Distance Functions for Defaults in Reactive Systems
- 224 Downloads
Default reasoning has become an important topic in software engineering. In particular, defaults can be used to revise specifications, to enhance reusability of existing systems, and to allow a more economic description of systems. In this paper we develop a framework for default specifications of reactive systems.
We present a formalisation of non-monotonicity in temporal logic based on the notion of default institution. Default institutions were defined as an extension of institutions in order to allow partial reuse of existing modules. The semantics of defaults is given by a (generalised) distance between interpretations. In this way, by defining a pre-order between temporal morphisms and using temporal logic as a specification language, we get a way of handling defaults in specifications of reactive systems. We illustrate the developed formalism with an example in which a specification is reused, but where the new behaviour contradicts the initial specification. In this example, the initial specification is seen as a default to which exceptions are added.
KeywordsTemporal Logic Linear Temporal Logic Nonmonotonic Reasoning Default Reasoning Proposition Letter
Unable to display preview. Download preview PDF.
- 1.Stefan Brass, Udo Lipeck, and Pedro Resende. Specification of object behaviour with defaults. In Udo Lipeck and Gerhard Koschorreck, editors, Proceedings of the International Workshop on Information Systems: Correctness and Reusability, ISCORE-93, pages 155–177, 1993.Google Scholar
- 5.Sofia Guerra. Defaults in the Specification of Reactive Systems. PhD thesis, Instituto Superior Técnico, Universidade Técnica de Lisboa, 1999.Google Scholar
- 6.Udo W. Lipeck and Stefan Brass. Object-oriented system specification using defaults. In K. V. Luck and H. Marburger, editors, Management and Processing Complex Data Structures, Proceedings 3rd Workshop on Information Systems and Artificial Intelligence, volume LNCS 777, pages 22–43, Berlin, 1994. Springer Verlag.Google Scholar
- 7.David Makinson. General patterns in non-monotonic reasoning. In C. J. Hogger, and J. A. Robinson, editors. Nonmonotonic Reasoning and Uncertain Reasoning, volume 3 of Handbook of Logic in Artificial Intelligence and Logic Programming. Oxford: Clarendon Press, 1994 Gabbay et al. , chapter 2, pages 35–110.Google Scholar
- 9.Amir Pnueli. The temporal logic of programs. In Proceedings of the 18th IEEE Symposium on Foundations of Computer Science, pages 46–57, 1977.Google Scholar
- 10.Pierre-Yves Schobbens. Exceptions in Algebraic Specifications. PhD thesis, Université Catholique de Louvain, Faculté des Sciences Appliquées, 1992.Google Scholar