theory Nominal2_FSet
imports FSet Nominal2_Supp
begin

lemma permute_rsp_fset[quot_respect]:
  "(op = ===> op \<approx> ===> op \<approx>) permute permute"
  apply (simp add: eqvts[symmetric])
  apply clarify
  apply (subst permute_minus_cancel(1)[symmetric, of "xb"])
  apply (subst mem_eqvt[symmetric])
  apply (subst (2) permute_minus_cancel(1)[symmetric, of "xb"])
  apply (subst mem_eqvt[symmetric])
  apply (erule_tac x="- x \<bullet> xb" in allE)
  apply simp
  done

instantiation FSet.fset :: (pt) pt
begin

term "permute :: perm \<Rightarrow> 'a list \<Rightarrow> 'a list"

quotient_definition
  "permute_fset :: perm \<Rightarrow> 'a fset \<Rightarrow> 'a fset"
is
  "permute :: perm \<Rightarrow> 'a list \<Rightarrow> 'a list"

lemma permute_list_zero: "0 \<bullet> (x :: 'a list) = x"
  by (rule permute_zero)

lemma permute_fset_zero: "0 \<bullet> (x :: 'a fset) = x"
  by (lifting permute_list_zero)

lemma permute_list_plus: "(p + q) \<bullet> (x :: 'a list) = p \<bullet> q \<bullet> x"
  by (rule permute_plus)

lemma permute_fset_plus: "(p + q) \<bullet> (x :: 'a fset) = p \<bullet> q \<bullet> x"
  by (lifting permute_list_plus)

instance
  apply default
  apply (rule permute_fset_zero)
  apply (rule permute_fset_plus)
  done

end

lemma permute_fset[simp,eqvt]:
  "p \<bullet> ({||} :: 'a :: pt fset) = {||}"
  "p \<bullet> finsert (x :: 'a :: pt) xs = finsert (p \<bullet> x) (p \<bullet> xs)"
  by (lifting permute_list.simps)

lemma map_eqvt[eqvt]: "pi \<bullet> (map f l) = map (pi \<bullet> f) (pi \<bullet> l)"
  apply (induct l)
  apply (simp_all)
  apply (simp only: eqvt_apply)
  done

lemma fmap_eqvt[eqvt]: "pi \<bullet> (fmap f l) = fmap (pi \<bullet> f) (pi \<bullet> l)"
  by (lifting map_eqvt)

lemma fset_to_set_eqvt[eqvt]: "pi \<bullet> (fset_to_set x) = fset_to_set (pi \<bullet> x)"
  by (lifting set_eqvt)

lemma supp_fset_to_set:
  "supp (fset_to_set x) = supp x"
  apply (simp add: supp_def)
  apply (simp add: eqvts)
  apply (simp add: fset_cong)
  done

lemma atom_fmap_cong:
  shows "(fmap atom x = fmap atom y) = (x = y)"
  apply(rule inj_fmap_eq_iff)
  apply(simp add: inj_on_def)
  done

lemma supp_fmap_atom:
  "supp (fmap atom x) = supp x"
  apply (simp add: supp_def)
  apply (simp add: eqvts eqvts_raw atom_fmap_cong)
  done

(*lemma "\<not> (memb x S) \<Longrightarrow> \<not> (memb y T) \<Longrightarrow> ((x # S) \<approx> (y # T)) = (x = y \<and> S \<approx> T)"*)

lemma infinite_Un:
  shows "infinite (S \<union> T) \<longleftrightarrow> infinite S \<or> infinite T"
  by simp

lemma supp_insert: "supp (insert (x :: 'a :: fs) xs) = supp x \<union> supp xs"
  oops

lemma supp_finsert:
  "supp (finsert (x :: 'a :: fs) S) = supp x \<union> supp S"
  apply (subst supp_fset_to_set[symmetric])
  apply simp
  (* apply (simp add: supp_insert supp_fset_to_set) *)
  oops

instance fset :: (fs) fs
  apply (default)
  apply (induct_tac x rule: fset_induct)
  apply (simp add: supp_def eqvts)
  (* apply (simp add: supp_finsert) *)
  (* apply default ? *)
  oops

end