theory Abs

imports "Nominal2_Atoms" "Nominal2_Eqvt" "Nominal2_Supp" "../QuotMain" "../QuotProd"

begin

(* lemmas that should be in Nominal \<dots>\<dots>must be cleaned *)

lemma in_permute_iff:

  shows "(p \<bullet> x) \<in> (p \<bullet> X) \<longleftrightarrow> x \<in> X"

apply(unfold mem_def permute_fun_def)[1]

apply(simp add: permute_bool_def) 

done

lemma fresh_star_permute_iff:

  shows "(p \<bullet> a) \<sharp>* (p \<bullet> x) \<longleftrightarrow> a \<sharp>* x"

apply(simp add: fresh_star_def)

apply(auto)

apply(drule_tac x="p \<bullet> xa" in bspec)

apply(unfold mem_def permute_fun_def)[1] 

apply(simp add: eqvts)

apply(simp add: fresh_permute_iff)

apply(rule_tac ?p1="- p" in fresh_permute_iff[THEN iffD1])

apply(simp)

apply(drule_tac x="- p \<bullet> xa" in bspec)

apply(rule_tac ?p1="p" in in_permute_iff[THEN iffD1])

apply(simp)

apply(simp)

done

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)"

notation

  alpha_gen ("_ \<approx>gen _ _ _ _")

lemma [mono]: "R1 \<le> R2 \<Longrightarrow> alpha_gen x R1 \<le> alpha_gen x R2"

  by (cases x) (auto simp add: le_fun_def le_bool_def alpha_gen.simps)

lemma alpha_gen_refl:

  assumes a: "R x x"

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

  using a by (simp add: alpha_gen fresh_star_def fresh_zero_perm)

lemma alpha_gen_sym:

  assumes a: "(bs, x) \<approx>gen R f p (cs, y)"

  and     b: "R (p \<bullet> x) y \<Longrightarrow> R (- p \<bullet> y) x"

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

  using a b by (simp add: alpha_gen fresh_star_def fresh_def supp_minus_perm)

lemma alpha_gen_trans:

  assumes a: "(bs, x) \<approx>gen R f p1 (cs, y)"

  and     b: "(cs, y) \<approx>gen R f p2 (ds, z)"

  and     c: "\<lbrakk>R (p1 \<bullet> x) y; R (p2 \<bullet> y) z\<rbrakk> \<Longrightarrow> R ((p2 + p1) \<bullet> x) z"

  shows "(bs, x) \<approx>gen R f (p2 + p1) (ds, z)"

  using a b c using supp_plus_perm

  apply(simp add: alpha_gen fresh_star_def fresh_def)

  apply(blast)

  done

lemma alpha_gen_eqvt:

  assumes a: "(bs, x) \<approx>gen R f q (cs, y)"

  and     b: "R (q \<bullet> x) y \<Longrightarrow> R (p \<bullet> (q \<bullet> x)) (p \<bullet> y)"

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

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

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

  using a b

  apply(simp add: alpha_gen c[symmetric] d[symmetric] Diff_eqvt[symmetric])

  apply(simp add: permute_eqvt[symmetric])

  apply(simp add: fresh_star_permute_iff)

  apply(clarsimp)

  done

fun

  alpha_abs 

where

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

notation

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

  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)"

fun

where

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

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

  apply(rule equivpI)

  unfolding reflp_def symp_def transp_def

  apply(simp_all)

  apply(clarify)

  apply(rule exI)

  apply(rule alpha_gen_refl)

  apply(simp)

  apply(clarify)

  apply(rule exI)

  apply(rule alpha_gen_sym)

  apply(assumption)

  apply(clarsimp)

  apply(clarify)

  apply(rule exI)

  apply(rule alpha_gen_trans)

  apply(assumption)

  apply(assumption)

  apply(simp)

  done

quotient_definition

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

as

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

lemma [quot_respect]:

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

lemma [quot_respect]:

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

lemma [quot_respect]:

lemma abs_induct:

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

instantiation abs :: (pt) pt

begin

quotient_definition

  "permute_abs::perm \<Rightarrow> ('a::pt abs) \<Rightarrow> 'a abs"

as

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

lemma permute_ABS [simp]:

  fixes x::"'a::pt"  (* ??? has to be 'a \<dots> 'b does not work *)

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

instance

  apply(default)

  apply(induct_tac [!] x rule: abs_induct)

  apply(simp_all)

  done

end

  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))"

lemma Abs_supports:

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

  fixes x::"'a::fs"

lemma supp_Abs:

  fixes x::"'a::fs"

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

instance abs :: (fs) fs

  fixes x::"'a::fs"

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

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

end