© 1989 by British Computer Society
First Steps Towards Fully Abstract Semantics for Object-Oriented Languages*

University of Cambridge Computer Laboratory, New Museums Site, Pembroke Street, Cambridge CB2 3QG, UK
A number of denotational models have been proposed for object-oriented languages. Authors of more recent models have expressed dissatisfaction with the lack of abstractness in earlier ones. They claim that these earlier models describe details of objects which are invisible to an external observer in short, that they are not fully abstract. In this paper, we present a formal characterisation of the visible behaviour of objects. We show that using a natural full abstractness criterion based on this definition, even more recent models of object-oriented languages are unnecessarily concrete. We go on to present a semantics for a very simple object-oriented language based on projections of state-transition graphs for programs, and demonstrate that it is fully abstract.
Received April 1989.
* This work supported by the SERC.
University of Cambridge Computer Laboratory, New Museums Site, Pembroke Street, Cambridge CB2 3QG