Research materials aimed at the development of methods, algorithms and programs for solving problems related to the recognition (qualification) of the states of operable systems are presented. Qualification results can be used to control the operation of systems in various conditions, to determine the rational period of the next recognition of the state, to assess the cost of systems put up for sale. The book is intended for specialists in the field of assessing the condition of objects and systems both during operation or preventive maintenance, and when preparing them for sale. It can be used by students and graduate students when studying issues of systems analysis.