摘要

We study the oscillation and nonoscillation of third order delay differential equations with positive and negative terms. We establish Kiguradze Lemma, and offer the novel and useful estimate x(tau(1)x(t)(t))/w(t) >= tau(1)(t)/t which plays an important role in our main results. First of all, we give Leighton-Wintner type criteria. Then, by using Riccati transformation, we establish new oscillation criteria including Kamenev-type oscillation criteria. Finally, we present a sufficient and necessary condition which guarantees that the nonoscillatory solution x(t) has an upper bound and tends to zero. Examples illustrate the validity and practicability of our results.

  • 单位
    中山大学; 广东教育学院; 广东药学院