#### Designing and developing a complex social engineering system based on fuzzy interval estimates

Abstract
The paper studies design and development of expenditure accounting system of an online shop using the fuzzy sets theory and fuzzy logic. It has also considered the construction principles of complex information systems and formulated the requirements for the system under design. Apart from that the authors dwell upon the fuzzy problem of multi-criteria optimization on basis of interval estimation. The program interface has been designed and main principles of work created by informational system have been described.