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
```