src/ZF/Bool.thy
author clasohm
Thu Sep 16 12:20:38 1993 +0200 (1993-09-16)
changeset 0 a5a9c433f639
child 14 1c0926788772
permissions -rw-r--r--
Initial revision
     1 (*  Title: 	ZF/bool.thy
     2     ID:         $Id$
     3     Author: 	Lawrence C Paulson, Cambridge University Computer Laboratory
     4     Copyright   1992  University of Cambridge
     5 
     6 Booleans in Zermelo-Fraenkel Set Theory 
     7 *)
     8 
     9 Bool = ZF +
    10 consts
    11     "1"		::      "i"     	("1")
    12     bool        ::      "i"
    13     cond        ::      "[i,i,i]=>i"
    14     not		::	"i=>i"
    15     and         ::      "[i,i]=>i"      (infixl 70)
    16     or		::      "[i,i]=>i"      (infixl 65)
    17     xor		::      "[i,i]=>i"      (infixl 65)
    18 
    19 rules
    20     one_def 	"1    == succ(0)"
    21     bool_def	"bool == {0,1}"
    22     cond_def	"cond(b,c,d) == if(b=1,c,d)"
    23     not_def	"not(b) == cond(b,0,1)"
    24     and_def	"a and b == cond(a,b,0)"
    25     or_def	"a or b == cond(a,1,b)"
    26     xor_def	"a xor b == cond(a,not(b),b)"
    27 end