--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/ZF/UNITY/Comp.thy Wed Aug 08 14:33:10 2001 +0200
@@ -0,0 +1,44 @@
+(* Title: ZF/UNITY/Comp.thy
+ ID: $Id$
+ Author: Sidi O Ehmety, Computer Laboratory
+ Copyright 1998 University of Cambridge
+
+Composition
+From Chandy and Sanders, "Reasoning About Program Composition",
+Technical Report 2000-003, University of Florida, 2000.
+
+Revised by Sidi Ehmety on January 2001
+
+Added: a strong form of the order relation over component and localize
+
+Theory ported from HOL.
+
+*)
+
+Comp = Union +
+
+constdefs
+
+ component :: [i, i] => o (infixl 65)
+ "F component H == (EX G. F Join G = H)"
+
+ strict_component :: [i, i] => o (infixl "strict'_component" 65)
+ "F strict_component H == F component H & F~=H"
+
+ (* A stronger form of the component relation *)
+ component_of :: "[i,i]=>o" (infixl "component'_of" 65)
+ "F component_of H == (EX G. F ok G & F Join G = H)"
+
+ strict_component_of :: "[i,i]=>o" (infixl "strict'_component'_of" 65)
+ "F strict_component_of H == F component_of H & F~=H"
+
+ (* preserves any state function f, in particular a variable *)
+ preserves :: (i=>i)=>i
+ "preserves(f) == {F:program. ALL z. F: stable({s:state. f(s) = z})}"
+
+localize :: "[i=>i, i] => i"
+ "localize(f,F) == mk_program(Init(F), Acts(F),
+ AllowedActs(F Int (UN G:preserves(f). Acts(G))))"
+
+
+ end