  In this paper, we propose a set theoretic approach for knowledge
representation. While the syntax of an application domain is captured by set
theoretic constructs including individuals, concepts and operators, knowledge
is formalized by equality assertions. We first present a primitive form that
uses minimal assumed knowledge and constructs. Then, assuming naive set theory,
we extend it by definitions, which are special kinds of knowledge.
Interestingly, we show that the primitive form is expressive enough to define
logic operators, not only propositional connectives but also quantifiers.
