(* Theory be Kirstin Peters *)

theory Pi

  imports "../Nominal2"

begin

atom_decl name

subsection {* Capture-Avoiding Substitution of Names *}

definition

  subst_name :: "name \<Rightarrow> name \<Rightarrow> name \<Rightarrow> name" ("_[_:::=_]" [110, 110, 110] 110)

where

  "a[b:::=c] \<equiv> if (a = b) then c else a"

declare subst_name_def[simp]

lemma subst_name_mix_eqvt[eqvt]:

  fixes p :: perm

  and   a :: name

  and   b :: name

  and   c :: name

  shows "p \<bullet> (a[b:::=c]) = (p \<bullet> a)[(p \<bullet> b):::=(p \<bullet> c)]"

proof -

  show ?thesis

    by(auto)

qed

nominal_primrec

  subst_name_list :: "name \<Rightarrow> (name \<times> name) list \<Rightarrow> name"

where

  "subst_name_list a [] = a"

| "subst_name_list a ((b, c)#xs) = (if (a = b) then c else (subst_name_list a xs))"

  apply(auto)

  apply(rule_tac y="b" in list.exhaust)

  by(auto)

termination (eqvt)

  by (lexicographic_order)

section {* The Synchronous Pi-Calculus *}

subsection {* Syntax: Synchronous, Monadic Pi-Calculus with n-ary, Mixed Choice *}

nominal_datatype

      guardedTerm_mix = Output name name piMix                     ("_!<_>\<onesuperior>._" [120, 120, 110] 110)

                      | Input name b::name P::piMix  binds b in P  ("_?<_>\<onesuperior>._" [120, 120, 110] 110)

                      | Tau piMix                                  ("<\<tau>\<onesuperior>>._" [110] 110)

  and sumList_mix     = SumNil                                     ("\<zero>\<onesuperior>")

                      | AddSummand guardedTerm_mix sumList_mix     (infixr "\<oplus>\<onesuperior>" 65)

  and piMix           = Res a::name P::piMix         binds a in P  ("<\<nu>_>\<onesuperior>_" [100, 100] 100)

                      | Par piMix piMix                            (infixr "\<parallel>\<onesuperior>" 85)

                      | Match name name piMix                      ("[_\<frown>\<onesuperior>_]_" [120, 120, 110] 110)

                      | Sum sumList_mix                            ("\<oplus>\<onesuperior>{_}" 90)

                      | Rep name b::name P::piMix    binds b in P  ("\<infinity>_?<_>\<onesuperior>._" [120, 120, 110] 110)

                      | Succ                                       ("succ\<onesuperior>")

lemmas piMix_strong_induct  = guardedTerm_mix_sumList_mix_piMix.strong_induct

lemmas piMix_fresh          = guardedTerm_mix_sumList_mix_piMix.fresh

lemmas piMix_eq_iff         = guardedTerm_mix_sumList_mix_piMix.eq_iff

lemmas piMix_distinct       = guardedTerm_mix_sumList_mix_piMix.distinct

lemmas piMix_size           = guardedTerm_mix_sumList_mix_piMix.size

subsection {* Alpha-Conversion Lemmata *}

lemma alphaRes_mix:

  fixes a :: name

  and   P :: piMix

  and   z :: name

  assumes "atom z \<sharp> P"

  shows "<\<nu>a>\<onesuperior>P = <\<nu>z>\<onesuperior>((atom a \<rightleftharpoons> atom z) \<bullet> P)"

proof(cases "a = z")

  assume "a = z"

  thus ?thesis

    by(simp)

next

  assume "a \<noteq> z"

  thus ?thesis

    using assms

    by (simp add: flip_def piMix_eq_iff Abs1_eq_iff fresh_permute_left)

qed

lemma alphaInput_mix:

  fixes a :: name

  and   b :: name

  and   P :: piMix

  and   z :: name

  assumes "atom z \<sharp> P"

  shows "a?<b>\<onesuperior>.P = a?<z>\<onesuperior>.((atom b \<rightleftharpoons> atom z) \<bullet> P)"

proof(cases "b = z")

  assume "b = z"

  thus ?thesis

    by(simp)

next

  assume "b \<noteq> z"

  thus ?thesis

    using assms

    by(simp add: flip_def piMix_eq_iff Abs1_eq_iff fresh_permute_left)

qed

lemma alphaRep_mix:

  fixes a :: name

  and   b :: name

  and   P :: piMix

  and   z :: name

  assumes "atom z \<sharp> P"

  shows "\<infinity>a?<b>\<onesuperior>.P = \<infinity>a?<z>\<onesuperior>.((atom b \<rightleftharpoons> atom z) \<bullet> P)"

proof(cases "b = z")

  assume "b = z"

  thus ?thesis

    by(simp)

next

  assume "b \<noteq> z"

  thus ?thesis

    using assms

    by(simp add: flip_def piMix_eq_iff Abs1_eq_iff fresh_permute_left)

qed

subsection {* Capture-Avoiding Substitution of Names *}

lemma testl:

  assumes a: "\<exists>y. f = Inl y"

  shows "(p \<bullet> (Sum_Type.Projl f)) = Sum_Type.Projl (p \<bullet> f)"

using a by auto

lemma testrr:

  assumes a: "\<exists>y. f = Inr (Inr y)"

  shows "(p \<bullet> (Sum_Type.Projr (Sum_Type.Projr f))) = Sum_Type.Projr (Sum_Type.Projr (p \<bullet> f))"

using a by auto

lemma testlr:

  assumes a: "\<exists>y. f = Inr (Inl y)"

  shows "(p \<bullet> (Sum_Type.Projl (Sum_Type.Projr f))) = Sum_Type.Projl (Sum_Type.Projr (p \<bullet> f))"

using a by auto

nominal_primrec (default "sum_case (\<lambda>x. Inl undefined) (sum_case (\<lambda>x. Inr (Inl undefined)) (\<lambda>x. Inr (Inr undefined)))")

  subsGuard_mix :: "guardedTerm_mix \<Rightarrow> name \<Rightarrow> name \<Rightarrow> guardedTerm_mix"  ("_[_::=\<onesuperior>\<onesuperior>_]" [100, 100, 100] 100) and

  subsList_mix  :: "sumList_mix \<Rightarrow> name \<Rightarrow> name \<Rightarrow> sumList_mix"          ("_[_::=\<onesuperior>\<twosuperior>_]" [100, 100, 100] 100) and

  subs_mix      :: "piMix \<Rightarrow> name \<Rightarrow> name \<Rightarrow> piMix"                      ("_[_::=\<onesuperior>_]" [100, 100, 100] 100)

where

  "(a!<b>\<onesuperior>.P)[x::=\<onesuperior>\<onesuperior>y] = (a[x:::=y])!<(b[x:::=y])>\<onesuperior>.(P[x::=\<onesuperior>y])"

| "\<lbrakk>atom b \<sharp> (x, y)\<rbrakk> \<Longrightarrow> (a?<b>\<onesuperior>.P)[x::=\<onesuperior>\<onesuperior>y] = (a[x:::=y])?<b>\<onesuperior>.(P[x::=\<onesuperior>y])"

| "(<\<tau>\<onesuperior>>.P)[x::=\<onesuperior>\<onesuperior>y] = <\<tau>\<onesuperior>>.(P[x::=\<onesuperior>y])"

| "(\<zero>\<onesuperior>)[x::=\<onesuperior>\<twosuperior>y] = \<zero>\<onesuperior>"

| "(g \<oplus>\<onesuperior> xg)[x::=\<onesuperior>\<twosuperior>y] = (g[x::=\<onesuperior>\<onesuperior>y]) \<oplus>\<onesuperior> (xg[x::=\<onesuperior>\<twosuperior>y])"

| "\<lbrakk>atom a \<sharp> (x, y)\<rbrakk> \<Longrightarrow> (<\<nu>a>\<onesuperior>P)[x::=\<onesuperior>y] = <\<nu>a>\<onesuperior>(P[x::=\<onesuperior>y])"

| "(P \<parallel>\<onesuperior> Q)[x::=\<onesuperior>y] = (P[x::=\<onesuperior>y]) \<parallel>\<onesuperior> (Q[x::=\<onesuperior>y])"

| "([a\<frown>\<onesuperior>b]P)[x::=\<onesuperior>y] = ([(a[x:::=y])\<frown>\<onesuperior>(b[x:::=y])](P[x::=\<onesuperior>y]))"

| "(\<oplus>\<onesuperior>{xg})[x::=\<onesuperior>y] = \<oplus>\<onesuperior>{(xg[x::=\<onesuperior>\<twosuperior>y])}"

| "\<lbrakk>atom b \<sharp> (x, y)\<rbrakk> \<Longrightarrow> (\<infinity>a?<b>\<onesuperior>.P)[x::=\<onesuperior>y] = \<infinity>(a[x:::=y])?<b>\<onesuperior>.(P[x::=\<onesuperior>y])"

| "(succ\<onesuperior>)[x::=\<onesuperior>y] = succ\<onesuperior>"

  using [[simproc del: alpha_lst]]

  apply(auto simp add: piMix_distinct piMix_eq_iff)

  --"Covered all cases"

  apply(case_tac x)

  apply(simp)

  apply(case_tac a)

  apply(simp)

  apply (rule_tac y="aa" and c="(b, c)" in guardedTerm_mix_sumList_mix_piMix.strong_exhaust(1))

  apply(blast)

  apply(auto simp add: fresh_star_def)[1]

  apply(blast)

  apply(simp)

  apply(blast)

  apply(simp)

  apply(case_tac b)

  apply(simp)

  apply(case_tac a)

  apply(simp)

  apply (rule_tac ya="aa" in guardedTerm_mix_sumList_mix_piMix.strong_exhaust(2))

  apply(blast)

  apply(blast)

  apply(simp)

  apply(case_tac ba)

  apply(simp)

  apply (rule_tac yb="a" and c="(bb,c)" in guardedTerm_mix_sumList_mix_piMix.strong_exhaust(3))

  using [[simproc del: alpha_lst]]

  apply(auto simp add: fresh_star_def)[1]

  apply(blast)

  apply(blast)

  apply(blast)

  using [[simproc del: alpha_lst]]

  apply(auto simp add: fresh_star_def)[1]

  apply(blast)

  apply(simp)

  apply(blast)

  --"compatibility"

  apply (simp only: meta_eq_to_obj_eq[OF subs_mix_def, symmetric, unfolded fun_eq_iff])

  apply (subgoal_tac "eqvt_at (\<lambda>(a, b, c). subs_mix a b c) (P, xa, ya)")

  apply (thin_tac "eqvt_at subsGuard_mix_subsList_mix_subs_mix_sumC (Inr (Inr (P, xa, ya)))")

  apply (thin_tac "eqvt_at subsGuard_mix_subsList_mix_subs_mix_sumC (Inr (Inr (Pa, xa, ya)))")

  prefer 2

  apply (simp only: eqvt_at_def subs_mix_def)

  apply rule

  apply(simp (no_asm))

  apply (subst testrr)

  apply (simp add: subsGuard_mix_subsList_mix_subs_mix_sumC_def)

  apply (simp add: THE_default_def)

apply (case_tac "Ex1 (subsGuard_mix_subsList_mix_subs_mix_graph (Inr (Inr (P, xa, ya))))")

apply simp_all[2]

apply auto[1]

apply (erule_tac x="x" in allE)

apply simp

apply (thin_tac "\<forall>p\<Colon>perm.

           p \<bullet> The (subsGuard_mix_subsList_mix_subs_mix_graph (Inr (Inr (P, xa, ya)))) =

           (if \<exists>!x\<Colon>guardedTerm_mix + sumList_mix + piMix.

                  subsGuard_mix_subsList_mix_subs_mix_graph (Inr (Inr (p \<bullet> P, p \<bullet> xa, p \<bullet> ya))) x

            then THE x\<Colon>guardedTerm_mix + sumList_mix + piMix.

                    subsGuard_mix_subsList_mix_subs_mix_graph (Inr (Inr (p \<bullet> P, p \<bullet> xa, p \<bullet> ya))) x

            else Inr (Inr undefined))")

apply (thin_tac "\<forall>p\<Colon>perm.

           p \<bullet> (if \<exists>!x\<Colon>guardedTerm_mix + sumList_mix + piMix.

                      subsGuard_mix_subsList_mix_subs_mix_graph (Inr (Inr (Pa, xa, ya))) x

                then THE x\<Colon>guardedTerm_mix + sumList_mix + piMix.

                        subsGuard_mix_subsList_mix_subs_mix_graph (Inr (Inr (Pa, xa, ya))) x

                else Inr (Inr undefined)) =

           (if \<exists>!x\<Colon>guardedTerm_mix + sumList_mix + piMix.

                  subsGuard_mix_subsList_mix_subs_mix_graph (Inr (Inr (p \<bullet> Pa, p \<bullet> xa, p \<bullet> ya))) x

            then THE x\<Colon>guardedTerm_mix + sumList_mix + piMix.

                    subsGuard_mix_subsList_mix_subs_mix_graph (Inr (Inr (p \<bullet> Pa, p \<bullet> xa, p \<bullet> ya))) x

            else Inr (Inr undefined))")

apply (thin_tac "atom b \<sharp> (xa, ya)")

apply (thin_tac "atom ba \<sharp> (xa, ya)")

apply (thin_tac "[[atom b]]lst. P = [[atom ba]]lst. Pa")

apply(cases rule: subsGuard_mix_subsList_mix_subs_mix_graph.cases)

apply assumption

apply (metis Inr_not_Inl)

apply (metis Inr_not_Inl)

apply (metis Inr_not_Inl)

apply (metis Inr_inject Inr_not_Inl)

apply (metis Inr_inject Inr_not_Inl)

apply (rule_tac x="<\<nu>a>\<onesuperior>Sum_Type.Projr

                            (Sum_Type.Projr

                              (subsGuard_mix_subsList_mix_subs_mix_sum (Inr (Inr (Pb, xb, y)))))" in exI)

apply clarify

apply (rule the1_equality)

apply blast apply assumption

apply (rule_tac x="Sum_Type.Projr

                       (Sum_Type.Projr (subsGuard_mix_subsList_mix_subs_mix_sum (Inr (Inr (Pb, xb, y))))) \<parallel>\<onesuperior>

                      Sum_Type.Projr

                       (Sum_Type.Projr (subsGuard_mix_subsList_mix_subs_mix_sum (Inr (Inr (Q, xb, y)))))" in exI)

apply clarify

apply (rule the1_equality)

apply blast apply assumption

apply (rule_tac x="[(a[xb:::=y])\<frown>\<onesuperior>(bb[xb:::=y])]Sum_Type.Projr

                                                    (Sum_Type.Projr

(subsGuard_mix_subsList_mix_subs_mix_sum (Inr (Inr (Pb, xb, y)))))" in exI)

apply clarify

apply (rule the1_equality)

apply blast apply assumption

apply (rule_tac x="\<oplus>\<onesuperior>{Sum_Type.Projl

                          (Sum_Type.Projr

                            (subsGuard_mix_subsList_mix_subs_mix_sum (Inr (Inl (xg, xb, y)))))}" in exI)

apply clarify

apply (rule the1_equality)

apply blast apply assumption

apply (rule_tac x="\<infinity>(a[xb:::=y])?<bb>\<onesuperior>.Sum_Type.Projr

                                           (Sum_Type.Projr

                                             (subsGuard_mix_subsList_mix_subs_mix_sum

                                               (Inr (Inr (Pb, xb, y)))))" in exI)

apply clarify

apply (rule the1_equality)

apply blast apply assumption

apply (rule_tac x="succ\<onesuperior>" in exI)

apply clarify

apply (rule the1_equality)

apply blast apply assumption

apply simp

(* Here the only real goal compatibility is left *)

  apply (erule Abs_lst1_fcb)

  apply (simp_all add: Abs_fresh_iff fresh_fun_eqvt_app)

  apply (subgoal_tac "atom ba \<sharp> (\<lambda>(a, x, y). subs_mix a x y) (P, xa, ya)")

  apply simp

  apply (erule fresh_eqvt_at)

  apply(simp add: finite_supp)

  apply(simp)

  apply(simp add: eqvt_at_def)

  apply(drule_tac x="(b \<leftrightarrow> ba)" in spec)

  apply(simp)

  done

termination (eqvt)

  by (lexicographic_order)

lemma forget_mix:

  fixes g  :: guardedTerm_mix

  and   xg :: sumList_mix

  and   P  :: piMix

  and   x  :: name

  and   y  :: name

  shows "atom x \<sharp> g \<longrightarrow> g[x::=\<onesuperior>\<onesuperior>y] = g"

  and   "atom x \<sharp> xg \<longrightarrow> xg[x::=\<onesuperior>\<twosuperior>y] = xg"

  and   "atom x \<sharp> P \<longrightarrow> P[x::=\<onesuperior>y] = P"

proof -

  show  "atom x \<sharp> g \<longrightarrow> g[x::=\<onesuperior>\<onesuperior>y] = g"

  and   "atom x \<sharp> xg \<longrightarrow> xg[x::=\<onesuperior>\<twosuperior>y] = xg"

  and   "atom x \<sharp> P \<longrightarrow> P[x::=\<onesuperior>y] = P"

    using assms

    apply(nominal_induct g and xg and P avoiding: x y rule: piMix_strong_induct)

    by(auto simp add: piMix_eq_iff piMix_fresh fresh_at_base)

qed

lemma fresh_fact_mix:

  fixes g  :: guardedTerm_mix

  and   xg :: sumList_mix

  and   P  :: piMix

  and   x  :: name

  and   y  :: name

  and   z  :: name

  assumes "atom z \<sharp> y"

  shows "(z = x \<or> atom z \<sharp> g) \<longrightarrow> atom z \<sharp> g[x::=\<onesuperior>\<onesuperior>y]"

  and   "(z = x \<or> atom z \<sharp> xg) \<longrightarrow> atom z \<sharp> xg[x::=\<onesuperior>\<twosuperior>y]"

  and   "(z = x \<or> atom z \<sharp> P) \<longrightarrow> atom z \<sharp> P[x::=\<onesuperior>y]"

proof -

  show  "(z = x \<or> atom z \<sharp> g) \<longrightarrow> atom z \<sharp> g[x::=\<onesuperior>\<onesuperior>y]"

  and   "(z = x \<or> atom z \<sharp> xg) \<longrightarrow> atom z \<sharp> xg[x::=\<onesuperior>\<twosuperior>y]"

  and   "(z = x \<or> atom z \<sharp> P) \<longrightarrow> atom z \<sharp> P[x::=\<onesuperior>y]"

    using assms

    apply(nominal_induct g and xg and P avoiding: x y z rule: piMix_strong_induct)

    by(auto simp add: piMix_fresh fresh_at_base)

qed

lemma substitution_lemma_mix:

  fixes g  :: guardedTerm_mix

  and   xg :: sumList_mix

  and   P  :: piMix

  and   s  :: name

  and   u  :: name

  and   x  :: name

  and   y  :: name

  assumes "x \<noteq> y"

  and     "atom x \<sharp> u"

  shows "g[x::=\<onesuperior>\<onesuperior>s][y::=\<onesuperior>\<onesuperior>u] = g[y::=\<onesuperior>\<onesuperior>u][x::=\<onesuperior>\<onesuperior>s[y:::=u]]"

  and   "xg[x::=\<onesuperior>\<twosuperior>s][y::=\<onesuperior>\<twosuperior>u] = xg[y::=\<onesuperior>\<twosuperior>u][x::=\<onesuperior>\<twosuperior>s[y:::=u]]"

  and   "P[x::=\<onesuperior>s][y::=\<onesuperior>u] = P[y::=\<onesuperior>u][x::=\<onesuperior>s[y:::=u]]"

proof -

  show  "g[x::=\<onesuperior>\<onesuperior>s][y::=\<onesuperior>\<onesuperior>u] = g[y::=\<onesuperior>\<onesuperior>u][x::=\<onesuperior>\<onesuperior>s[y:::=u]]"

  and   "xg[x::=\<onesuperior>\<twosuperior>s][y::=\<onesuperior>\<twosuperior>u] = xg[y::=\<onesuperior>\<twosuperior>u][x::=\<onesuperior>\<twosuperior>s[y:::=u]]"

  and   "P[x::=\<onesuperior>s][y::=\<onesuperior>u] = P[y::=\<onesuperior>u][x::=\<onesuperior>s[y:::=u]]"

    using assms

    apply(nominal_induct g and xg and P avoiding: x y s u rule: piMix_strong_induct)

    apply(simp_all add: fresh_fact_mix forget_mix)

    by(auto simp add: fresh_at_base)

qed

lemma perm_eq_subst_mix:

  fixes g  :: guardedTerm_mix

  and   xg :: sumList_mix

  and   P  :: piMix

  and   x  :: name

  and   y  :: name

  shows "atom y \<sharp> g \<longrightarrow> (atom x \<rightleftharpoons> atom y) \<bullet> g = g[x::=\<onesuperior>\<onesuperior>y]"

  and   "atom y \<sharp> xg \<longrightarrow> (atom x \<rightleftharpoons> atom y) \<bullet> xg = xg[x::=\<onesuperior>\<twosuperior>y]"

  and   "atom y \<sharp> P \<longrightarrow> (atom x \<rightleftharpoons> atom y) \<bullet> P = P[x::=\<onesuperior>y]"

proof -

  show  "atom y \<sharp> g \<longrightarrow> (atom x \<rightleftharpoons> atom y) \<bullet> g = g[x::=\<onesuperior>\<onesuperior>y]"

  and   "atom y \<sharp> xg \<longrightarrow> (atom x \<rightleftharpoons> atom y) \<bullet> xg = xg[x::=\<onesuperior>\<twosuperior>y]"

  and   "atom y \<sharp> P \<longrightarrow> (atom x \<rightleftharpoons> atom y) \<bullet> P = P[x::=\<onesuperior>y]"

    apply(nominal_induct g and xg and P avoiding: x y rule: piMix_strong_induct)

    by(auto simp add: piMix_fresh fresh_at_base)

qed

lemma subst_id_mix:

  fixes g  :: guardedTerm_mix

  and   xg :: sumList_mix

  and   P  :: piMix

  and   x  :: name

  shows "g[x::=\<onesuperior>\<onesuperior>x] = g" and "xg[x::=\<onesuperior>\<twosuperior>x] = xg" and "P[x::=\<onesuperior>x] = P"

proof -

  show  "g[x::=\<onesuperior>\<onesuperior>x] = g" and "xg[x::=\<onesuperior>\<twosuperior>x] = xg" and "P[x::=\<onesuperior>x] = P"

    apply(nominal_induct g and xg and P avoiding: x rule: piMix_strong_induct)

    by(auto)

qed

lemma alphaRes_subst_mix:

  fixes a :: name

  and   P :: piMix

  and   z :: name

  assumes "atom z \<sharp> P"

  shows "<\<nu>a>\<onesuperior>P = <\<nu>z>\<onesuperior>(P[a::=\<onesuperior>z])"

proof(cases "a = z")

  assume "a = z"

  thus ?thesis

    by(simp add: subst_id_mix)

next

  assume "a \<noteq> z"

  thus ?thesis

    using assms

    by(simp add: alphaRes_mix perm_eq_subst_mix)

qed

lemma alphaInput_subst_mix:

  fixes a :: name

  and   b :: name

  and   P :: piMix

  and   z :: name

  assumes "atom z \<sharp> P"

  shows "a?<b>\<onesuperior>.P = a?<z>\<onesuperior>.(P[b::=\<onesuperior>z])"

proof(cases "b = z")

  assume "b = z"

  thus ?thesis

    by(simp add: subst_id_mix)

next

  assume "b \<noteq> z"