Time For Some Fuzzy Thinking

By Philip Elmer-DeWitt

. In the pages of Books in Print, listed among works like Fuzzy Bear and Fuzzy Wuzzy Puppy, are some strange-sounding titles: Fuzzy Systems, Fuzzy Set Theory and Fuzzy Reasoning & Its Applications. The bedtime reading of scientists gone soft in the head? No, these academic tomes are the collected output of 25 years of mostly American research in fuzzy logic, a branch of mathematics designed to help computers simulate the various kinds of vagueness and uncertainty found in everyday life. Despite a distinguished corps of devoted followers, however, fuzzy logic has been largely relegated to the back shelves of computer science -- at least in the U.S.

But not, it turns out, in Japan. As they have so often in the past, the Japanese have seized on an American invention and found practical uses for it. Suddenly the term fuzzy and products based on principles of fuzzy logic seem to be everywhere in Japan: in television documentaries, in corporate magazine ads and in novel electronic gadgets ranging from computer-controlled air conditioners to golf-swing analyzers. The concept of fuzziness has struck a cultural chord in a society whose religions and philosophies are attuned to ambiguity and contradiction. Says Noboru Wakami, a senior researcher at Matsushita: "It's like soy sauce and sushi -- a perfect match."

What is fuzzy logic? The original concept, developed in the mid-'60s by Lofti Zadeh, a Russian-born professor of computer science at the University of California, Berkeley, is that things in the real world do not fall into the neat, crisp categories defined by traditional set theory, like the set of even numbers or the set of left-handed baseball players. In standard Aristotelian logic, as in computer science, membership in a class or set is not a matter of degree. Either a number is even, or it is not. But this on-or-off, black-or- white, 0-or-1 approach falls apart when applied to many everyday classifications, like the set of beautiful women, the set of tall men or the set of very cold days.

To deal with such cases, Zadeh proposed that membership in a set be measured not as a 0 or a 1, but as a value between 0 and 1. Thus, in the set of tall men, George Bush (6 ft. 2 in.) might have a membership value of 0.7, while Kareem Abdul-Jabbar (7 ft. 2 in.) might have a 0.99. Zadeh and his students went on to elaborate a full fuzzy mathematics, devising precise rules for combining vague expressions like "somewhat fast," "very hot" and "usually wrong."

This mathematics turns out to be surprisingly useful for controlling robots, machine tools and various electronic systems. A conventional air conditioner, for example, recognizes only two basic states: too hot or too cold. When geared for thermostat control, the cooling system either operates at full blast or shuts off completely. A fuzzy air conditioner, by contrast, would recognize that some room temperatures are closer to the human comfort zone than others. Its cooling system would begin to slow down gradually as the room temperature approached the desired setting. Result: a more comfortable room and a smaller electric bill.

Fuzzy logic began to find applications in industry in the early '70s, when it was teamed with another form of advanced computer science called the expert system. A product of research into artificial intelligence, expert systems solve complex problems somewhat like human experts do -- by applying rules of thumb. (Example: when the oven gets very hot, turn the gas down a bit.) In 1980 F.L. Smidth & Co. of Copenhagen began marketing the first commercial fuzzy expert system: a computer program that controlled the fuel-intake rate and gas flow of a rotating kiln used to make cement.

Despite such successes, fuzzy logic was not well received in the U.S. Scientists pointed out that uncertainty and vagueness could be represented perfectly well by more traditional means, like statistics or probability theory. Some of the criticism bordered on the vituperative, and the tenets of fuzzy logic were dismissed with terms ranging from "comical" to "content- free."

The Japanese, however, showed no such resistance, perhaps because their culture is not so deeply rooted in scientific rationalism. Says Bart Kosko, a Zadeh protege and a professor of electrical engineering at the University of Southern California: "Fuzziness begins where Western logic ends." In the early '80s several Japanese firms plunged enthusiastically into fuzzy research. By 1985 Hitachi had installed the technology's most celebrated showpiece: a subway system in Sendai, about 200 miles north of Tokyo, that is operated by a fuzzy computer. Not only does it give an astonishingly smooth ride (passengers do not need to hang on to straps), but it is also 10% more energy efficient than systems driven by human conductors.

Japanese researchers are pursuing more than 100 new applications for fuzzy logic. Nissan has patented fuzzy auto transmission and antiskid braking , systems. Yamaichi Securities has introduced a fuzzy stock-market investment program for signaling shifts in market sentiment. Canon is working on a fuzzy auto-focus camera. Matsushita has delivered a fuzzy automobile-traffic controller, and is about to unveil a fuzzy shower system that adjusts to changes in water temperature to prevent morning scaldings. And in the strongest endorsement of the technology to date, the Ministry of International Trade and Industry opened the Laboratory for International Fuzzy Engineering Research in Yokohama and called for funding of some $34 million over the next six years.

The U.S. is not totally out of the fuzzy picture yet. A small firm in Irvine, Calif., Togai InfraLogic, has already achieved several of the goals MITI set for itself, including a fuzzy computer chip that can perform 28,600 fuzzy-logical inferences per sec. (FLIPS). And NASA is experimenting with fuzzy controllers that could help astronauts pilot the shuttle in earth orbit. The results so far, say NASA officials, are encouraging, and there is growing interest at such aerospace firms as Rockwell and Boeing. "The only barrier remaining" to wider use of fuzzy logic, says Kosko, "is the philosophical resistance of the West."

With reporting by Norihiko Shirouzu/Tokyo