Observing localities, with I. Castellani, M. Hennessy and A. Kiehn, in Theoretical Computer Science (TCS) Vol. 114 (1993), 31-61.

We introduce a refined version of observation for CCS which allows the observer to see the distributed nature of processes. Using several examples we argue that a semantic theory based on such observations is not only intuitive but may also be of use when formalising the relationship between implementations and specifications. Technically, we show that the resulting theory of location equivalence is very similar to that of bisimulation equivalence, e.g. it can be characterised by a simple modal logic. A comparison with distributed bisimulations is also given.