src/ZF/Sum.thy
author wenzelm
Fri Oct 17 17:40:02 1997 +0200 (1997-10-17 ago)
changeset 3923 c257b82a1200
parent 2469 b50b8c0eec01
child 3940 1d5bee4d047f
permissions -rw-r--r--
global;
     1 (*  Title:      ZF/sum.thy
     2     ID:         $Id$
     3     Author:     Lawrence C Paulson, Cambridge University Computer Laboratory
     4     Copyright   1993  University of Cambridge
     5 
     6 Disjoint sums in Zermelo-Fraenkel Set Theory 
     7 "Part" primitive for simultaneous recursive type definitions
     8 *)
     9 
    10 Sum = Bool + pair + 
    11 
    12 global
    13 
    14 consts
    15     "+"         :: [i,i]=>i                     (infixr 65)
    16     Inl,Inr     :: i=>i
    17     case        :: [i=>i, i=>i, i]=>i
    18     Part        :: [i,i=>i] => i
    19 
    20 path Sum
    21 
    22 defs
    23     sum_def     "A+B == {0}*A Un {1}*B"
    24     Inl_def     "Inl(a) == <0,a>"
    25     Inr_def     "Inr(b) == <1,b>"
    26     case_def    "case(c,d) == (%<y,z>. cond(y, d(z), c(z)))"
    27 
    28   (*operator for selecting out the various summands*)
    29     Part_def    "Part(A,h) == {x: A. EX z. x = h(z)}"
    30 end