بررسي كامل بودن توابع ويژه مسأله گلرستد براي معادله ديفرانسيل با مشتقات جزيي از نوع مركب تغيير يافته

On the Completeness of The System of Eigenfunctions of The Gellerstedt Problem For a Degenerating Equation of Mixed Type

In this paper, we prove the completeness in the elliptic part of the domain of the system of eigenfunctions of the Gellerstedt problem for a degenerating equation of mixed type. Simultaneously, we consider the completeness of the system of eigenfunctions of the Tricomi and Neuman - Tricomi problems, which arise in studing the Gellerstedt problem.