A new paper providing a definitive and detailed development of the semantics of actor systems is available via anonymous ftp.
Comments are especially welcome.
We present an actor language which is an extension of a simple functional language, and provide a precise operational semantics for this extension. Actor configurations are open distributed systems, meaning we explicitly take into account the interface with external components in the specification of an actor system. We define and study various notions of equivalence on actor expressions and configurations. Copies may be ordered from Stanford. The dissertation also is available in compressed postscript form.