Abstract. The study is devoted to the development of the theory of construction of intelligent systems, created to solve problems in arbitrary subject areas. The decision process consists of modeling the subject area based on the use of an ontological representation, involving logic, and assigning individual elements of the model as triads consisting of an extensional, intensional, and connotation. The paper proposes definitions of the levels of intelligence. Each such level determines its level of capabilities of the intelligent system.

Keywords: intellect, intelligent system, intelligence level, subject area, ontology, ontological model.