具正负变系数时滞微分方程的正解

On Existence of The Positive Solutions for Delay Differential Equations With Positive and Negative Coefficients

本文给出了具正负变系数时滞微分方程Ｘ’（ｔ）＋Ｐ（ｔ）Ｘ（ｔ－τ）－ｑ（ｔ）Ｘ（ｔ－σ）＝０的一个正解存在条件，其与充要条件相当接近。

Sufficient conditions are established for solutions of equations X'(t)+P(t)X(t-τ)-q(t-s)=0here τ>σ≥0,Italmost approaches the necessary and sufficient condition .