src/ZF/qpair.thy
author lcp
Mon, 15 Aug 1994 18:07:03 +0200
changeset 520 806d3f00590d
parent 124 858ab9a9b047
permissions -rw-r--r--
ZF/equalities/Sigma_cons: new ZF/equalities/cons_eq: new ZF/equalities.thy: added final newline

(*  Title: 	ZF/qpair.thy
    ID:         $Id$
    Author: 	Lawrence C Paulson, Cambridge University Computer Laboratory
    Copyright   1993  University of Cambridge

Quine-inspired ordered pairs and disjoint sums, for non-well-founded data
structures in ZF.  Does not precisely follow Quine's construction.  Thanks
to Thomas Forster for suggesting this approach!

W. V. Quine, On Ordered Pairs and Relations, in Selected Logic Papers,
1966.
*)

QPair = Sum + "simpdata" +
consts
  QPair     :: "[i, i] => i"               	("<(_;/ _)>")
  qsplit    :: "[[i,i] => i, i] => i"
  qfsplit   :: "[[i,i] => o, i] => o"
  qconverse :: "i => i"
  "@QSUM"   :: "[idt, i, i] => i"               ("(3QSUM _:_./ _)" 10)
  " <*>"    :: "[i, i] => i"         		("(_ <*>/ _)" [81, 80] 80)
  QSigma    :: "[i, i => i] => i"

  "<+>"     :: "[i,i]=>i"      			(infixr 65)
  QInl,QInr :: "i=>i"
  qcase     :: "[i=>i, i=>i, i]=>i"

translations
  "QSUM x:A. B"  => "QSigma(A, %x. B)"
  "A <*> B"      => "QSigma(A, _K(B))"

rules
  QPair_def       "<a;b> == a+b"
  qsplit_def      "qsplit(c,p)  == THE y. EX a b. p=<a;b> & y=c(a,b)"
  qfsplit_def     "qfsplit(R,z) == EX x y. z=<x;y> & R(x,y)"
  qconverse_def   "qconverse(r) == {z. w:r, EX x y. w=<x;y> & z=<y;x>}"
  QSigma_def      "QSigma(A,B)  ==  UN x:A. UN y:B(x). {<x;y>}"

  qsum_def        "A <+> B      == ({0} <*> A) Un ({1} <*> B)"
  QInl_def        "QInl(a)      == <0;a>"
  QInr_def        "QInr(b)      == <1;b>"
  qcase_def       "qcase(c,d)   == qsplit(%y z. cond(y, d(z), c(z)))"
end

ML

val print_translation =
  [("QSigma", dependent_tr' ("@QSUM", " <*>"))];