy. P (fst xy) (snd xy))"
haftmann@37591
   422
  by (simp add: prod_case_unfold)
haftmann@37166
   423
haftmann@37166
   424
lemma split_weak_cong: "p = q \<Longrightarrow> split c p = split c q"
haftmann@37166
   425
  -- {* Prevents simplification of @{term c}: much faster *}
huffman@40929
   426
  by (fact prod.weak_case_cong)
haftmann@37166
   427
haftmann@37166
   428
lemma cond_split_eta: "(!!x y. f x y = g (x, y)) ==> (%(x, y). f x y) = g"
haftmann@37166
   429
  by (simp add: split_eta)
haftmann@37166
   430
blanchet@47740
   431
lemma split_paired_all [no_atp]: "(!!x. PROP P x) == (!!a b. PROP P (a, b))"
wenzelm@11820
   432
proof
wenzelm@11820
   433
  fix a b
wenzelm@11820
   434
  assume "!!x. PROP P x"
wenzelm@19535
   435
  then show "PROP P (a, b)" .
wenzelm@11820
   436
next
wenzelm@11820
   437
  fix x
wenzelm@11820
   438
  assume "!!a b. PROP P (a, b)"
wenzelm@19535
   439
  from `PROP P (fst x, snd x)` show "PROP P x" by simp
wenzelm@11820
   440
qed
wenzelm@11820
   441
hoelzl@50104
   442
lemma case_prod_distrib: "f (case x of (x, y) \<Rightarrow> g x y) = (case x of (x, y) \<Rightarrow> f (g x y))"
hoelzl@50104
   443
  by (cases x) simp
hoelzl@50104
   444
wenzelm@11838
   445
text {*
wenzelm@11838
   446
  The rule @{thm [source] split_paired_all} does not work with the
wenzelm@11838
   447
  Simplifier because it also affects premises in congrence rules,
wenzelm@11838
   448
  where this can lead to premises of the form @{text "!!a b. ... =
wenzelm@11838
   449
  ?P(a, b)"} which cannot be solved by reflexivity.
wenzelm@11838
   450
*}
wenzelm@11838
   451
haftmann@26358
   452
lemmas split_tupled_all = split_paired_all unit_all_eq2
haftmann@26358
   453
wenzelm@26480
   454
ML {*
wenzelm@11838
   455
  (* replace parameters of product type by individual component parameters *)
wenzelm@11838
   456
  local (* filtering with exists_paired_all is an essential optimization *)
wenzelm@16121
   457
    fun exists_paired_all (Const ("all", _) $ Abs (_, T, t)) =
wenzelm@11838
   458
          can HOLogic.dest_prodT T orelse exists_paired_all t
wenzelm@11838
   459
      | exists_paired_all (t $ u) = exists_paired_all t orelse exists_paired_all u
wenzelm@11838
   460
      | exists_paired_all (Abs (_, _, t)) = exists_paired_all t
wenzelm@11838
   461
      | exists_paired_all _ = false;
wenzelm@51717
   462
    val ss =
wenzelm@51717
   463
      simpset_of
wenzelm@51717
   464
       (put_simpset HOL_basic_ss @{context}
wenzelm@51717
   465
        addsimps [@{thm split_paired_all}, @{thm unit_all_eq2}, @{thm unit_abs_eta_conv}]
wenzelm@51717
   466
        addsimprocs [@{simproc unit_eq}]);
wenzelm@11838
   467
  in
wenzelm@51717
   468
    fun split_all_tac ctxt = SUBGOAL (fn (t, i) =>
wenzelm@51717
   469
      if exists_paired_all t then safe_full_simp_tac (put_simpset ss ctxt) i else no_tac);
wenzelm@51717
   470
wenzelm@51717
   471
    fun unsafe_split_all_tac ctxt = SUBGOAL (fn (t, i) =>
wenzelm@51717
   472
      if exists_paired_all t then full_simp_tac (put_simpset ss ctxt) i else no_tac);
wenzelm@51717
   473
wenzelm@51717
   474
    fun split_all ctxt th =
wenzelm@51717
   475
      if exists_paired_all (Thm.prop_of th)
wenzelm@51717
   476
      then full_simplify (put_simpset ss ctxt) th else th;
wenzelm@11838
   477
  end;
wenzelm@26340
   478
*}
wenzelm@11838
   479
wenzelm@51703
   480
setup {* map_theory_claset (fn ctxt => ctxt addSbefore ("split_all_tac", split_all_tac)) *}
wenzelm@11838
   481
blanchet@47740
   482
lemma split_paired_All [simp, no_atp]: "(ALL x. P x) = (ALL a b. P (a, b))"
wenzelm@11838
   483
  -- {* @{text "[iff]"} is not a good idea because it makes @{text blast} loop *}
wenzelm@11838
   484
  by fast
wenzelm@11838
   485
blanchet@47740
   486
lemma split_paired_Ex [simp, no_atp]: "(EX x. P x) = (EX a b. P (a, b))"
haftmann@26358
   487
  by fast
haftmann@26358
   488
blanchet@47740
   489
lemma split_paired_The [no_atp]: "(THE x. P x) = (THE (a, b). P (a, b))"
wenzelm@11838
   490
  -- {* Can't be added to simpset: loops! *}
haftmann@26358
   491
  by (simp add: split_eta)
wenzelm@11838
   492
wenzelm@11838
   493
text {*
wenzelm@11838
   494
  Simplification procedure for @{thm [source] cond_split_eta}.  Using
wenzelm@11838
   495
  @{thm [source] split_eta} as a rewrite rule is not general enough,
wenzelm@11838
   496
  and using @{thm [source] cond_split_eta} directly would render some
wenzelm@11838
   497
  existing proofs very inefficient; similarly for @{text
haftmann@26358
   498
  split_beta}.
haftmann@26358
   499
*}
wenzelm@11838
   500
wenzelm@26480
   501
ML {*
wenzelm@11838
   502
local
wenzelm@51717
   503
  val cond_split_eta_ss =
wenzelm@51717
   504
    simpset_of (put_simpset HOL_basic_ss @{context} addsimps @{thms cond_split_eta});
wenzelm@35364
   505
  fun Pair_pat k 0 (Bound m) = (m = k)
wenzelm@35364
   506
    | Pair_pat k i (Const (@{const_name Pair},  _) $ Bound m $ t) =
wenzelm@35364
   507
        i > 0 andalso m = k + i andalso Pair_pat k (i - 1) t
wenzelm@35364
   508
    | Pair_pat _ _ _ = false;
wenzelm@35364
   509
  fun no_args k i (Abs (_, _, t)) = no_args (k + 1) i t
wenzelm@35364
   510
    | no_args k i (t $ u) = no_args k i t andalso no_args k i u
wenzelm@35364
   511
    | no_args k i (Bound m) = m < k orelse m > k + i
wenzelm@35364
   512
    | no_args _ _ _ = true;
wenzelm@35364
   513
  fun split_pat tp i (Abs  (_, _, t)) = if tp 0 i t then SOME (i, t) else NONE
haftmann@37591
   514
    | split_pat tp i (Const (@{const_name prod_case}, _) $ Abs (_, _, t)) = split_pat tp (i + 1) t
wenzelm@35364
   515
    | split_pat tp i _ = NONE;
wenzelm@51717
   516
  fun metaeq ctxt lhs rhs = mk_meta_eq (Goal.prove ctxt [] []
wenzelm@35364
   517
        (HOLogic.mk_Trueprop (HOLogic.mk_eq (lhs, rhs)))
wenzelm@51717
   518
        (K (simp_tac (put_simpset cond_split_eta_ss ctxt) 1)));
wenzelm@11838
   519
wenzelm@35364
   520
  fun beta_term_pat k i (Abs (_, _, t)) = beta_term_pat (k + 1) i t
wenzelm@35364
   521
    | beta_term_pat k i (t $ u) =
wenzelm@35364
   522
        Pair_pat k i (t $ u) orelse (beta_term_pat k i t andalso beta_term_pat k i u)
wenzelm@35364
   523
    | beta_term_pat k i t = no_args k i t;
wenzelm@35364
   524
  fun eta_term_pat k i (f $ arg) = no_args k i f andalso Pair_pat k i arg
wenzelm@35364
   525
    | eta_term_pat _ _ _ = false;
wenzelm@11838
   526
  fun subst arg k i (Abs (x, T, t)) = Abs (x, T, subst arg (k+1) i t)
wenzelm@35364
   527
    | subst arg k i (t $ u) =
wenzelm@35364
   528
        if Pair_pat k i (t $ u) then incr_boundvars k arg
wenzelm@35364
   529
        else (subst arg k i t $ subst arg k i u)
wenzelm@35364
   530
    | subst arg k i t = t;
wenzelm@43595
   531
in
wenzelm@51717
   532
  fun beta_proc ctxt (s as Const (@{const_name prod_case}, _) $ Abs (_, _, t) $ arg) =
wenzelm@11838
   533
        (case split_pat beta_term_pat 1 t of
wenzelm@51717
   534
          SOME (i, f) => SOME (metaeq ctxt s (subst arg 0 i f))
skalberg@15531
   535
        | NONE => NONE)
wenzelm@35364
   536
    | beta_proc _ _ = NONE;
wenzelm@51717
   537
  fun eta_proc ctxt (s as Const (@{const_name prod_case}, _) $ Abs (_, _, t)) =
wenzelm@11838
   538
        (case split_pat eta_term_pat 1 t of
wenzelm@51717
   539
          SOME (_, ft) => SOME (metaeq ctxt s (let val (f $ arg) = ft in f end))
skalberg@15531
   540
        | NONE => NONE)
wenzelm@35364
   541
    | eta_proc _ _ = NONE;
wenzelm@11838
   542
end;
wenzelm@11838
   543
*}
wenzelm@51717
   544
simproc_setup split_beta ("split f z") = {* fn _ => fn ctxt => fn ct => beta_proc ctxt (term_of ct) *}
wenzelm@51717
   545
simproc_setup split_eta ("split f") = {* fn _ => fn ctxt => fn ct => eta_proc ctxt (term_of ct) *}
wenzelm@11838
   546
berghofe@26798
   547
lemma split_beta [mono]: "(%(x, y). P x y) z = P (fst z) (snd z)"
wenzelm@11838
   548
  by (subst surjective_pairing, rule split_conv)
wenzelm@11838
   549
hoelzl@50104
   550
lemma split_beta': "(\<lambda>(x,y). f x y) = (\<lambda>x. f (fst x) (snd x))"
hoelzl@50104
   551
  by (auto simp: fun_eq_iff)
hoelzl@50104
   552
hoelzl@50104
   553
blanchet@35828
   554
lemma split_split [no_atp]: "R(split c p) = (ALL x y. p = (x, y) --> R(c x y))"
wenzelm@11838
   555
  -- {* For use with @{text split} and the Simplifier. *}
paulson@15481
   556
  by (insert surj_pair [of p], clarify, simp)
wenzelm@11838
   557
wenzelm@11838
   558
text {*
wenzelm@11838
   559
  @{thm [source] split_split} could be declared as @{text "[split]"}
wenzelm@11838
   560
  done after the Splitter has been speeded up significantly;
wenzelm@11838
   561
  precompute the constants involved and don't do anything unless the
wenzelm@11838
   562
  current goal contains one of those constants.
wenzelm@11838
   563
*}
wenzelm@11838
   564
blanchet@35828
   565
lemma split_split_asm [no_atp]: "R (split c p) = (~(EX x y. p = (x, y) & (~R (c x y))))"
paulson@14208
   566
by (subst split_split, simp)
wenzelm@11838
   567
wenzelm@11838
   568
text {*
wenzelm@11838
   569
  \medskip @{term split} used as a logical connective or set former.
wenzelm@11838
   570
wenzelm@11838
   571
  \medskip These rules are for use with @{text blast}; could instead
huffman@40929
   572
  call @{text simp} using @{thm [source] prod.split} as rewrite. *}
wenzelm@11838
   573
wenzelm@11838
   574
lemma splitI2: "!!p. [| !!a b. p = (a, b) ==> c a b |] ==> split c p"
wenzelm@11838
   575
  apply (simp only: split_tupled_all)
wenzelm@11838
   576
  apply (simp (no_asm_simp))
wenzelm@11838
   577
  done
wenzelm@11838
   578
wenzelm@11838
   579
lemma splitI2': "!!p. [| !!a b. (a, b) = p ==> c a b x |] ==> split c p x"
wenzelm@11838
   580
  apply (simp only: split_tupled_all)
wenzelm@11838
   581
  apply (simp (no_asm_simp))
wenzelm@11838
   582
  done
wenzelm@11838
   583
wenzelm@11838
   584
lemma splitE: "split c p ==> (!!x y. p = (x, y) ==> c x y ==> Q) ==> Q"
haftmann@37591
   585
  by (induct p) auto
wenzelm@11838
   586
wenzelm@11838
   587
lemma splitE': "split c p z ==> (!!x y. p = (x, y) ==> c x y z ==> Q) ==> Q"
haftmann@37591
   588
  by (induct p) auto
wenzelm@11838
   589
wenzelm@11838
   590
lemma splitE2:
wenzelm@11838
   591
  "[| Q (split P z);  !!x y. [|z = (x, y); Q (P x y)|] ==> R |] ==> R"
wenzelm@11838
   592
proof -
wenzelm@11838
   593
  assume q: "Q (split P z)"
wenzelm@11838
   594
  assume r: "!!x y. [|z = (x, y); Q (P x y)|] ==> R"
wenzelm@11838
   595
  show R
wenzelm@11838
   596
    apply (rule r surjective_pairing)+
wenzelm@11838
   597
    apply (rule split_beta [THEN subst], rule q)
wenzelm@11838
   598
    done
wenzelm@11838
   599
qed
wenzelm@11838
   600
wenzelm@11838
   601
lemma splitD': "split R (a,b) c ==> R a b c"
wenzelm@11838
   602
  by simp
wenzelm@11838
   603
wenzelm@11838
   604
lemma mem_splitI: "z: c a b ==> z: split c (a, b)"
wenzelm@11838
   605
  by simp
wenzelm@11838
   606
wenzelm@11838
   607
lemma mem_splitI2: "!!p. [| !!a b. p = (a, b) ==> z: c a b |] ==> z: split c p"
paulson@14208
   608
by (simp only: split_tupled_all, simp)
wenzelm@11838
   609
wenzelm@18372
   610
lemma mem_splitE:
haftmann@37166
   611
  assumes major: "z \<in> split c p"
haftmann@37166
   612
    and cases: "\<And>x y. p = (x, y) \<Longrightarrow> z \<in> c x y \<Longrightarrow> Q"
wenzelm@18372
   613
  shows Q
haftmann@37591
   614
  by (rule major [unfolded prod_case_unfold] cases surjective_pairing)+
wenzelm@11838
   615
wenzelm@11838
   616
declare mem_splitI2 [intro!] mem_splitI [intro!] splitI2' [intro!] splitI2 [intro!] splitI [intro!]
wenzelm@11838
   617
declare mem_splitE [elim!] splitE' [elim!] splitE [elim!]
wenzelm@11838
   618
wenzelm@26340
   619
ML {*
wenzelm@11838
   620
local (* filtering with exists_p_split is an essential optimization *)
haftmann@37591
   621
  fun exists_p_split (Const (@{const_name prod_case},_) $ _ $ (Const (@{const_name Pair},_)$_$_)) = true
wenzelm@11838
   622
    | exists_p_split (t $ u) = exists_p_split t orelse exists_p_split u
wenzelm@11838
   623
    | exists_p_split (Abs (_, _, t)) = exists_p_split t
wenzelm@11838
   624
    | exists_p_split _ = false;
wenzelm@11838
   625
in
wenzelm@51717
   626
fun split_conv_tac ctxt = SUBGOAL (fn (t, i) =>
wenzelm@51717
   627
  if exists_p_split t
wenzelm@51717
   628
  then safe_full_simp_tac (put_simpset HOL_basic_ss ctxt addsimps @{thms split_conv}) i
wenzelm@51717
   629
  else no_tac);
wenzelm@11838
   630
end;
wenzelm@26340
   631
*}
wenzelm@26340
   632
wenzelm@11838
   633
(* This prevents applications of splitE for already splitted arguments leading
wenzelm@11838
   634
   to quite time-consuming computations (in particular for nested tuples) *)
wenzelm@51703
   635
setup {* map_theory_claset (fn ctxt => ctxt addSbefore ("split_conv_tac", split_conv_tac)) *}
wenzelm@11838
   636
blanchet@54147
   637
lemma split_eta_SetCompr [simp, no_atp]: "(%u. EX x y. u = (x, y) & P (x, y)) = P"
wenzelm@18372
   638
  by (rule ext) fast
wenzelm@11838
   639
blanchet@54147
   640
lemma split_eta_SetCompr2 [simp, no_atp]: "(%u. EX x y. u = (x, y) & P x y) = split P"
wenzelm@18372
   641
  by (rule ext) fast
wenzelm@11838
   642
wenzelm@11838
   643
lemma split_part [simp]: "(%(a,b). P & Q a b) = (%ab. P & split Q ab)"
wenzelm@11838
   644
  -- {* Allows simplifications of nested splits in case of independent predicates. *}
wenzelm@18372
   645
  by (rule ext) blast
wenzelm@11838
   646
nipkow@14337
   647
(* Do NOT make this a simp rule as it
nipkow@14337
   648
   a) only helps in special situations
nipkow@14337
   649
   b) can lead to nontermination in the presence of split_def
nipkow@14337
   650
*)
nipkow@14337
   651
lemma split_comp_eq: 
paulson@20415
   652
  fixes f :: "'a => 'b => 'c" and g :: "'d => 'a"
paulson@20415
   653
  shows "(%u. f (g (fst u)) (snd u)) = (split (%x. f (g x)))"
wenzelm@18372
   654
  by (rule ext) auto
oheimb@14101
   655
haftmann@26358
   656
lemma pair_imageI [intro]: "(a, b) : A ==> f a b : (%(a, b). f a b) ` A"
haftmann@26358
   657
  apply (rule_tac x = "(a, b)" in image_eqI)
haftmann@26358
   658
   apply auto
haftmann@26358
   659
  done
haftmann@26358
   660
wenzelm@11838
   661
lemma The_split_eq [simp]: "(THE (x',y'). x = x' & y = y') = (x, y)"
wenzelm@11838
   662
  by blast
wenzelm@11838
   663
wenzelm@11838
   664
(*
wenzelm@11838
   665
the following  would be slightly more general,
wenzelm@11838
   666
but cannot be used as rewrite rule:
wenzelm@11838
   667
### Cannot add premise as rewrite rule because it contains (type) unknowns:
wenzelm@11838
   668
### ?y = .x
wenzelm@11838
   669
Goal "[| P y; !!x. P x ==> x = y |] ==> (@(x',y). x = x' & P y) = (x,y)"
paulson@14208
   670
by (rtac some_equality 1)
paulson@14208
   671
by ( Simp_tac 1)
paulson@14208
   672
by (split_all_tac 1)
paulson@14208
   673
by (Asm_full_simp_tac 1)
wenzelm@11838
   674
qed "The_split_eq";
wenzelm@11838
   675
*)
wenzelm@11838
   676
wenzelm@11838
   677
text {*
wenzelm@11838
   678
  Setup of internal @{text split_rule}.
wenzelm@11838
   679
*}
wenzelm@11838
   680
wenzelm@45607
   681
lemmas prod_caseI = prod.cases [THEN iffD2]
haftmann@24699
   682
haftmann@24699
   683
lemma prod_caseI2: "!!p. [| !!a b. p = (a, b) ==> c a b |] ==> prod_case c p"
haftmann@37678
   684
  by (fact splitI2)
haftmann@24699
   685
haftmann@24699
   686
lemma prod_caseI2': "!!p. [| !!a b. (a, b) = p ==> c a b x |] ==> prod_case c p x"
haftmann@37678
   687
  by (fact splitI2')
haftmann@24699
   688
haftmann@24699
   689
lemma prod_caseE: "prod_case c p ==> (!!x y. p = (x, y) ==> c x y ==> Q) ==> Q"
haftmann@37678
   690
  by (fact splitE)
haftmann@24699
   691
haftmann@24699
   692
lemma prod_caseE': "prod_case c p z ==> (!!x y. p = (x, y) ==> c x y z ==> Q) ==> Q"
haftmann@37678
   693
  by (fact splitE')
haftmann@24699
   694
haftmann@37678
   695
declare prod_caseI [intro!]
haftmann@24699
   696
bulwahn@26143
   697
lemma prod_case_beta:
bulwahn@26143
   698
  "prod_case f p = f (fst p) (snd p)"
haftmann@37591
   699
  by (fact split_beta)
bulwahn@26143
   700
haftmann@24699
   701
lemma prod_cases3 [cases type]:
haftmann@24699
   702
  obtains (fields) a b c where "y = (a, b, c)"
haftmann@24699
   703
  by (cases y, case_tac b) blast
haftmann@24699
   704
haftmann@24699
   705
lemma prod_induct3 [case_names fields, induct type]:
haftmann@24699
   706
    "(!!a b c. P (a, b, c)) ==> P x"
haftmann@24699
   707
  by (cases x) blast
haftmann@24699
   708
haftmann@24699
   709
lemma prod_cases4 [cases type]:
haftmann@24699
   710
  obtains (fields) a b c d where "y = (a, b, c, d)"
haftmann@24699
   711
  by (cases y, case_tac c) blast
haftmann@24699
   712
haftmann@24699
   713
lemma prod_induct4 [case_names fields, induct type]:
haftmann@24699
   714
    "(!!a b c d. P (a, b, c, d)) ==> P x"
haftmann@24699
   715
  by (cases x) blast
haftmann@24699
   716
haftmann@24699
   717
lemma prod_cases5 [cases type]:
haftmann@24699
   718
  obtains (fields) a b c d e where "y = (a, b, c, d, e)"
haftmann@24699
   719
  by (cases y, case_tac d) blast
haftmann@24699
   720
haftmann@24699
   721
lemma prod_induct5 [case_names fields, induct type]:
haftmann@24699
   722
    "(!!a b c d e. P (a, b, c, d, e)) ==> P x"
haftmann@24699
   723
  by (cases x) blast
haftmann@24699
   724
haftmann@24699
   725
lemma prod_cases6 [cases type]:
haftmann@24699
   726
  obtains (fields) a b c d e f where "y = (a, b, c, d, e, f)"
haftmann@24699
   727
  by (cases y, case_tac e) blast
haftmann@24699
   728
haftmann@24699
   729
lemma prod_induct6 [case_names fields, induct type]:
haftmann@24699
   730
    "(!!a b c d e f. P (a, b, c, d, e, f)) ==> P x"
haftmann@24699
   731
  by (cases x) blast
haftmann@24699
   732
haftmann@24699
   733
lemma prod_cases7 [cases type]:
haftmann@24699
   734
  obtains (fields) a b c d e f g where "y = (a, b, c, d, e, f, g)"
haftmann@24699
   735
  by (cases y, case_tac f) blast
haftmann@24699
   736
haftmann@24699
   737
lemma prod_induct7 [case_names fields, induct type]:
haftmann@24699
   738
    "(!!a b c d e f g. P (a, b, c, d, e, f, g)) ==> P x"
haftmann@24699
   739
  by (cases x) blast
haftmann@24699
   740
haftmann@37166
   741
lemma split_def:
haftmann@37166
   742
  "split = (\<lambda>c p. c (fst p) (snd p))"
haftmann@37591
   743
  by (fact prod_case_unfold)
haftmann@37166
   744
haftmann@37166
   745
definition internal_split :: "('a \<Rightarrow> 'b \<Rightarrow> 'c) \<Rightarrow> 'a \<times> 'b \<Rightarrow> 'c" where
haftmann@37166
   746
  "internal_split == split"
haftmann@37166
   747
haftmann@37166
   748
lemma internal_split_conv: "internal_split c (a, b) = c a b"
haftmann@37166
   749
  by (simp only: internal_split_def split_conv)
haftmann@37166
   750
wenzelm@48891
   751
ML_file "Tools/split_rule.ML"
haftmann@37166
   752
setup Split_Rule.setup
haftmann@37166
   753
haftmann@37166
   754
hide_const internal_split
haftmann@37166
   755
haftmann@24699
   756
haftmann@26358
   757
subsubsection {* Derived operations *}
haftmann@26358
   758
haftmann@37387
   759
definition curry    :: "('a \<times> 'b \<Rightarrow> 'c) \<Rightarrow> 'a \<Rightarrow> 'b \<Rightarrow> 'c" where
haftmann@37387
   760
  "curry = (\<lambda>c x y. c (x, y))"
haftmann@37166
   761
haftmann@37166
   762
lemma curry_conv [simp, code]: "curry f a b = f (a, b)"
haftmann@37166
   763
  by (simp add: curry_def)
haftmann@37166
   764
haftmann@37166
   765
lemma curryI [intro!]: "f (a, b) \<Longrightarrow> curry f a b"
haftmann@37166
   766
  by (simp add: curry_def)
haftmann@37166
   767
haftmann@37166
   768
lemma curryD [dest!]: "curry f a b \<Longrightarrow> f (a, b)"
haftmann@37166
   769
  by (simp add: curry_def)
haftmann@37166
   770
haftmann@37166
   771
lemma curryE: "curry f a b \<Longrightarrow> (f (a, b) \<Longrightarrow> Q) \<Longrightarrow> Q"
haftmann@37166
   772
  by (simp add: curry_def)
haftmann@37166
   773
haftmann@37166
   774
lemma curry_split [simp]: "curry (split f) = f"
haftmann@37166
   775
  by (simp add: curry_def split_def)
haftmann@37166
   776
haftmann@37166
   777
lemma split_curry [simp]: "split (curry f) = f"
haftmann@37166
   778
  by (simp add: curry_def split_def)
haftmann@37166
   779
Andreas@54630
   780
lemma curry_K: "curry (\<lambda>x. c) = (\<lambda>x y. c)"
Andreas@54630
   781
by(simp add: fun_eq_iff)
Andreas@54630
   782
haftmann@26358
   783
text {*
haftmann@26358
   784
  The composition-uncurry combinator.
haftmann@26358
   785
*}
haftmann@26358
   786
haftmann@37751
   787
notation fcomp (infixl "\<circ>>" 60)
haftmann@26358
   788
haftmann@37751
   789
definition scomp :: "('a \<Rightarrow> 'b \<times> 'c) \<Rightarrow> ('b \<Rightarrow> 'c \<Rightarrow> 'd) \<Rightarrow> 'a \<Rightarrow> 'd" (infixl "\<circ>\<rightarrow>" 60) where
haftmann@37751
   790
  "f \<circ>\<rightarrow> g = (\<lambda>x. prod_case g (f x))"
haftmann@26358
   791
haftmann@37678
   792
lemma scomp_unfold: "scomp = (\<lambda>f g x. g (fst (f x)) (snd (f x)))"
nipkow@39302
   793
  by (simp add: fun_eq_iff scomp_def prod_case_unfold)
haftmann@37678
   794
haftmann@37751
   795
lemma scomp_apply [simp]: "(f \<circ>\<rightarrow> g) x = prod_case g (f x)"
haftmann@37751
   796
  by (simp add: scomp_unfold prod_case_unfold)
haftmann@26358
   797
haftmann@37751
   798
lemma Pair_scomp: "Pair x \<circ>\<rightarrow> f = f x"
huffman@44921
   799
  by (simp add: fun_eq_iff)
haftmann@26358
   800
haftmann@37751
   801
lemma scomp_Pair: "x \<circ>\<rightarrow> Pair = x"
huffman@44921
   802
  by (simp add: fun_eq_iff)
haftmann@26358
   803
haftmann@37751
   804
lemma scomp_scomp: "(f \<circ>\<rightarrow> g) \<circ>\<rightarrow> h = f \<circ>\<rightarrow> (\<lambda>x. g x \<circ>\<rightarrow> h)"
nipkow@39302
   805
  by (simp add: fun_eq_iff scomp_unfold)
haftmann@26358
   806
haftmann@37751
   807
lemma scomp_fcomp: "(f \<circ>\<rightarrow> g) \<circ>> h = f \<circ>\<rightarrow> (\<lambda>x. g x \<circ>> h)"
nipkow@39302
   808
  by (simp add: fun_eq_iff scomp_unfold fcomp_def)
haftmann@26358
   809
haftmann@37751
   810
lemma fcomp_scomp: "(f \<circ>> g) \<circ>\<rightarrow> h = f \<circ>> (g \<circ>\<rightarrow> h)"
huffman@44921
   811
  by (simp add: fun_eq_iff scomp_unfold)
haftmann@26358
   812
haftmann@52435
   813
code_printing
haftmann@52435
   814
  constant scomp \<rightharpoonup> (Eval) infixl 3 "#->"
haftmann@31202
   815
haftmann@37751
   816
no_notation fcomp (infixl "\<circ>>" 60)
haftmann@37751
   817
no_notation scomp (infixl "\<circ>\<rightarrow>" 60)
haftmann@26358
   818
haftmann@26358
   819
text {*
haftmann@40607
   820
  @{term map_pair} --- action of the product functor upon
krauss@36664
   821
  functions.
haftmann@26358
   822
*}
haftmann@21195
   823
haftmann@40607
   824
definition map_pair :: "('a \<Rightarrow> 'c) \<Rightarrow> ('b \<Rightarrow> 'd) \<Rightarrow> 'a \<times> 'b \<Rightarrow> 'c \<times> 'd" where
haftmann@40607
   825
  "map_pair f g = (\<lambda>(x, y). (f x, g y))"
haftmann@26358
   826
haftmann@40607
   827
lemma map_pair_simp [simp, code]:
haftmann@40607
   828
  "map_pair f g (a, b) = (f a, g b)"
haftmann@40607
   829
  by (simp add: map_pair_def)
haftmann@26358
   830
haftmann@41505
   831
enriched_type map_pair: map_pair
huffman@44921
   832
  by (auto simp add: split_paired_all)
nipkow@37278
   833
haftmann@40607
   834
lemma fst_map_pair [simp]:
haftmann@40607
   835
  "fst (map_pair f g x) = f (fst x)"
haftmann@40607
   836
  by (cases x) simp_all
nipkow@37278
   837
haftmann@40607
   838
lemma snd_prod_fun [simp]:
haftmann@40607
   839
  "snd (map_pair f g x) = g (snd x)"
haftmann@40607
   840
  by (cases x) simp_all
nipkow@37278
   841
haftmann@40607
   842
lemma fst_comp_map_pair [simp]:
haftmann@40607
   843
  "fst \<circ> map_pair f g = f \<circ> fst"
haftmann@40607
   844
  by (rule ext) simp_all
nipkow@37278
   845
haftmann@40607
   846
lemma snd_comp_map_pair [simp]:
haftmann@40607
   847
  "snd \<circ> map_pair f g = g \<circ> snd"
haftmann@40607
   848
  by (rule ext) simp_all
haftmann@26358
   849
haftmann@40607
   850
lemma map_pair_compose:
haftmann@40607
   851
  "map_pair (f1 o f2) (g1 o g2) = (map_pair f1 g1 o map_pair f2 g2)"
haftmann@40607
   852
  by (rule ext) (simp add: map_pair.compositionality comp_def)
haftmann@26358
   853
haftmann@40607
   854
lemma map_pair_ident [simp]:
haftmann@40607
   855
  "map_pair (%x. x) (%y. y) = (%z. z)"
haftmann@40607
   856
  by (rule ext) (simp add: map_pair.identity)
haftmann@40607
   857
haftmann@40607
   858
lemma map_pair_imageI [intro]:
haftmann@40607
   859
  "(a, b) \<in> R \<Longrightarrow> (f a, g b) \<in> map_pair f g ` R"
haftmann@40607
   860
  by (rule image_eqI) simp_all
haftmann@21195
   861
haftmann@26358
   862
lemma prod_fun_imageE [elim!]:
haftmann@40607
   863
  assumes major: "c \<in> map_pair f g ` R"
haftmann@40607
   864
    and cases: "\<And>x y. c = (f x, g y) \<Longrightarrow> (x, y) \<in> R \<Longrightarrow> P"
haftmann@26358
   865
  shows P
haftmann@26358
   866
  apply (rule major [THEN imageE])
haftmann@37166
   867
  apply (case_tac x)
haftmann@26358
   868
  apply (rule cases)
haftmann@40607
   869
  apply simp_all
haftmann@26358
   870
  done
haftmann@26358
   871
haftmann@37166
   872
definition apfst :: "('a \<Rightarrow> 'c) \<Rightarrow> 'a \<times> 'b \<Rightarrow> 'c \<times> 'b" where
haftmann@40607
   873
  "apfst f = map_pair f id"
haftmann@26358
   874
haftmann@37166
   875
definition apsnd :: "('b \<Rightarrow> 'c) \<Rightarrow> 'a \<times> 'b \<Rightarrow> 'a \<times> 'c" where
haftmann@40607
   876
  "apsnd f = map_pair id f"
haftmann@26358
   877
haftmann@26358
   878
lemma apfst_conv [simp, code]:
haftmann@26358
   879
  "apfst f (x, y) = (f x, y)" 
haftmann@26358
   880
  by (simp add: apfst_def)
haftmann@26358
   881
hoelzl@33638
   882
lemma apsnd_conv [simp, code]:
haftmann@26358
   883
  "apsnd f (x, y) = (x, f y)" 
haftmann@26358
   884
  by (simp add: apsnd_def)
haftmann@21195
   885
haftmann@33594
   886
lemma fst_apfst [simp]:
haftmann@33594
   887
  "fst (apfst f x) = f (fst x)"
haftmann@33594
   888
  by (cases x) simp
haftmann@33594
   889
haftmann@51173
   890
lemma fst_comp_apfst [simp]:
haftmann@51173
   891
  "fst \<circ> apfst f = f \<circ> fst"
haftmann@51173
   892
  by (simp add: fun_eq_iff)
haftmann@51173
   893
haftmann@33594
   894
lemma fst_apsnd [simp]:
haftmann@33594
   895
  "fst (apsnd f x) = fst x"
haftmann@33594
   896
  by (cases x) simp
haftmann@33594
   897
haftmann@51173
   898
lemma fst_comp_apsnd [simp]:
haftmann@51173
   899
  "fst \<circ> apsnd f = fst"
haftmann@51173
   900
  by (simp add: fun_eq_iff)
haftmann@51173
   901
haftmann@33594
   902
lemma snd_apfst [simp]:
haftmann@33594
   903
  "snd (apfst f x) = snd x"
haftmann@33594
   904
  by (cases x) simp
haftmann@33594
   905
haftmann@51173
   906
lemma snd_comp_apfst [simp]:
haftmann@51173
   907
  "snd \<circ> apfst f = snd"
haftmann@51173
   908
  by (simp add: fun_eq_iff)
haftmann@51173
   909
haftmann@33594
   910
lemma snd_apsnd [simp]:
haftmann@33594
   911
  "snd (apsnd f x) = f (snd x)"
haftmann@33594
   912
  by (cases x) simp
haftmann@33594
   913
haftmann@51173
   914
lemma snd_comp_apsnd [simp]:
haftmann@51173
   915
  "snd \<circ> apsnd f = f \<circ> snd"
haftmann@51173
   916
  by (simp add: fun_eq_iff)
haftmann@51173
   917
haftmann@33594
   918
lemma apfst_compose:
haftmann@33594
   919
  "apfst f (apfst g x) = apfst (f \<circ> g) x"
haftmann@33594
   920
  by (cases x) simp
haftmann@33594
   921
haftmann@33594
   922
lemma apsnd_compose:
haftmann@33594
   923
  "apsnd f (apsnd g x) = apsnd (f \<circ> g) x"
haftmann@33594
   924
  by (cases x) simp
haftmann@33594
   925
haftmann@33594
   926
lemma apfst_apsnd [simp]:
haftmann@33594
   927
  "apfst f (apsnd g x) = (f (fst x), g (snd x))"
haftmann@33594
   928
  by (cases x) simp
haftmann@33594
   929
haftmann@33594
   930
lemma apsnd_apfst [simp]:
haftmann@33594
   931
  "apsnd f (apfst g x) = (g (fst x), f (snd x))"
haftmann@33594
   932
  by (cases x) simp
haftmann@33594
   933
haftmann@33594
   934
lemma apfst_id [simp] :
haftmann@33594
   935
  "apfst id = id"
nipkow@39302
   936
  by (simp add: fun_eq_iff)
haftmann@33594
   937
haftmann@33594
   938
lemma apsnd_id [simp] :
haftmann@33594
   939
  "apsnd id = id"
nipkow@39302
   940
  by (simp add: fun_eq_iff)
haftmann@33594
   941
haftmann@33594
   942
lemma apfst_eq_conv [simp]:
haftmann@33594
   943
  "apfst f x = apfst g x \<longleftrightarrow> f (fst x) = g (fst x)"
haftmann@33594
   944
  by (cases x) simp
haftmann@33594
   945
haftmann@33594
   946
lemma apsnd_eq_conv [simp]:
haftmann@33594
   947
  "apsnd f x = apsnd g x \<longleftrightarrow> f (snd x) = g (snd x)"
haftmann@33594
   948
  by (cases x) simp
haftmann@33594
   949
hoelzl@33638
   950
lemma apsnd_apfst_commute:
hoelzl@33638
   951
  "apsnd f (apfst g p) = apfst g (apsnd f p)"
hoelzl@33638
   952
  by simp
haftmann@21195
   953
haftmann@26358
   954
text {*
haftmann@26358
   955
  Disjoint union of a family of sets -- Sigma.
haftmann@26358
   956
*}
haftmann@26358
   957
haftmann@45986
   958
definition Sigma :: "'a set \<Rightarrow> ('a \<Rightarrow> 'b set) \<Rightarrow> ('a \<times> 'b) set" where
haftmann@26358
   959
  Sigma_def: "Sigma A B == UN x:A. UN y:B x. {Pair x y}"
haftmann@26358
   960
haftmann@26358
   961
abbreviation
haftmann@45986
   962
  Times :: "'a set \<Rightarrow> 'b set \<Rightarrow> ('a \<times> 'b) set"
haftmann@26358
   963
    (infixr "<*>" 80) where
haftmann@26358
   964
  "A <*> B == Sigma A (%_. B)"
haftmann@26358
   965
haftmann@26358
   966
notation (xsymbols)
haftmann@26358
   967
  Times  (infixr "\<times>" 80)
berghofe@15394
   968
haftmann@26358
   969
notation (HTML output)
haftmann@26358
   970
  Times  (infixr "\<times>" 80)
haftmann@26358
   971
nipkow@45662
   972
hide_const (open) Times
nipkow@45662
   973
haftmann@26358
   974
syntax
wenzelm@35115
   975
  "_Sigma" :: "[pttrn, 'a set, 'b set] => ('a * 'b) set"  ("(3SIGMA _:_./ _)" [0, 0, 10] 10)
haftmann@26358
   976
translations
wenzelm@35115
   977
  "SIGMA x:A. B" == "CONST Sigma A (%x. B)"
haftmann@26358
   978
haftmann@26358
   979
lemma SigmaI [intro!]: "[| a:A;  b:B(a) |] ==> (a,b) : Sigma A B"
haftmann@26358
   980
  by (unfold Sigma_def) blast
haftmann@26358
   981
haftmann@26358
   982
lemma SigmaE [elim!]:
haftmann@26358
   983
    "[| c: Sigma A B;
haftmann@26358
   984
        !!x y.[| x:A;  y:B(x);  c=(x,y) |] ==> P
haftmann@26358
   985
     |] ==> P"
haftmann@26358
   986
  -- {* The general elimination rule. *}
haftmann@26358
   987
  by (unfold Sigma_def) blast
haftmann@20588
   988
haftmann@26358
   989
text {*
haftmann@26358
   990
  Elimination of @{term "(a, b) : A \<times> B"} -- introduces no
haftmann@26358
   991
  eigenvariables.
haftmann@26358
   992
*}
haftmann@26358
   993
haftmann@26358
   994
lemma SigmaD1: "(a, b) : Sigma A B ==> a : A"
haftmann@26358
   995
  by blast
haftmann@26358
   996
haftmann@26358
   997
lemma SigmaD2: "(a, b) : Sigma A B ==> b : B a"
haftmann@26358
   998
  by blast
haftmann@26358
   999
haftmann@26358
  1000
lemma SigmaE2:
haftmann@26358
  1001
    "[| (a, b) : Sigma A B;
haftmann@26358
  1002
        [| a:A;  b:B(a) |] ==> P
haftmann@26358
  1003
     |] ==> P"
haftmann@26358
  1004
  by blast
haftmann@20588
  1005
haftmann@26358
  1006
lemma Sigma_cong:
haftmann@26358
  1007
     "\<lbrakk>A = B; !!x. x \<in> B \<Longrightarrow> C x = D x\<rbrakk>
haftmann@26358
  1008
      \<Longrightarrow> (SIGMA x: A. C x) = (SIGMA x: B. D x)"
haftmann@26358
  1009
  by auto
haftmann@26358
  1010
haftmann@26358
  1011
lemma Sigma_mono: "[| A <= C; !!x. x:A ==> B x <= D x |] ==> Sigma A B <= Sigma C D"
haftmann@26358
  1012
  by blast
haftmann@26358
  1013
haftmann@26358
  1014
lemma Sigma_empty1 [simp]: "Sigma {} B = {}"
haftmann@26358
  1015
  by blast
haftmann@26358
  1016
haftmann@26358
  1017
lemma Sigma_empty2 [simp]: "A <*> {} = {}"
haftmann@26358
  1018
  by blast
haftmann@26358
  1019
haftmann@26358
  1020
lemma UNIV_Times_UNIV [simp]: "UNIV <*> UNIV = UNIV"
haftmann@26358
  1021
  by auto
haftmann@21908
  1022
haftmann@26358
  1023
lemma Compl_Times_UNIV1 [simp]: "- (UNIV <*> A) = UNIV <*> (-A)"
haftmann@26358
  1024
  by auto
haftmann@26358
  1025
haftmann@26358
  1026
lemma Compl_Times_UNIV2 [simp]: "- (A <*> UNIV) = (-A) <*> UNIV"
haftmann@26358
  1027
  by auto
haftmann@26358
  1028
haftmann@26358
  1029
lemma mem_Sigma_iff [iff]: "((a,b): Sigma A B) = (a:A & b:B(a))"
haftmann@26358
  1030
  by blast
haftmann@26358
  1031
haftmann@26358
  1032
lemma Times_subset_cancel2: "x:C ==> (A <*> C <= B <*> C) = (A <= B)"
haftmann@26358
  1033
  by blast
haftmann@26358
  1034
haftmann@26358
  1035
lemma Times_eq_cancel2: "x:C ==> (A <*> C = B <*> C) = (A = B)"
haftmann@26358
  1036
  by (blast elim: equalityE)
haftmann@20588
  1037
haftmann@26358
  1038
lemma SetCompr_Sigma_eq:
haftmann@26358
  1039
    "Collect (split (%x y. P x & Q x y)) = (SIGMA x:Collect P. Collect (Q x))"
haftmann@26358
  1040
  by blast
haftmann@26358
  1041
haftmann@26358
  1042
lemma Collect_split [simp]: "{(a,b). P a & Q b} = Collect P <*> Collect Q"
haftmann@26358
  1043
  by blast
haftmann@26358
  1044
haftmann@26358
  1045
lemma UN_Times_distrib:
haftmann@26358
  1046
  "(UN (a,b):(A <*> B). E a <*> F b) = (UNION A E) <*> (UNION B F)"
haftmann@26358
  1047
  -- {* Suggested by Pierre Chartier *}
haftmann@26358
  1048
  by blast
haftmann@26358
  1049
blanchet@47740
  1050
lemma split_paired_Ball_Sigma [simp, no_atp]:
haftmann@26358
  1051
    "(ALL z: Sigma A B. P z) = (ALL x:A. ALL y: B x. P(x,y))"
haftmann@26358
  1052
  by blast
haftmann@26358
  1053
blanchet@47740
  1054
lemma split_paired_Bex_Sigma [simp, no_atp]:
haftmann@26358
  1055
    "(EX z: Sigma A B. P z) = (EX x:A. EX y: B x. P(x,y))"
haftmann@26358
  1056
  by blast
haftmann@21908
  1057
haftmann@26358
  1058
lemma Sigma_Un_distrib1: "(SIGMA i:I Un J. C(i)) = (SIGMA i:I. C(i)) Un (SIGMA j:J. C(j))"
haftmann@26358
  1059
  by blast
haftmann@26358
  1060
haftmann@26358
  1061
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
  1062
  by blast
haftmann@26358
  1063
haftmann@26358
  1064
lemma Sigma_Int_distrib1: "(SIGMA i:I Int J. C(i)) = (SIGMA i:I. C(i)) Int (SIGMA j:J. C(j))"
haftmann@26358
  1065
  by blast
haftmann@26358
  1066
haftmann@26358
  1067
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
  1068
  by blast
haftmann@26358
  1069
haftmann@26358
  1070
lemma Sigma_Diff_distrib1: "(SIGMA i:I - J. C(i)) = (SIGMA i:I. C(i)) - (SIGMA j:J. C(j))"
haftmann@26358
  1071
  by blast
haftmann@26358
  1072
haftmann@26358
  1073
lemma Sigma_Diff_distrib2: "(SIGMA i:I. A(i) - B(i)) = (SIGMA i:I. A(i)) - (SIGMA i:I. B(i))"
haftmann@26358
  1074
  by blast
haftmann@21908
  1075
haftmann@26358
  1076
lemma Sigma_Union: "Sigma (Union X) B = (UN A:X. Sigma A B)"
haftmann@26358
  1077
  by blast
haftmann@26358
  1078
haftmann@26358
  1079
text {*
haftmann@26358
  1080
  Non-dependent versions are needed to avoid the need for higher-order
haftmann@26358
  1081
  matching, especially when the rules are re-oriented.
haftmann@26358
  1082
*}
haftmann@21908
  1083
haftmann@26358
  1084
lemma Times_Un_distrib1: "(A Un B) <*> C = (A <*> C) Un (B <*> C)"
nipkow@28719
  1085
by blast
haftmann@26358
  1086
haftmann@26358
  1087
lemma Times_Int_distrib1: "(A Int B) <*> C = (A <*> C) Int (B <*> C)"
nipkow@28719
  1088
by blast
haftmann@26358
  1089
haftmann@26358
  1090
lemma Times_Diff_distrib1: "(A - B) <*> C = (A <*> C) - (B <*> C)"
nipkow@28719
  1091
by blast
haftmann@26358
  1092
hoelzl@36622
  1093
lemma Times_empty[simp]: "A \<times> B = {} \<longleftrightarrow> A = {} \<or> B = {}"
hoelzl@36622
  1094
  by auto
hoelzl@36622
  1095
hoelzl@50104
  1096
lemma times_eq_iff: "A \<times> B = C \<times> D \<longleftrightarrow> A = C \<and> B = D \<or> ((A = {} \<or> B = {}) \<and> (C = {} \<or> D = {}))"
hoelzl@50104
  1097
  by auto
hoelzl@50104
  1098
hoelzl@36622
  1099
lemma fst_image_times[simp]: "fst ` (A \<times> B) = (if B = {} then {} else A)"
huffman@44921
  1100
  by force
hoelzl@36622
  1101
hoelzl@36622
  1102
lemma snd_image_times[simp]: "snd ` (A \<times> B) = (if A = {} then {} else B)"
huffman@44921
  1103
  by force
hoelzl@36622
  1104
nipkow@28719
  1105
lemma insert_times_insert[simp]:
nipkow@28719
  1106
  "insert a A \<times> insert b B =
nipkow@28719
  1107
   insert (a,b) (A \<times> insert b B \<union> insert a A \<times> B)"
nipkow@28719
  1108
by blast
haftmann@26358
  1109
paulson@33271
  1110
lemma vimage_Times: "f -` (A \<times> B) = ((fst \<circ> f) -` A) \<inter> ((snd \<circ> f) -` B)"
wenzelm@47988
  1111
  apply auto
wenzelm@47988
  1112
  apply (case_tac "f x")
wenzelm@47988
  1113
  apply auto
wenzelm@47988
  1114
  done
paulson@33271
  1115
hoelzl@50104
  1116
lemma times_Int_times: "A \<times> B \<inter> C \<times> D = (A \<inter> C) \<times> (B \<inter> D)"
hoelzl@50104
  1117
  by auto
hoelzl@50104
  1118
haftmann@35822
  1119
lemma swap_inj_on:
hoelzl@36622
  1120
  "inj_on (\<lambda>(i, j). (j, i)) A"
hoelzl@36622
  1121
  by (auto intro!: inj_onI)
haftmann@35822
  1122
haftmann@35822
  1123
lemma swap_product:
haftmann@35822
  1124
  "(%(i, j). (j, i)) ` (A \<times> B) = B \<times> A"
haftmann@35822
  1125
  by (simp add: split_def image_def) blast
haftmann@35822
  1126
hoelzl@36622
  1127
lemma image_split_eq_Sigma:
hoelzl@36622
  1128
  "(\<lambda>x. (f x, g x)) ` A = Sigma (f ` A) (\<lambda>x. g ` (f -` {x} \<inter> A))"
haftmann@46128
  1129
proof (safe intro!: imageI)
hoelzl@36622
  1130
  fix a b assume *: "a \<in> A" "b \<in> A" and eq: "f a = f b"
hoelzl@36622
  1131
  show "(f b, g a) \<in> (\<lambda>x. (f x, g x)) ` A"
hoelzl@36622
  1132
    using * eq[symmetric] by auto
hoelzl@36622
  1133
qed simp_all
haftmann@35822
  1134
haftmann@46128
  1135
definition product :: "'a set \<Rightarrow> 'b set \<Rightarrow> ('a \<times> 'b) set" where
haftmann@46128
  1136
  [code_abbrev]: "product A B = A \<times> B"
haftmann@46128
  1137
haftmann@46128
  1138
hide_const (open) product
haftmann@46128
  1139
haftmann@46128
  1140
lemma member_product:
haftmann@46128
  1141
  "x \<in> Product_Type.product A B \<longleftrightarrow> x \<in> A \<times> B"
haftmann@46128
  1142
  by (simp add: product_def)
haftmann@46128
  1143
haftmann@40607
  1144
text {* The following @{const map_pair} lemmas are due to Joachim Breitner: *}
haftmann@40607
  1145
haftmann@40607
  1146
lemma map_pair_inj_on:
haftmann@40607
  1147
  assumes "inj_on f A" and "inj_on g B"
haftmann@40607
  1148
  shows "inj_on (map_pair f g) (A \<times> B)"
haftmann@40607
  1149
proof (rule inj_onI)
haftmann@40607
  1150
  fix x :: "'a \<times> 'c" and y :: "'a \<times> 'c"
haftmann@40607
  1151
  assume "x \<in> A \<times> B" hence "fst x \<in> A" and "snd x \<in> B" by auto
haftmann@40607
  1152
  assume "y \<in> A \<times> B" hence "fst y \<in> A" and "snd y \<in> B" by auto
haftmann@40607
  1153
  assume "map_pair f g x = map_pair f g y"
haftmann@40607
  1154
  hence "fst (map_pair f g x) = fst (map_pair f g y)" by (auto)
haftmann@40607
  1155
  hence "f (fst x) = f (fst y)" by (cases x,cases y,auto)
haftmann@40607
  1156
  with `inj_on f A` and `fst x \<in> A` and `fst y \<in> A`
haftmann@40607
  1157
  have "fst x = fst y" by (auto dest:dest:inj_onD)
haftmann@40607
  1158
  moreover from `map_pair f g x = map_pair f g y`
haftmann@40607
  1159
  have "snd (map_pair f g x) = snd (map_pair f g y)" by (auto)
haftmann@40607
  1160
  hence "g (snd x) = g (snd y)" by (cases x,cases y,auto)
haftmann@40607
  1161
  with `inj_on g B` and `snd x \<in> B` and `snd y \<in> B`
haftmann@40607
  1162
  have "snd x = snd y" by (auto dest:dest:inj_onD)
haftmann@40607
  1163
  ultimately show "x = y" by(rule prod_eqI)
haftmann@40607
  1164
qed
haftmann@40607
  1165
haftmann@40607
  1166
lemma map_pair_surj:
hoelzl@40702
  1167
  fixes f :: "'a \<Rightarrow> 'b" and g :: "'c \<Rightarrow> 'd"
haftmann@40607
  1168
  assumes "surj f" and "surj g"
haftmann@40607
  1169
  shows "surj (map_pair f g)"
haftmann@40607
  1170
unfolding surj_def
haftmann@40607
  1171
proof
haftmann@40607
  1172
  fix y :: "'b \<times> 'd"
haftmann@40607
  1173
  from `surj f` obtain a where "fst y = f a" by (auto elim:surjE)
haftmann@40607
  1174
  moreover
haftmann@40607
  1175
  from `surj g` obtain b where "snd y = g b" by (auto elim:surjE)
haftmann@40607
  1176
  ultimately have "(fst y, snd y) = map_pair f g (a,b)" by auto
haftmann@40607
  1177
  thus "\<exists>x. y = map_pair f g x" by auto
haftmann@40607
  1178
qed
haftmann@40607
  1179
haftmann@40607
  1180
lemma map_pair_surj_on:
haftmann@40607
  1181
  assumes "f ` A = A'" and "g ` B = B'"
haftmann@40607
  1182
  shows "map_pair f g ` (A \<times> B) = A' \<times> B'"
haftmann@40607
  1183
unfolding image_def
haftmann@40607
  1184
proof(rule set_eqI,rule iffI)
haftmann@40607
  1185
  fix x :: "'a \<times> 'c"
haftmann@40607
  1186
  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
  1187
  then obtain y where "y \<in> A \<times> B" and "x = map_pair f g y" by blast
haftmann@40607
  1188
  from `image f A = A'` and `y \<in> A \<times> B` have "f (fst y) \<in> A'" by auto
haftmann@40607
  1189
  moreover from `image g B = B'` and `y \<in> A \<times> B` have "g (snd y) \<in> B'" by auto
haftmann@40607
  1190
  ultimately have "(f (fst y), g (snd y)) \<in> (A' \<times> B')" by auto
haftmann@40607
  1191
  with `x = map_pair f g y` show "x \<in> A' \<times> B'" by (cases y, auto)
haftmann@40607
  1192
next
haftmann@40607
  1193
  fix x :: "'a \<times> 'c"
haftmann@40607
  1194
  assume "x \<in> A' \<times> B'" hence "fst x \<in> A'" and "snd x \<in> B'" by auto
haftmann@40607
  1195
  from `image f A = A'` and `fst x \<in> A'` have "fst x \<in> image f A" by auto
haftmann@40607
  1196
  then obtain a where "a \<in> A" and "fst x = f a" by (rule imageE)
haftmann@40607
  1197
  moreover from `image g B = B'` and `snd x \<in> B'`
haftmann@40607
  1198
  obtain b where "b \<in> B" and "snd x = g b" by auto
haftmann@40607
  1199
  ultimately have "(fst x, snd x) = map_pair f g (a,b)" by auto
haftmann@40607
  1200
  moreover from `a \<in> A` and  `b \<in> B` have "(a , b) \<in> A \<times> B" by auto
haftmann@40607
  1201
  ultimately have "\<exists>y \<in> A \<times> B. x = map_pair f g y" by auto
haftmann@40607
  1202
  thus "x \<in> {x. \<exists>y \<in> A \<times> B. x = map_pair f g y}" by auto
haftmann@40607
  1203
qed
haftmann@40607
  1204
haftmann@21908
  1205
bulwahn@49764
  1206
subsection {* Simproc for rewriting a set comprehension into a pointfree expression *}
bulwahn@49764
  1207
bulwahn@49764
  1208
ML_file "Tools/set_comprehension_pointfree.ML"
bulwahn@49764
  1209
bulwahn@49764
  1210
setup {*
wenzelm@51717
  1211
  Code_Preproc.map_pre (fn ctxt => ctxt addsimprocs
bulwahn@49764
  1212
    [Raw_Simplifier.make_simproc {name = "set comprehension", lhss = [@{cpat "Collect ?P"}],
bulwahn@49764
  1213
    proc = K Set_Comprehension_Pointfree.code_simproc, identifier = []}])
bulwahn@49764
  1214
*}
bulwahn@49764
  1215
bulwahn@49764
  1216
haftmann@37166
  1217
subsection {* Inductively defined sets *}
berghofe@15394
  1218
wenzelm@48891
  1219
ML_file "Tools/inductive_set.ML"
haftmann@31723
  1220
setup Inductive_Set.setup
haftmann@24699
  1221
haftmann@37166
  1222
haftmann@37166
  1223
subsection {* Legacy theorem bindings and duplicates *}
haftmann@37166
  1224
haftmann@37166
  1225
lemma PairE:
haftmann@37166
  1226
  obtains x y where "p = (x, y)"
haftmann@37166
  1227
  by (fact prod.exhaust)
haftmann@37166
  1228
haftmann@37166
  1229
lemmas Pair_eq = prod.inject
blanchet@55393
  1230
lemmas fst_conv = prod.sel(1)
blanchet@55393
  1231
lemmas snd_conv = prod.sel(2)
blanchet@55393
  1232
lemmas pair_collapse = prod.collapse
blanchet@55393
  1233
lemmas split = split_conv
huffman@44066
  1234
lemmas Pair_fst_snd_eq = prod_eq_iff
huffman@44066
  1235
huffman@45204
  1236
hide_const (open) prod
huffman@45204
  1237
nipkow@10213
  1238
end