Set.thy

HOL/subset.thy, equalities.thy, mono.thy: new
HOL/Lfp.thy: now depends upon mono
HOL/Gfp.thy: depends upon Lfp, not just mono

(*  Title:      HOL/set.thy
    ID:         $Id$
    Author:     Tobias Nipkow
    Copyright   1993  University of Cambridge
*)

Set = Ord +

types
  'a set

arities
  set :: (term) term
  set :: (term) ord
  set :: (term) minus


consts

  (* Constants *)

  Collect       :: "('a => bool) => 'a set"               (*comprehension*)
  Compl         :: "('a set) => 'a set"                   (*complement*)
  Int           :: "['a set, 'a set] => 'a set"       (infixl 70)
  Un            :: "['a set, 'a set] => 'a set"       (infixl 65)
  UNION, INTER  :: "['a set, 'a => 'b set] => 'b set"     (*general*)
  UNION1        :: "['a => 'b set] => 'b set"         (binder "UN " 10)
  INTER1        :: "['a => 'b set] => 'b set"         (binder "INT " 10)
  Union, Inter  :: "(('a set)set) => 'a set"              (*of a set*)
  range         :: "('a => 'b) => 'b set"                 (*of function*)
  Ball, Bex     :: "['a set, 'a => bool] => bool"         (*bounded quantifiers*)
  inj, surj     :: "('a => 'b) => bool"                   (*inj/surjective*)
  inj_onto      :: "['a => 'b, 'a set] => bool"
  "``"          :: "['a => 'b, 'a set] => ('b set)"   (infixl 90)
  ":"           :: "['a, 'a set] => bool"             (infixl 50) (*membership*)
  "~:"          :: "['a, 'a set] => bool"             ("(_ ~:/ _)" [50, 51] 50)

  (* Finite Sets *)

  insert        :: "['a, 'a set] => 'a set"
  "{}"          :: "'a set"                           ("{}")
  "@Finset"     :: "args => 'a set"                   ("{(_)}")


  (** Binding Constants **)

  "@Coll"       :: "[idt, bool] => 'a set"            ("(1{_./ _})")
  "@SetCompr"   :: "['a, idts, bool] => 'a set"       ("{_ |/_./ _}")

  (* Big Intersection / Union *)

  "@INTER"      :: "[idt, 'a set, 'b set] => 'b set"  ("(3INT _:_./ _)" 10)
  "@UNION"      :: "[idt, 'a set, 'b set] => 'b set"  ("(3UN _:_./ _)" 10)

  (* Bounded Quantifiers *)

  "@Ball"       :: "[idt, 'a set, bool] => bool"      ("(3! _:_./ _)" 10)
  "@Bex"        :: "[idt, 'a set, bool] => bool"      ("(3? _:_./ _)" 10)
  "*Ball"       :: "[idt, 'a set, bool] => bool"      ("(3ALL _:_./ _)" 10)
  "*Bex"        :: "[idt, 'a set, bool] => bool"      ("(3EX _:_./ _)" 10)


translations
  "x ~: y"      == "~ (x : y)"
  "{x, xs}"     == "insert(x, {xs})"
  "{x}"         == "insert(x, {})"
  "{x. P}"      == "Collect(%x. P)"
  "INT x:A. B"  == "INTER(A, %x. B)"
  "UN x:A. B"   == "UNION(A, %x. B)"
  "! x:A. P"    == "Ball(A, %x. P)"
  "? x:A. P"    == "Bex(A, %x. P)"
  "ALL x:A. P"  => "Ball(A, %x. P)"
  "EX x:A. P"   => "Bex(A, %x. P)"


rules

  (* Isomorphisms between Predicates and Sets *)

  mem_Collect_eq    "(a : {x.P(x)}) = P(a)"
  Collect_mem_eq    "{x.x:A} = A"

  (* Definitions *)

  Ball_def      "Ball(A, P)     == ! x. x:A --> P(x)"
  Bex_def       "Bex(A, P)      == ? x. x:A & P(x)"
  subset_def    "A <= B         == ! x:A. x:B"
  Compl_def     "Compl(A)       == {x. ~x:A}"
  Un_def        "A Un B         == {x.x:A | x:B}"
  Int_def       "A Int B        == {x.x:A & x:B}"
  set_diff_def  "A-B            == {x. x:A & ~x:B}"
  INTER_def     "INTER(A, B)    == {y. ! x:A. y: B(x)}"
  UNION_def     "UNION(A, B)    == {y. ? x:A. y: B(x)}"
  INTER1_def    "INTER1(B)      == INTER({x.True}, B)"
  UNION1_def    "UNION1(B)      == UNION({x.True}, B)"
  Inter_def     "Inter(S)       == (INT x:S. x)"
  Union_def     "Union(S)       == (UN x:S. x)"
  empty_def     "{}             == {x. False}"
  insert_def    "insert(a, B)   == {x.x=a} Un B"
  range_def     "range(f)       == {y. ? x. y=f(x)}"
  image_def     "f``A           == {y. ? x:A. y=f(x)}"
  inj_def       "inj(f)         == ! x y. f(x)=f(y) --> x=y"
  inj_onto_def  "inj_onto(f, A) == ! x:A. ! y:A. f(x)=f(y) --> x=y"
  surj_def      "surj(f)        == ! y. ? x. y=f(x)"

end

ML

local

(* Translates between { e | x1..xn. P} and {u. ? x1..xn. u=e & P} *)

fun dummyC(s) = Const(s,dummyT);

val ex_tr = snd(mk_binder_tr("? ","Ex"));

fun nvars(Const("_idts",_) $ _ $ idts) = nvars(idts)+1
  | nvars(_) = 1;

fun setcompr_tr[e,idts,b] =
  let val eq = dummyC("op =") $ Bound(nvars(idts)) $ e
      val P = dummyC("op &") $ eq $ b
      val exP = ex_tr [idts,P]
  in dummyC("Collect") $ Abs("",dummyT,exP) end;

val ex_tr' = snd(mk_binder_tr' ("Ex","DUMMY"));

fun setcompr_tr'[Abs(_,_,P)] =
  let fun ok(Const("Ex",_)$Abs(_,_,P),n) = ok(P,n+1)
        | ok(Const("op &",_) $ (Const("op =",_) $ Bound(m) $ _) $ _, n) =
            if n>0 andalso m=n then () else raise Match

      fun tr'(_ $ abs) =
        let val _ $ idts $ (_ $ (_ $ _ $ e) $ Q) = ex_tr'[abs]
        in dummyC("@SetCompr") $ e $ idts $ Q end
  in ok(P,0); tr'(P) end;

in

val parse_translation = [("@SetCompr",setcompr_tr)];
val print_translation = [("Collect",setcompr_tr')];

val print_ast_translation =
  map HOL.alt_ast_tr' [("@Ball", "*Ball"), ("@Bex", "*Bex")];

end;