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
     4     Copyright   1998  University of Cambridge
     5 
     6 Extending of state sets
     7   function f (forget)    maps the extended state to the original state
     8   function g (forgotten) maps the extended state to the "extending part"
     9 *)
    10 
    11 Extend = Union + Comp +
    12 
    13 constdefs
    14 
    15   extend_set :: "['a*'b => 'c, 'a set] => 'c set"
    16     "extend_set h A == h `` (A Times UNIV)"
    17 
    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 
    21   extend :: "['a*'b => 'c, 'a program] => 'c program"
    22     "extend h F == mk_program (extend_set h (Init F),
    23 			       extend_act h `` Acts F)"
    24 
    25 locale Extend =
    26   fixes 
    27     f       :: 'c => 'a
    28     g       :: 'c => 'b
    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 
    33   assumes
    34     inj_h  "inj h"
    35     surj_h "surj h"
    36   defines
    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