中文摘要：

通过定义有界闭凸子集到Banach空间上的一个算子，应用压缩映像原理讨论了带有正负系数的二阶中立型时滞微分方程非振动解的存在性，得到该方程非振动解存在的一个充分条件．

英文摘要：

The purpose of this paper is to prove the existence of non-oscillatory solutions to second-order neutral time-lag differential equation with positive/negative coefficient by using contraction--image principle through defining an operator from a bounded, closed, and convex subset into Banach space. This paper has presented a sufficient condition for the existence of non-oscillatory solution to the above equation.