theory Abs

imports "Nominal2_Atoms" 

        "Nominal2_Eqvt" 

        "Nominal2_Supp" 

        "Nominal2_FSet"

        "../Quotient" 

        "../Quotient_Product" 

begin

fun

  alpha_gen 

where

  alpha_gen[simp del]:

  "alpha_gen (bs, x) R f pi (cs, y) \<longleftrightarrow> 

     f x - bs = f y - cs \<and> 

     (f x - bs) \<sharp>* pi \<and> 

     R (pi \<bullet> x) y \<and>

     pi \<bullet> bs = cs"

fun

  alpha_res

where

  alpha_res[simp del]:

  "alpha_res (bs, x) R f pi (cs, y) \<longleftrightarrow> 

     f x - bs = f y - cs \<and> 

     (f x - bs) \<sharp>* pi \<and> 

     R (pi \<bullet> x) y"

fun

  alpha_lst

where

  alpha_lst[simp del]:

  "alpha_lst (bs, x) R f pi (cs, y) \<longleftrightarrow> 

     f x - set bs = f y - set cs \<and> 

     (f x - set bs) \<sharp>* pi \<and> 

     R (pi \<bullet> x) y \<and>

     pi \<bullet> bs = cs"

lemmas alphas = alpha_gen.simps alpha_res.simps alpha_lst.simps

notation

  alpha_gen ("_ \<approx>gen _ _ _ _" [100, 100, 100, 100, 100] 100) and

  alpha_res ("_ \<approx>res _ _ _ _" [100, 100, 100, 100, 100] 100) and

  alpha_lst ("_ \<approx>lst _ _ _ _" [100, 100, 100, 100, 100] 100) 

(* monos *)

lemma [mono]: 

  shows "R1 \<le> R2 \<Longrightarrow> alpha_gen bs R1 \<le> alpha_gen bs R2"

  and   "R1 \<le> R2 \<Longrightarrow> alpha_res bs R1 \<le> alpha_res bs R2"

  and   "R1 \<le> R2 \<Longrightarrow> alpha_lst cs R1 \<le> alpha_lst cs R2"

  by (case_tac [!] bs, case_tac [!] cs) 

     (auto simp add: le_fun_def le_bool_def alphas)

lemma alpha_gen_refl:

  assumes a: "R x x"

  shows "(bs, x) \<approx>gen R f 0 (bs, x)"

  and   "(bs, x) \<approx>res R f 0 (bs, x)"

  and   "(cs, x) \<approx>lst R f 0 (cs, x)"

  using a 

  unfolding alphas

  unfolding fresh_star_def

  by (simp_all add: fresh_zero_perm)

lemma alpha_gen_sym:

  assumes a: "R (p \<bullet> x) y \<Longrightarrow> R (- p \<bullet> y) x"

  shows "(bs, x) \<approx>gen R f p (cs, y) \<Longrightarrow> (cs, y) \<approx>gen R f (- p) (bs, x)"

  and   "(bs, x) \<approx>res R f p (cs, y) \<Longrightarrow> (cs, y) \<approx>res R f (- p) (bs, x)"

  and   "(ds, x) \<approx>lst R f p (es, y) \<Longrightarrow> (es, y) \<approx>lst R f (- p) (ds, x)"

  using a

  unfolding alphas

  unfolding fresh_star_def

  by (auto simp add:  fresh_minus_perm)

lemma alpha_gen_trans:

  assumes a: "\<lbrakk>R (p \<bullet> x) y; R (q \<bullet> y) z\<rbrakk> \<Longrightarrow> R ((q + p) \<bullet> x) z"

  shows "\<lbrakk>(bs, x) \<approx>gen R f p (cs, y); (cs, y) \<approx>gen R f q (ds, z)\<rbrakk> \<Longrightarrow> (bs, x) \<approx>gen R f (q + p) (ds, z)"

  and   "\<lbrakk>(bs, x) \<approx>res R f p (cs, y); (cs, y) \<approx>res R f q (ds, z)\<rbrakk> \<Longrightarrow> (bs, x) \<approx>res R f (q + p) (ds, z)"

  and   "\<lbrakk>(es, x) \<approx>lst R f p (gs, y); (gs, y) \<approx>lst R f q (hs, z)\<rbrakk> \<Longrightarrow> (es, x) \<approx>lst R f (q + p) (hs, z)"

  using a 

  unfolding alphas

  unfolding fresh_star_def

  by (simp_all add: fresh_plus_perm)

lemma alpha_gen_eqvt:

  assumes a: "R (q \<bullet> x) y \<Longrightarrow> R (p \<bullet> (q \<bullet> x)) (p \<bullet> y)"

  and     b: "p \<bullet> (f x) = f (p \<bullet> x)"

  and     c: "p \<bullet> (f y) = f (p \<bullet> y)"

  shows "(bs, x) \<approx>gen R f q (cs, y) \<Longrightarrow> (p \<bullet> bs, p \<bullet> x) \<approx>gen R f (p \<bullet> q) (p \<bullet> cs, p \<bullet> y)"

  and   "(bs, x) \<approx>res R f q (cs, y) \<Longrightarrow> (p \<bullet> bs, p \<bullet> x) \<approx>res R f (p \<bullet> q) (p \<bullet> cs, p \<bullet> y)"

  and   "(ds, x) \<approx>lst R f q (es, y) \<Longrightarrow> (p \<bullet> ds, p \<bullet> x) \<approx>lst R f (p \<bullet> q) (p \<bullet> es, p \<bullet> y)" 

  unfolding alphas

  unfolding set_eqvt[symmetric]

  unfolding b[symmetric] c[symmetric]

  unfolding Diff_eqvt[symmetric]

  unfolding permute_eqvt[symmetric]

  using a

  by (auto simp add: fresh_star_permute_iff)

fun

  alpha_abs 

where

  "alpha_abs (bs, x) (cs, y) \<longleftrightarrow> (\<exists>p. (bs, x) \<approx>gen (op=) supp p (cs, y))"

notation

  alpha_abs ("_ \<approx>abs _")

lemma alpha_abs_swap:

  assumes a1: "a \<notin> (supp x) - bs"

  and     a2: "b \<notin> (supp x) - bs"

  shows "(bs, x) \<approx>abs ((a \<rightleftharpoons> b) \<bullet> bs, (a \<rightleftharpoons> b) \<bullet> x)"

  using a1 a2

  unfolding Diff_iff

  unfolding alpha_abs.simps

  unfolding alphas

  unfolding supp_eqvt[symmetric] Diff_eqvt[symmetric]

  unfolding fresh_star_def fresh_def

  unfolding swap_set_not_in[OF a1 a2] 

  by (rule_tac x="(a \<rightleftharpoons> b)" in exI)

     (auto simp add: supp_perm swap_atom)

fun

  supp_abs_fun

where

  "supp_abs_fun (bs, x) = (supp x) - bs"

lemma supp_abs_fun_lemma:

  assumes a: "x \<approx>abs y" 

  shows "supp_abs_fun x = supp_abs_fun y"

  using a

  apply(induct rule: alpha_abs.induct)

  apply(simp add: alpha_gen)

  done

quotient_type 'a abs_gen = "(atom set \<times> 'a::pt)" / "alpha_abs"

  apply(rule equivpI)

  unfolding reflp_def symp_def transp_def

  apply(simp_all)

  (* refl *)

  apply(clarify)

  apply(rule_tac x="0" in exI)

  apply(rule alpha_gen_refl)

  apply(simp)

  (* symm *)

  apply(clarify)

  apply(rule_tac x="- p" in exI)

  apply(rule alpha_gen_sym)

  apply(clarsimp)

  apply(assumption)

  (* trans *)

  apply(clarify)

  apply(rule_tac x="pa + p" in exI)

  apply(rule alpha_gen_trans)

  apply(auto)

  done

quotient_definition

  "Abs::atom set \<Rightarrow> ('a::pt) \<Rightarrow> 'a abs_gen"

is

  "Pair::atom set \<Rightarrow> ('a::pt) \<Rightarrow> (atom set \<times> 'a)"

lemma [quot_respect]:

  shows "((op =) ===> (op =) ===> alpha_abs) Pair Pair"

  apply(clarsimp)

  apply(rule exI)

  apply(rule alpha_gen_refl)

  apply(simp)

  done

lemma [quot_respect]:

  shows "((op =) ===> alpha_abs ===> alpha_abs) permute permute"

  apply(clarsimp)

  apply(rule exI)

  apply(rule alpha_gen_eqvt)

  apply(simp_all add: supp_eqvt)

  done

lemma [quot_respect]:

  shows "(alpha_abs ===> (op =)) supp_abs_fun supp_abs_fun"

  apply(simp add: supp_abs_fun_lemma)

  done

lemma abs_induct:

  "\<lbrakk>\<And>as (x::'a::pt). P (Abs as x)\<rbrakk> \<Longrightarrow> P t"

  apply(lifting prod.induct[where 'a="atom set" and 'b="'a"])

  done

(* TEST case *)

lemmas abs_induct2 = prod.induct[where 'a="atom set" and 'b="'a::pt", quot_lifted]

thm abs_induct abs_induct2

instantiation abs_gen :: (pt) pt

begin

quotient_definition

  "permute_abs_gen::perm \<Rightarrow> ('a::pt abs_gen) \<Rightarrow> 'a abs_gen"

is

  "permute:: perm \<Rightarrow> (atom set \<times> 'a::pt) \<Rightarrow> (atom set \<times> 'a::pt)"

(* ??? has to be 'a \<dots> 'b does not work *)

lemma permute_ABS [simp]:

  fixes x::"'a::pt"  

  shows "(p \<bullet> (Abs as x)) = Abs (p \<bullet> as) (p \<bullet> x)"

  thm permute_prod.simps

  by (lifting permute_prod.simps(1)[where 'a="atom set" and 'b="'a"])

instance

  apply(default)

  apply(induct_tac [!] x rule: abs_induct)

  apply(simp_all)

  done

end

quotient_definition

  "supp_Abs_fun :: ('a::pt) abs_gen \<Rightarrow> atom \<Rightarrow> bool"

is

  "supp_abs_fun"

lemma supp_Abs_fun_simp:

  shows "supp_Abs_fun (Abs bs x) = (supp x) - bs"

  by (lifting supp_abs_fun.simps(1))

lemma supp_Abs_fun_eqvt [eqvt]:

  shows "(p \<bullet> supp_Abs_fun x) = supp_Abs_fun (p \<bullet> x)"

  apply(induct_tac x rule: abs_induct)

  apply(simp add: supp_Abs_fun_simp supp_eqvt Diff_eqvt)

  done

lemma supp_Abs_fun_fresh:

  shows "a \<sharp> Abs bs x \<Longrightarrow> a \<sharp> supp_Abs_fun (Abs bs x)"

  apply(rule fresh_fun_eqvt_app)

  apply(simp add: eqvts_raw)

  apply(simp)

  done

lemma Abs_swap:

  assumes a1: "a \<notin> (supp x) - bs"

  and     a2: "b \<notin> (supp x) - bs"

  shows "(Abs bs x) = (Abs ((a \<rightleftharpoons> b) \<bullet> bs) ((a \<rightleftharpoons> b) \<bullet> x))"

  using a1 a2 by (lifting alpha_abs_swap)

lemma Abs_supports:

  shows "((supp x) - as) supports (Abs as x)"

  unfolding supports_def

  apply(clarify)

  apply(simp (no_asm))

  apply(subst Abs_swap[symmetric])

  apply(simp_all)

  done

lemma finite_supp_Abs_subset1:

  assumes "finite (supp x)"

  shows "(supp x) - as \<subseteq> supp (Abs as x)"

  apply(simp add: supp_conv_fresh)

  apply(auto)

  apply(drule_tac supp_Abs_fun_fresh)

  apply(simp only: supp_Abs_fun_simp)

  apply(simp add: fresh_def)

  apply(simp add: supp_finite_atom_set assms)

  done

lemma finite_supp_Abs_subset2:

  assumes "finite (supp x)"

  shows "supp (Abs as x) \<subseteq> (supp x) - as"

  apply(rule supp_is_subset)

  apply(rule Abs_supports)

  apply(simp add: assms)

  done

lemma finite_supp_Abs:

  assumes "finite (supp x)"

  shows "supp (Abs as x) = (supp x) - as"

  apply(rule_tac subset_antisym)

  apply(rule finite_supp_Abs_subset2[OF assms])

  apply(rule finite_supp_Abs_subset1[OF assms])

  done

lemma supp_Abs:

  fixes x::"'a::fs"

  shows "supp (Abs as x) = (supp x) - as"

  apply(rule finite_supp_Abs)

  apply(simp add: finite_supp)

  done

instance abs_gen :: (fs) fs

  apply(default)

  apply(induct_tac x rule: abs_induct)

  apply(simp add: supp_Abs)

  apply(simp add: finite_supp)

  done

lemma Abs_fresh_iff:

  fixes x::"'a::fs"

  shows "a \<sharp> Abs bs x \<longleftrightarrow> a \<in> bs \<or> (a \<notin> bs \<and> a \<sharp> x)"

  apply(simp add: fresh_def)

  apply(simp add: supp_Abs)

  apply(auto)

  done

lemma Abs_eq_iff:

  shows "Abs bs x = Abs cs y \<longleftrightarrow> (\<exists>p. (bs, x) \<approx>gen (op =) supp p (cs, y))"

  by (lifting alpha_abs.simps(1))

(* 

  below is a construction site for showing that in the

  single-binder case, the old and new alpha equivalence 

  coincide

*)

fun

  alpha1

where

  "alpha1 (a, x) (b, y) \<longleftrightarrow> (a = b \<and> x = y) \<or> (a \<noteq> b \<and> x = (a \<rightleftharpoons> b) \<bullet> y \<and> a \<sharp> y)"

notation 

  alpha1 ("_ \<approx>abs1 _")

fun

  alpha2

where

  "alpha2 (a, x) (b, y) \<longleftrightarrow> (\<exists>c. c \<sharp> (a,b,x,y) \<and> ((c \<rightleftharpoons> a) \<bullet> x) = ((c \<rightleftharpoons> b) \<bullet> y))"

notation 

  alpha2 ("_ \<approx>abs2 _")

lemma alpha_old_new:

  assumes a: "(a, x) \<approx>abs1 (b, y)" "sort_of a = sort_of b"

  shows "({a}, x) \<approx>abs ({b}, y)"

using a

apply(simp)

apply(erule disjE)

apply(simp)

apply(rule exI)

apply(rule alpha_gen_refl)

apply(simp)

apply(rule_tac x="(a \<rightleftharpoons> b)" in  exI)

apply(simp add: alpha_gen)

apply(simp add: fresh_def)

apply(rule conjI)

apply(rule_tac ?p1="(a \<rightleftharpoons> b)" in  permute_eq_iff[THEN iffD1])

apply(rule trans)

apply(simp add: Diff_eqvt supp_eqvt)

apply(subst swap_set_not_in)

back

apply(simp)

apply(simp)

apply(simp add: permute_set_eq)

apply(rule conjI)

apply(rule_tac ?p1="(a \<rightleftharpoons> b)" in fresh_star_permute_iff[THEN iffD1])

apply(simp add: permute_self)

apply(simp add: Diff_eqvt supp_eqvt)

apply(simp add: permute_set_eq)

apply(subgoal_tac "supp (a \<rightleftharpoons> b) \<subseteq> {a, b}")

apply(simp add: fresh_star_def fresh_def)

apply(blast)

apply(simp add: supp_swap)

apply(simp add: eqvts)

done

lemma perm_induct_test:

  fixes P :: "perm => bool"

  assumes fin: "finite (supp p)" 

  assumes zero: "P 0"

  assumes swap: "\<And>a b. \<lbrakk>sort_of a = sort_of b; a \<noteq> b\<rbrakk> \<Longrightarrow> P (a \<rightleftharpoons> b)"

  assumes plus: "\<And>p1 p2. \<lbrakk>supp p1 \<inter> supp p2 = {}; P p1; P p2\<rbrakk> \<Longrightarrow> P (p1 + p2)"

  shows "P p"

using fin

apply(induct F\<equiv>"supp p" arbitrary: p rule: finite_induct)

oops

lemma ii:

  assumes "\<forall>x \<in> A. p \<bullet> x = x"

  shows "p \<bullet> A = A"

using assms

apply(auto)

apply (metis Collect_def Collect_mem_eq Int_absorb assms eqvt_bound inf_Int_eq mem_def mem_permute_iff)

apply (metis Collect_def Collect_mem_eq Int_absorb assms eqvt_apply eqvt_bound eqvt_lambda inf_Int_eq mem_def mem_permute_iff permute_minus_cancel(2) permute_pure)

done

lemma alpha_abs_Pair:

  shows "(bs, (x1, x2)) \<approx>gen (\<lambda>(x1,x2) (y1,y2). x1=y1 \<and> x2=y2) (\<lambda>(x,y). supp x \<union> supp y) p (cs, (y1, y2))

         \<longleftrightarrow> ((bs, x1) \<approx>gen (op=) supp p (cs, y1) \<and> (bs, x2) \<approx>gen (op=) supp p (cs, y2))"         

  apply(simp add: alpha_gen)

  apply(simp add: fresh_star_def)

  apply(simp add: ball_Un Un_Diff)

  apply(rule iffI)

  apply(simp)

  defer

  apply(simp)

  apply(rule conjI)

  apply(clarify)

  apply(simp add: supp_eqvt[symmetric] Diff_eqvt[symmetric])

  apply(rule sym)

  apply(rule ii)

  apply(simp add: fresh_def supp_perm)

  apply(clarify)

  apply(simp add: supp_eqvt[symmetric] Diff_eqvt[symmetric])