Analogue of the Tricomi problem for the mixed-type equation with fractional derivative. Inverse problems

Abstract: In this work, an analogue of the Tricomi problem for equations of mixed type with a fractional derivative is investigated. In one part of the domain, the considered equation is a subdiffusion equation with a fractional derivative of order ? 2 (0; 1) in the sense of Riemann-Liouville, and in the other it is a wave equation. Assuming the parameter ? to be unknown, the corresponding inverse problem is studied . It was found an additional condition, that provides not only uniqueness but also existance of the desired parameter. It should be noted that the inverse problem of determining the fractional derivative for the subdiffusion and wave equations has been studied by many mathematicians. But in the case of the Tricomi problem for a mixed-type equation, the questions of determining the fractional time derivative are studied for the first time.