Oscillation theory of third-order nonlinear functional differential equations

In this paper, we are concerned with oscillation of solutions of a certain class of third-order nonlinear delay differential equations of the form % x^(t)+p(t)x^^(t)+q(t)f(x(τ (t)))=0. We establish some new oscillation results that extend and improve some results in the literature in the sense that our results do not require that % τ ^(t)≥ 0. Some examples are considered to illustrate the main results and some conjectures and open problems are presented.