Basic concepts of the theory of fuzzy sets
All information can be divided into one of two categories: certain and uncertain. Uncertain information can be further divided into two sub-categories: incomplete precise information that uses probability methods and imprecise information that uses the fuzzy set theory to give verbal statements a numerical clarity without losing imprecision. This article details how project managers can use the fuzzy set theory to evaluate project uncertainty. In doing so, it explains the formulas for calculating uncertainty according to the fuzzy set theory and discusses these in relation to gauging project risk. It also examines these in relation to the classical set theory. It then identifies the procedure of linguistic analysis for using fuzzy set theory and the purpose of using-and the primary obstacle in applying-this theory. This article is a supplement to a larger article written by these authors: Risk Management by Expert Systems.