SUFFICIENT AND NECESSARY CONDITIONS FOR DISCRETENESS OF SPECTRUM OF EULER DIFFERENTIAL OPERATORS
Euler微分算子谱是离散的充分必要条件

In this paper, the 2nd order symmetric Euler differential expressions with real-valued coefficients are considered. Some results concerning the discreteness of spectrum of Euler differential operators is obtained. Especially, the necessary and sufficient conditions are given which ensure that the spectrum of Euler differential operators is discrete.