Abstract: The subject of the research are methods and algorithms aimed at practical solution of problems of pattern recognition in the weakly formalized fields of knowledge, such as medical field, technical field, geological reconnaissance diagnostics, forecasting and construction of expert systems. The solutions of such problems entered into use a large number of incorrect (heuristic) algorithms. The authors focus on such aspects as the need for the development of the theory of corrective operations, the necessity for the synthesis of correct algorithms minimum complexity, solving the stability issues by using mathematical methods. Special attention is paid to the construction of the algorithm, correct on the whole set of recognizable objects, based on existing algorithms and decision rules drawn up for the studied area. The logical approach may be a technology of constructing a theory of the synthesis of the correct recognition algorithms based on existing family of algorithms. The article shows that these methods allow creating algorithms that implement certain expert conclusion, despite the lack of adequate mathematical models of the relationships between image and its properties, incomplete and contradictory of data. The main conclusion of the research is in a logical analysis of a given subject area, in terms of variables valued logic. The authors propose approaches to the design of procedures for recognition of precedents on the basis of incorrect set of algorithms and constructed logical decision rules. The main contribution of the authors in the study of the topic is the proposed algorithm, expanding the area of the solutions obtained and correct on the whole set of recognizable objects. The novelty of the study is the use of variables valued logic that improves the correctness of encoded information and increase the expressiveness of the conclusions.