Computing with Words - A Paradigm Shift
Lotfi Zadeh,
UC-Berkeley
11:00 am Thu. Feb. 8 in 3139 CS&S
Computing - in its traditional sense - involves for the most part manipulation
of numbers. By contrast, humans employ words in computing and reasoning,
arriving at conclusions expressed as words from premises expressed in a
natural language. By their nature, words are less precise than numbers. For
this reason, computing with words is generally less precise than computing
with numbers. This raises the question: What is the point of computing with
words in preference to computing with numbers? There are two major
imperatives. First, computing with words is a necessity when the available
information is too imprecise to justify the use of numbers. And second,
computing with words is advantageous when there is a tolerance for imprecision
that can be exploited to achieve tractability, robustness, low solution cost,
and better rapport with reality.
In our approach, the point of departure in computing with words is a
collection of propositions expressed in a natural language, with a proposition
viewed as an implicit constraint on a variable. The constraints can assume a
variety of forms, among which are possibilistic, probabilistic, conjunctive
and random-set types. For purposes of computation, the rules of inference in
fuzzy logic are employed to propagate the constraints from premises to
conclusions. Finally, the fuzzy constraints in conclusions are retranslated
into propositions expressed in a natural language.