340 Chapter 8 Fuzzy InFormatIon retrIeval
8.2 FUZZY SET BASICS
Most of us have some contact with conventional logic, in which a statement
is either true or false with nothing in between. Although this principle of
true or false has dominated Western logic for the last 2,000 years, the idea
that things must be either true or false is nonsense in many cases. For exam-
ple, is the statement “I am rich” completely true or false? The answer is prob-
ably true or false or neither since the question we need to consider is how
rich is rich. A man with a million dollars may be rich or not rich depending
on the condition of comparison. This idea of gradations of truth is familiar
to every one of us who faces decision making of any sort. The breakthr ...