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