For the classification problem, of which categories having vague or ve
rbal definition, Okuda et al. [Proc. 3rd IFSA Congr. (1989) 755] propo
sed a model in which each category is defined by fuzzy sets, and each
appearance frequency is explained by the probability of Zadeh's fuzzy
event. They called this model fuzzy observation. Membership functions
are usually given directly by the user's subjectivity. But these membe
rship functions cannot be used in the fuzzy observation model because
they have no assurance to meet the restriction as the fuzzy event. In
this paper we propose a method to obtain the membership functions whic
h satisfy the restriction as the fuzzy event against to given probabil
ity density function, and discuss the effectiveness of the method. (C)
1998 Elsevier Science B.V.