src/ZF/Sum.thy
author wenzelm
Mon Oct 20 10:53:42 1997 +0200 (1997-10-20)
changeset 3940 1d5bee4d047f
parent 3923 c257b82a1200
child 5325 f7a5e06adea1
permissions -rw-r--r--
local;
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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 + pair + 
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global
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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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local
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defs
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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) == (%<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