Oscillation theorems for perturbed differential equations of second order

摘要

By means of a Riccati transform and averaging technique some oscillation criteria are established for perturbed nonlinear differential equations of second order $$ (p(t)x'(t))'+q(t)|x(phi(t))|^{lpha+1} ext{sgn},x(phi(t)) + g(t,x(t))=0 ag{$P_1$} $$ ($P_2$) and ($P_3$) satisfying the condition (H). A comparison theorem and examples are given.