Expressing Runtime Structure and Synchronisation in Concurrent OO Languages with MONSTR

The extended term graph rewriting formalism of MONSTR is described, together with some of its more important rigorously established properties, particularly regarding serialisability and acyclicity. This basis is used for giving a convenient description of the global runtime structure of a concurrent object oriented language. The formalism proves especially convenient for describing very precisely a variety of intended synchronisation properties of objects in a concurrent OOL, and this exibility is illustrated by considering a variety of possible operational semantics for a simple counter object. A lower bound object example illustrates that even more extreme synchronisation properties for objects may be contemplated without stretching the capabilities of the MONSTR formalism. The presentation is independent of any speci c high level OOL.