It is well known that “fuzziness”—information granules and fuzzy sets as one
of its formal manifestations— is one of important characteristics of human
cognition and comprehension of reality. Fuzzy phenomena exist in nature and
are encountered quite vividly within human society. The notion of a fuzzy
set has been introduced by L. A., Zadeh in 1965 in order to formalize human
concepts, in connection with the representation of human natural language
and computing with words. Fuzzy sets and fuzzy logic are used for modeling
imprecise modes of reasoning that play a pivotal role in the remarkable
human abilities to make rational decisions in an environment affected by uncertainty
and imprecision. A growing number of applications of fuzzy sets
originated from the “empirical-semantic” approach. From this perspective,
we were focused on some practical interpretations of fuzzy sets rather than
being oriented towards investigations of the underlying mathematical structures
of fuzzy sets themselves. For instance, in the context of control theory
where fuzzy sets have played an interesting and practically relevant function,
the practical facet of fuzzy sets has been stressed quite significantly.