src/HOL/HOL.thy

proper syntax during class specification

(*  Title:      HOL/HOL.thy
    ID:         $Id$
    Author:     Tobias Nipkow, Markus Wenzel, and Larry Paulson
*)

header {* The basis of Higher-Order Logic *}

theory HOL
imports CPure
uses
  ("hologic.ML")
  "~~/src/Tools/IsaPlanner/zipper.ML"
  "~~/src/Tools/IsaPlanner/isand.ML"
  "~~/src/Tools/IsaPlanner/rw_tools.ML"
  "~~/src/Tools/IsaPlanner/rw_inst.ML"
  "~~/src/Provers/project_rule.ML"
  "~~/src/Provers/induct_method.ML"
  "~~/src/Provers/hypsubst.ML"
  "~~/src/Provers/splitter.ML"
  "~~/src/Provers/classical.ML"
  "~~/src/Provers/blast.ML"
  "~~/src/Provers/clasimp.ML"
  "~~/src/Provers/eqsubst.ML"
  "~~/src/Provers/quantifier1.ML"
  ("simpdata.ML")
  "~~/src/Tools/code/code_name.ML"
  "~~/src/Tools/code/code_funcgr.ML"
  "~~/src/Tools/code/code_thingol.ML"
  "~~/src/Tools/code/code_target.ML"
  "~~/src/Tools/code/code_package.ML"
  "~~/src/Tools/nbe.ML"
begin

subsection {* Primitive logic *}

subsubsection {* Core syntax *}

classes type
defaultsort type

global

typedecl bool

arities
  bool :: type
  "fun" :: (type, type) type

judgment
  Trueprop      :: "bool => prop"                   ("(_)" 5)

consts
  Not           :: "bool => bool"                   ("~ _" [40] 40)
  True          :: bool
  False         :: bool
  arbitrary     :: 'a

  The           :: "('a => bool) => 'a"
  All           :: "('a => bool) => bool"           (binder "ALL " 10)
  Ex            :: "('a => bool) => bool"           (binder "EX " 10)
  Ex1           :: "('a => bool) => bool"           (binder "EX! " 10)
  Let           :: "['a, 'a => 'b] => 'b"

  "op ="        :: "['a, 'a] => bool"               (infixl "=" 50)
  "op &"        :: "[bool, bool] => bool"           (infixr "&" 35)
  "op |"        :: "[bool, bool] => bool"           (infixr "|" 30)
  "op -->"      :: "[bool, bool] => bool"           (infixr "-->" 25)

local

consts
  If            :: "[bool, 'a, 'a] => 'a"           ("(if (_)/ then (_)/ else (_))" 10)


subsubsection {* Additional concrete syntax *}

notation (output)
  "op ="  (infix "=" 50)

abbreviation
  not_equal :: "['a, 'a] => bool"  (infixl "~=" 50) where
  "x ~= y == ~ (x = y)"

notation (output)
  not_equal  (infix "~=" 50)

notation (xsymbols)
  Not  ("\<not> _" [40] 40) and
  "op &"  (infixr "\<and>" 35) and
  "op |"  (infixr "\<or>" 30) and
  "op -->"  (infixr "\<longrightarrow>" 25) and
  not_equal  (infix "\<noteq>" 50)

notation (HTML output)
  Not  ("\<not> _" [40] 40) and
  "op &"  (infixr "\<and>" 35) and
  "op |"  (infixr "\<or>" 30) and
  not_equal  (infix "\<noteq>" 50)

abbreviation (iff)
  iff :: "[bool, bool] => bool"  (infixr "<->" 25) where
  "A <-> B == A = B"

notation (xsymbols)
  iff  (infixr "\<longleftrightarrow>" 25)


nonterminals
  letbinds  letbind
  case_syn  cases_syn

syntax
  "_The"        :: "[pttrn, bool] => 'a"                 ("(3THE _./ _)" [0, 10] 10)

  "_bind"       :: "[pttrn, 'a] => letbind"              ("(2_ =/ _)" 10)
  ""            :: "letbind => letbinds"                 ("_")
  "_binds"      :: "[letbind, letbinds] => letbinds"     ("_;/ _")
  "_Let"        :: "[letbinds, 'a] => 'a"                ("(let (_)/ in (_))" 10)

  "_case_syntax":: "['a, cases_syn] => 'b"               ("(case _ of/ _)" 10)
  "_case1"      :: "['a, 'b] => case_syn"                ("(2_ =>/ _)" 10)
  ""            :: "case_syn => cases_syn"               ("_")
  "_case2"      :: "[case_syn, cases_syn] => cases_syn"  ("_/ | _")

translations
  "THE x. P"              == "The (%x. P)"
  "_Let (_binds b bs) e"  == "_Let b (_Let bs e)"
  "let x = a in e"        == "Let a (%x. e)"

print_translation {*
(* To avoid eta-contraction of body: *)
[("The", fn [Abs abs] =>
     let val (x,t) = atomic_abs_tr' abs
     in Syntax.const "_The" $ x $ t end)]
*}

syntax (xsymbols)
  "_case1"      :: "['a, 'b] => case_syn"                ("(2_ \<Rightarrow>/ _)" 10)

notation (xsymbols)
  All  (binder "\<forall>" 10) and
  Ex  (binder "\<exists>" 10) and
  Ex1  (binder "\<exists>!" 10)

notation (HTML output)
  All  (binder "\<forall>" 10) and
  Ex  (binder "\<exists>" 10) and
  Ex1  (binder "\<exists>!" 10)

notation (HOL)
  All  (binder "! " 10) and
  Ex  (binder "? " 10) and
  Ex1  (binder "?! " 10)


subsubsection {* Axioms and basic definitions *}

axioms
  eq_reflection:  "(x=y) ==> (x==y)"

  refl:           "t = (t::'a)"

  ext:            "(!!x::'a. (f x ::'b) = g x) ==> (%x. f x) = (%x. g x)"
    -- {*Extensionality is built into the meta-logic, and this rule expresses
         a related property.  It is an eta-expanded version of the traditional
         rule, and similar to the ABS rule of HOL*}

  the_eq_trivial: "(THE x. x = a) = (a::'a)"

  impI:           "(P ==> Q) ==> P-->Q"
  mp:             "[| P-->Q;  P |] ==> Q"


defs
  True_def:     "True      == ((%x::bool. x) = (%x. x))"
  All_def:      "All(P)    == (P = (%x. True))"
  Ex_def:       "Ex(P)     == !Q. (!x. P x --> Q) --> Q"
  False_def:    "False     == (!P. P)"
  not_def:      "~ P       == P-->False"
  and_def:      "P & Q     == !R. (P-->Q-->R) --> R"
  or_def:       "P | Q     == !R. (P-->R) --> (Q-->R) --> R"
  Ex1_def:      "Ex1(P)    == ? x. P(x) & (! y. P(y) --> y=x)"

axioms
  iff:          "(P-->Q) --> (Q-->P) --> (P=Q)"
  True_or_False:  "(P=True) | (P=False)"

defs
  Let_def:      "Let s f == f(s)"
  if_def:       "If P x y == THE z::'a. (P=True --> z=x) & (P=False --> z=y)"

finalconsts
  "op ="
  "op -->"
  The
  arbitrary

axiomatization
  undefined :: 'a

axiomatization where
  undefined_fun: "undefined x = undefined"


subsubsection {* Generic classes and algebraic operations *}

class default = type +
  fixes default :: "'a"

class zero = type + 
  fixes zero :: "'a"  ("\<^loc>0")

class one = type +
  fixes one  :: "'a"  ("\<^loc>1")

hide (open) const zero one

class plus = type +
  fixes plus :: "'a \<Rightarrow> 'a \<Rightarrow> 'a"  (infixl "\<^loc>+" 65)

class minus = type +
  fixes uminus :: "'a \<Rightarrow> 'a" 
    and minus :: "'a \<Rightarrow> 'a \<Rightarrow> 'a"  (infixl "\<^loc>-" 65)

class times = type +
  fixes times :: "'a \<Rightarrow> 'a \<Rightarrow> 'a"  (infixl "\<^loc>*" 70)

class inverse = type +
  fixes inverse :: "'a \<Rightarrow> 'a"
    and divide :: "'a \<Rightarrow> 'a \<Rightarrow> 'a"  (infixl "\<^loc>'/" 70)

class abs = type +
  fixes abs :: "'a \<Rightarrow> 'a"

class sgn = type +
  fixes sgn :: "'a \<Rightarrow> 'a"

notation
  uminus  ("- _" [81] 80)

notation (xsymbols)
  abs  ("\<bar>_\<bar>")
notation (HTML output)
  abs  ("\<bar>_\<bar>")

class ord = type +
  fixes less_eq :: "'a \<Rightarrow> 'a \<Rightarrow> bool"
    and less :: "'a \<Rightarrow> 'a \<Rightarrow> bool"
begin

notation
  less_eq  ("op \<^loc><=") and
  less_eq  ("(_/ \<^loc><= _)" [51, 51] 50) and
  less  ("op \<^loc><") and
  less  ("(_/ \<^loc>< _)"  [51, 51] 50)
  
notation (xsymbols)
  less_eq  ("op \<^loc>\<le>") and
  less_eq  ("(_/ \<^loc>\<le> _)"  [51, 51] 50)

notation (HTML output)
  less_eq  ("op \<^loc>\<le>") and
  less_eq  ("(_/ \<^loc>\<le> _)"  [51, 51] 50)

abbreviation (input)
  greater  (infix "\<^loc>>" 50) where
  "x \<^loc>> y \<equiv> y \<^loc>< x"

abbreviation (input)
  greater_eq  (infix "\<^loc>>=" 50) where
  "x \<^loc>>= y \<equiv> y \<^loc><= x"

notation (input)
  greater_eq  (infix "\<^loc>\<ge>" 50)

definition
  Least :: "('a \<Rightarrow> bool) \<Rightarrow> 'a" (binder "\<^loc>LEAST " 10)
where
  "Least P == (THE x. P x \<and> (\<forall>y. P y \<longrightarrow> x \<^loc>\<le> y))"

end

notation
  less_eq  ("op <=") and
  less_eq  ("(_/ <= _)" [51, 51] 50) and
  less  ("op <") and
  less  ("(_/ < _)"  [51, 51] 50)
  
notation (xsymbols)
  less_eq  ("op \<le>") and
  less_eq  ("(_/ \<le> _)"  [51, 51] 50)

notation (HTML output)
  less_eq  ("op \<le>") and
  less_eq  ("(_/ \<le> _)"  [51, 51] 50)

abbreviation (input)
  greater  (infix ">" 50) where
  "x > y \<equiv> y < x"

abbreviation (input)
  greater_eq  (infix ">=" 50) where
  "x >= y \<equiv> y <= x"

notation (input)
  greater_eq  (infix "\<ge>" 50)

syntax
  "_index1"  :: index    ("\<^sub>1")
translations
  (index) "\<^sub>1" => (index) "\<^bsub>\<struct>\<^esub>"

typed_print_translation {*
let
  fun tr' c = (c, fn show_sorts => fn T => fn ts =>
    if T = dummyT orelse not (! show_types) andalso can Term.dest_Type T then raise Match
    else Syntax.const Syntax.constrainC $ Syntax.const c $ Syntax.term_of_typ show_sorts T);
in map tr' [@{const_syntax HOL.one}, @{const_syntax HOL.zero}] end;
*} -- {* show types that are presumably too general *}


subsection {* Fundamental rules *}

subsubsection {* Equality *}

text {* Thanks to Stephan Merz *}
lemma subst:
  assumes eq: "s = t" and p: "P s"
  shows "P t"
proof -
  from eq have meta: "s \<equiv> t"
    by (rule eq_reflection)
  from p show ?thesis
    by (unfold meta)
qed

lemma sym: "s = t ==> t = s"
  by (erule subst) (rule refl)

lemma ssubst: "t = s ==> P s ==> P t"
  by (drule sym) (erule subst)

lemma trans: "[| r=s; s=t |] ==> r=t"
  by (erule subst)

lemma meta_eq_to_obj_eq: 
  assumes meq: "A == B"
  shows "A = B"
  by (unfold meq) (rule refl)

text {* Useful with @{text erule} for proving equalities from known equalities. *}
     (* a = b
        |   |
        c = d   *)
lemma box_equals: "[| a=b;  a=c;  b=d |] ==> c=d"
apply (rule trans)
apply (rule trans)
apply (rule sym)
apply assumption+
done

text {* For calculational reasoning: *}

lemma forw_subst: "a = b ==> P b ==> P a"
  by (rule ssubst)

lemma back_subst: "P a ==> a = b ==> P b"
  by (rule subst)


subsubsection {*Congruence rules for application*}

(*similar to AP_THM in Gordon's HOL*)
lemma fun_cong: "(f::'a=>'b) = g ==> f(x)=g(x)"
apply (erule subst)
apply (rule refl)
done

(*similar to AP_TERM in Gordon's HOL and FOL's subst_context*)
lemma arg_cong: "x=y ==> f(x)=f(y)"
apply (erule subst)
apply (rule refl)
done

lemma arg_cong2: "\<lbrakk> a = b; c = d \<rbrakk> \<Longrightarrow> f a c = f b d"
apply (erule ssubst)+
apply (rule refl)
done

lemma cong: "[| f = g; (x::'a) = y |] ==> f(x) = g(y)"
apply (erule subst)+
apply (rule refl)
done


subsubsection {*Equality of booleans -- iff*}

lemma iffI: assumes "P ==> Q" and "Q ==> P" shows "P=Q"
  by (iprover intro: iff [THEN mp, THEN mp] impI assms)

lemma iffD2: "[| P=Q; Q |] ==> P"
  by (erule ssubst)

lemma rev_iffD2: "[| Q; P=Q |] ==> P"
  by (erule iffD2)

lemma iffD1: "Q = P \<Longrightarrow> Q \<Longrightarrow> P"
  by (drule sym) (rule iffD2)

lemma rev_iffD1: "Q \<Longrightarrow> Q = P \<Longrightarrow> P"
  by (drule sym) (rule rev_iffD2)

lemma iffE:
  assumes major: "P=Q"
    and minor: "[| P --> Q; Q --> P |] ==> R"
  shows R
  by (iprover intro: minor impI major [THEN iffD2] major [THEN iffD1])


subsubsection {*True*}

lemma TrueI: "True"
  unfolding True_def by (rule refl)

lemma eqTrueI: "P ==> P = True"
  by (iprover intro: iffI TrueI)

lemma eqTrueE: "P = True ==> P"
  by (erule iffD2) (rule TrueI)


subsubsection {*Universal quantifier*}

lemma allI: assumes "!!x::'a. P(x)" shows "ALL x. P(x)"
  unfolding All_def by (iprover intro: ext eqTrueI assms)

lemma spec: "ALL x::'a. P(x) ==> P(x)"
apply (unfold All_def)
apply (rule eqTrueE)
apply (erule fun_cong)
done

lemma allE:
  assumes major: "ALL x. P(x)"
    and minor: "P(x) ==> R"
  shows R
  by (iprover intro: minor major [THEN spec])

lemma all_dupE:
  assumes major: "ALL x. P(x)"
    and minor: "[| P(x); ALL x. P(x) |] ==> R"
  shows R
  by (iprover intro: minor major major [THEN spec])


subsubsection {* False *}

text {*
  Depends upon @{text spec}; it is impossible to do propositional
  logic before quantifiers!
*}

lemma FalseE: "False ==> P"
  apply (unfold False_def)
  apply (erule spec)
  done

lemma False_neq_True: "False = True ==> P"
  by (erule eqTrueE [THEN FalseE])


subsubsection {* Negation *}

lemma notI:
  assumes "P ==> False"
  shows "~P"
  apply (unfold not_def)
  apply (iprover intro: impI assms)
  done

lemma False_not_True: "False ~= True"
  apply (rule notI)
  apply (erule False_neq_True)
  done

lemma True_not_False: "True ~= False"
  apply (rule notI)
  apply (drule sym)
  apply (erule False_neq_True)
  done

lemma notE: "[| ~P;  P |] ==> R"
  apply (unfold not_def)
  apply (erule mp [THEN FalseE])
  apply assumption
  done

lemma notI2: "(P \<Longrightarrow> \<not> Pa) \<Longrightarrow> (P \<Longrightarrow> Pa) \<Longrightarrow> \<not> P"
  by (erule notE [THEN notI]) (erule meta_mp)


subsubsection {*Implication*}

lemma impE:
  assumes "P-->Q" "P" "Q ==> R"
  shows "R"
by (iprover intro: assms mp)

(* Reduces Q to P-->Q, allowing substitution in P. *)
lemma rev_mp: "[| P;  P --> Q |] ==> Q"
by (iprover intro: mp)

lemma contrapos_nn:
  assumes major: "~Q"
      and minor: "P==>Q"
  shows "~P"
by (iprover intro: notI minor major [THEN notE])

(*not used at all, but we already have the other 3 combinations *)
lemma contrapos_pn:
  assumes major: "Q"
      and minor: "P ==> ~Q"
  shows "~P"
by (iprover intro: notI minor major notE)

lemma not_sym: "t ~= s ==> s ~= t"
  by (erule contrapos_nn) (erule sym)

lemma eq_neq_eq_imp_neq: "[| x = a ; a ~= b; b = y |] ==> x ~= y"
  by (erule subst, erule ssubst, assumption)

(*still used in HOLCF*)
lemma rev_contrapos:
  assumes pq: "P ==> Q"
      and nq: "~Q"
  shows "~P"
apply (rule nq [THEN contrapos_nn])
apply (erule pq)
done

subsubsection {*Existential quantifier*}

lemma exI: "P x ==> EX x::'a. P x"
apply (unfold Ex_def)
apply (iprover intro: allI allE impI mp)
done

lemma exE:
  assumes major: "EX x::'a. P(x)"
      and minor: "!!x. P(x) ==> Q"
  shows "Q"
apply (rule major [unfolded Ex_def, THEN spec, THEN mp])
apply (iprover intro: impI [THEN allI] minor)
done


subsubsection {*Conjunction*}

lemma conjI: "[| P; Q |] ==> P&Q"
apply (unfold and_def)
apply (iprover intro: impI [THEN allI] mp)
done

lemma conjunct1: "[| P & Q |] ==> P"
apply (unfold and_def)
apply (iprover intro: impI dest: spec mp)
done

lemma conjunct2: "[| P & Q |] ==> Q"
apply (unfold and_def)
apply (iprover intro: impI dest: spec mp)
done

lemma conjE:
  assumes major: "P&Q"
      and minor: "[| P; Q |] ==> R"
  shows "R"
apply (rule minor)
apply (rule major [THEN conjunct1])
apply (rule major [THEN conjunct2])
done

lemma context_conjI:
  assumes "P" "P ==> Q" shows "P & Q"
by (iprover intro: conjI assms)


subsubsection {*Disjunction*}

lemma disjI1: "P ==> P|Q"
apply (unfold or_def)
apply (iprover intro: allI impI mp)
done

lemma disjI2: "Q ==> P|Q"
apply (unfold or_def)
apply (iprover intro: allI impI mp)
done

lemma disjE:
  assumes major: "P|Q"
      and minorP: "P ==> R"
      and minorQ: "Q ==> R"
  shows "R"
by (iprover intro: minorP minorQ impI
                 major [unfolded or_def, THEN spec, THEN mp, THEN mp])


subsubsection {*Classical logic*}

lemma classical:
  assumes prem: "~P ==> P"
  shows "P"
apply (rule True_or_False [THEN disjE, THEN eqTrueE])
apply assumption
apply (rule notI [THEN prem, THEN eqTrueI])
apply (erule subst)
apply assumption
done

lemmas ccontr = FalseE [THEN classical, standard]

(*notE with premises exchanged; it discharges ~R so that it can be used to
  make elimination rules*)
lemma rev_notE:
  assumes premp: "P"
      and premnot: "~R ==> ~P"
  shows "R"
apply (rule ccontr)
apply (erule notE [OF premnot premp])
done

(*Double negation law*)
lemma notnotD: "~~P ==> P"
apply (rule classical)
apply (erule notE)
apply assumption
done

lemma contrapos_pp:
  assumes p1: "Q"
      and p2: "~P ==> ~Q"
  shows "P"
by (iprover intro: classical p1 p2 notE)


subsubsection {*Unique existence*}

lemma ex1I:
  assumes "P a" "!!x. P(x) ==> x=a"
  shows "EX! x. P(x)"
by (unfold Ex1_def, iprover intro: assms exI conjI allI impI)

text{*Sometimes easier to use: the premises have no shared variables.  Safe!*}
lemma ex_ex1I:
  assumes ex_prem: "EX x. P(x)"
      and eq: "!!x y. [| P(x); P(y) |] ==> x=y"
  shows "EX! x. P(x)"
by (iprover intro: ex_prem [THEN exE] ex1I eq)

lemma ex1E:
  assumes major: "EX! x. P(x)"
      and minor: "!!x. [| P(x);  ALL y. P(y) --> y=x |] ==> R"
  shows "R"
apply (rule major [unfolded Ex1_def, THEN exE])
apply (erule conjE)
apply (iprover intro: minor)
done

lemma ex1_implies_ex: "EX! x. P x ==> EX x. P x"
apply (erule ex1E)
apply (rule exI)
apply assumption
done


subsubsection {*THE: definite description operator*}

lemma the_equality:
  assumes prema: "P a"
      and premx: "!!x. P x ==> x=a"
  shows "(THE x. P x) = a"
apply (rule trans [OF _ the_eq_trivial])
apply (rule_tac f = "The" in arg_cong)
apply (rule ext)
apply (rule iffI)
 apply (erule premx)
apply (erule ssubst, rule prema)
done

lemma theI:
  assumes "P a" and "!!x. P x ==> x=a"
  shows "P (THE x. P x)"
by (iprover intro: assms the_equality [THEN ssubst])

lemma theI': "EX! x. P x ==> P (THE x. P x)"
apply (erule ex1E)
apply (erule theI)
apply (erule allE)
apply (erule mp)
apply assumption
done

(*Easier to apply than theI: only one occurrence of P*)
lemma theI2:
  assumes "P a" "!!x. P x ==> x=a" "!!x. P x ==> Q x"
  shows "Q (THE x. P x)"
by (iprover intro: assms theI)

lemma the1I2: assumes "EX! x. P x" "\<And>x. P x \<Longrightarrow> Q x" shows "Q (THE x. P x)"
by(iprover intro:assms(2) theI2[where P=P and Q=Q] ex1E[OF assms(1)]
           elim:allE impE)

lemma the1_equality [elim?]: "[| EX!x. P x; P a |] ==> (THE x. P x) = a"
apply (rule the_equality)
apply  assumption
apply (erule ex1E)
apply (erule all_dupE)
apply (drule mp)
apply  assumption
apply (erule ssubst)
apply (erule allE)
apply (erule mp)
apply assumption
done

lemma the_sym_eq_trivial: "(THE y. x=y) = x"
apply (rule the_equality)
apply (rule refl)
apply (erule sym)
done


subsubsection {*Classical intro rules for disjunction and existential quantifiers*}

lemma disjCI:
  assumes "~Q ==> P" shows "P|Q"
apply (rule classical)
apply (iprover intro: assms disjI1 disjI2 notI elim: notE)
done

lemma excluded_middle: "~P | P"
by (iprover intro: disjCI)

text {*
  case distinction as a natural deduction rule.
  Note that @{term "~P"} is the second case, not the first
*}
lemma case_split_thm:
  assumes prem1: "P ==> Q"
      and prem2: "~P ==> Q"
  shows "Q"
apply (rule excluded_middle [THEN disjE])
apply (erule prem2)
apply (erule prem1)
done
lemmas case_split = case_split_thm [case_names True False]

(*Classical implies (-->) elimination. *)
lemma impCE:
  assumes major: "P-->Q"
      and minor: "~P ==> R" "Q ==> R"
  shows "R"
apply (rule excluded_middle [of P, THEN disjE])
apply (iprover intro: minor major [THEN mp])+
done

(*This version of --> elimination works on Q before P.  It works best for
  those cases in which P holds "almost everywhere".  Can't install as
  default: would break old proofs.*)
lemma impCE':
  assumes major: "P-->Q"
      and minor: "Q ==> R" "~P ==> R"
  shows "R"
apply (rule excluded_middle [of P, THEN disjE])
apply (iprover intro: minor major [THEN mp])+
done

(*Classical <-> elimination. *)
lemma iffCE:
  assumes major: "P=Q"
      and minor: "[| P; Q |] ==> R"  "[| ~P; ~Q |] ==> R"
  shows "R"
apply (rule major [THEN iffE])
apply (iprover intro: minor elim: impCE notE)
done

lemma exCI:
  assumes "ALL x. ~P(x) ==> P(a)"
  shows "EX x. P(x)"
apply (rule ccontr)
apply (iprover intro: assms exI allI notI notE [of "\<exists>x. P x"])
done


subsubsection {* Intuitionistic Reasoning *}

lemma impE':
  assumes 1: "P --> Q"
    and 2: "Q ==> R"
    and 3: "P --> Q ==> P"
  shows R
proof -
  from 3 and 1 have P .
  with 1 have Q by (rule impE)
  with 2 show R .
qed

lemma allE':
  assumes 1: "ALL x. P x"
    and 2: "P x ==> ALL x. P x ==> Q"
  shows Q
proof -
  from 1 have "P x" by (rule spec)
  from this and 1 show Q by (rule 2)
qed

lemma notE':
  assumes 1: "~ P"
    and 2: "~ P ==> P"
  shows R
proof -
  from 2 and 1 have P .
  with 1 show R by (rule notE)
qed

lemma TrueE: "True ==> P ==> P" .
lemma notFalseE: "~ False ==> P ==> P" .

lemmas [Pure.elim!] = disjE iffE FalseE conjE exE TrueE notFalseE
  and [Pure.intro!] = iffI conjI impI TrueI notI allI refl
  and [Pure.elim 2] = allE notE' impE'
  and [Pure.intro] = exI disjI2 disjI1

lemmas [trans] = trans
  and [sym] = sym not_sym
  and [Pure.elim?] = iffD1 iffD2 impE

use "hologic.ML"


subsubsection {* Atomizing meta-level connectives *}

lemma atomize_all [atomize]: "(!!x. P x) == Trueprop (ALL x. P x)"
proof
  assume "!!x. P x"
  then show "ALL x. P x" ..
next
  assume "ALL x. P x"
  then show "!!x. P x" by (rule allE)
qed

lemma atomize_imp [atomize]: "(A ==> B) == Trueprop (A --> B)"
proof
  assume r: "A ==> B"
  show "A --> B" by (rule impI) (rule r)
next
  assume "A --> B" and A
  then show B by (rule mp)
qed

lemma atomize_not: "(A ==> False) == Trueprop (~A)"
proof
  assume r: "A ==> False"
  show "~A" by (rule notI) (rule r)
next
  assume "~A" and A
  then show False by (rule notE)
qed

lemma atomize_eq [atomize]: "(x == y) == Trueprop (x = y)"
proof
  assume "x == y"
  show "x = y" by (unfold `x == y`) (rule refl)
next
  assume "x = y"
  then show "x == y" by (rule eq_reflection)
qed

lemma atomize_conj [atomize]:
  includes meta_conjunction_syntax
  shows "(A && B) == Trueprop (A & B)"
proof
  assume conj: "A && B"
  show "A & B"
  proof (rule conjI)
    from conj show A by (rule conjunctionD1)
    from conj show B by (rule conjunctionD2)
  qed
next
  assume conj: "A & B"
  show "A && B"
  proof -
    from conj show A ..
    from conj show B ..
  qed
qed

lemmas [symmetric, rulify] = atomize_all atomize_imp
  and [symmetric, defn] = atomize_all atomize_imp atomize_eq


subsection {* Package setup *}

subsubsection {* Classical Reasoner setup *}

lemma thin_refl:
  "\<And>X. \<lbrakk> x=x; PROP W \<rbrakk> \<Longrightarrow> PROP W" .

ML {*
structure Hypsubst = HypsubstFun(
struct
  structure Simplifier = Simplifier
  val dest_eq = HOLogic.dest_eq
  val dest_Trueprop = HOLogic.dest_Trueprop
  val dest_imp = HOLogic.dest_imp
  val eq_reflection = @{thm HOL.eq_reflection}
  val rev_eq_reflection = @{thm HOL.meta_eq_to_obj_eq}
  val imp_intr = @{thm HOL.impI}
  val rev_mp = @{thm HOL.rev_mp}
  val subst = @{thm HOL.subst}
  val sym = @{thm HOL.sym}
  val thin_refl = @{thm thin_refl};
end);
open Hypsubst;

structure Classical = ClassicalFun(
struct
  val mp = @{thm HOL.mp}
  val not_elim = @{thm HOL.notE}
  val classical = @{thm HOL.classical}
  val sizef = Drule.size_of_thm
  val hyp_subst_tacs = [Hypsubst.hyp_subst_tac]
end);

structure BasicClassical: BASIC_CLASSICAL = Classical; 
open BasicClassical;

ML_Context.value_antiq "claset"
  (Scan.succeed ("claset", "Classical.local_claset_of (ML_Context.the_local_context ())"));

structure ResAtpset = NamedThmsFun(val name = "atp" val description = "ATP rules");

structure ResBlacklist = NamedThmsFun(val name = "noatp" val description = "Theorems blacklisted for ATP");
*}

(*ResBlacklist holds theorems blacklisted to sledgehammer. 
  These theorems typically produce clauses that are prolific (match too many equality or
  membership literals) and relate to seldom-used facts. Some duplicate other rules.*)

setup {*
let
  (*prevent substitution on bool*)
  fun hyp_subst_tac' i thm = if i <= Thm.nprems_of thm andalso
    Term.exists_Const (fn ("op =", Type (_, [T, _])) => T <> Type ("bool", []) | _ => false)
      (nth (Thm.prems_of thm) (i - 1)) then Hypsubst.hyp_subst_tac i thm else no_tac thm;
in
  Hypsubst.hypsubst_setup
  #> ContextRules.addSWrapper (fn tac => hyp_subst_tac' ORELSE' tac)
  #> Classical.setup
  #> ResAtpset.setup
  #> ResBlacklist.setup
end
*}

declare iffI [intro!]
  and notI [intro!]
  and impI [intro!]
  and disjCI [intro!]
  and conjI [intro!]
  and TrueI [intro!]
  and refl [intro!]

declare iffCE [elim!]
  and FalseE [elim!]
  and impCE [elim!]
  and disjE [elim!]
  and conjE [elim!]
  and conjE [elim!]

declare ex_ex1I [intro!]
  and allI [intro!]
  and the_equality [intro]
  and exI [intro]

declare exE [elim!]
  allE [elim]

ML {* val HOL_cs = @{claset} *}

lemma contrapos_np: "~ Q ==> (~ P ==> Q) ==> P"
  apply (erule swap)
  apply (erule (1) meta_mp)
  done

declare ex_ex1I [rule del, intro! 2]
  and ex1I [intro]

lemmas [intro?] = ext
  and [elim?] = ex1_implies_ex

(*Better then ex1E for classical reasoner: needs no quantifier duplication!*)
lemma alt_ex1E [elim!]:
  assumes major: "\<exists>!x. P x"
      and prem: "\<And>x. \<lbrakk> P x; \<forall>y y'. P y \<and> P y' \<longrightarrow> y = y' \<rbrakk> \<Longrightarrow> R"
  shows R
apply (rule ex1E [OF major])
apply (rule prem)
apply (tactic {* ares_tac @{thms allI} 1 *})+
apply (tactic {* etac (Classical.dup_elim @{thm allE}) 1 *})
apply iprover
done

ML {*
structure Blast = BlastFun(
struct
  type claset = Classical.claset
  val equality_name = @{const_name "op ="}
  val not_name = @{const_name Not}
  val notE = @{thm HOL.notE}
  val ccontr = @{thm HOL.ccontr}
  val contr_tac = Classical.contr_tac
  val dup_intr = Classical.dup_intr
  val hyp_subst_tac = Hypsubst.blast_hyp_subst_tac
  val claset = Classical.claset
  val rep_cs = Classical.rep_cs
  val cla_modifiers = Classical.cla_modifiers
  val cla_meth' = Classical.cla_meth'
end);
val Blast_tac = Blast.Blast_tac;
val blast_tac = Blast.blast_tac;
*}

setup Blast.setup


subsubsection {* Simplifier *}

lemma eta_contract_eq: "(%s. f s) = f" ..

lemma simp_thms:
  shows not_not: "(~ ~ P) = P"
  and Not_eq_iff: "((~P) = (~Q)) = (P = Q)"
  and
    "(P ~= Q) = (P = (~Q))"
    "(P | ~P) = True"    "(~P | P) = True"
    "(x = x) = True"
  and not_True_eq_False: "(\<not> True) = False"
  and not_False_eq_True: "(\<not> False) = True"
  and
    "(~P) ~= P"  "P ~= (~P)"
    "(True=P) = P"
  and eq_True: "(P = True) = P"
  and "(False=P) = (~P)"
  and eq_False: "(P = False) = (\<not> P)"
  and
    "(True --> P) = P"  "(False --> P) = True"
    "(P --> True) = True"  "(P --> P) = True"
    "(P --> False) = (~P)"  "(P --> ~P) = (~P)"
    "(P & True) = P"  "(True & P) = P"
    "(P & False) = False"  "(False & P) = False"
    "(P & P) = P"  "(P & (P & Q)) = (P & Q)"
    "(P & ~P) = False"    "(~P & P) = False"
    "(P | True) = True"  "(True | P) = True"
    "(P | False) = P"  "(False | P) = P"
    "(P | P) = P"  "(P | (P | Q)) = (P | Q)" and
    "(ALL x. P) = P"  "(EX x. P) = P"  "EX x. x=t"  "EX x. t=x"
    -- {* needed for the one-point-rule quantifier simplification procs *}
    -- {* essential for termination!! *} and
    "!!P. (EX x. x=t & P(x)) = P(t)"
    "!!P. (EX x. t=x & P(x)) = P(t)"
    "!!P. (ALL x. x=t --> P(x)) = P(t)"
    "!!P. (ALL x. t=x --> P(x)) = P(t)"
  by (blast, blast, blast, blast, blast, iprover+)

lemma disj_absorb: "(A | A) = A"
  by blast

lemma disj_left_absorb: "(A | (A | B)) = (A | B)"
  by blast

lemma conj_absorb: "(A & A) = A"
  by blast

lemma conj_left_absorb: "(A & (A & B)) = (A & B)"
  by blast

lemma eq_ac:
  shows eq_commute: "(a=b) = (b=a)"
    and eq_left_commute: "(P=(Q=R)) = (Q=(P=R))"
    and eq_assoc: "((P=Q)=R) = (P=(Q=R))" by (iprover, blast+)
lemma neq_commute: "(a~=b) = (b~=a)" by iprover

lemma conj_comms:
  shows conj_commute: "(P&Q) = (Q&P)"
    and conj_left_commute: "(P&(Q&R)) = (Q&(P&R))" by iprover+
lemma conj_assoc: "((P&Q)&R) = (P&(Q&R))" by iprover

lemmas conj_ac = conj_commute conj_left_commute conj_assoc

lemma disj_comms:
  shows disj_commute: "(P|Q) = (Q|P)"
    and disj_left_commute: "(P|(Q|R)) = (Q|(P|R))" by iprover+
lemma disj_assoc: "((P|Q)|R) = (P|(Q|R))" by iprover

lemmas disj_ac = disj_commute disj_left_commute disj_assoc

lemma conj_disj_distribL: "(P&(Q|R)) = (P&Q | P&R)" by iprover
lemma conj_disj_distribR: "((P|Q)&R) = (P&R | Q&R)" by iprover

lemma disj_conj_distribL: "(P|(Q&R)) = ((P|Q) & (P|R))" by iprover
lemma disj_conj_distribR: "((P&Q)|R) = ((P|R) & (Q|R))" by iprover

lemma imp_conjR: "(P --> (Q&R)) = ((P-->Q) & (P-->R))" by iprover
lemma imp_conjL: "((P&Q) -->R)  = (P --> (Q --> R))" by iprover
lemma imp_disjL: "((P|Q) --> R) = ((P-->R)&(Q-->R))" by iprover

text {* These two are specialized, but @{text imp_disj_not1} is useful in @{text "Auth/Yahalom"}. *}
lemma imp_disj_not1: "(P --> Q | R) = (~Q --> P --> R)" by blast
lemma imp_disj_not2: "(P --> Q | R) = (~R --> P --> Q)" by blast

lemma imp_disj1: "((P-->Q)|R) = (P--> Q|R)" by blast
lemma imp_disj2: "(Q|(P-->R)) = (P--> Q|R)" by blast

lemma imp_cong: "(P = P') ==> (P' ==> (Q = Q')) ==> ((P --> Q) = (P' --> Q'))"
  by iprover

lemma de_Morgan_disj: "(~(P | Q)) = (~P & ~Q)" by iprover
lemma de_Morgan_conj: "(~(P & Q)) = (~P | ~Q)" by blast
lemma not_imp: "(~(P --> Q)) = (P & ~Q)" by blast
lemma not_iff: "(P~=Q) = (P = (~Q))" by blast
lemma disj_not1: "(~P | Q) = (P --> Q)" by blast
lemma disj_not2: "(P | ~Q) = (Q --> P)"  -- {* changes orientation :-( *}
  by blast
lemma imp_conv_disj: "(P --> Q) = ((~P) | Q)" by blast

lemma iff_conv_conj_imp: "(P = Q) = ((P --> Q) & (Q --> P))" by iprover


lemma cases_simp: "((P --> Q) & (~P --> Q)) = Q"
  -- {* Avoids duplication of subgoals after @{text split_if}, when the true and false *}
  -- {* cases boil down to the same thing. *}
  by blast

lemma not_all: "(~ (! x. P(x))) = (? x.~P(x))" by blast
lemma imp_all: "((! x. P x) --> Q) = (? x. P x --> Q)" by blast
lemma not_ex: "(~ (? x. P(x))) = (! x.~P(x))" by iprover
lemma imp_ex: "((? x. P x) --> Q) = (! x. P x --> Q)" by iprover
lemma all_not_ex: "(ALL x. P x) = (~ (EX x. ~ P x ))" by blast

declare All_def [noatp]

lemma ex_disj_distrib: "(? x. P(x) | Q(x)) = ((? x. P(x)) | (? x. Q(x)))" by iprover
lemma all_conj_distrib: "(!x. P(x) & Q(x)) = ((! x. P(x)) & (! x. Q(x)))" by iprover

text {*
  \medskip The @{text "&"} congruence rule: not included by default!
  May slow rewrite proofs down by as much as 50\% *}

lemma conj_cong:
    "(P = P') ==> (P' ==> (Q = Q')) ==> ((P & Q) = (P' & Q'))"
  by iprover

lemma rev_conj_cong:
    "(Q = Q') ==> (Q' ==> (P = P')) ==> ((P & Q) = (P' & Q'))"
  by iprover

text {* The @{text "|"} congruence rule: not included by default! *}

lemma disj_cong:
    "(P = P') ==> (~P' ==> (Q = Q')) ==> ((P | Q) = (P' | Q'))"
  by blast


text {* \medskip if-then-else rules *}

lemma if_True: "(if True then x else y) = x"
  by (unfold if_def) blast

lemma if_False: "(if False then x else y) = y"
  by (unfold if_def) blast

lemma if_P: "P ==> (if P then x else y) = x"
  by (unfold if_def) blast

lemma if_not_P: "~P ==> (if P then x else y) = y"
  by (unfold if_def) blast

lemma split_if: "P (if Q then x else y) = ((Q --> P(x)) & (~Q --> P(y)))"
  apply (rule case_split [of Q])
   apply (simplesubst if_P)
    prefer 3 apply (simplesubst if_not_P, blast+)
  done

lemma split_if_asm: "P (if Q then x else y) = (~((Q & ~P x) | (~Q & ~P y)))"
by (simplesubst split_if, blast)

lemmas if_splits [noatp] = split_if split_if_asm

lemma if_cancel: "(if c then x else x) = x"
by (simplesubst split_if, blast)

lemma if_eq_cancel: "(if x = y then y else x) = x"
by (simplesubst split_if, blast)

lemma if_bool_eq_conj: "(if P then Q else R) = ((P-->Q) & (~P-->R))"
  -- {* This form is useful for expanding @{text "if"}s on the RIGHT of the @{text "==>"} symbol. *}
  by (rule split_if)

lemma if_bool_eq_disj: "(if P then Q else R) = ((P&Q) | (~P&R))"
  -- {* And this form is useful for expanding @{text "if"}s on the LEFT. *}
  apply (simplesubst split_if, blast)
  done

lemma Eq_TrueI: "P ==> P == True" by (unfold atomize_eq) iprover
lemma Eq_FalseI: "~P ==> P == False" by (unfold atomize_eq) iprover

text {* \medskip let rules for simproc *}

lemma Let_folded: "f x \<equiv> g x \<Longrightarrow>  Let x f \<equiv> Let x g"
  by (unfold Let_def)

lemma Let_unfold: "f x \<equiv> g \<Longrightarrow>  Let x f \<equiv> g"
  by (unfold Let_def)

text {*
  The following copy of the implication operator is useful for
  fine-tuning congruence rules.  It instructs the simplifier to simplify
  its premise.
*}

constdefs
  simp_implies :: "[prop, prop] => prop"  (infixr "=simp=>" 1)
  "simp_implies \<equiv> op ==>"

lemma simp_impliesI:
  assumes PQ: "(PROP P \<Longrightarrow> PROP Q)"
  shows "PROP P =simp=> PROP Q"
  apply (unfold simp_implies_def)
  apply (rule PQ)
  apply assumption
  done

lemma simp_impliesE:
  assumes PQ:"PROP P =simp=> PROP Q"
  and P: "PROP P"
  and QR: "PROP Q \<Longrightarrow> PROP R"
  shows "PROP R"
  apply (rule QR)
  apply (rule PQ [unfolded simp_implies_def])
  apply (rule P)
  done

lemma simp_implies_cong:
  assumes PP' :"PROP P == PROP P'"
  and P'QQ': "PROP P' ==> (PROP Q == PROP Q')"
  shows "(PROP P =simp=> PROP Q) == (PROP P' =simp=> PROP Q')"
proof (unfold simp_implies_def, rule equal_intr_rule)
  assume PQ: "PROP P \<Longrightarrow> PROP Q"
  and P': "PROP P'"
  from PP' [symmetric] and P' have "PROP P"
    by (rule equal_elim_rule1)
  then have "PROP Q" by (rule PQ)
  with P'QQ' [OF P'] show "PROP Q'" by (rule equal_elim_rule1)
next
  assume P'Q': "PROP P' \<Longrightarrow> PROP Q'"
  and P: "PROP P"
  from PP' and P have P': "PROP P'" by (rule equal_elim_rule1)
  then have "PROP Q'" by (rule P'Q')
  with P'QQ' [OF P', symmetric] show "PROP Q"
    by (rule equal_elim_rule1)
qed

lemma uncurry:
  assumes "P \<longrightarrow> Q \<longrightarrow> R"
  shows "P \<and> Q \<longrightarrow> R"
  using assms by blast

lemma iff_allI:
  assumes "\<And>x. P x = Q x"
  shows "(\<forall>x. P x) = (\<forall>x. Q x)"
  using assms by blast

lemma iff_exI:
  assumes "\<And>x. P x = Q x"
  shows "(\<exists>x. P x) = (\<exists>x. Q x)"
  using assms by blast

lemma all_comm:
  "(\<forall>x y. P x y) = (\<forall>y x. P x y)"
  by blast

lemma ex_comm:
  "(\<exists>x y. P x y) = (\<exists>y x. P x y)"
  by blast

use "simpdata.ML"
ML {* open Simpdata *}

setup {*
  Simplifier.method_setup Splitter.split_modifiers
  #> (fn thy => (change_simpset_of thy (fn _ => Simpdata.simpset_simprocs); thy))
  #> Splitter.setup
  #> Clasimp.setup
  #> EqSubst.setup
*}

text {* Simproc for proving @{text "(y = x) == False"} from premise @{text "~(x = y)"}: *}

simproc_setup neq ("x = y") = {* fn _ =>
let
  val neq_to_EQ_False = @{thm not_sym} RS @{thm Eq_FalseI};
  fun is_neq eq lhs rhs thm =
    (case Thm.prop_of thm of
      _ $ (Not $ (eq' $ l' $ r')) =>
        Not = HOLogic.Not andalso eq' = eq andalso
        r' aconv lhs andalso l' aconv rhs
    | _ => false);
  fun proc ss ct =
    (case Thm.term_of ct of
      eq $ lhs $ rhs =>
        (case find_first (is_neq eq lhs rhs) (Simplifier.prems_of_ss ss) of
          SOME thm => SOME (thm RS neq_to_EQ_False)
        | NONE => NONE)
     | _ => NONE);
in proc end;
*}

simproc_setup let_simp ("Let x f") = {*
let
  val (f_Let_unfold, x_Let_unfold) =
    let val [(_$(f$x)$_)] = prems_of @{thm Let_unfold}
    in (cterm_of @{theory} f, cterm_of @{theory} x) end
  val (f_Let_folded, x_Let_folded) =
    let val [(_$(f$x)$_)] = prems_of @{thm Let_folded}
    in (cterm_of @{theory} f, cterm_of @{theory} x) end;
  val g_Let_folded =
    let val [(_$_$(g$_))] = prems_of @{thm Let_folded} in cterm_of @{theory} g end;

  fun proc _ ss ct =
    let
      val ctxt = Simplifier.the_context ss;
      val thy = ProofContext.theory_of ctxt;
      val t = Thm.term_of ct;
      val ([t'], ctxt') = Variable.import_terms false [t] ctxt;
    in Option.map (hd o Variable.export ctxt' ctxt o single)
      (case t' of Const ("Let",_) $ x $ f => (* x and f are already in normal form *)
        if is_Free x orelse is_Bound x orelse is_Const x
        then SOME @{thm Let_def}
        else
          let
            val n = case f of (Abs (x,_,_)) => x | _ => "x";
            val cx = cterm_of thy x;
            val {T=xT,...} = rep_cterm cx;
            val cf = cterm_of thy f;
            val fx_g = Simplifier.rewrite ss (Thm.capply cf cx);
            val (_$_$g) = prop_of fx_g;
            val g' = abstract_over (x,g);
          in (if (g aconv g')
               then
                  let
                    val rl =
                      cterm_instantiate [(f_Let_unfold,cf),(x_Let_unfold,cx)] @{thm Let_unfold};
                  in SOME (rl OF [fx_g]) end
               else if Term.betapply (f,x) aconv g then NONE (*avoid identity conversion*)
               else let
                     val abs_g'= Abs (n,xT,g');
                     val g'x = abs_g'$x;
                     val g_g'x = symmetric (beta_conversion false (cterm_of thy g'x));
                     val rl = cterm_instantiate
                               [(f_Let_folded,cterm_of thy f),(x_Let_folded,cx),
                                (g_Let_folded,cterm_of thy abs_g')]
                               @{thm Let_folded};
                   in SOME (rl OF [transitive fx_g g_g'x])
                   end)
          end
      | _ => NONE)
    end
in proc end *}


lemma True_implies_equals: "(True \<Longrightarrow> PROP P) \<equiv> PROP P"
proof
  assume "True \<Longrightarrow> PROP P"
  from this [OF TrueI] show "PROP P" .
next
  assume "PROP P"
  then show "PROP P" .
qed

lemma ex_simps:
  "!!P Q. (EX x. P x & Q)   = ((EX x. P x) & Q)"
  "!!P Q. (EX x. P & Q x)   = (P & (EX x. Q x))"
  "!!P Q. (EX x. P x | Q)   = ((EX x. P x) | Q)"
  "!!P Q. (EX x. P | Q x)   = (P | (EX x. Q x))"
  "!!P Q. (EX x. P x --> Q) = ((ALL x. P x) --> Q)"
  "!!P Q. (EX x. P --> Q x) = (P --> (EX x. Q x))"
  -- {* Miniscoping: pushing in existential quantifiers. *}
  by (iprover | blast)+

lemma all_simps:
  "!!P Q. (ALL x. P x & Q)   = ((ALL x. P x) & Q)"
  "!!P Q. (ALL x. P & Q x)   = (P & (ALL x. Q x))"
  "!!P Q. (ALL x. P x | Q)   = ((ALL x. P x) | Q)"
  "!!P Q. (ALL x. P | Q x)   = (P | (ALL x. Q x))"
  "!!P Q. (ALL x. P x --> Q) = ((EX x. P x) --> Q)"
  "!!P Q. (ALL x. P --> Q x) = (P --> (ALL x. Q x))"
  -- {* Miniscoping: pushing in universal quantifiers. *}
  by (iprover | blast)+

lemmas [simp] =
  triv_forall_equality (*prunes params*)
  True_implies_equals  (*prune asms `True'*)
  if_True
  if_False
  if_cancel
  if_eq_cancel
  imp_disjL
  (*In general it seems wrong to add distributive laws by default: they
    might cause exponential blow-up.  But imp_disjL has been in for a while
    and cannot be removed without affecting existing proofs.  Moreover,
    rewriting by "(P|Q --> R) = ((P-->R)&(Q-->R))" might be justified on the
    grounds that it allows simplification of R in the two cases.*)
  conj_assoc
  disj_assoc
  de_Morgan_conj
  de_Morgan_disj
  imp_disj1
  imp_disj2
  not_imp
  disj_not1
  not_all
  not_ex
  cases_simp
  the_eq_trivial
  the_sym_eq_trivial
  ex_simps
  all_simps
  simp_thms

lemmas [cong] = imp_cong simp_implies_cong
lemmas [split] = split_if

ML {* val HOL_ss = @{simpset} *}

text {* Simplifies x assuming c and y assuming ~c *}
lemma if_cong:
  assumes "b = c"
      and "c \<Longrightarrow> x = u"
      and "\<not> c \<Longrightarrow> y = v"
  shows "(if b then x else y) = (if c then u else v)"
  unfolding if_def using assms by simp

text {* Prevents simplification of x and y:
  faster and allows the execution of functional programs. *}
lemma if_weak_cong [cong]:
  assumes "b = c"
  shows "(if b then x else y) = (if c then x else y)"
  using assms by (rule arg_cong)

text {* Prevents simplification of t: much faster *}
lemma let_weak_cong:
  assumes "a = b"
  shows "(let x = a in t x) = (let x = b in t x)"
  using assms by (rule arg_cong)

text {* To tidy up the result of a simproc.  Only the RHS will be simplified. *}
lemma eq_cong2:
  assumes "u = u'"
  shows "(t \<equiv> u) \<equiv> (t \<equiv> u')"
  using assms by simp

lemma if_distrib:
  "f (if c then x else y) = (if c then f x else f y)"
  by simp

text {* This lemma restricts the effect of the rewrite rule u=v to the left-hand
  side of an equality.  Used in @{text "{Integ,Real}/simproc.ML"} *}
lemma restrict_to_left:
  assumes "x = y"
  shows "(x = z) = (y = z)"
  using assms by simp


subsubsection {* Generic cases and induction *}

text {* Rule projections: *}

ML {*
structure ProjectRule = ProjectRuleFun
(struct
  val conjunct1 = @{thm conjunct1};
  val conjunct2 = @{thm conjunct2};
  val mp = @{thm mp};
end)
*}

constdefs
  induct_forall where "induct_forall P == \<forall>x. P x"
  induct_implies where "induct_implies A B == A \<longrightarrow> B"
  induct_equal where "induct_equal x y == x = y"
  induct_conj where "induct_conj A B == A \<and> B"

lemma induct_forall_eq: "(!!x. P x) == Trueprop (induct_forall (\<lambda>x. P x))"
  by (unfold atomize_all induct_forall_def)

lemma induct_implies_eq: "(A ==> B) == Trueprop (induct_implies A B)"
  by (unfold atomize_imp induct_implies_def)

lemma induct_equal_eq: "(x == y) == Trueprop (induct_equal x y)"
  by (unfold atomize_eq induct_equal_def)

lemma induct_conj_eq:
  includes meta_conjunction_syntax
  shows "(A && B) == Trueprop (induct_conj A B)"
  by (unfold atomize_conj induct_conj_def)

lemmas induct_atomize = induct_forall_eq induct_implies_eq induct_equal_eq induct_conj_eq
lemmas induct_rulify [symmetric, standard] = induct_atomize
lemmas induct_rulify_fallback =
  induct_forall_def induct_implies_def induct_equal_def induct_conj_def


lemma induct_forall_conj: "induct_forall (\<lambda>x. induct_conj (A x) (B x)) =
    induct_conj (induct_forall A) (induct_forall B)"
  by (unfold induct_forall_def induct_conj_def) iprover

lemma induct_implies_conj: "induct_implies C (induct_conj A B) =
    induct_conj (induct_implies C A) (induct_implies C B)"
  by (unfold induct_implies_def induct_conj_def) iprover

lemma induct_conj_curry: "(induct_conj A B ==> PROP C) == (A ==> B ==> PROP C)"
proof
  assume r: "induct_conj A B ==> PROP C" and A B
  show "PROP C" by (rule r) (simp add: induct_conj_def `A` `B`)
next
  assume r: "A ==> B ==> PROP C" and "induct_conj A B"
  show "PROP C" by (rule r) (simp_all add: `induct_conj A B` [unfolded induct_conj_def])
qed

lemmas induct_conj = induct_forall_conj induct_implies_conj induct_conj_curry

hide const induct_forall induct_implies induct_equal induct_conj

text {* Method setup. *}

ML {*
  structure InductMethod = InductMethodFun
  (struct
    val cases_default = @{thm case_split}
    val atomize = @{thms induct_atomize}
    val rulify = @{thms induct_rulify}
    val rulify_fallback = @{thms induct_rulify_fallback}
  end);
*}

setup InductMethod.setup



subsection {* Other simple lemmas and lemma duplicates *}

lemma Let_0 [simp]: "Let 0 f = f 0"
  unfolding Let_def ..

lemma Let_1 [simp]: "Let 1 f = f 1"
  unfolding Let_def ..

lemma ex1_eq [iff]: "EX! x. x = t" "EX! x. t = x"
  by blast+

lemma choice_eq: "(ALL x. EX! y. P x y) = (EX! f. ALL x. P x (f x))"
  apply (rule iffI)
  apply (rule_tac a = "%x. THE y. P x y" in ex1I)
  apply (fast dest!: theI')
  apply (fast intro: ext the1_equality [symmetric])
  apply (erule ex1E)
  apply (rule allI)
  apply (rule ex1I)
  apply (erule spec)
  apply (erule_tac x = "%z. if z = x then y else f z" in allE)
  apply (erule impE)
  apply (rule allI)
  apply (rule_tac P = "xa = x" in case_split_thm)
  apply (drule_tac [3] x = x in fun_cong, simp_all)
  done

lemma mk_left_commute:
  fixes f (infix "\<otimes>" 60)
  assumes a: "\<And>x y z. (x \<otimes> y) \<otimes> z = x \<otimes> (y \<otimes> z)" and
          c: "\<And>x y. x \<otimes> y = y \<otimes> x"
  shows "x \<otimes> (y \<otimes> z) = y \<otimes> (x \<otimes> z)"
  by (rule trans [OF trans [OF c a] arg_cong [OF c, of "f y"]])

lemmas eq_sym_conv = eq_commute

lemma nnf_simps:
  "(\<not>(P \<and> Q)) = (\<not> P \<or> \<not> Q)" "(\<not> (P \<or> Q)) = (\<not> P \<and> \<not>Q)" "(P \<longrightarrow> Q) = (\<not>P \<or> Q)" 
  "(P = Q) = ((P \<and> Q) \<or> (\<not>P \<and> \<not> Q))" "(\<not>(P = Q)) = ((P \<and> \<not> Q) \<or> (\<not>P \<and> Q))" 
  "(\<not> \<not>(P)) = P"
by blast+


subsection {* Basic ML bindings *}

ML {*
val FalseE = @{thm FalseE}
val Let_def = @{thm Let_def}
val TrueI = @{thm TrueI}
val allE = @{thm allE}
val allI = @{thm allI}
val all_dupE = @{thm all_dupE}
val arg_cong = @{thm arg_cong}
val box_equals = @{thm box_equals}
val ccontr = @{thm ccontr}
val classical = @{thm classical}
val conjE = @{thm conjE}
val conjI = @{thm conjI}
val conjunct1 = @{thm conjunct1}
val conjunct2 = @{thm conjunct2}
val disjCI = @{thm disjCI}
val disjE = @{thm disjE}
val disjI1 = @{thm disjI1}
val disjI2 = @{thm disjI2}
val eq_reflection = @{thm eq_reflection}
val ex1E = @{thm ex1E}
val ex1I = @{thm ex1I}
val ex1_implies_ex = @{thm ex1_implies_ex}
val exE = @{thm exE}
val exI = @{thm exI}
val excluded_middle = @{thm excluded_middle}
val ext = @{thm ext}
val fun_cong = @{thm fun_cong}
val iffD1 = @{thm iffD1}
val iffD2 = @{thm iffD2}
val iffI = @{thm iffI}
val impE = @{thm impE}
val impI = @{thm impI}
val meta_eq_to_obj_eq = @{thm meta_eq_to_obj_eq}
val mp = @{thm mp}
val notE = @{thm notE}
val notI = @{thm notI}
val not_all = @{thm not_all}
val not_ex = @{thm not_ex}
val not_iff = @{thm not_iff}
val not_not = @{thm not_not}
val not_sym = @{thm not_sym}
val refl = @{thm refl}
val rev_mp = @{thm rev_mp}
val spec = @{thm spec}
val ssubst = @{thm ssubst}
val subst = @{thm subst}
val sym = @{thm sym}
val trans = @{thm trans}
*}


subsection {* Code generator basic setup -- see further @{text Code_Setup.thy} *}

setup "CodeName.setup #> CodeTarget.setup #> Nbe.setup"

class eq (attach "op =") = type

code_datatype True False

lemma [code func]:
  shows "False \<and> x \<longleftrightarrow> False"
    and "True \<and> x \<longleftrightarrow> x"
    and "x \<and> False \<longleftrightarrow> False"
    and "x \<and> True \<longleftrightarrow> x" by simp_all

lemma [code func]:
  shows "False \<or> x \<longleftrightarrow> x"
    and "True \<or> x \<longleftrightarrow> True"
    and "x \<or> False \<longleftrightarrow> x"
    and "x \<or> True \<longleftrightarrow> True" by simp_all

lemma [code func]:
  shows "\<not> True \<longleftrightarrow> False"
    and "\<not> False \<longleftrightarrow> True" by (rule HOL.simp_thms)+

instance bool :: eq ..

lemma [code func]:
  shows "False = P \<longleftrightarrow> \<not> P"
    and "True = P \<longleftrightarrow> P" 
    and "P = False \<longleftrightarrow> \<not> P" 
    and "P = True \<longleftrightarrow> P" by simp_all

code_datatype Trueprop "prop"

code_datatype "TYPE('a)"


subsection {* Legacy tactics and ML bindings *}

ML {*
fun strip_tac i = REPEAT (resolve_tac [impI, allI] i);

(* combination of (spec RS spec RS ...(j times) ... spec RS mp) *)
local
  fun wrong_prem (Const ("All", _) $ (Abs (_, _, t))) = wrong_prem t
    | wrong_prem (Bound _) = true
    | wrong_prem _ = false;
  val filter_right = filter (not o wrong_prem o HOLogic.dest_Trueprop o hd o Thm.prems_of);
in
  fun smp i = funpow i (fn m => filter_right ([spec] RL m)) ([mp]);
  fun smp_tac j = EVERY'[dresolve_tac (smp j), atac];
end;

val all_conj_distrib = thm "all_conj_distrib";
val all_simps = thms "all_simps";
val atomize_not = thm "atomize_not";
val case_split = thm "case_split_thm";
val case_split_thm = thm "case_split_thm"
val cases_simp = thm "cases_simp";
val choice_eq = thm "choice_eq"
val cong = thm "cong"
val conj_comms = thms "conj_comms";
val conj_cong = thm "conj_cong";
val de_Morgan_conj = thm "de_Morgan_conj";
val de_Morgan_disj = thm "de_Morgan_disj";
val disj_assoc = thm "disj_assoc";
val disj_comms = thms "disj_comms";
val disj_cong = thm "disj_cong";
val eq_ac = thms "eq_ac";
val eq_cong2 = thm "eq_cong2"
val Eq_FalseI = thm "Eq_FalseI";
val Eq_TrueI = thm "Eq_TrueI";
val Ex1_def = thm "Ex1_def"
val ex_disj_distrib = thm "ex_disj_distrib";
val ex_simps = thms "ex_simps";
val if_cancel = thm "if_cancel";
val if_eq_cancel = thm "if_eq_cancel";
val if_False = thm "if_False";
val iff_conv_conj_imp = thm "iff_conv_conj_imp";
val iff = thm "iff"
val if_splits = thms "if_splits";
val if_True = thm "if_True";
val if_weak_cong = thm "if_weak_cong"
val imp_all = thm "imp_all";
val imp_cong = thm "imp_cong";
val imp_conjL = thm "imp_conjL";
val imp_conjR = thm "imp_conjR";
val imp_conv_disj = thm "imp_conv_disj";
val simp_implies_def = thm "simp_implies_def";
val simp_thms = thms "simp_thms";
val split_if = thm "split_if";
val the1_equality = thm "the1_equality"
val theI = thm "theI"
val theI' = thm "theI'"
val True_implies_equals = thm "True_implies_equals";
val nnf_conv = Simplifier.rewrite (HOL_basic_ss addsimps simp_thms @ @{thms "nnf_simps"})

*}

end