Some oscillation criteria for delay differential equations of even order (Q1086421)

Consider the delay differential equation \[ (1)\quad (a(t)x^{(n- v)})^{(v)}+q(t)f(x[g_ 1(t)])h(\dot x[q_ 2(t)])=0, \] where n is even, \(1\leq v\leq n-1\), \(a,g_ 1,g_ 2\), \(q: [t_ 0,\infty)\to R,\) f, \(h: R\to R\) are continuous, \(a(t)>0\) and q(t) nonnegative and not identically zero on any ray of the form \([t^*,\infty)\) for some \(t^*\geq t_ 0\) and \(g_ i(t)\to \infty\) as \(t\to \infty\), for \(i=1,2\). The authors study some oscillation criteria for the solutions of equation (1). Examples are given to illustrate the hypotheses of the results established in this paper.