Abstract
The purpose of this study is to develop a fuzzy expert system based on the analysis of biomedical images for the diagnosis of oncological diseases using breast cancer as an example. The main directions of application of mathematical methods in medical diagnosis are analyzed, their drawbacks are evaluated, and principles of diagnosis, based on fuzzy logic, are formulated. Mathematical models and algorithms are developed, formalizing the process of diagnostic decision-making based on fuzzy logic with quantitative and qualitative parameters of the patient's condition; mathematical models of membership functions are developed, formalizing the representation of quantitative and qualitative parameters of the patient's condition in the form of fuzzy sets, used in models and algorithms for diagnosing and determining the diagnosis in the case of breast cancer.