--- a/src/HOL/Lambda/ParRed.thy Tue Sep 07 11:51:53 2010 +0200
+++ /dev/null Thu Jan 01 00:00:00 1970 +0000
@@ -1,115 +0,0 @@
-(* Title: HOL/Lambda/ParRed.thy
- Author: Tobias Nipkow
- Copyright 1995 TU Muenchen
-
-Properties of => and "cd", in particular the diamond property of => and
-confluence of beta.
-*)
-
-header {* Parallel reduction and a complete developments *}
-
-theory ParRed imports Lambda Commutation begin
-
-
-subsection {* Parallel reduction *}
-
-inductive par_beta :: "[dB, dB] => bool" (infixl "=>" 50)
- where
- var [simp, intro!]: "Var n => Var n"
- | abs [simp, intro!]: "s => t ==> Abs s => Abs t"
- | app [simp, intro!]: "[| s => s'; t => t' |] ==> s \<degree> t => s' \<degree> t'"
- | beta [simp, intro!]: "[| s => s'; t => t' |] ==> (Abs s) \<degree> t => s'[t'/0]"
-
-inductive_cases par_beta_cases [elim!]:
- "Var n => t"
- "Abs s => Abs t"
- "(Abs s) \<degree> t => u"
- "s \<degree> t => u"
- "Abs s => t"
-
-
-subsection {* Inclusions *}
-
-text {* @{text "beta \<subseteq> par_beta \<subseteq> beta^*"} \medskip *}
-
-lemma par_beta_varL [simp]:
- "(Var n => t) = (t = Var n)"
- by blast
-
-lemma par_beta_refl [simp]: "t => t" (* par_beta_refl [intro!] causes search to blow up *)
- by (induct t) simp_all
-
-lemma beta_subset_par_beta: "beta <= par_beta"
- apply (rule predicate2I)
- apply (erule beta.induct)
- apply (blast intro!: par_beta_refl)+
- done
-
-lemma par_beta_subset_beta: "par_beta <= beta^**"
- apply (rule predicate2I)
- apply (erule par_beta.induct)
- apply blast
- apply (blast del: rtranclp.rtrancl_refl intro: rtranclp.rtrancl_into_rtrancl)+
- -- {* @{thm[source] rtrancl_refl} complicates the proof by increasing the branching factor *}
- done
-
-
-subsection {* Misc properties of @{text "par_beta"} *}
-
-lemma par_beta_lift [simp]:
- "t => t' \<Longrightarrow> lift t n => lift t' n"
- by (induct t arbitrary: t' n) fastsimp+
-
-lemma par_beta_subst:
- "s => s' \<Longrightarrow> t => t' \<Longrightarrow> t[s/n] => t'[s'/n]"
- apply (induct t arbitrary: s s' t' n)
- apply (simp add: subst_Var)
- apply (erule par_beta_cases)
- apply simp
- apply (simp add: subst_subst [symmetric])
- apply (fastsimp intro!: par_beta_lift)
- apply fastsimp
- done
-
-
-subsection {* Confluence (directly) *}
-
-lemma diamond_par_beta: "diamond par_beta"
- apply (unfold diamond_def commute_def square_def)
- apply (rule impI [THEN allI [THEN allI]])
- apply (erule par_beta.induct)
- apply (blast intro!: par_beta_subst)+
- done
-
-
-subsection {* Complete developments *}
-
-fun
- "cd" :: "dB => dB"
-where
- "cd (Var n) = Var n"
-| "cd (Var n \<degree> t) = Var n \<degree> cd t"
-| "cd ((s1 \<degree> s2) \<degree> t) = cd (s1 \<degree> s2) \<degree> cd t"
-| "cd (Abs u \<degree> t) = (cd u)[cd t/0]"
-| "cd (Abs s) = Abs (cd s)"
-
-lemma par_beta_cd: "s => t \<Longrightarrow> t => cd s"
- apply (induct s arbitrary: t rule: cd.induct)
- apply auto
- apply (fast intro!: par_beta_subst)
- done
-
-
-subsection {* Confluence (via complete developments) *}
-
-lemma diamond_par_beta2: "diamond par_beta"
- apply (unfold diamond_def commute_def square_def)
- apply (blast intro: par_beta_cd)
- done
-
-theorem beta_confluent: "confluent beta"
- apply (rule diamond_par_beta2 diamond_to_confluence
- par_beta_subset_beta beta_subset_par_beta)+
- done
-
-end