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Winter 1994 (2.4)
Pages 47-52
What is Fuzzy Logic?
Related articles:
Interview with Lotfi Zadeh, Creator of Fuzzy Logic - by Betty Blair
Lotfi Zadeh Reflects on his Youth
Commencement Speech - When You Can't Stop For Lunch - Berkeley, 1997
Fuzzy Logic on the Internet - Mark Hopkins, 1994
Short Biographical Sketch - Lotfi Zadeh
Illustration: From Bart Kosko: Fuzzy Thinking: The New Science of Fuzzy Logic, Hyperion, New York 1993.Fuzzy Logic is not what it sounds like. It's not a nebulous, cloudy, vague way of thinking; in fact, it's quite the opposite. When anything becomes too complex to fully understand, then it becomes uncertain. The more complex something is, the more inexact or "fuzzier" it will be. Fuzzy Logic provides a very precise approach for dealing with uncertainty which grows out of the complexity of human behavior.
The concept was first articulated by Lotfi Zadeh in a paper published in 1965, ("Fuzzy Sets," Information and Control 8:3, 338-53) which provided the theoretical basis for fuzzy computer chips which appeared 20 years later.
Unlike traditional or classical logic, which attempts to categorize information into binary patterns such as black / white, true / false, yes / no, or all / nothing, Fuzzy Logic pays attention to the "excluded middle" and tries to account for the "grays", the partially true and partially false situations which make up 99.9% of human reasoning in everyday life. It builds upon the assumption that everything consists of degrees on a sliding scale-whether it be truth, age, beauty, wealth, color, race, or anything else that is effected by the dynamic nature of human behavior and perception. The question Zadeh always insists upon asking is, "To what degree is something true or false?"
Zadeh looks around him in the real world which he finds pervaded by concepts which do not have sharply defined boundaries, where information is often incomplete or sometimes unreliable. In fact, he would classify most words as having fuzzy meanings-virtually every adjective or adverb in ordinary speech. These concepts become clear if seen in transition from membership to non-membership in gradual, rather than abrupt, increments.
In quest for precision, scientists have generally attempted to manipulate the real world into artificial mathematical models that make no provision for gradation. They have tried to describe the laws governing the incredibly complex behavior of humans, both singly and in groups, in mathematical terms similar to those employed in the analysis of inanimate systems, which, in Zadeh's view, has been, and will continue to be, a misdirected effort.
Because the human mind can't handle so many isolated separate ideas at one time, it tends to bundle similarly-related objects into categories in such a way as to reduce the complexity of the information processing task. It is this incredible capacity of the human mind to manipulate these fuzzy or unsharp categories that distinguishes human intelligence from the machine intelligence of current generation computers.
Because Fuzzy Logic provides the tools to classify information into broad, coarse categorizations or groupings, it has infinite possibilities for application which have proven to be much cheaper, simpler and more effective than other systems in handling complex information. Fuzzy Logic has extremely broad implications for many fields not just electrical engineering and computer technology which have been fairly quick to incorporate its theoretical principles. Numerous consumer goods especially household products and electronic equipment-microwaves, cameras, and camcorders already incorporate Fuzzy Logic into their design. So have computer control systems such as the famous subway of Sendai, Japan, or numerous complex diagnostic and monitoring biomedical systems which are starting to be used in hospitals.
But other fields such as the social sciences-economy, finance, psychology, sociology, politics, religion, ethics, law, medicine, geography, folklore, anthropology that deal with the complexity of human behavior-are just beginning to explore the infinite possibilities of Fuzzy Logic.
Zadeh was not the first to think about "shades of gray". Philosophers such as Plato indicated that there was a third region (beyond "true" and "false") where opposites "tumbled about". Hegel, Marx, Engels and Lukasiewicz, among others, also dealt with middle regions. But it was Zadeh who first developed the general theory and laid the foundation for what Fuzzy Logic is today.
For a well-researched, very readable, popular description of Lotfi Zadeh and the development of the field of Fuzzy Logic, refer to Daniel McNeill and Paul Freiberger's award winning book, Fuzzy Logic: The Revolutionary Computer Technology that is Changing our World, 1993. For a technical introduction to the field, see Zadeh's Fuzzy Sets and Applications: Selected Papers. Edited by Yager, Ovchnikov, Tong, and Nguyen. New York: Wiley, 1987.
Cruising the Internet
in Pursuit of Fuzzy Logic
by Mark Hopkins
Looking for the quickest way to feel the pulse of what's happening worldwide in Fuzzy Logic? Then try "cruising" the "super information highway" of the Internet. Log on to the Newsgroup <comp.ai.fuzzy> (computer-artificial intelligence-fuzzy) and you'll find yourself in a vast world with access to projects that take months and years before they will be published.
The Internet is a grand experiment in democracy. It's a bit like entering a vast room where your one tiny voice echos to the other side of the globe. One's race, nationality, ethnicity, gender, religion, age, social and economic status are set aside and the only thing that matters is the message. In a sense, it's a bit like stuffing a message into a bottle and casting it into a vast ocean. The only difference is that the right people with the right information can respond to you in minutes.
In the Fuzzy Logic Newsgroup, English is the primary language although two of the 450 messages posted during these past two months (September and October) were in Italian and German. Netters logged on from scores of countries all over the world. Germany and the UK were among the most active. But Japan, China, and Russia were conspicuously missing. (Perhaps Japan has its own network and it may be too expensive for the others. In Azerbaijan, for example, modem connection fees cost $120 per quarter which is about equivalent to a year's salary.)
Newcomers Welcome
Generally, the Fuzzy Logic Newsgroup seems to be characterized by individuals in pursuit of knowledge. As it is a relatively new field, the "netters" seem quite patient with newcomers.
Many postings are devoted to formal announcements including "Calls for Papers", proceedings of conferences, lectures, and tutorials. For example, there was an invitation to join Lotfi Zadeh for "Tea and Cookies" on October 4 at a lecture about "Fuzzy Graphs and Information Granularity" at an "Artificial Intelligence, Vision and Robotics Conference" at Berkeley.
Conferences are worldwide. The IFSA (International Fuzzy Systems Conference) is being held in Brazil in 1995; Artificial Neural Network and Expert Systems in New Zealand; Control Systems and Computer Sciences in Bucharest, Romania. Others were slated for the Czech Republic and Portugal.
Books are a frequent topic of conversation-new books, good books, beginners' books, used technical books for sale, and professors seeking recommended texts for classes. International students were curious where they could find universities with Fuzzy Courses. Grants and Post-doctoral positions were announced from UK.
Then there's the occasional personal comment that pops up about some major figures in the field such as "Does anyone know when Zadeh is coming to Braunschieg, Germany, in 1995?" or "What is Bart Kosko's e-mail address?" (Kosko wrote a popular book about Fuzzy Thinking.)
Broad ApplicationsPerhaps the most interesting aspect of cruising the Internet is discovering so many new applications for Fuzzy. In the process of preparing this article about Lotfi Zadeh, Azerbaijan International posted an inquiry for the "most interesting applications of Fuzzy Logic" and received 19 personal messages within four days.
Biomedical applications are being used to diagnose breast cancer, rheumatoid arthritis, post-menopausal osteoporosis, and heart disease; to monitor anesthesia, blood pressure, insulin for diabetes, postoperative pain controller; to do magnetic resonance images of the brain; and to set up intelligent bedside monitors and hospital communication networks.
There were applications in finances, geography, philosophy, ecology, agricultural processes, water treatment, baggage handling at Denver International Airport, remote sensing images from satellite images, recognition of handwriting and nuclear science, stock market and weather. Boeing in Seattle has incorporated Fuzzy in a controller for Navy #6 autopilots which trails a long wire antenna for communications with submarines. Someone was even concerned about ethics, commenting that "we have basic ethical systems that operate at polarities-guilt and innocence, true and false, premeditated and meditated acts. Do we ever measure how guilty someone is? Can we apply Fuzzy Logic to ethics? Should we?"
It seems applications of Fuzzy Logic are infinite; the future, ripe for invention; and the Internet, a major pathway to discovery.
From Azerbaijan International (2.4) Winter 1994.
© Azerbaijan International 1994. All rights reserved.Back to Index AI 2.4 (Winter 1994)
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