10496
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(* Title: HOL/BCV/Err.thy
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ID: $Id$
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Author: Tobias Nipkow
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Copyright 2000 TUM
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The error type
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*)
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header "The Error Type"
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theory Err = Semilat:
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datatype 'a err = Err | OK 'a
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types 'a ebinop = "'a => 'a => 'a err"
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'a esl = "'a set * 'a ord * 'a ebinop"
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consts
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ok_val :: "'a err => 'a"
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primrec
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"ok_val (OK x) = x"
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constdefs
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lift :: "('a => 'b err) => ('a err => 'b err)"
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"lift f e == case e of Err => Err | OK x => f x"
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lift2 :: "('a => 'b => 'c err) => 'a err => 'b err => 'c err"
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"lift2 f e1 e2 ==
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case e1 of Err => Err
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| OK x => (case e2 of Err => Err | OK y => f x y)"
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le :: "'a ord => 'a err ord"
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"le r e1 e2 ==
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case e2 of Err => True |
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OK y => (case e1 of Err => False | OK x => x <=_r y)"
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sup :: "('a => 'b => 'c) => ('a err => 'b err => 'c err)"
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"sup f == lift2(%x y. OK(x +_f y))"
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err :: "'a set => 'a err set"
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"err A == insert Err {x . ? y:A. x = OK y}"
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esl :: "'a sl => 'a esl"
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"esl == %(A,r,f). (A,r, %x y. OK(f x y))"
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sl :: "'a esl => 'a err sl"
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"sl == %(A,r,f). (err A, le r, lift2 f)"
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syntax
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err_semilat :: "'a esl => bool"
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translations
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"err_semilat L" == "semilat(Err.sl L)"
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lemma not_Err_eq:
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"(x \<noteq> Err) = (\<exists>a. x = OK a)"
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by (cases x) auto
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lemma not_OK_eq:
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"(\<forall>y. x \<noteq> OK y) = (x = Err)"
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by (cases x) auto
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lemma unfold_lesub_err:
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"e1 <=_(le r) e2 == le r e1 e2"
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by (simp add: lesub_def)
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lemma le_err_refl:
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"!x. x <=_r x ==> e <=_(Err.le r) e"
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apply (unfold lesub_def Err.le_def)
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apply (simp split: err.split)
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done
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lemma le_err_trans [rule_format]:
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"order r ==> e1 <=_(le r) e2 --> e2 <=_(le r) e3 --> e1 <=_(le r) e3"
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apply (unfold unfold_lesub_err le_def)
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apply (simp split: err.split)
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apply (blast intro: order_trans)
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done
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lemma le_err_antisym [rule_format]:
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"order r ==> e1 <=_(le r) e2 --> e2 <=_(le r) e1 --> e1=e2"
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apply (unfold unfold_lesub_err le_def)
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apply (simp split: err.split)
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apply (blast intro: order_antisym)
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done
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lemma OK_le_err_OK:
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"(OK x <=_(le r) OK y) = (x <=_r y)"
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by (simp add: unfold_lesub_err le_def)
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lemma order_le_err [iff]:
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"order(le r) = order r"
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apply (rule iffI)
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apply (subst order_def)
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apply (blast dest: order_antisym OK_le_err_OK [THEN iffD2]
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intro: order_trans OK_le_err_OK [THEN iffD1])
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apply (subst order_def)
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apply (blast intro: le_err_refl le_err_trans le_err_antisym
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dest: order_refl)
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done
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lemma le_Err [iff]: "e <=_(le r) Err"
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by (simp add: unfold_lesub_err le_def)
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lemma Err_le_conv [iff]:
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"Err <=_(le r) e = (e = Err)"
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by (simp add: unfold_lesub_err le_def split: err.split)
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lemma le_OK_conv [iff]:
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"e <=_(le r) OK x = (? y. e = OK y & y <=_r x)"
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by (simp add: unfold_lesub_err le_def split: err.split)
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lemma OK_le_conv:
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"OK x <=_(le r) e = (e = Err | (? y. e = OK y & x <=_r y))"
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by (simp add: unfold_lesub_err le_def split: err.split)
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lemma top_Err [iff]: "top (le r) Err";
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by (simp add: top_def)
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lemma OK_less_conv [rule_format, iff]:
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"OK x <_(le r) e = (e=Err | (? y. e = OK y & x <_r y))"
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by (simp add: lesssub_def lesub_def le_def split: err.split)
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lemma not_Err_less [rule_format, iff]:
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"~(Err <_(le r) x)"
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by (simp add: lesssub_def lesub_def le_def split: err.split)
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lemma semilat_errI:
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"semilat(A,r,f) ==> semilat(err A, Err.le r, lift2(%x y. OK(f x y)))"
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apply (unfold semilat_Def closed_def plussub_def lesub_def lift2_def Err.le_def err_def)
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apply (simp split: err.split)
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apply blast
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done
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lemma err_semilat_eslI:
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"!!L. semilat L ==> err_semilat(esl L)"
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apply (unfold sl_def esl_def)
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apply (simp (no_asm_simp) only: split_tupled_all)
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apply (simp add: semilat_errI)
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done
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lemma acc_err [simp, intro!]: "acc r ==> acc(le r)"
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apply (unfold acc_def lesub_def le_def lesssub_def)
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apply (simp add: wf_eq_minimal split: err.split)
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apply clarify
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apply (case_tac "Err : Q")
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apply blast
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apply (erule_tac x = "{a . OK a : Q}" in allE)
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apply (case_tac "x")
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apply fast
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apply blast
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done
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lemma Err_in_err [iff]: "Err : err A"
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by (simp add: err_def)
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lemma Ok_in_err [iff]: "(OK x : err A) = (x:A)"
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by (auto simp add: err_def)
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(** lift **)
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lemma lift_in_errI:
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"[| e : err S; !x:S. e = OK x --> f x : err S |] ==> lift f e : err S"
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apply (unfold lift_def)
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apply (simp split: err.split)
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apply blast
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done
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(** lift2 **)
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lemma Err_lift2 [simp]:
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"Err +_(lift2 f) x = Err"
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by (simp add: lift2_def plussub_def)
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lemma lift2_Err [simp]:
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"x +_(lift2 f) Err = Err"
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by (simp add: lift2_def plussub_def split: err.split)
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lemma OK_lift2_OK [simp]:
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"OK x +_(lift2 f) OK y = x +_f y"
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by (simp add: lift2_def plussub_def split: err.split)
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(** sup **)
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lemma Err_sup_Err [simp]:
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"Err +_(Err.sup f) x = Err"
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by (simp add: plussub_def Err.sup_def Err.lift2_def)
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lemma Err_sup_Err2 [simp]:
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"x +_(Err.sup f) Err = Err"
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by (simp add: plussub_def Err.sup_def Err.lift2_def split: err.split)
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lemma Err_sup_OK [simp]:
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"OK x +_(Err.sup f) OK y = OK(x +_f y)"
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by (simp add: plussub_def Err.sup_def Err.lift2_def)
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lemma Err_sup_eq_OK_conv [iff]:
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"(Err.sup f ex ey = OK z) = (? x y. ex = OK x & ey = OK y & f x y = z)"
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apply (unfold Err.sup_def lift2_def plussub_def)
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apply (rule iffI)
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apply (simp split: err.split_asm)
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apply clarify
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apply simp
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done
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lemma Err_sup_eq_Err [iff]:
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"(Err.sup f ex ey = Err) = (ex=Err | ey=Err)"
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apply (unfold Err.sup_def lift2_def plussub_def)
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apply (simp split: err.split)
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done
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(*** semilat (err A) (le r) f ***)
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lemma semilat_le_err_Err_plus [simp]:
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"[| x: err A; semilat(err A, le r, f) |] ==> Err +_f x = Err"
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by (blast intro: le_iff_plus_unchanged [THEN iffD1] le_iff_plus_unchanged2 [THEN iffD1])
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lemma semilat_le_err_plus_Err [simp]:
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"[| x: err A; semilat(err A, le r, f) |] ==> x +_f Err = Err"
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by (blast intro: le_iff_plus_unchanged [THEN iffD1] le_iff_plus_unchanged2 [THEN iffD1])
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lemma semilat_le_err_OK1:
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"[| x:A; y:A; semilat(err A, le r, f); OK x +_f OK y = OK z |]
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==> x <=_r z";
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apply (rule OK_le_err_OK [THEN iffD1])
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apply (erule subst)
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apply simp
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done
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lemma semilat_le_err_OK2:
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"[| x:A; y:A; semilat(err A, le r, f); OK x +_f OK y = OK z |]
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==> y <=_r z"
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apply (rule OK_le_err_OK [THEN iffD1])
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apply (erule subst)
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apply simp
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done
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lemma eq_order_le:
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"[| x=y; order r |] ==> x <=_r y"
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apply (unfold order_def)
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apply blast
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done
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lemma OK_plus_OK_eq_Err_conv [simp]:
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"[| x:A; y:A; semilat(err A, le r, fe) |] ==>
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((OK x) +_fe (OK y) = Err) = (~(? z:A. x <=_r z & y <=_r z))"
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proof -
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have plus_le_conv3: "!!A x y z f r.
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[| semilat (A,r,f); x +_f y <=_r z; x:A; y:A; z:A |]
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==> x <=_r z \<and> y <=_r z"
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by (rule plus_le_conv [THEN iffD1])
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case antecedent
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thus ?thesis
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apply (rule_tac iffI)
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apply clarify
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apply (drule OK_le_err_OK [THEN iffD2])
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apply (drule OK_le_err_OK [THEN iffD2])
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apply (drule semilat_lub)
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apply assumption
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apply assumption
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apply simp
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apply simp
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apply simp
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apply simp
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apply (case_tac "(OK x) +_fe (OK y)")
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apply assumption
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apply (rename_tac z)
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apply (subgoal_tac "OK z: err A")
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apply (drule eq_order_le)
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apply blast
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apply (blast dest: plus_le_conv3)
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apply (erule subst)
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apply (blast intro: closedD)
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done
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qed
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(*** semilat (err(Union AS)) ***)
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(* FIXME? *)
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lemma all_bex_swap_lemma [iff]:
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"(!x. (? y:A. x = f y) --> P x) = (!y:A. P(f y))"
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by blast
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lemma closed_err_Union_lift2I:
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"[| !A:AS. closed (err A) (lift2 f); AS ~= {};
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!A:AS.!B:AS. A~=B --> (!a:A.!b:B. a +_f b = Err) |]
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==> closed (err(Union AS)) (lift2 f)"
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apply (unfold closed_def err_def)
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apply simp
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apply clarify
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apply simp
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apply fast
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done
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(* If AS = {} the thm collapses to
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order r & closed {Err} f & Err +_f Err = Err
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which may not hold *)
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lemma err_semilat_UnionI:
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"[| !A:AS. err_semilat(A, r, f); AS ~= {};
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!A:AS.!B:AS. A~=B --> (!a:A.!b:B. ~ a <=_r b & a +_f b = Err) |]
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==> err_semilat(Union AS, r, f)"
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apply (unfold semilat_def sl_def)
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apply (simp add: closed_err_Union_lift2I)
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apply (rule conjI)
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apply blast
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apply (simp add: err_def)
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apply (rule conjI)
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apply clarify
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apply (rename_tac A a u B b)
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apply (case_tac "A = B")
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apply simp
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apply simp
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apply (rule conjI)
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apply clarify
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apply (rename_tac A a u B b)
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apply (case_tac "A = B")
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apply simp
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apply simp
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apply clarify
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apply (rename_tac A ya yb B yd z C c a b)
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apply (case_tac "A = B")
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apply (case_tac "A = C")
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apply simp
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apply (rotate_tac -1)
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apply simp
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apply (rotate_tac -1)
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apply (case_tac "B = C")
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apply simp
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apply (rotate_tac -1)
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apply simp
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done
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end
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