Quite a popular form tells about mathematical models for making optimal decisions. Much attention is paid to the unconventional way of formalizing the goals of systems, which consists in the fact that instead of the objective function, a preference ratio is set on many states of systems. When studying complex systems (social, biological, environmental, etc.), this method of formalizing their goals allows in some cases to build a more adequate model than when using target functions. The book is designed for a wide range of people interested in cybernetics, decision theory, as well as relationship algebra and its applications.