# HG changeset patch
# User Chengsong
# Date 1655997004 -3600
# Node ID b672be21ffac4ddfb98d8c4a7729cc244e25e64f
# Parent  b2bea5968b8955b747d5b968674ebcde1bbc6f1e
hello

diff -r b2bea5968b89 -r b672be21ffac thys3/BlexerSimp.thy
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/thys3/BlexerSimp.thy	Thu Jun 23 16:10:04 2022 +0100
@@ -0,0 +1,702 @@
+theory BlexerSimp
+  imports Blexer 
+begin
+
+fun distinctWith :: "'a list \<Rightarrow> ('a \<Rightarrow> 'a \<Rightarrow> bool) \<Rightarrow> 'a set \<Rightarrow> 'a list"
+  where
+  "distinctWith [] eq acc = []"
+| "distinctWith (x # xs) eq acc = 
+     (if (\<exists> y \<in> acc. eq x y) then distinctWith xs eq acc 
+      else x # (distinctWith xs eq ({x} \<union> acc)))"
+
+
+fun eq1 ("_ ~1 _" [80, 80] 80) where  
+  "AZERO ~1 AZERO = True"
+| "(AONE bs1) ~1 (AONE bs2) = True"
+| "(ACHAR bs1 c) ~1 (ACHAR bs2 d) = (if c = d then True else False)"
+| "(ASEQ bs1 ra1 ra2) ~1 (ASEQ bs2 rb1 rb2) = (ra1 ~1 rb1 \<and> ra2 ~1 rb2)"
+| "(AALTs bs1 []) ~1 (AALTs bs2 []) = True"
+| "(AALTs bs1 (r1 # rs1)) ~1 (AALTs bs2 (r2 # rs2)) = (r1 ~1 r2 \<and> (AALTs bs1 rs1) ~1 (AALTs bs2 rs2))"
+| "(ASTAR bs1 r1) ~1 (ASTAR bs2 r2) = r1 ~1 r2"
+| "_ ~1 _ = False"
+
+
+
+lemma eq1_L:
+  assumes "x ~1 y"
+  shows "L (erase x) = L (erase y)"
+  using assms
+  apply(induct rule: eq1.induct)
+  apply(auto elim: eq1.elims)
+  apply presburger
+  done
+
+fun flts :: "arexp list \<Rightarrow> arexp list"
+  where 
+  "flts [] = []"
+| "flts (AZERO # rs) = flts rs"
+| "flts ((AALTs bs  rs1) # rs) = (map (fuse bs) rs1) @ flts rs"
+| "flts (r1 # rs) = r1 # flts rs"
+
+
+
+fun bsimp_ASEQ :: "bit list \<Rightarrow> arexp \<Rightarrow> arexp \<Rightarrow> arexp"
+  where
+  "bsimp_ASEQ _ AZERO _ = AZERO"
+| "bsimp_ASEQ _ _ AZERO = AZERO"
+| "bsimp_ASEQ bs1 (AONE bs2) r2 = fuse (bs1 @ bs2) r2"
+| "bsimp_ASEQ bs1 r1 r2 = ASEQ  bs1 r1 r2"
+
+lemma bsimp_ASEQ0[simp]:
+  shows "bsimp_ASEQ bs r1 AZERO = AZERO"
+  by (case_tac r1)(simp_all)
+
+lemma bsimp_ASEQ1:
+  assumes "r1 \<noteq> AZERO" "r2 \<noteq> AZERO" "\<nexists>bs. r1 = AONE bs"
+  shows "bsimp_ASEQ bs r1 r2 = ASEQ bs r1 r2"
+  using assms
+  apply(induct bs r1 r2 rule: bsimp_ASEQ.induct)
+  apply(auto)
+  done
+
+lemma bsimp_ASEQ2[simp]:
+  shows "bsimp_ASEQ bs1 (AONE bs2) r2 = fuse (bs1 @ bs2) r2"
+  by (case_tac r2) (simp_all)
+
+
+fun bsimp_AALTs :: "bit list \<Rightarrow> arexp list \<Rightarrow> arexp"
+  where
+  "bsimp_AALTs _ [] = AZERO"
+| "bsimp_AALTs bs1 [r] = fuse bs1 r"
+| "bsimp_AALTs bs1 rs = AALTs bs1 rs"
+
+
+
+
+fun bsimp :: "arexp \<Rightarrow> arexp" 
+  where
+  "bsimp (ASEQ bs1 r1 r2) = bsimp_ASEQ bs1 (bsimp r1) (bsimp r2)"
+| "bsimp (AALTs bs1 rs) = bsimp_AALTs bs1 (distinctWith (flts (map bsimp rs)) eq1 {}) "
+| "bsimp r = r"
+
+
+fun 
+  bders_simp :: "arexp \<Rightarrow> string \<Rightarrow> arexp"
+where
+  "bders_simp r [] = r"
+| "bders_simp r (c # s) = bders_simp (bsimp (bder c r)) s"
+
+definition blexer_simp where
+ "blexer_simp r s \<equiv> if bnullable (bders_simp (intern r) s) then 
+                    decode (bmkeps (bders_simp (intern r) s)) r else None"
+
+
+
+lemma bders_simp_append:
+  shows "bders_simp r (s1 @ s2) = bders_simp (bders_simp r s1) s2"
+  apply(induct s1 arbitrary: r s2)
+  apply(simp_all)
+  done
+
+lemma bmkeps_fuse:
+  assumes "bnullable r"
+  shows "bmkeps (fuse bs r) = bs @ bmkeps r"
+  using assms
+  by (induct r rule: bnullable.induct) (auto)
+
+lemma bmkepss_fuse: 
+  assumes "bnullables rs"
+  shows "bmkepss (map (fuse bs) rs) = bs @ bmkepss rs"
+  using assms
+  apply(induct rs arbitrary: bs)
+  apply(auto simp add: bmkeps_fuse bnullable_fuse)
+  done
+
+lemma bder_fuse:
+  shows "bder c (fuse bs a) = fuse bs  (bder c a)"
+  apply(induct a arbitrary: bs c)
+  apply(simp_all)
+  done
+
+
+
+
+inductive 
+  rrewrite:: "arexp \<Rightarrow> arexp \<Rightarrow> bool" ("_ \<leadsto> _" [99, 99] 99)
+and 
+  srewrite:: "arexp list \<Rightarrow> arexp list \<Rightarrow> bool" (" _ s\<leadsto> _" [100, 100] 100)
+where
+  bs1: "ASEQ bs AZERO r2 \<leadsto> AZERO"
+| bs2: "ASEQ bs r1 AZERO \<leadsto> AZERO"
+| bs3: "ASEQ bs1 (AONE bs2) r \<leadsto> fuse (bs1@bs2) r"
+| bs4: "r1 \<leadsto> r2 \<Longrightarrow> ASEQ bs r1 r3 \<leadsto> ASEQ bs r2 r3"
+| bs5: "r3 \<leadsto> r4 \<Longrightarrow> ASEQ bs r1 r3 \<leadsto> ASEQ bs r1 r4"
+| bs6: "AALTs bs [] \<leadsto> AZERO"
+| bs7: "AALTs bs [r] \<leadsto> fuse bs r"
+| bs10: "rs1 s\<leadsto> rs2 \<Longrightarrow> AALTs bs rs1 \<leadsto> AALTs bs rs2"
+| ss1:  "[] s\<leadsto> []"
+| ss2:  "rs1 s\<leadsto> rs2 \<Longrightarrow> (r # rs1) s\<leadsto> (r # rs2)"
+| ss3:  "r1 \<leadsto> r2 \<Longrightarrow> (r1 # rs) s\<leadsto> (r2 # rs)"
+| ss4:  "(AZERO # rs) s\<leadsto> rs"
+| ss5:  "(AALTs bs1 rs1 # rsb) s\<leadsto> ((map (fuse bs1) rs1) @ rsb)"
+| ss6:  "L (erase a2) \<subseteq> L (erase a1) \<Longrightarrow> (rsa@[a1]@rsb@[a2]@rsc) s\<leadsto> (rsa@[a1]@rsb@rsc)"
+
+
+inductive 
+  rrewrites:: "arexp \<Rightarrow> arexp \<Rightarrow> bool" ("_ \<leadsto>* _" [100, 100] 100)
+where 
+  rs1[intro, simp]:"r \<leadsto>* r"
+| rs2[intro]: "\<lbrakk>r1 \<leadsto>* r2; r2 \<leadsto> r3\<rbrakk> \<Longrightarrow> r1 \<leadsto>* r3"
+
+inductive 
+  srewrites:: "arexp list \<Rightarrow> arexp list \<Rightarrow> bool" ("_ s\<leadsto>* _" [100, 100] 100)
+where 
+  sss1[intro, simp]:"rs s\<leadsto>* rs"
+| sss2[intro]: "\<lbrakk>rs1 s\<leadsto> rs2; rs2 s\<leadsto>* rs3\<rbrakk> \<Longrightarrow> rs1 s\<leadsto>* rs3"
+
+
+lemma r_in_rstar : "r1 \<leadsto> r2 \<Longrightarrow> r1 \<leadsto>* r2"
+  using rrewrites.intros(1) rrewrites.intros(2) by blast
+
+lemma rs_in_rstar: 
+  shows "r1 s\<leadsto> r2 \<Longrightarrow> r1 s\<leadsto>* r2"
+  using rrewrites.intros(1) rrewrites.intros(2) by blast
+
+
+lemma rrewrites_trans[trans]: 
+  assumes a1: "r1 \<leadsto>* r2"  and a2: "r2 \<leadsto>* r3"
+  shows "r1 \<leadsto>* r3"
+  using a2 a1
+  apply(induct r2 r3 arbitrary: r1 rule: rrewrites.induct) 
+  apply(auto)
+  done
+
+lemma srewrites_trans[trans]: 
+  assumes a1: "r1 s\<leadsto>* r2"  and a2: "r2 s\<leadsto>* r3"
+  shows "r1 s\<leadsto>* r3"
+  using a1 a2
+  apply(induct r1 r2 arbitrary: r3 rule: srewrites.induct) 
+   apply(auto)
+  done
+
+
+
+lemma contextrewrites0: 
+  "rs1 s\<leadsto>* rs2 \<Longrightarrow> AALTs bs rs1 \<leadsto>* AALTs bs rs2"
+  apply(induct rs1 rs2 rule: srewrites.inducts)
+   apply simp
+  using bs10 r_in_rstar rrewrites_trans by blast
+
+lemma contextrewrites1: 
+  "r \<leadsto>* r' \<Longrightarrow> AALTs bs (r # rs) \<leadsto>* AALTs bs (r' # rs)"
+  apply(induct r r' rule: rrewrites.induct)
+   apply simp
+  using bs10 ss3 by blast
+
+lemma srewrite1: 
+  shows "rs1 s\<leadsto> rs2 \<Longrightarrow> (rs @ rs1) s\<leadsto> (rs @ rs2)"
+  apply(induct rs)
+   apply(auto)
+  using ss2 by auto
+
+lemma srewrites1: 
+  shows "rs1 s\<leadsto>* rs2 \<Longrightarrow> (rs @ rs1) s\<leadsto>* (rs @ rs2)"
+  apply(induct rs1 rs2 rule: srewrites.induct)
+   apply(auto)
+  using srewrite1 by blast
+
+lemma srewrite2: 
+  shows  "r1 \<leadsto> r2 \<Longrightarrow> True"
+  and "rs1 s\<leadsto> rs2 \<Longrightarrow> (rs1 @ rs) s\<leadsto>* (rs2 @ rs)"
+  apply(induct rule: rrewrite_srewrite.inducts)
+  apply(auto)
+  apply (metis append_Cons append_Nil srewrites1)
+  apply(meson srewrites.simps ss3)
+  apply (meson srewrites.simps ss4)
+  apply (meson srewrites.simps ss5)
+  by (metis append_Cons append_Nil srewrites.simps ss6)
+  
+
+lemma srewrites3: 
+  shows "rs1 s\<leadsto>* rs2 \<Longrightarrow> (rs1 @ rs) s\<leadsto>* (rs2 @ rs)"
+  apply(induct rs1 rs2 arbitrary: rs rule: srewrites.induct)
+   apply(auto)
+  by (meson srewrite2(2) srewrites_trans)
+
+(*
+lemma srewrites4:
+  assumes "rs3 s\<leadsto>* rs4" "rs1 s\<leadsto>* rs2" 
+  shows "(rs1 @ rs3) s\<leadsto>* (rs2 @ rs4)"
+  using assms
+  apply(induct rs3 rs4 arbitrary: rs1 rs2 rule: srewrites.induct)
+  apply (simp add: srewrites3)
+  using srewrite1 by blast
+*)
+
+lemma srewrites6:
+  assumes "r1 \<leadsto>* r2" 
+  shows "[r1] s\<leadsto>* [r2]"
+  using assms
+  apply(induct r1 r2 rule: rrewrites.induct)
+   apply(auto)
+  by (meson srewrites.simps srewrites_trans ss3)
+
+lemma srewrites7:
+  assumes "rs3 s\<leadsto>* rs4" "r1 \<leadsto>* r2" 
+  shows "(r1 # rs3) s\<leadsto>* (r2 # rs4)"
+  using assms
+  by (smt (verit, best) append_Cons append_Nil srewrites1 srewrites3 srewrites6 srewrites_trans)
+
+lemma ss6_stronger_aux:
+  shows "(rs1 @ rs2) s\<leadsto>* (rs1 @ distinctWith rs2 eq1 (set rs1))"
+  apply(induct rs2 arbitrary: rs1)
+  apply(auto)
+  prefer 2
+  apply(drule_tac x="rs1 @ [a]" in meta_spec)
+  apply(simp)
+  apply(drule_tac x="rs1" in meta_spec)
+  apply(subgoal_tac "(rs1 @ a # rs2) s\<leadsto>* (rs1 @ rs2)")
+  using srewrites_trans apply blast
+  apply(subgoal_tac "\<exists>rs1a rs1b. rs1 = rs1a @ [x] @ rs1b")
+  prefer 2
+  apply (simp add: split_list)
+  apply(erule exE)+
+  apply(simp)
+  using eq1_L rs_in_rstar ss6 by force
+
+lemma ss6_stronger:
+  shows "rs1 s\<leadsto>* distinctWith rs1 eq1 {}"
+  by (metis append_Nil list.set(1) ss6_stronger_aux)
+
+
+lemma rewrite_preserves_fuse: 
+  shows "r2 \<leadsto> r3 \<Longrightarrow> fuse bs r2 \<leadsto> fuse bs r3"
+  and   "rs2 s\<leadsto> rs3 \<Longrightarrow> map (fuse bs) rs2 s\<leadsto>* map (fuse bs) rs3"
+proof(induct rule: rrewrite_srewrite.inducts)
+  case (bs3 bs1 bs2 r)
+  then show ?case
+    by (metis fuse.simps(5) fuse_append rrewrite_srewrite.bs3) 
+next
+  case (bs7 bs r)
+  then show ?case
+    by (metis fuse.simps(4) fuse_append rrewrite_srewrite.bs7) 
+next
+  case (ss2 rs1 rs2 r)
+  then show ?case
+    using srewrites7 by force 
+next
+  case (ss3 r1 r2 rs)
+  then show ?case by (simp add: r_in_rstar srewrites7)
+next
+  case (ss5 bs1 rs1 rsb)
+  then show ?case 
+    apply(simp)
+    by (metis (mono_tags, lifting) comp_def fuse_append map_eq_conv rrewrite_srewrite.ss5 srewrites.simps)
+next
+  case (ss6 a1 a2 rsa rsb rsc)
+  then show ?case 
+    apply(simp only: map_append)
+    by (smt (verit, best) erase_fuse list.simps(8) list.simps(9) rrewrite_srewrite.ss6 srewrites.simps)
+qed (auto intro: rrewrite_srewrite.intros)
+
+
+lemma rewrites_fuse:  
+  assumes "r1 \<leadsto>* r2"
+  shows "fuse bs r1 \<leadsto>* fuse bs r2"
+using assms
+apply(induction r1 r2 arbitrary: bs rule: rrewrites.induct)
+apply(auto intro: rewrite_preserves_fuse rrewrites_trans)
+done
+
+
+lemma star_seq:  
+  assumes "r1 \<leadsto>* r2"
+  shows "ASEQ bs r1 r3 \<leadsto>* ASEQ bs r2 r3"
+using assms
+apply(induct r1 r2 arbitrary: r3 rule: rrewrites.induct)
+apply(auto intro: rrewrite_srewrite.intros)
+done
+
+lemma star_seq2:  
+  assumes "r3 \<leadsto>* r4"
+  shows "ASEQ bs r1 r3 \<leadsto>* ASEQ bs r1 r4"
+  using assms
+apply(induct r3 r4 arbitrary: r1 rule: rrewrites.induct)
+apply(auto intro: rrewrite_srewrite.intros)
+done
+
+lemma continuous_rewrite: 
+  assumes "r1 \<leadsto>* AZERO"
+  shows "ASEQ bs1 r1 r2 \<leadsto>* AZERO"
+using assms bs1 star_seq by blast
+
+(*
+lemma continuous_rewrite2: 
+  assumes "r1 \<leadsto>* AONE bs"
+  shows "ASEQ bs1 r1 r2 \<leadsto>* (fuse (bs1 @ bs) r2)"
+  using assms  by (meson bs3 rrewrites.simps star_seq)
+*)
+
+lemma bsimp_aalts_simpcases: 
+  shows "AONE bs \<leadsto>* bsimp (AONE bs)"  
+  and   "AZERO \<leadsto>* bsimp AZERO" 
+  and   "ACHAR bs c \<leadsto>* bsimp (ACHAR bs c)"
+  by (simp_all)
+
+lemma bsimp_AALTs_rewrites: 
+  shows "AALTs bs1 rs \<leadsto>* bsimp_AALTs bs1 rs"
+  by (smt (verit) bs6 bs7 bsimp_AALTs.elims rrewrites.simps)
+
+lemma trivialbsimp_srewrites: 
+  "\<lbrakk>\<And>x. x \<in> set rs \<Longrightarrow> x \<leadsto>* f x \<rbrakk> \<Longrightarrow> rs s\<leadsto>* (map f rs)"
+  apply(induction rs)
+   apply simp
+  apply(simp)
+  using srewrites7 by auto
+
+
+
+lemma fltsfrewrites: "rs s\<leadsto>* flts rs"
+  apply(induction rs rule: flts.induct)
+  apply(auto intro: rrewrite_srewrite.intros)
+  apply (meson srewrites.simps srewrites1 ss5)
+  using rs1 srewrites7 apply presburger
+  using srewrites7 apply force
+  apply (simp add: srewrites7)
+  by (simp add: srewrites7)
+
+lemma bnullable0:
+shows "r1 \<leadsto> r2 \<Longrightarrow> bnullable r1 = bnullable r2" 
+  and "rs1 s\<leadsto> rs2 \<Longrightarrow> bnullables rs1 = bnullables rs2" 
+  apply(induct rule: rrewrite_srewrite.inducts)
+  apply(auto simp add:  bnullable_fuse)
+   apply (meson UnCI bnullable_fuse imageI)
+  using bnullable_correctness nullable_correctness by blast 
+
+
+lemma rewritesnullable: 
+  assumes "r1 \<leadsto>* r2" 
+  shows "bnullable r1 = bnullable r2"
+using assms 
+  apply(induction r1 r2 rule: rrewrites.induct)
+  apply simp
+  using bnullable0(1) by auto
+
+lemma rewrite_bmkeps_aux: 
+  shows "r1 \<leadsto> r2 \<Longrightarrow> (bnullable r1 \<and> bnullable r2 \<Longrightarrow> bmkeps r1 = bmkeps r2)"
+  and   "rs1 s\<leadsto> rs2 \<Longrightarrow> (bnullables rs1 \<and> bnullables rs2 \<Longrightarrow> bmkepss rs1 = bmkepss rs2)" 
+proof (induct rule: rrewrite_srewrite.inducts)
+  case (bs3 bs1 bs2 r)
+  then show ?case by (simp add: bmkeps_fuse) 
+next
+  case (bs7 bs r)
+  then show ?case by (simp add: bmkeps_fuse) 
+next
+  case (ss3 r1 r2 rs)
+  then show ?case
+    using bmkepss.simps bnullable0(1) by presburger
+next
+  case (ss5 bs1 rs1 rsb)
+  then show ?case
+    by (simp add: bmkepss1 bmkepss2 bmkepss_fuse bnullable_fuse)
+next
+  case (ss6 a1 a2 rsa rsb rsc)
+  then show ?case
+    by (smt (verit, best) Nil_is_append_conv bmkepss1 bmkepss2 bnullable_correctness in_set_conv_decomp list.distinct(1) list.set_intros(1) nullable_correctness set_ConsD subsetD)
+qed (auto)
+
+lemma rewrites_bmkeps: 
+  assumes "r1 \<leadsto>* r2" "bnullable r1" 
+  shows "bmkeps r1 = bmkeps r2"
+  using assms
+proof(induction r1 r2 rule: rrewrites.induct)
+  case (rs1 r)
+  then show "bmkeps r = bmkeps r" by simp
+next
+  case (rs2 r1 r2 r3)
+  then have IH: "bmkeps r1 = bmkeps r2" by simp
+  have a1: "bnullable r1" by fact
+  have a2: "r1 \<leadsto>* r2" by fact
+  have a3: "r2 \<leadsto> r3" by fact
+  have a4: "bnullable r2" using a1 a2 by (simp add: rewritesnullable) 
+  then have "bmkeps r2 = bmkeps r3"
+    using a3 bnullable0(1) rewrite_bmkeps_aux(1) by blast 
+  then show "bmkeps r1 = bmkeps r3" using IH by simp
+qed
+
+
+lemma rewrites_to_bsimp: 
+  shows "r \<leadsto>* bsimp r"
+proof (induction r rule: bsimp.induct)
+  case (1 bs1 r1 r2)
+  have IH1: "r1 \<leadsto>* bsimp r1" by fact
+  have IH2: "r2 \<leadsto>* bsimp r2" by fact
+  { assume as: "bsimp r1 = AZERO \<or> bsimp r2 = AZERO"
+    with IH1 IH2 have "r1 \<leadsto>* AZERO \<or> r2 \<leadsto>* AZERO" by auto
+    then have "ASEQ bs1 r1 r2 \<leadsto>* AZERO"
+      by (metis bs2 continuous_rewrite rrewrites.simps star_seq2)  
+    then have "ASEQ bs1 r1 r2 \<leadsto>* bsimp (ASEQ bs1 r1 r2)" using as by auto
+  }
+  moreover
+  { assume "\<exists>bs. bsimp r1 = AONE bs"
+    then obtain bs where as: "bsimp r1 = AONE bs" by blast
+    with IH1 have "r1 \<leadsto>* AONE bs" by simp
+    then have "ASEQ bs1 r1 r2 \<leadsto>* fuse (bs1 @ bs) r2" using bs3 star_seq by blast
+    with IH2 have "ASEQ bs1 r1 r2 \<leadsto>* fuse (bs1 @ bs) (bsimp r2)"
+      using rewrites_fuse by (meson rrewrites_trans) 
+    then have "ASEQ bs1 r1 r2 \<leadsto>* bsimp (ASEQ bs1 (AONE bs) r2)" by simp
+    then have "ASEQ bs1 r1 r2 \<leadsto>* bsimp (ASEQ bs1 r1 r2)" by (simp add: as) 
+  } 
+  moreover
+  { assume as1: "bsimp r1 \<noteq> AZERO" "bsimp r2 \<noteq> AZERO" and as2: "(\<nexists>bs. bsimp r1 = AONE bs)" 
+    then have "bsimp_ASEQ bs1 (bsimp r1) (bsimp r2) = ASEQ bs1 (bsimp r1) (bsimp r2)" 
+      by (simp add: bsimp_ASEQ1) 
+    then have "ASEQ bs1 r1 r2 \<leadsto>* bsimp_ASEQ bs1 (bsimp r1) (bsimp r2)" using as1 as2 IH1 IH2
+      by (metis rrewrites_trans star_seq star_seq2) 
+    then have "ASEQ bs1 r1 r2 \<leadsto>* bsimp (ASEQ bs1 r1 r2)" by simp
+  } 
+  ultimately show "ASEQ bs1 r1 r2 \<leadsto>* bsimp (ASEQ bs1 r1 r2)" by blast
+next
+  case (2 bs1 rs)
+  have IH: "\<And>x. x \<in> set rs \<Longrightarrow> x \<leadsto>* bsimp x" by fact
+  then have "rs s\<leadsto>* (map bsimp rs)" by (simp add: trivialbsimp_srewrites)
+  also have "... s\<leadsto>* flts (map bsimp rs)" by (simp add: fltsfrewrites) 
+  also have "... s\<leadsto>* distinctWith (flts (map bsimp rs)) eq1 {}" by (simp add: ss6_stronger)
+  finally have "AALTs bs1 rs \<leadsto>* AALTs bs1 (distinctWith (flts (map bsimp rs)) eq1 {})"
+    using contextrewrites0 by auto
+  also have "... \<leadsto>* bsimp_AALTs  bs1 (distinctWith (flts (map bsimp rs)) eq1 {})"
+    by (simp add: bsimp_AALTs_rewrites)     
+  finally show "AALTs bs1 rs \<leadsto>* bsimp (AALTs bs1 rs)" by simp
+qed (simp_all)
+
+
+lemma to_zero_in_alt: 
+  shows "AALT bs (ASEQ [] AZERO r) r2 \<leadsto> AALT bs AZERO r2"
+  by (simp add: bs1 bs10 ss3)
+
+
+
+lemma  bder_fuse_list: 
+  shows "map (bder c \<circ> fuse bs1) rs1 = map (fuse bs1 \<circ> bder c) rs1"
+  apply(induction rs1)
+  apply(simp_all add: bder_fuse)
+  done
+
+lemma map1:
+  shows "(map f [a]) = [f a]"
+  by (simp)
+
+lemma rewrite_preserves_bder: 
+  shows "r1 \<leadsto> r2 \<Longrightarrow> (bder c r1) \<leadsto>* (bder c r2)"
+  and   "rs1 s\<leadsto> rs2 \<Longrightarrow> map (bder c) rs1 s\<leadsto>* map (bder c) rs2"
+proof(induction rule: rrewrite_srewrite.inducts)
+  case (bs1 bs r2)
+  then show ?case
+    by (simp add: continuous_rewrite) 
+next
+  case (bs2 bs r1)
+  then show ?case 
+    apply(auto)
+    apply (meson bs6 contextrewrites0 rrewrite_srewrite.bs2 rs2 ss3 ss4 sss1 sss2)
+    by (simp add: r_in_rstar rrewrite_srewrite.bs2)
+next
+  case (bs3 bs1 bs2 r)
+  then show ?case 
+    apply(simp)
+    
+    by (metis (no_types, lifting) bder_fuse bs10 bs7 fuse_append rrewrites.simps ss4 to_zero_in_alt)
+next
+  case (bs4 r1 r2 bs r3)
+  have as: "r1 \<leadsto> r2" by fact
+  have IH: "bder c r1 \<leadsto>* bder c r2" by fact
+  from as IH show "bder c (ASEQ bs r1 r3) \<leadsto>* bder c (ASEQ bs r2 r3)"
+    by (metis bder.simps(5) bnullable0(1) contextrewrites1 rewrite_bmkeps_aux(1) star_seq)
+next
+  case (bs5 r3 r4 bs r1)
+  have as: "r3 \<leadsto> r4" by fact 
+  have IH: "bder c r3 \<leadsto>* bder c r4" by fact 
+  from as IH show "bder c (ASEQ bs r1 r3) \<leadsto>* bder c (ASEQ bs r1 r4)"
+    apply(simp)
+    apply(auto)
+    using contextrewrites0 r_in_rstar rewrites_fuse srewrites6 srewrites7 star_seq2 apply presburger
+    using star_seq2 by blast
+next
+  case (bs6 bs)
+  then show ?case
+    using rrewrite_srewrite.bs6 by force 
+next
+  case (bs7 bs r)
+  then show ?case
+    by (simp add: bder_fuse r_in_rstar rrewrite_srewrite.bs7) 
+next
+  case (bs10 rs1 rs2 bs)
+  then show ?case
+    using contextrewrites0 by force    
+next
+  case ss1
+  then show ?case by simp
+next
+  case (ss2 rs1 rs2 r)
+  then show ?case
+    by (simp add: srewrites7) 
+next
+  case (ss3 r1 r2 rs)
+  then show ?case
+    by (simp add: srewrites7) 
+next
+  case (ss4 rs)
+  then show ?case
+    using rrewrite_srewrite.ss4 by fastforce 
+next
+  case (ss5 bs1 rs1 rsb)
+  then show ?case 
+    apply(simp)
+    using bder_fuse_list map_map rrewrite_srewrite.ss5 srewrites.simps by blast
+next
+  case (ss6 a1 a2 bs rsa rsb)
+  then show ?case
+    apply(simp only: map_append map1)
+    apply(rule srewrites_trans)
+    apply(rule rs_in_rstar)
+    apply(rule_tac rrewrite_srewrite.ss6)
+    using Der_def der_correctness apply auto[1]
+    by blast
+qed
+
+lemma rewrites_preserves_bder: 
+  assumes "r1 \<leadsto>* r2"
+  shows "bder c r1 \<leadsto>* bder c r2"
+using assms  
+apply(induction r1 r2 rule: rrewrites.induct)
+apply(simp_all add: rewrite_preserves_bder rrewrites_trans)
+done
+
+
+lemma central:  
+  shows "bders r s \<leadsto>* bders_simp r s"
+proof(induct s arbitrary: r rule: rev_induct)
+  case Nil
+  then show "bders r [] \<leadsto>* bders_simp r []" by simp
+next
+  case (snoc x xs)
+  have IH: "\<And>r. bders r xs \<leadsto>* bders_simp r xs" by fact
+  have "bders r (xs @ [x]) = bders (bders r xs) [x]" by (simp add: bders_append)
+  also have "... \<leadsto>* bders (bders_simp r xs) [x]" using IH
+    by (simp add: rewrites_preserves_bder)
+  also have "... \<leadsto>* bders_simp (bders_simp r xs) [x]" using IH
+    by (simp add: rewrites_to_bsimp)
+  finally show "bders r (xs @ [x]) \<leadsto>* bders_simp r (xs @ [x])" 
+    by (simp add: bders_simp_append)
+qed
+
+lemma main_aux: 
+  assumes "bnullable (bders r s)"
+  shows "bmkeps (bders r s) = bmkeps (bders_simp r s)"
+proof -
+  have "bders r s \<leadsto>* bders_simp r s" by (rule central)
+  then 
+  show "bmkeps (bders r s) = bmkeps (bders_simp r s)" using assms
+    by (rule rewrites_bmkeps)
+qed  
+
+
+
+
+theorem main_blexer_simp: 
+  shows "blexer r s = blexer_simp r s"
+  unfolding blexer_def blexer_simp_def
+  by (metis central main_aux rewritesnullable)
+
+theorem blexersimp_correctness: 
+  shows "lexer r s = blexer_simp r s"
+  using blexer_correctness main_blexer_simp by simp
+
+
+
+
+fun bsimpStrong6 :: "arexp \<Rightarrow> arexp" 
+  where
+  "bsimpStrong6 (ASEQ bs1 r1 r2) = bsimp_ASEQ bs1 (bsimpStrong6 r1) (bsimpStrong6 r2)"
+| "bsimpStrong6 (AALTs bs1 rs) = bsimp_AALTs bs1 (distinctWith (flts (map bsimpStrong6 rs)) eq1 {}) "
+| "bsimpStrong6 r = r"
+
+
+fun 
+  bdersStrong6 :: "arexp \<Rightarrow> string \<Rightarrow> arexp"
+where
+  "bdersStrong6 r [] = r"
+| "bdersStrong6 r (c # s) = bdersStrong6 (bsimpStrong6 (bder c r)) s"
+
+definition blexerStrong where
+ "blexerStrong r s \<equiv> if bnullable (bdersStrong6 (intern r) s) then 
+                    decode (bmkeps (bdersStrong6 (intern r) s)) r else None"
+
+fun ABIncludedByC :: "'a \<Rightarrow> 'b \<Rightarrow> 'c \<Rightarrow> ('a \<Rightarrow> 'b \<Rightarrow> 'c) \<Rightarrow> ('c \<Rightarrow> 'c \<Rightarrow> bool) \<Rightarrow> bool" where
+  "ABIncludedByC a b c f subseteqPred = subseteqPred (f a b) c"
+
+fun furtherSEQ :: "rexp \<Rightarrow> rexp \<Rightarrow> rexp list" and 
+   turnIntoTerms :: "rexp \<Rightarrow> rexp list "
+   where
+  "furtherSEQ ONE r2 =  turnIntoTerms r2 "
+| "furtherSEQ r11 r2 = [SEQ r11 r2]"
+| "turnIntoTerms (SEQ ONE r2) =  turnIntoTerms r2"
+| "turnIntoTerms (SEQ r1 r2) = concat (map (\<lambda>r11. furtherSEQ r11 r2) (turnIntoTerms r1))"
+| "turnIntoTerms r = [r]"
+
+fun regConcat :: "rexp \<Rightarrow> rexp list \<Rightarrow> rexp" where
+  "regConcat acc [] = acc"
+| "regConcat ONE (r # rs1) = regConcat r rs1"
+| "regConcat acc (r # rs1) = regConcat (SEQ acc r) rs1"
+
+fun attachCtx :: "arexp \<Rightarrow> rexp list \<Rightarrow> rexp set" where
+  "attachCtx r ctx = set (turnIntoTerms (regConcat (erase r) ctx))"
+
+(*
+def regConcat(acc: Rexp, rs: List[Rexp]) : Rexp = rs match {
+  case Nil => acc
+  case r :: rs1 => 
+    // if(acc == ONE) 
+    //   regConcat(r, rs1) 
+    // else
+      regConcat(SEQ(acc, r), rs1)
+}
+
+def attachCtx(r: ARexp, ctx: List[Rexp]) : Set[Rexp] = {
+  turnIntoTerms((regConcat(erase(r), ctx)))
+    .toSet
+}
+
+def attachCtxcc(r: Rexp, ctx: List[Rexp]) : Set[Rexp] =
+  turnIntoTerms(regConcat(r, ctx)).toSet
+
+def ABIncludedByC[A, B, C](a: A, b: B, c: C, f: (A, B) => C, 
+subseteqPred: (C, C) => Boolean) : Boolean = {
+  subseteqPred(f(a, b), c)
+}
+def rs1_subseteq_rs2(rs1: Set[Rexp], rs2: Set[Rexp]) : Boolean = 
+  //rs1 \subseteq rs2
+  rs1.forall(rs2.contains)
+
+
+}
+*)
+
+fun rs1_subseteq_rs2 :: "rexp set \<Rightarrow> rexp set \<Rightarrow> bool" where
+  "rs1_subseteq_rs2 rs1 rs2 = (rs1 \<subseteq> rs2)"
+
+fun prune6 :: "rexp set \<Rightarrow> arexp \<Rightarrow> rexp list \<Rightarrow> arexp" where
+  "prune6 acc a ctx = (if (ABIncludedByC a ctx acc attachCtx rs1_subseteq_rs2) then AZERO else 
+                        (case a of (ASEQ bs r1 r2) \<Rightarrow> bsimp_ASEQ bs (prune6 acc r1 (erase r2 # ctx)) r2
+                                 | AALTs bs rs0 \<Rightarrow> bsimp_AALTs bs (map (\<lambda>r. filter notZero (prune6 acc r ctx)) rs0))  )"
+
+
+fun dB6 :: "arexp list \<Rightarrow> rexp set \<Rightarrow> arexp list" where
+  "dB6 [] acc = []"
+| "dB6 (a # as) acc = (if (erase a \<in> acc) then (dB6 as acc) 
+                       else (let pruned = prune6 acc x in 
+                              (case pruned of
+                                 AZERO \<Rightarrow> dB6 as acc
+                               |xPrime \<Rightarrow> xPrime # (dB6 xs ((turnIntoTerms (erase pruned)) \<union> acc)  ) ) ))   "
+
+
+end