Prioritized fuzzy logic based information processing in relational databases

Many years of research related to fuzzy logic and fuzzy set theory extensions to relational databases have not lead to stable implementations, standardized languages or fuzzy relational database application development tools and methods. The main goal of this paper is the modelling and the implementation of a set of tools that allow usage of fuzzy logic enriched with priorities in relational database applications. In order to achieve that goal, at first, the relational data model is extended with the elements of fuzzy set theory. After that, a fuzzy extension of the SQL query language, called the PFSQL, is defined. An interpreter for that language is integrated inside an implementation of the fuzzy JDBC driver. An implementation of the CASE tool for modelling of fuzzy relational database schemas rounds up a set of tools for the implementation of Java fuzzy database applications. In this sense, this paper presents a step towards a methodology for the fuzzy relational database application development. 2012 Elsevier B.V. All rights reserved.