Oscillations of second order neutral functional differential equations

摘要

Consider the second order neutral functional differential equation d2dt2[x(t)+∑ni=1nix(t−ti)]+ω∑mj=1ξjx(t−αj)=0 where δ = ± 1, ηi, τi, ξj, and αj, i = 1,2, …, n, j = 1,2, …, m, are real numbers. Some new oscillation criteria are given for oscillation of (E). The results of this paper improve noticeably some known results.