src/HOL/UNITY/Extend.thy
 author paulson Wed Mar 03 10:32:35 1999 +0100 (1999-03-03) changeset 6297 5b9fbdfe22b7 child 6677 629b4b3d5bee permissions -rw-r--r--
new theory of extending the state space
```     1 (*  Title:      HOL/UNITY/Extend.thy
```
```     2     ID:         \$Id\$
```
```     3     Author:     Lawrence C Paulson, Cambridge University Computer Laboratory
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```     4     Copyright   1998  University of Cambridge
```
```     5
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```     6 Extending of state sets
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```     7   function f (forget)    maps the extended state to the original state
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```     8   function g (forgotten) maps the extended state to the "extending part"
```
```     9 *)
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```    10
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```    11 Extend = Union + Comp +
```
```    12
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```    13 constdefs
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```    14
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```    15   extend_set :: "['a*'b => 'c, 'a set] => 'c set"
```
```    16     "extend_set h A == h `` (A Times UNIV)"
```
```    17
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```    18   extend_act :: "['a*'b => 'c, ('a*'a) set] => ('c * 'c) set"
```
```    19     "extend_act h == (%act. UN (s,s'): act. UN y. {(h(s,y), h(s',y))})"
```
```    20
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```    21   extend :: "['a*'b => 'c, 'a program] => 'c program"
```
```    22     "extend h F == mk_program (extend_set h (Init F),
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```    23 			       extend_act h `` Acts F)"
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```    24
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```    25 locale Extend =
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```    26   fixes
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```    27     f       :: 'c => 'a
```
```    28     g       :: 'c => 'b
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```    29     h       :: "'a*'b => 'c"    (*isomorphism between 'a * 'b and 'c *)
```
```    30     slice   :: ['c set, 'b] => 'a set
```
```    31     f_act   :: "('c * 'c) set => ('a*'a) set"
```
```    32
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```    33   assumes
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```    34     inj_h  "inj h"
```
```    35     surj_h "surj h"
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```    36   defines
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```    37     f_def       "f z == fst (inv h z)"
```
```    38     g_def       "g z == snd (inv h z)"
```
```    39     slice_def   "slice Z y == {x. h(x,y) : Z}"
```
```    40     f_act_def   "f_act act == (%(z,z'). (f z, f z')) `` act"
```
```    41
```
```    42 end
```