src/ZF/Bool.thy
changeset 0 a5a9c433f639
child 14 1c0926788772
     1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/src/ZF/Bool.thy	Thu Sep 16 12:20:38 1993 +0200
     1.3 @@ -0,0 +1,27 @@
     1.4 +(*  Title: 	ZF/bool.thy
     1.5 +    ID:         $Id$
     1.6 +    Author: 	Lawrence C Paulson, Cambridge University Computer Laboratory
     1.7 +    Copyright   1992  University of Cambridge
     1.8 +
     1.9 +Booleans in Zermelo-Fraenkel Set Theory 
    1.10 +*)
    1.11 +
    1.12 +Bool = ZF +
    1.13 +consts
    1.14 +    "1"		::      "i"     	("1")
    1.15 +    bool        ::      "i"
    1.16 +    cond        ::      "[i,i,i]=>i"
    1.17 +    not		::	"i=>i"
    1.18 +    and         ::      "[i,i]=>i"      (infixl 70)
    1.19 +    or		::      "[i,i]=>i"      (infixl 65)
    1.20 +    xor		::      "[i,i]=>i"      (infixl 65)
    1.21 +
    1.22 +rules
    1.23 +    one_def 	"1    == succ(0)"
    1.24 +    bool_def	"bool == {0,1}"
    1.25 +    cond_def	"cond(b,c,d) == if(b=1,c,d)"
    1.26 +    not_def	"not(b) == cond(b,0,1)"
    1.27 +    and_def	"a and b == cond(a,b,0)"
    1.28 +    or_def	"a or b == cond(a,1,b)"
    1.29 +    xor_def	"a xor b == cond(a,not(b),b)"
    1.30 +end