The paper considers how methods of a logical inference search in the calculus
of positively constructed formulas may be applied to represent and study discrete event systems. The formalisms of discrete event systems and positively constructed formulas are briefly described. A method for constructing a product of automata using constructive inference in the positively constructed formulas calculus is proposed. Based on the given specication on
the behaviour of the system, a method for constructing a supremal controllable sublanguage of the specication is presented.