src/HOL/UNITY/Extend.thy

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/HOL/UNITY/Extend.thy	Wed Mar 03 10:32:35 1999 +0100
@@ -0,0 +1,42 @@
+(*  Title:      HOL/UNITY/Extend.thy
+    ID:         $Id$
+    Author:     Lawrence C Paulson, Cambridge University Computer Laboratory
+    Copyright   1998  University of Cambridge
+
+Extending of state sets
+  function f (forget)    maps the extended state to the original state
+  function g (forgotten) maps the extended state to the "extending part"
+*)
+
+Extend = Union + Comp +
+
+constdefs
+
+  extend_set :: "['a*'b => 'c, 'a set] => 'c set"
+    "extend_set h A == h `` (A Times UNIV)"
+
+  extend_act :: "['a*'b => 'c, ('a*'a) set] => ('c * 'c) set"
+    "extend_act h == (%act. UN (s,s'): act. UN y. {(h(s,y), h(s',y))})"
+
+  extend :: "['a*'b => 'c, 'a program] => 'c program"
+    "extend h F == mk_program (extend_set h (Init F),
+			       extend_act h `` Acts F)"
+
+locale Extend =
+  fixes 
+    f       :: 'c => 'a
+    g       :: 'c => 'b
+    h       :: "'a*'b => 'c"    (*isomorphism between 'a * 'b and 'c *)
+    slice   :: ['c set, 'b] => 'a set
+    f_act   :: "('c * 'c) set => ('a*'a) set"
+
+  assumes
+    inj_h  "inj h"
+    surj_h "surj h"
+  defines
+    f_def       "f z == fst (inv h z)"
+    g_def       "g z == snd (inv h z)"
+    slice_def   "slice Z y == {x. h(x,y) : Z}"
+    f_act_def   "f_act act == (%(z,z'). (f z, f z')) `` act"
+
+end