Subject: categories: Paper announcement

From: Luca Cattani <[email-masked]>
Date: Fri, 12 Nov 1999 14:05:07 +0000

The following paper is available at

   http://www.cl.cam.ac.uk/~glc25/premcl.html   .

It will also be available soon as BRICS Report, RS-99-36 (see 
www.brics.dk/Publications), and as Cambridge University Computer Laboratory 
Technical Report n. 477 (contact [email-masked] to obtain a hard 
copy) :

             Presheaf Models for CCS-like Languages    

        Gian Luca Cattani                   Glynn Winskel
       Computer Laboratory                      BRICS
     University of Cambridge            University of Aarhus
           England                             Denmark

Abstract
=========

The aim of this paper is to harness the mathematical machinery around 
presheaves for the purposes of process calculi. Joyal, Nielsen and Winskel 
proposed a general definition of bisimulation from open maps. Here we show 
that open-map bisimulations within a range of presheaf models are congruences 
for a general process language, in which CCS and related languages are easily 
encoded. The results are then transferred to traditional models for processes. 
By first establishing the congruence results for presheaf models, abstract, 
general proofs of congruence properties can be provided and the awkwardness 
caused through traditional models not always possessing the cartesian 
liftings, used in the break-down of process operations, are side-stepped. The 
abstract results are applied to show that hereditary history-preserving 
bisimulation is a congruence for CCS-like languages to which is added a 
refinement operator on event structures as proposed by van Glabbeek and Goltz.