src/ZF/Sum.thy
author clasohm
Thu Sep 16 12:20:38 1993 +0200 (1993-09-16)
changeset 0 a5a9c433f639
child 124 858ab9a9b047
permissions -rw-r--r--
Initial revision
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(*  Title: 	ZF/sum.thy
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    ID:         $Id$
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    Author: 	Lawrence C Paulson, Cambridge University Computer Laboratory
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    Copyright   1993  University of Cambridge
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Disjoint sums in Zermelo-Fraenkel Set Theory 
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"Part" primitive for simultaneous recursive type definitions
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*)
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Sum = Bool +
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consts
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    "+"    	:: "[i,i]=>i"      		(infixr 65)
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    Inl,Inr     :: "i=>i"
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    case        :: "[i=>i, i=>i, i]=>i"
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    Part        :: "[i,i=>i] => i"
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rules
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    sum_def     "A+B == {0}*A Un {1}*B"
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    Inl_def     "Inl(a) == <0,a>"
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    Inr_def     "Inr(b) == <1,b>"
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    case_def    "case(c,d) == split(%y z. cond(y, d(z), c(z)))"
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  (*operator for selecting out the various summands*)
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    Part_def	"Part(A,h) == {x: A. EX z. x = h(z)}"
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end