1.Introduction. The classical Sturmian comparison theory for the second order ordi-nary differential equations is known to be the basis for study of numerous important properties of their solutions and, first of all, of their oscillatory properties. The principal advance in this direction was achieved due to the results of Sturmian theory (Sturmian Comparison Theorem, Oscillation and Non-oscillation Theorem, Zeros-Separation The-orem) although many of the more recent investigations (especially for nonlinear equa-tions) are no more based on this theory [4].
展开▼
