Fuzzy logic for formal specification of systems

Abstract

Natural languages are daily used to write system specifications. However, language specifications can be confusing and very hard to model and identify. Formal methods for assuring the right behavior of software work very well despite their cost, but it is usually being imposed that specifications are made by means of crisp relations and classical propositional logic. Otherwise, specification can not be properly developed with standard techniques. Since most procedures related to human decisions require fuzzy information, we definitively need to develop alternative approaches allowing fuzziness in order to improve software specification. In this paper we show how fuzzy logic techniques can be used to write specifications in a fuzzy framework, as a previous step in the process of analysis and design of new software. As an example, we consider a multiprocessor system, showing how to make a formal specification of the system focused in a particular goal: to improve the performance of the system. We briefly introduce the classical formal specification by means of formal methods, and then we show more in detail the same specification by means of fuzzy techniques (fuzzy sets and granules as new generic types of data). Several possibilities for formal specification are presented. In this way, we will show how an information closer to the natural language can be managed in terms of fuzzy sets and fuzzy inference rules.