
diff -r 2585e2a7a7ab -r 5c063eeda622 AFP-Submission/Lexer.thy
--- a/AFP-Submission/Lexer.thy	Tue Jun 14 12:37:46 2016 +0100
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,493 +0,0 @@
-(*  Title:       POSIX Lexing with Derivatives of Regular Expressions
-    Authors:     Fahad Ausaf <fahad.ausaf at icloud.com>, 2016
-                 Roy Dyckhoff <roy.dyckhoff at st-andrews.ac.uk>, 2016
-                 Christian Urban <christian.urban at kcl.ac.uk>, 2016
-    Maintainer:  Christian Urban <christian.urban at kcl.ac.uk>
-*) 
-
-theory Lexer
-  imports Derivatives
-begin
-
-section {* Values *}
-
-datatype 'a val = 
-  Void
-| Atm 'a
-| Seq "'a val" "'a val"
-| Right "'a val"
-| Left "'a val"
-| Stars "('a val) list"
-
-
-section {* The string behind a value *}
-
-fun 
-  flat :: "'a val \<Rightarrow> 'a list"
-where
-  "flat (Void) = []"
-| "flat (Atm c) = [c]"
-| "flat (Left v) = flat v"
-| "flat (Right v) = flat v"
-| "flat (Seq v1 v2) = (flat v1) @ (flat v2)"
-| "flat (Stars []) = []"
-| "flat (Stars (v#vs)) = (flat v) @ (flat (Stars vs))" 
-
-lemma flat_Stars [simp]:
- "flat (Stars vs) = concat (map flat vs)"
-by (induct vs) (auto)
-
-section {* Relation between values and regular expressions *}
-
-inductive 
-  Prf :: "'a val \<Rightarrow> 'a rexp \<Rightarrow> bool" ("\<turnstile> _ : _" [100, 100] 100)
-where
- "\<lbrakk>\<turnstile> v1 : r1; \<turnstile> v2 : r2\<rbrakk> \<Longrightarrow> \<turnstile> Seq v1 v2 : Times r1 r2"
-| "\<turnstile> v1 : r1 \<Longrightarrow> \<turnstile> Left v1 : Plus r1 r2"
-| "\<turnstile> v2 : r2 \<Longrightarrow> \<turnstile> Right v2 : Plus r1 r2"
-| "\<turnstile> Void : One"
-| "\<turnstile> Atm c : Atom c"
-| "\<turnstile> Stars [] : Star r"
-| "\<lbrakk>\<turnstile> v : r; \<turnstile> Stars vs : Star r\<rbrakk> \<Longrightarrow> \<turnstile> Stars (v # vs) : Star r"
-
-inductive_cases Prf_elims:
-  "\<turnstile> v : Zero"
-  "\<turnstile> v : Times r1 r2"
-  "\<turnstile> v : Plus r1 r2"
-  "\<turnstile> v : One"
-  "\<turnstile> v : Atom c"
-(*  "\<turnstile> vs : Star r"*)
-
-lemma Prf_flat_lang:
-  assumes "\<turnstile> v : r" shows "flat v \<in> lang r"
-using assms
-by(induct v r rule: Prf.induct) (auto)
-
-lemma Prf_Stars:
-  assumes "\<forall>v \<in> set vs. \<turnstile> v : r"
-  shows "\<turnstile> Stars vs : Star r"
-using assms
-by(induct vs) (auto intro: Prf.intros)
-
-lemma Star_string:
-  assumes "s \<in> star A"
-  shows "\<exists>ss. concat ss = s \<and> (\<forall>s \<in> set ss. s \<in> A)"
-using assms
-by (metis in_star_iff_concat set_mp)
-
-lemma Star_val:
-  assumes "\<forall>s\<in>set ss. \<exists>v. s = flat v \<and> \<turnstile> v : r"
-  shows "\<exists>vs. concat (map flat vs) = concat ss \<and> (\<forall>v\<in>set vs. \<turnstile> v : r)"
-using assms
-apply(induct ss)
-apply(auto)
-apply (metis empty_iff list.set(1))
-by (metis concat.simps(2) list.simps(9) set_ConsD)
-
-lemma L_flat_Prf1:
-  assumes "\<turnstile> v : r" shows "flat v \<in> lang r"
-using assms
-by (induct)(auto)
-
-lemma L_flat_Prf2:
-  assumes "s \<in> lang r" shows "\<exists>v. \<turnstile> v : r \<and> flat v = s"
-using assms
-apply(induct r arbitrary: s)
-apply(auto intro: Prf.intros)
-using Prf.intros(2) flat.simps(3) apply blast
-using Prf.intros(3) flat.simps(4) apply blast
-apply (metis Prf.intros(1) concE flat.simps(5))
-apply(subgoal_tac "\<exists>vs::('a val) list. concat (map flat vs) = s \<and> (\<forall>v \<in> set vs. \<turnstile> v : r)")
-apply(auto)[1]
-apply(rule_tac x="Stars vs" in exI)
-apply(simp)
-apply (simp add: Prf_Stars)
-apply(drule Star_string)
-apply(auto)
-apply(rule Star_val)
-apply(auto)
-done
-
-lemma L_flat_Prf:
-  "lang r = {flat v | v. \<turnstile> v : r}"
-using L_flat_Prf1 L_flat_Prf2 by blast
-
-
-section {* Sulzmann and Lu functions *}
-
-fun 
-  mkeps :: "'a rexp \<Rightarrow> 'a val"
-where
-  "mkeps(One) = Void"
-| "mkeps(Times r1 r2) = Seq (mkeps r1) (mkeps r2)"
-| "mkeps(Plus r1 r2) = (if nullable(r1) then Left (mkeps r1) else Right (mkeps r2))"
-| "mkeps(Star r) = Stars []"
-
-fun injval :: "'a rexp \<Rightarrow> 'a \<Rightarrow> 'a val \<Rightarrow> 'a val"
-where
-  "injval (Atom d) c Void = Atm d"
-| "injval (Plus r1 r2) c (Left v1) = Left(injval r1 c v1)"
-| "injval (Plus r1 r2) c (Right v2) = Right(injval r2 c v2)"
-| "injval (Times r1 r2) c (Seq v1 v2) = Seq (injval r1 c v1) v2"
-| "injval (Times r1 r2) c (Left (Seq v1 v2)) = Seq (injval r1 c v1) v2"
-| "injval (Times r1 r2) c (Right v2) = Seq (mkeps r1) (injval r2 c v2)"
-| "injval (Star r) c (Seq v (Stars vs)) = Stars ((injval r c v) # vs)" 
-
-
-section {* Mkeps, injval *}
-
-lemma mkeps_nullable:
-  assumes "nullable r" 
-  shows "\<turnstile> mkeps r : r"
-using assms
-by (induct r) 
-   (auto intro: Prf.intros)
-
-lemma mkeps_flat:
-  assumes "nullable r" 
-  shows "flat (mkeps r) = []"
-using assms
-by (induct r) (auto)
-
-
-lemma Prf_injval:
-  assumes "\<turnstile> v : deriv c r" 
-  shows "\<turnstile> (injval r c v) : r"
-using assms
-apply(induct r arbitrary: c v rule: rexp.induct)
-apply(auto intro!: Prf.intros mkeps_nullable elim!: Prf_elims split: if_splits)
-(* Star *)
-apply(rotate_tac 2)
-apply(erule Prf.cases)
-apply(simp_all)[7]
-apply(auto)
-apply (metis Prf.intros(6) Prf.intros(7))
-by (metis Prf.intros(7))
-
-lemma Prf_injval_flat:
-  assumes "\<turnstile> v : deriv c r" 
-  shows "flat (injval r c v) = c # (flat v)"
-using assms
-apply(induct r arbitrary: v c)
-apply(auto elim!: Prf_elims split: if_splits)
-apply(metis mkeps_flat)
-apply(rotate_tac 2)
-apply(erule Prf.cases)
-apply(simp_all)[7]
-done
-
-(* HERE *)
-
-section {* Our Alternative Posix definition *}
-
-inductive 
-  Posix :: "'a list \<Rightarrow> 'a rexp \<Rightarrow> 'a val \<Rightarrow> bool" ("_ \<in> _ \<rightarrow> _" [100, 100, 100] 100)
-where
-  Posix_One: "[] \<in> One \<rightarrow> Void"
-| Posix_Atom: "[c] \<in> (Atom c) \<rightarrow> (Atm c)"
-| Posix_Plus1: "s \<in> r1 \<rightarrow> v \<Longrightarrow> s \<in> (Plus r1 r2) \<rightarrow> (Left v)"
-| Posix_Plus2: "\<lbrakk>s \<in> r2 \<rightarrow> v; s \<notin> lang r1\<rbrakk> \<Longrightarrow> s \<in> (Plus r1 r2) \<rightarrow> (Right v)"
-| Posix_Times: "\<lbrakk>s1 \<in> r1 \<rightarrow> v1; s2 \<in> r2 \<rightarrow> v2;
-    \<not>(\<exists>s\<^sub>3 s\<^sub>4. s\<^sub>3 \<noteq> [] \<and> s\<^sub>3 @ s\<^sub>4 = s2 \<and> (s1 @ s\<^sub>3) \<in> lang r1 \<and> s\<^sub>4 \<in> lang r2)\<rbrakk> \<Longrightarrow> 
-    (s1 @ s2) \<in> (Times r1 r2) \<rightarrow> (Seq v1 v2)"
-| Posix_Star1: "\<lbrakk>s1 \<in> r \<rightarrow> v; s2 \<in> Star r \<rightarrow> Stars vs; flat v \<noteq> [];
-    \<not>(\<exists>s\<^sub>3 s\<^sub>4. s\<^sub>3 \<noteq> [] \<and> s\<^sub>3 @ s\<^sub>4 = s2 \<and> (s1 @ s\<^sub>3) \<in> lang r \<and> s\<^sub>4 \<in> lang (Star r))\<rbrakk>
-    \<Longrightarrow> (s1 @ s2) \<in> Star r \<rightarrow> Stars (v # vs)"
-| Posix_Star2: "[] \<in> Star r \<rightarrow> Stars []"
-
-inductive_cases Posix_elims:
-  "s \<in> Zero \<rightarrow> v"
-  "s \<in> One \<rightarrow> v"
-  "s \<in> Atom c \<rightarrow> v"
-  "s \<in> Plus r1 r2 \<rightarrow> v"
-  "s \<in> Times r1 r2 \<rightarrow> v"
-  "s \<in> Star r \<rightarrow> v"
-
-lemma Posix1:
-  assumes "s \<in> r \<rightarrow> v"
-  shows "s \<in> lang r" "flat v = s"
-using assms
-by (induct s r v rule: Posix.induct) (auto)
-
-
-lemma Posix1a:
-  assumes "s \<in> r \<rightarrow> v"
-  shows "\<turnstile> v : r"
-using assms
-by (induct s r v rule: Posix.induct)(auto intro: Prf.intros)
-
-
-lemma Posix_mkeps:
-  assumes "nullable r"
-  shows "[] \<in> r \<rightarrow> mkeps r"
-using assms
-apply(induct r)
-apply(auto intro: Posix.intros simp add: nullable_iff)
-apply(subst append.simps(1)[symmetric])
-apply(rule Posix.intros)
-apply(auto)
-done
-
-
-lemma Posix_determ:
-  assumes "s \<in> r \<rightarrow> v1" "s \<in> r \<rightarrow> v2"
-  shows "v1 = v2"
-using assms
-proof (induct s r v1 arbitrary: v2 rule: Posix.induct)
-  case (Posix_One v2)
-  have "[] \<in> One \<rightarrow> v2" by fact
-  then show "Void = v2" by cases auto
-next 
-  case (Posix_Atom c v2)
-  have "[c] \<in> Atom c \<rightarrow> v2" by fact
-  then show "Atm c = v2" by cases auto
-next 
-  case (Posix_Plus1 s r1 v r2 v2)
-  have "s \<in> Plus r1 r2 \<rightarrow> v2" by fact
-  moreover
-  have "s \<in> r1 \<rightarrow> v" by fact
-  then have "s \<in> lang r1" by (simp add: Posix1)
-  ultimately obtain v' where eq: "v2 = Left v'" "s \<in> r1 \<rightarrow> v'" by cases auto 
-  moreover
-  have IH: "\<And>v2. s \<in> r1 \<rightarrow> v2 \<Longrightarrow> v = v2" by fact
-  ultimately have "v = v'" by simp
-  then show "Left v = v2" using eq by simp
-next 
-  case (Posix_Plus2 s r2 v r1 v2)
-  have "s \<in> Plus r1 r2 \<rightarrow> v2" by fact
-  moreover
-  have "s \<notin> lang r1" by fact
-  ultimately obtain v' where eq: "v2 = Right v'" "s \<in> r2 \<rightarrow> v'" 
-    by cases (auto simp add: Posix1) 
-  moreover
-  have IH: "\<And>v2. s \<in> r2 \<rightarrow> v2 \<Longrightarrow> v = v2" by fact
-  ultimately have "v = v'" by simp
-  then show "Right v = v2" using eq by simp
-next
-  case (Posix_Times s1 r1 v1 s2 r2 v2 v')
-  have "(s1 @ s2) \<in> Times r1 r2 \<rightarrow> v'" 
-       "s1 \<in> r1 \<rightarrow> v1" "s2 \<in> r2 \<rightarrow> v2"
-       "\<not> (\<exists>s\<^sub>3 s\<^sub>4. s\<^sub>3 \<noteq> [] \<and> s\<^sub>3 @ s\<^sub>4 = s2 \<and> s1 @ s\<^sub>3 \<in> lang r1 \<and> s\<^sub>4 \<in> lang r2)" by fact+
-  then obtain v1' v2' where "v' = Seq v1' v2'" "s1 \<in> r1 \<rightarrow> v1'" "s2 \<in> r2 \<rightarrow> v2'"
-  apply(cases) apply (auto simp add: append_eq_append_conv2)
-  using Posix1(1) by fastforce+
-  moreover
-  have IHs: "\<And>v1'. s1 \<in> r1 \<rightarrow> v1' \<Longrightarrow> v1 = v1'"
-            "\<And>v2'. s2 \<in> r2 \<rightarrow> v2' \<Longrightarrow> v2 = v2'" by fact+
-  ultimately show "Seq v1 v2 = v'" by simp
-next
-  case (Posix_Star1 s1 r v s2 vs v2)
-  have "(s1 @ s2) \<in> Star r \<rightarrow> v2" 
-       "s1 \<in> r \<rightarrow> v" "s2 \<in> Star r \<rightarrow> Stars vs" "flat v \<noteq> []"
-       "\<not> (\<exists>s\<^sub>3 s\<^sub>4. s\<^sub>3 \<noteq> [] \<and> s\<^sub>3 @ s\<^sub>4 = s2 \<and> s1 @ s\<^sub>3 \<in> lang r \<and> s\<^sub>4 \<in> lang (Star r))" by fact+
-  then obtain v' vs' where "v2 = Stars (v' # vs')" "s1 \<in> r \<rightarrow> v'" "s2 \<in> (Star r) \<rightarrow> (Stars vs')"
-  apply(cases) apply (auto simp add: append_eq_append_conv2)
-  using Posix1(1) apply fastforce
-  apply (metis Posix1(1) Posix_Star1.hyps(6) append_Nil append_Nil2)
-  using Posix1(2) by blast
-  moreover
-  have IHs: "\<And>v2. s1 \<in> r \<rightarrow> v2 \<Longrightarrow> v = v2"
-            "\<And>v2. s2 \<in> Star r \<rightarrow> v2 \<Longrightarrow> Stars vs = v2" by fact+
-  ultimately show "Stars (v # vs) = v2" by auto
-next
-  case (Posix_Star2 r v2)
-  have "[] \<in> Star r \<rightarrow> v2" by fact
-  then show "Stars [] = v2" by cases (auto simp add: Posix1)
-qed
-
-
-lemma Posix_injval:
-  assumes "s \<in> (deriv c r) \<rightarrow> v"
-  shows "(c # s) \<in> r \<rightarrow> (injval r c v)"
-using assms
-proof(induct r arbitrary: s v rule: rexp.induct)
-  case Zero
-  have "s \<in> deriv c Zero \<rightarrow> v" by fact
-  then have "s \<in> Zero \<rightarrow> v" by simp
-  then have "False" by cases
-  then show "(c # s) \<in> Zero \<rightarrow> (injval Zero c v)" by simp
-next
-  case One
-  have "s \<in> deriv c One \<rightarrow> v" by fact
-  then have "s \<in> Zero \<rightarrow> v" by simp
-  then have "False" by cases
-  then show "(c # s) \<in> One \<rightarrow> (injval One c v)" by simp
-next 
-  case (Atom d)
-  consider (eq) "c = d" | (ineq) "c \<noteq> d" by blast
-  then show "(c # s) \<in> (Atom d) \<rightarrow> (injval (Atom d) c v)"
-  proof (cases)
-    case eq
-    have "s \<in> deriv c (Atom d) \<rightarrow> v" by fact
-    then have "s \<in> One \<rightarrow> v" using eq by simp
-    then have eqs: "s = [] \<and> v = Void" by cases simp
-    show "(c # s) \<in> Atom d \<rightarrow> injval (Atom d) c v" using eq eqs 
-    by (auto intro: Posix.intros)
-  next
-    case ineq
-    have "s \<in> deriv c (Atom d) \<rightarrow> v" by fact
-    then have "s \<in> Zero \<rightarrow> v" using ineq by simp
-    then have "False" by cases
-    then show "(c # s) \<in> Atom d \<rightarrow> injval (Atom d) c v" by simp
-  qed
-next
-  case (Plus r1 r2)
-  have IH1: "\<And>s v. s \<in> deriv c r1 \<rightarrow> v \<Longrightarrow> (c # s) \<in> r1 \<rightarrow> injval r1 c v" by fact
-  have IH2: "\<And>s v. s \<in> deriv c r2 \<rightarrow> v \<Longrightarrow> (c # s) \<in> r2 \<rightarrow> injval r2 c v" by fact
-  have "s \<in> deriv c (Plus r1 r2) \<rightarrow> v" by fact
-  then have "s \<in> Plus (deriv c r1) (deriv c r2) \<rightarrow> v" by simp
-  then consider (left) v' where "v = Left v'" "s \<in> deriv c r1 \<rightarrow> v'" 
-              | (right) v' where "v = Right v'" "s \<notin> lang (deriv c r1)" "s \<in> deriv c r2 \<rightarrow> v'" 
-              by cases auto
-  then show "(c # s) \<in> Plus r1 r2 \<rightarrow> injval (Plus r1 r2) c v"
-  proof (cases)
-    case left
-    have "s \<in> deriv c r1 \<rightarrow> v'" by fact
-    then have "(c # s) \<in> r1 \<rightarrow> injval r1 c v'" using IH1 by simp
-    then have "(c # s) \<in> Plus r1 r2 \<rightarrow> injval (Plus r1 r2) c (Left v')" by (auto intro: Posix.intros)
-    then show "(c # s) \<in> Plus r1 r2 \<rightarrow> injval (Plus r1 r2) c v" using left by simp
-  next 
-    case right
-    have "s \<notin> lang (deriv c r1)" by fact
-    then have "c # s \<notin> lang r1" by (simp add: lang_deriv Deriv_def)
-    moreover 
-    have "s \<in> deriv c r2 \<rightarrow> v'" by fact
-    then have "(c # s) \<in> r2 \<rightarrow> injval r2 c v'" using IH2 by simp
-    ultimately have "(c # s) \<in> Plus r1 r2 \<rightarrow> injval (Plus r1 r2) c (Right v')" 
-      by (auto intro: Posix.intros)
-    then show "(c # s) \<in> Plus r1 r2 \<rightarrow> injval (Plus r1 r2) c v" using right by simp
-  qed
-next
-  case (Times r1 r2)
-  have IH1: "\<And>s v. s \<in> deriv c r1 \<rightarrow> v \<Longrightarrow> (c # s) \<in> r1 \<rightarrow> injval r1 c v" by fact
-  have IH2: "\<And>s v. s \<in> deriv c r2 \<rightarrow> v \<Longrightarrow> (c # s) \<in> r2 \<rightarrow> injval r2 c v" by fact
-  have "s \<in> deriv c (Times r1 r2) \<rightarrow> v" by fact
-  then consider 
-        (left_nullable) v1 v2 s1 s2 where 
-        "v = Left (Seq v1 v2)"  "s = s1 @ s2" 
-        "s1 \<in> deriv c r1 \<rightarrow> v1" "s2 \<in> r2 \<rightarrow> v2" "nullable r1" 
-        "\<not> (\<exists>s\<^sub>3 s\<^sub>4. s\<^sub>3 \<noteq> [] \<and> s\<^sub>3 @ s\<^sub>4 = s2 \<and> s1 @ s\<^sub>3 \<in> lang (deriv c r1) \<and> s\<^sub>4 \<in> lang r2)"
-      | (right_nullable) v1 s1 s2 where 
-        "v = Right v1" "s = s1 @ s2"  
-        "s \<in> deriv c r2 \<rightarrow> v1" "nullable r1" "s1 @ s2 \<notin> lang (Times (deriv c r1) r2)"
-      | (not_nullable) v1 v2 s1 s2 where
-        "v = Seq v1 v2" "s = s1 @ s2" 
-        "s1 \<in> deriv c r1 \<rightarrow> v1" "s2 \<in> r2 \<rightarrow> v2" "\<not>nullable r1" 
-        "\<not> (\<exists>s\<^sub>3 s\<^sub>4. s\<^sub>3 \<noteq> [] \<and> s\<^sub>3 @ s\<^sub>4 = s2 \<and> s1 @ s\<^sub>3 \<in> lang (deriv c r1) \<and> s\<^sub>4 \<in> lang r2)"
-        by (force split: if_splits elim!: Posix_elims simp add: lang_deriv Deriv_def)   
-  then show "(c # s) \<in> Times r1 r2 \<rightarrow> injval (Times r1 r2) c v" 
-    proof (cases)
-      case left_nullable
-      have "s1 \<in> deriv c r1 \<rightarrow> v1" by fact
-      then have "(c # s1) \<in> r1 \<rightarrow> injval r1 c v1" using IH1 by simp
-      moreover
-      have "\<not> (\<exists>s\<^sub>3 s\<^sub>4. s\<^sub>3 \<noteq> [] \<and> s\<^sub>3 @ s\<^sub>4 = s2 \<and> s1 @ s\<^sub>3 \<in> lang (deriv c r1) \<and> s\<^sub>4 \<in> lang r2)" by fact
-      then have "\<not> (\<exists>s\<^sub>3 s\<^sub>4. s\<^sub>3 \<noteq> [] \<and> s\<^sub>3 @ s\<^sub>4 = s2 \<and> (c # s1) @ s\<^sub>3 \<in> lang r1 \<and> s\<^sub>4 \<in> lang r2)" 
-         by (simp add: lang_deriv Deriv_def)
-      ultimately have "((c # s1) @ s2) \<in> Times r1 r2 \<rightarrow> Seq (injval r1 c v1) v2" using left_nullable by (rule_tac Posix.intros)
-      then show "(c # s) \<in> Times r1 r2 \<rightarrow> injval (Times r1 r2) c v" using left_nullable by simp
-    next
-      case right_nullable
-      have "nullable r1" by fact
-      then have "[] \<in> r1 \<rightarrow> (mkeps r1)" by (rule Posix_mkeps)
-      moreover
-      have "s \<in> deriv c r2 \<rightarrow> v1" by fact
-      then have "(c # s) \<in> r2 \<rightarrow> (injval r2 c v1)" using IH2 by simp
-      moreover
-      have "s1 @ s2 \<notin> lang (Times (deriv c r1) r2)" by fact
-      then have "\<not> (\<exists>s\<^sub>3 s\<^sub>4. s\<^sub>3 \<noteq> [] \<and> s\<^sub>3 @ s\<^sub>4 = c # s \<and> [] @ s\<^sub>3 \<in> lang r1 \<and> s\<^sub>4 \<in> lang r2)" 
-        using right_nullable 
-        apply (auto simp add: lang_deriv Deriv_def append_eq_Cons_conv)
-        by (metis concI mem_Collect_eq)
-      ultimately have "([] @ (c # s)) \<in> Times r1 r2 \<rightarrow> Seq (mkeps r1) (injval r2 c v1)"
-      by(rule Posix.intros)
-      then show "(c # s) \<in> Times r1 r2 \<rightarrow> injval (Times r1 r2) c v" using right_nullable by simp
-    next
-      case not_nullable
-      have "s1 \<in> deriv c r1 \<rightarrow> v1" by fact
-      then have "(c # s1) \<in> r1 \<rightarrow> injval r1 c v1" using IH1 by simp
-      moreover
-      have "\<not> (\<exists>s\<^sub>3 s\<^sub>4. s\<^sub>3 \<noteq> [] \<and> s\<^sub>3 @ s\<^sub>4 = s2 \<and> s1 @ s\<^sub>3 \<in> lang (deriv c r1) \<and> s\<^sub>4 \<in> lang r2)" by fact
-      then have "\<not> (\<exists>s\<^sub>3 s\<^sub>4. s\<^sub>3 \<noteq> [] \<and> s\<^sub>3 @ s\<^sub>4 = s2 \<and> (c # s1) @ s\<^sub>3 \<in> lang r1 \<and> s\<^sub>4 \<in> lang r2)" by (simp add: lang_deriv Deriv_def)
-      ultimately have "((c # s1) @ s2) \<in> Times r1 r2 \<rightarrow> Seq (injval r1 c v1) v2" using not_nullable 
-        by (rule_tac Posix.intros) (simp_all) 
-      then show "(c # s) \<in> Times r1 r2 \<rightarrow> injval (Times r1 r2) c v" using not_nullable by simp
-    qed
-next
-  case (Star r)
-  have IH: "\<And>s v. s \<in> deriv c r \<rightarrow> v \<Longrightarrow> (c # s) \<in> r \<rightarrow> injval r c v" by fact
-  have "s \<in> deriv c (Star r) \<rightarrow> v" by fact
-  then consider
-      (cons) v1 vs s1 s2 where 
-        "v = Seq v1 (Stars vs)" "s = s1 @ s2" 
-        "s1 \<in> deriv c r \<rightarrow> v1" "s2 \<in> (Star r) \<rightarrow> (Stars vs)"
-        "\<not> (\<exists>s\<^sub>3 s\<^sub>4. s\<^sub>3 \<noteq> [] \<and> s\<^sub>3 @ s\<^sub>4 = s2 \<and> s1 @ s\<^sub>3 \<in> lang (deriv c r) \<and> s\<^sub>4 \<in> lang (Star r))" 
-        apply(auto elim!: Posix_elims(1-5) simp add: lang_deriv Deriv_def intro: Posix.intros)
-        apply(rotate_tac 3)
-        apply(erule_tac Posix_elims(6))
-        apply (simp add: Posix.intros(6))
-        using Posix.intros(7) by blast
-    then show "(c # s) \<in> Star r \<rightarrow> injval (Star r) c v" 
-    proof (cases)
-      case cons
-          have "s1 \<in> deriv c r \<rightarrow> v1" by fact
-          then have "(c # s1) \<in> r \<rightarrow> injval r c v1" using IH by simp
-        moreover
-          have "s2 \<in> Star r \<rightarrow> Stars vs" by fact
-        moreover 
-          have "(c # s1) \<in> r \<rightarrow> injval r c v1" by fact 
-          then have "flat (injval r c v1) = (c # s1)" by (rule Posix1)
-          then have "flat (injval r c v1) \<noteq> []" by simp
-        moreover 
-          have "\<not> (\<exists>s\<^sub>3 s\<^sub>4. s\<^sub>3 \<noteq> [] \<and> s\<^sub>3 @ s\<^sub>4 = s2 \<and> s1 @ s\<^sub>3 \<in> lang (deriv c r) \<and> s\<^sub>4 \<in> lang (Star r))" by fact
-          then have "\<not> (\<exists>s\<^sub>3 s\<^sub>4. s\<^sub>3 \<noteq> [] \<and> s\<^sub>3 @ s\<^sub>4 = s2 \<and> (c # s1) @ s\<^sub>3 \<in> lang r \<and> s\<^sub>4 \<in> lang (Star r))" 
-            by (simp add: lang_deriv Deriv_def)
-        ultimately 
-        have "((c # s1) @ s2) \<in> Star r \<rightarrow> Stars (injval r c v1 # vs)" by (rule Posix.intros)
-        then show "(c # s) \<in> Star r \<rightarrow> injval (Star r) c v" using cons by(simp)
-    qed
-qed
-
-
-section {* The Lexer by Sulzmann and Lu  *}
-
-fun 
-  lexer :: "'a rexp \<Rightarrow> 'a list \<Rightarrow> ('a val) option"
-where
-  "lexer r [] = (if nullable r then Some(mkeps r) else None)"
-| "lexer r (c#s) = (case (lexer (deriv c r) s) of  
-                    None \<Rightarrow> None
-                  | Some(v) \<Rightarrow> Some(injval r c v))"
-
-
-lemma lexer_correct_None:
-  shows "s \<notin> lang r \<longleftrightarrow> lexer r s = None"
-using assms
-apply(induct s arbitrary: r)
-apply(simp add: nullable_iff)
-apply(drule_tac x="deriv a r" in meta_spec)
-apply(auto simp add: lang_deriv Deriv_def)
-done
-
-lemma lexer_correct_Some:
-  shows "s \<in> lang r \<longleftrightarrow> (\<exists>v. lexer r s = Some(v) \<and> s \<in> r \<rightarrow> v)"
-using assms
-apply(induct s arbitrary: r)
-apply(auto simp add: Posix_mkeps nullable_iff)[1]
-apply(drule_tac x="deriv a r" in meta_spec)
-apply(simp add: lang_deriv Deriv_def)
-apply(rule iffI)
-apply(auto intro: Posix_injval simp add: Posix1(1))
-done 
-
-lemma lexer_correctness:
-  shows "(lexer r s = Some v) \<longleftrightarrow> s \<in> r \<rightarrow> v"
-  and   "(lexer r s = None) \<longleftrightarrow> \<not>(\<exists>v. s \<in> r \<rightarrow> v)"
-apply(auto)
-using lexer_correct_None lexer_correct_Some apply fastforce
-using Posix1(1) Posix_determ lexer_correct_Some apply blast
-using Posix1(1) lexer_correct_None apply blast
-using lexer_correct_None lexer_correct_Some by blast
-
-
-end
\ No newline at end of file




