(*  Title:      HOL/Quotient_Examples/FSet.thy

    Author:     Cezary Kaliszyk, TU Munich

    Author:     Christian Urban, TU Munich

A reasoning infrastructure for the type of finite sets.

*)

theory FSet

imports Quotient_List

begin

text {* Definiton of List relation and the quotient type *}

fun

  list_eq :: "'a list \<Rightarrow> 'a list \<Rightarrow> bool" (infix "\<approx>" 50)

where

  "list_eq xs ys = (set xs = set ys)"

lemma list_eq_equivp:

  shows "equivp list_eq"

  unfolding equivp_reflp_symp_transp

  unfolding reflp_def symp_def transp_def

  by auto

quotient_type

  'a fset = "'a list" / "list_eq"

  by (rule list_eq_equivp)

text {* Raw definitions of membership, sublist, cardinality,

  intersection

*}

definition

  memb :: "'a \<Rightarrow> 'a list \<Rightarrow> bool"

where

  "memb x xs \<equiv> x \<in> set xs"

definition

  sub_list :: "'a list \<Rightarrow> 'a list \<Rightarrow> bool"

where

  "sub_list xs ys \<equiv> set xs \<subseteq> set ys"

definition

  fcard_raw :: "'a list \<Rightarrow> nat"

where

  "fcard_raw xs = card (set xs)"

primrec

  finter_raw :: "'a list \<Rightarrow> 'a list \<Rightarrow> 'a list"

where

  "finter_raw [] ys = []"

| "finter_raw (x # xs) ys =

    (if x \<in> set ys then x # (finter_raw xs ys) else finter_raw xs ys)"

primrec

  fminus_raw :: "'a list \<Rightarrow> 'a list \<Rightarrow> 'a list"

where

  "fminus_raw ys [] = ys"

| "fminus_raw ys (x # xs) = fminus_raw (removeAll x ys) xs"

definition

  rsp_fold

where

  "rsp_fold f = (\<forall>u v w. (f u (f v w) = f v (f u w)))"

primrec

  ffold_raw :: "('a \<Rightarrow> 'b \<Rightarrow> 'b) \<Rightarrow> 'b \<Rightarrow> 'a list \<Rightarrow> 'b"

where

  "ffold_raw f z [] = z"

| "ffold_raw f z (a # xs) =

     (if (rsp_fold f) then

       if a \<in> set xs then ffold_raw f z xs

       else f a (ffold_raw f z xs)

     else z)"

text {* Composition Quotient *}

lemma list_all2_refl1:

  shows "(list_all2 op \<approx>) r r"

  by (rule list_all2_refl) (metis equivp_def fset_equivp)

lemma compose_list_refl:

  shows "(list_all2 op \<approx> OOO op \<approx>) r r"

proof

  have *: "r \<approx> r" by (rule equivp_reflp[OF fset_equivp])

  show "list_all2 op \<approx> r r" by (rule list_all2_refl1)

  with * show "(op \<approx> OO list_all2 op \<approx>) r r" ..

qed

lemma Quotient_fset_list:

  shows "Quotient (list_all2 op \<approx>) (map abs_fset) (map rep_fset)"

  by (fact list_quotient[OF Quotient_fset])

lemma map_rel_cong: "b \<approx> ba \<Longrightarrow> map f b \<approx> map f ba"

  unfolding list_eq.simps

  by (simp only: set_map)

lemma quotient_compose_list[quot_thm]:

  shows  "Quotient ((list_all2 op \<approx>) OOO (op \<approx>))

    (abs_fset \<circ> (map abs_fset)) ((map rep_fset) \<circ> rep_fset)"

  unfolding Quotient_def comp_def

proof (intro conjI allI)

  fix a r s

  show "abs_fset (map abs_fset (map rep_fset (rep_fset a))) = a"

    by (simp add: abs_o_rep[OF Quotient_fset] Quotient_abs_rep[OF Quotient_fset] map_id)

  have b: "list_all2 op \<approx> (map rep_fset (rep_fset a)) (map rep_fset (rep_fset a))"

    by (rule list_all2_refl1)

  have c: "(op \<approx> OO list_all2 op \<approx>) (map rep_fset (rep_fset a)) (map rep_fset (rep_fset a))"

    by (rule, rule equivp_reflp[OF fset_equivp]) (rule b)

  show "(list_all2 op \<approx> OOO op \<approx>) (map rep_fset (rep_fset a)) (map rep_fset (rep_fset a))"

    by (rule, rule list_all2_refl1) (rule c)

  show "(list_all2 op \<approx> OOO op \<approx>) r s = ((list_all2 op \<approx> OOO op \<approx>) r r \<and>

        (list_all2 op \<approx> OOO op \<approx>) s s \<and> abs_fset (map abs_fset r) = abs_fset (map abs_fset s))"

  proof (intro iffI conjI)

    show "(list_all2 op \<approx> OOO op \<approx>) r r" by (rule compose_list_refl)

    show "(list_all2 op \<approx> OOO op \<approx>) s s" by (rule compose_list_refl)

  next

    assume a: "(list_all2 op \<approx> OOO op \<approx>) r s"

    then have b: "map abs_fset r \<approx> map abs_fset s"

    proof (elim pred_compE)

      fix b ba

      assume c: "list_all2 op \<approx> r b"

      assume d: "b \<approx> ba"

      assume e: "list_all2 op \<approx> ba s"

      have f: "map abs_fset r = map abs_fset b"

        using Quotient_rel[OF Quotient_fset_list] c by blast

      have "map abs_fset ba = map abs_fset s"

        using Quotient_rel[OF Quotient_fset_list] e by blast

      then have g: "map abs_fset s = map abs_fset ba" by simp

      then show "map abs_fset r \<approx> map abs_fset s" using d f map_rel_cong by simp

    qed

    then show "abs_fset (map abs_fset r) = abs_fset (map abs_fset s)"

      using Quotient_rel[OF Quotient_fset] by blast

  next

    assume a: "(list_all2 op \<approx> OOO op \<approx>) r r \<and> (list_all2 op \<approx> OOO op \<approx>) s s

      \<and> abs_fset (map abs_fset r) = abs_fset (map abs_fset s)"

    then have s: "(list_all2 op \<approx> OOO op \<approx>) s s" by simp

    have d: "map abs_fset r \<approx> map abs_fset s"

      by (subst Quotient_rel[OF Quotient_fset]) (simp add: a)

    have b: "map rep_fset (map abs_fset r) \<approx> map rep_fset (map abs_fset s)"

      by (rule map_rel_cong[OF d])

    have y: "list_all2 op \<approx> (map rep_fset (map abs_fset s)) s"

      by (fact rep_abs_rsp_left[OF Quotient_fset_list, OF list_all2_refl1[of s]])

    have c: "(op \<approx> OO list_all2 op \<approx>) (map rep_fset (map abs_fset r)) s"

      by (rule pred_compI) (rule b, rule y)

    have z: "list_all2 op \<approx> r (map rep_fset (map abs_fset r))"

      by (fact rep_abs_rsp[OF Quotient_fset_list, OF list_all2_refl1[of r]])

    then show "(list_all2 op \<approx> OOO op \<approx>) r s"

      using a c pred_compI by simp

  qed

qed

lemma set_finter_raw[simp]:

  "set (finter_raw xs ys) = set xs \<inter> set ys"

  by (induct xs) (auto simp add: memb_def)

lemma set_fminus_raw[simp]: 

  "set (fminus_raw xs ys) = (set xs - set ys)"

  by (induct ys arbitrary: xs) (auto)

lemma append_rsp[quot_respect]:

  shows "(op \<approx> ===> op \<approx> ===> op \<approx>) append append"

  by (simp)

lemma sub_list_rsp[quot_respect]:

  shows "(op \<approx> ===> op \<approx> ===> op =) sub_list sub_list"

  by (auto simp add: sub_list_def)

lemma memb_rsp[quot_respect]:

  shows "(op = ===> op \<approx> ===> op =) memb memb"

  by (auto simp add: memb_def)

lemma nil_rsp[quot_respect]:

  shows "(op \<approx>) Nil Nil"

  by simp

lemma cons_rsp[quot_respect]:

  shows "(op = ===> op \<approx> ===> op \<approx>) Cons Cons"

  by simp

lemma map_rsp[quot_respect]:

  shows "(op = ===> op \<approx> ===> op \<approx>) map map"

  by auto

lemma set_rsp[quot_respect]:

  "(op \<approx> ===> op =) set set"

  by auto

lemma list_equiv_rsp[quot_respect]:

  shows "(op \<approx> ===> op \<approx> ===> op =) op \<approx> op \<approx>"

  by auto

lemma finter_raw_rsp[quot_respect]:

  shows "(op \<approx> ===> op \<approx> ===> op \<approx>) finter_raw finter_raw"

  by simp

lemma removeAll_rsp[quot_respect]:

  shows "(op = ===> op \<approx> ===> op \<approx>) removeAll removeAll"

  by simp

lemma fminus_raw_rsp[quot_respect]:

  shows "(op \<approx> ===> op \<approx> ===> op \<approx>) fminus_raw fminus_raw"

  by simp

lemma fcard_raw_rsp[quot_respect]:

  shows "(op \<approx> ===> op =) fcard_raw fcard_raw"

  by (simp add: fcard_raw_def)

lemma not_memb_nil:

  shows "\<not> memb x []"

  by (simp add: memb_def)

lemma memb_cons_iff:

  shows "memb x (y # xs) = (x = y \<or> memb x xs)"

  by (induct xs) (auto simp add: memb_def)

lemma memb_absorb:

  shows "memb x xs \<Longrightarrow> x # xs \<approx> xs"

  by (induct xs) (auto simp add: memb_def)

lemma none_memb_nil:

  "(\<forall>x. \<not> memb x xs) = (xs \<approx> [])"

  by (simp add: memb_def)

lemma memb_commute_ffold_raw:

  "rsp_fold f \<Longrightarrow> h \<in> set b \<Longrightarrow> ffold_raw f z b = f h (ffold_raw f z (removeAll h b))"

  apply (induct b)

  apply (auto simp add: rsp_fold_def)

  done

lemma ffold_raw_rsp_pre:

  "set a = set b \<Longrightarrow> ffold_raw f z a = ffold_raw f z b"

  apply (induct a arbitrary: b)

  apply (simp)

  apply (simp (no_asm_use))

  apply (rule conjI)

  apply (rule_tac [!] impI)

  apply (rule_tac [!] conjI)

  apply (rule_tac [!] impI)

  apply (metis insert_absorb)

  apply (metis List.insert_def List.set.simps(2) List.set_insert ffold_raw.simps(2))

  apply (metis Diff_insert_absorb insertI1 memb_commute_ffold_raw set_removeAll)

  apply(drule_tac x="removeAll a1 b" in meta_spec)

  apply(auto)

  apply(drule meta_mp)

  apply(blast)

  by (metis List.set.simps(2) emptyE ffold_raw.simps(2) in_listsp_conv_set listsp.simps mem_def)

lemma ffold_raw_rsp[quot_respect]:

  shows "(op = ===> op = ===> op \<approx> ===> op =) ffold_raw ffold_raw"

  unfolding fun_rel_def

  by(auto intro: ffold_raw_rsp_pre)

lemma concat_rsp_pre:

  assumes a: "list_all2 op \<approx> x x'"

  and     b: "x' \<approx> y'"

  and     c: "list_all2 op \<approx> y' y"

  and     d: "\<exists>x\<in>set x. xa \<in> set x"

  shows "\<exists>x\<in>set y. xa \<in> set x"

proof -

  obtain xb where e: "xb \<in> set x" and f: "xa \<in> set xb" using d by auto

  have "\<exists>y. y \<in> set x' \<and> xb \<approx> y" by (rule list_all2_find_element[OF e a])

  then obtain ya where h: "ya \<in> set x'" and i: "xb \<approx> ya" by auto

  have "ya \<in> set y'" using b h by simp

  then have "\<exists>yb. yb \<in> set y \<and> ya \<approx> yb" using c by (rule list_all2_find_element)

  then show ?thesis using f i by auto

qed

lemma concat_rsp[quot_respect]:

  shows "(list_all2 op \<approx> OOO op \<approx> ===> op \<approx>) concat concat"

proof (rule fun_relI, elim pred_compE)

  fix a b ba bb

  assume a: "list_all2 op \<approx> a ba"

  assume b: "ba \<approx> bb"

  assume c: "list_all2 op \<approx> bb b"

  have "\<forall>x. (\<exists>xa\<in>set a. x \<in> set xa) = (\<exists>xa\<in>set b. x \<in> set xa)" 

  proof

    fix x

    show "(\<exists>xa\<in>set a. x \<in> set xa) = (\<exists>xa\<in>set b. x \<in> set xa)" 

    proof

      assume d: "\<exists>xa\<in>set a. x \<in> set xa"

      show "\<exists>xa\<in>set b. x \<in> set xa" by (rule concat_rsp_pre[OF a b c d])

    next

      assume e: "\<exists>xa\<in>set b. x \<in> set xa"

      have a': "list_all2 op \<approx> ba a" by (rule list_all2_symp[OF list_eq_equivp, OF a])

      have b': "bb \<approx> ba" by (rule equivp_symp[OF list_eq_equivp, OF b])

      have c': "list_all2 op \<approx> b bb" by (rule list_all2_symp[OF list_eq_equivp, OF c])

      show "\<exists>xa\<in>set a. x \<in> set xa" by (rule concat_rsp_pre[OF c' b' a' e])

    qed

  qed

  then show "concat a \<approx> concat b" by auto

qed

lemma [quot_respect]:

  by auto

text {* Distributive lattice with bot *}

lemma append_inter_distrib:

  "x @ (finter_raw y z) \<approx> finter_raw (x @ y) (x @ z)"

  apply (induct x)

  apply (auto)

  done

instantiation fset :: (type) "{bounded_lattice_bot, distrib_lattice, minus}"

begin

quotient_definition

  "bot :: 'a fset" is "[] :: 'a list"

abbreviation

  fempty  ("{||}")

where

  "{||} \<equiv> bot :: 'a fset"

quotient_definition

  "less_eq_fset \<Colon> ('a fset \<Rightarrow> 'a fset \<Rightarrow> bool)"

is

  "sub_list \<Colon> ('a list \<Rightarrow> 'a list \<Rightarrow> bool)"

abbreviation

  f_subset_eq :: "'a fset \<Rightarrow> 'a fset \<Rightarrow> bool" (infix "|\<subseteq>|" 50)

where

  "xs |\<subseteq>| ys \<equiv> xs \<le> ys"

definition

  less_fset :: "'a fset \<Rightarrow> 'a fset \<Rightarrow> bool"

where  

  "xs < ys \<equiv> xs \<le> ys \<and> xs \<noteq> (ys::'a fset)"

abbreviation

  fsubset :: "'a fset \<Rightarrow> 'a fset \<Rightarrow> bool" (infix "|\<subset>|" 50)

where

  "xs |\<subset>| ys \<equiv> xs < ys"

quotient_definition

  "sup :: 'a fset \<Rightarrow> 'a fset \<Rightarrow> 'a fset"

is

  "append :: 'a list \<Rightarrow> 'a list \<Rightarrow> 'a list"

abbreviation

  funion (infixl "|\<union>|" 65)

where

  "xs |\<union>| ys \<equiv> sup xs (ys::'a fset)"

quotient_definition

  "inf :: 'a fset \<Rightarrow> 'a fset \<Rightarrow> 'a fset"

is

  "finter_raw :: 'a list \<Rightarrow> 'a list \<Rightarrow> 'a list"

abbreviation

  finter (infixl "|\<inter>|" 65)

where

  "xs |\<inter>| ys \<equiv> inf xs (ys::'a fset)"

quotient_definition

  "minus :: 'a fset \<Rightarrow> 'a fset \<Rightarrow> 'a fset"

is

  "fminus_raw :: 'a list \<Rightarrow> 'a list \<Rightarrow> 'a list"

instance

proof

  fix x y z :: "'a fset"

  show "x |\<subset>| y \<longleftrightarrow> x |\<subseteq>| y \<and> \<not> y |\<subseteq>| x"

    unfolding less_fset_def 

    by (descending) (auto simp add: sub_list_def)

  show "x |\<subseteq>| x"  by (descending) (simp add: sub_list_def)

  show "{||} |\<subseteq>| x" by (descending) (simp add: sub_list_def)

  show "x |\<subseteq>| x |\<union>| y" by (descending) (simp add: sub_list_def)

  show "y |\<subseteq>| x |\<union>| y" by (descending) (simp add: sub_list_def)

  show "x |\<inter>| y |\<subseteq>| x"

    by (descending) (simp add: sub_list_def memb_def[symmetric])

  show "x |\<inter>| y |\<subseteq>| y" 

    by (descending) (simp add: sub_list_def memb_def[symmetric])

  show "x |\<union>| (y |\<inter>| z) = x |\<union>| y |\<inter>| (x |\<union>| z)" 

    by (descending) (rule append_inter_distrib)

next

  fix x y z :: "'a fset"

  assume a: "x |\<subseteq>| y"

  assume b: "y |\<subseteq>| z"

  show "x |\<subseteq>| z" using a b 

    by (descending) (simp add: sub_list_def)

next

  fix x y :: "'a fset"

  assume a: "x |\<subseteq>| y"

  assume b: "y |\<subseteq>| x"

  show "x = y" using a b 

    by (descending) (unfold sub_list_def list_eq.simps, blast)

next

  fix x y z :: "'a fset"

  assume a: "y |\<subseteq>| x"

  assume b: "z |\<subseteq>| x"

  show "y |\<union>| z |\<subseteq>| x" using a b 

    by (descending) (simp add: sub_list_def)

next

  fix x y z :: "'a fset"

  assume a: "x |\<subseteq>| y"

  assume b: "x |\<subseteq>| z"

  show "x |\<subseteq>| y |\<inter>| z" using a b 

    by (descending) (simp add: sub_list_def memb_def[symmetric])

qed

end

section {* Finsert and Membership *}

quotient_definition

  "finsert :: 'a \<Rightarrow> 'a fset \<Rightarrow> 'a fset"

is "Cons"

syntax

  "@Finset"     :: "args => 'a fset"  ("{|(_)|}")

translations

  "{|x, xs|}" == "CONST finsert x {|xs|}"

  "{|x|}"     == "CONST finsert x {||}"

quotient_definition

  fin (infix "|\<in>|" 50)

where

  "fin :: 'a \<Rightarrow> 'a fset \<Rightarrow> bool" is "memb"

abbreviation

  fnotin :: "'a \<Rightarrow> 'a fset \<Rightarrow> bool" (infix "|\<notin>|" 50)

where

  "x |\<notin>| S \<equiv> \<not> (x |\<in>| S)"

section {* Other constants on the Quotient Type *}

quotient_definition

  "fcard :: 'a fset \<Rightarrow> nat"

is

  fcard_raw

quotient_definition

  "fmap :: ('a \<Rightarrow> 'b) \<Rightarrow> 'a fset \<Rightarrow> 'b fset"

is

  map

quotient_definition

  "fdelete :: 'a \<Rightarrow> 'a fset \<Rightarrow> 'a fset"

  is removeAll

quotient_definition

  "fset :: 'a fset \<Rightarrow> 'a set"

  is "set"

quotient_definition

  "ffold :: ('a \<Rightarrow> 'b \<Rightarrow> 'b) \<Rightarrow> 'b \<Rightarrow> 'a fset \<Rightarrow> 'b"

  is "ffold_raw"

quotient_definition

  "fconcat :: ('a fset) fset \<Rightarrow> 'a fset"

is

  "concat"

quotient_definition

  "ffilter :: ('a \<Rightarrow> bool) \<Rightarrow> 'a fset \<Rightarrow> 'a fset"

is

  "filter"

text {* Compositional Respectfullness and Preservation *}

lemma [quot_respect]: "(list_all2 op \<approx> OOO op \<approx>) [] []"

  by (fact compose_list_refl)

lemma [quot_preserve]: "(abs_fset \<circ> map f) [] = abs_fset []"

  by simp

lemma [quot_respect]:

  shows "(op \<approx> ===> list_all2 op \<approx> OOO op \<approx> ===> list_all2 op \<approx> OOO op \<approx>) Cons Cons"

  apply auto

  apply (rule_tac b="x # b" in pred_compI)

  apply auto

  apply (rule_tac b="x # ba" in pred_compI)

  apply auto