Fuzzy preference queries to relational databases

The manipulation of databases is an integral part of a world which is becoming increasingly and pervasively information-focused. This book puts forward a suggestion to advocate preference queries and fuzzy sets as a central concern in database queries and offers an important contribution to the design of intelligent information systems. It provides a comprehensive study on fuzzy preference queries in the context of relational databases. Preference queries, a recent hot topic in database research, provide a basis for rank-ordering the items retrieved, which is especially valuable for large sets of answers. This book aims to show that fuzzy set theory constitutes a highly expressive framework for modeling preference queries. It presents a study of the algorithmic aspects related to the evaluation of such queries in order to demonstrate that this framework offers a good trade-off between expressivity and efficiency. Numerous examples and proofs are liberally and lucidly demonstrated throughout, and greatly enhance the detailed theoretical aspects explored in the book. Researchers working in databases will greatly benefit from this comprehensive and up-to-date study of fuzzy preference queries, and it will also become an invaluable reference point for postgraduate students interested in advanced database techniques.

Introduction. Reminders on Relational Databases. Basic Notions on Fuzzy Sets. Non-Fuzzy Approaches to Preference Queries: A Brief Overview. Simple Fuzzy Queries. Fuzzy Queries Involving Quantified Statements or Aggregates. Division and Antidivision of Fuzzy Relations. Bipolar Fuzzy Queries. Fuzzy Group By. Empty and Plethoric Answers.