Preface

The appearance of the first issue of the Iranian Journal of Fuzzy Systems, or IJFS for short, is an important event—an event which reflects substantial research activity in Iran aimed at advancing the frontiers of fuzzy logic, soft computing and their applications. On perusing the contents of the first issue, one cannot but be highly impressed by the quality of reported research, its wide range and its up-to-dateness. The contributors, the editors and the editorial board deserve congratulations on launching IJFS; we should like to extend to all our best wishes for further successes. It is a centuries-old tradition to base scientific theories on Aristotelian logic—a logical system whose centerpiece is the principle of the excluded-middle: truth is bivalent, meaning that every proposition, p, is either true or false, with no shades of truth allowed. But as we move further into the age of computation and automated reasoning, it becomes increasingly apparent that bivalence is in fundamental conflict with reality. In the real world, truth is pervasively a matter of degree, and partiality is the norm rather than exception. It is this reality that underlies the conceptual structure of fuzzy logic. In fuzzy logic, everything is, or is allowed to be, a matter of degree. What is undeniably true is that bivalent-logic-based scientific theories have led to brilliant successes that are visible to all. We have conquered space, we have built incredibly fast computers, we have the Internet, and we can communicate via mobile telephones. But alongside the brilliant successes, we see instances of significant failures and slow progress. We cannot construct robots that can compete with children in agility; we cannot write programs which can summarize a book; and we cannot automate driving a car in city traffic. What is the reason for successes, on one hand, and failures on the other? Humans have a remarkable capability to perform a wide variety of physical and mental tasks, e.g., driving a car in city traffic, without any measurements and any computations. In performing such tasks, humans employ perceptions—perceptions of time, distance, speed, shape and other attributes of physical and mental objects. Perceptions are intrinsically imprecise, reflecting the bounded ability of sensory organs, and ultimately the brain, to resolve detail and store information. A concomitant of imprecision of perceptions is that bivalent-logic-based systems are inherently limited in their capability to operate on perception-based information. It is this limitation of conventional bivalent-logic-based approaches that underlies the lack of significant progress in problem-areas in which perceptions play an important role. Fuzzy logic abandons bivalence. In so doing, fuzzy logic opens the door to exploration of new directions in the advancement of machine intelligence and systems analysis. The role model for fuzzy logic is the human mind. From a system-theoretic point of view, fuzzy logic is linked to all of the important aspects of systems theory-modeling, identification, analysis, synthesis stability, filtering, and estimation. In particular, interest in stability theory of fuzzy control systems has grown markedly in recent years. Alongside the growth in theory, industrial, consumer, financial, medical and other applications of fuzzy systems have proliferated in Japan, Europe, the United States, China and many other countries. There are still some who view fuzzy set theory and fuzzy logic with a skeptical eye, but the initial widespread resistance to the basic ideas of fuzzy set theory and fuzzy logic has been relegated to history. A key component of the theory of fuzzy systems is the calculus of fuzzy if-then rules. This tool is the basis for the linguistic approach—an approach which provides an alternative to the conventional numerically-based approaches to systems design and analysis. An important aspect of the linguistic approach is that it obviates the need for precise mathematical models of control and decision processes. The linguistic approach is associated with an extensive literature and is likely to be an object of considerable attention in IJFS. The Iranian Journal of Fuzzy Systems should play an important role as a forum for presentation of new ideas and new applications. We should like to extend to Dr. Mashinchi and Borzooei our special congratulations for pioneering the Journal and for contributing so much and in so many ways to the advancement of the theory of fuzzy systems and its applications.