src/ZF/Bool.thy
author clasohm
Tue Feb 06 12:27:17 1996 +0100 (1996-02-06)
changeset 1478 2b8c2a7547ab
parent 1401 0c439768f45c
child 1629 b5e43a60443a
permissions -rw-r--r--
expanded tabs
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(*  Title:      ZF/bool.thy
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    ID:         $Id$
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    Author:     Lawrence C Paulson, Cambridge University Computer Laboratory
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    Copyright   1992  University of Cambridge
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Booleans in Zermelo-Fraenkel Set Theory 
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2 is equal to bool, but serves a different purpose
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*)
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Bool = ZF + "simpdata" +
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consts
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    "1"         :: i               ("1")
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    "2"         :: i             ("2")
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    bool        :: i
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    cond        :: [i,i,i]=>i
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    not         :: i=>i
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    "and"       :: [i,i]=>i      (infixl 70)
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    or          :: [i,i]=>i      (infixl 65)
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    xor         :: [i,i]=>i      (infixl 65)
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translations
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   "1"  == "succ(0)"
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   "2"  == "succ(1)"
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defs
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    bool_def    "bool == {0,1}"
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    cond_def    "cond(b,c,d) == if(b=1,c,d)"
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    not_def     "not(b) == cond(b,0,1)"
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    and_def     "a and b == cond(a,b,0)"
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    or_def      "a or b == cond(a,1,b)"
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    xor_def     "a xor b == cond(a,not(b),b)"
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end