Interval criteria for oscillation of second-order nonlinear neutral differential equations
Some new oscillation criteria are established in this paper for the second-order non-linear neutral delay differential equation [r (t) (x(t) + p(t)x(t - tau))']' + q(t) f (x(t - delta)) = 0, where tau and delta are nonnegative constants, r, p, q is an element of C([t(0), infinity), R), and f is an element of C(R, R). These results are different from most known ones in the sense that they are based on the information only on a sequence of subintervals of [t(0), infinity), rather than on the whole half-line. Our results are sharper than some previous results about neutral and delay differential equations. In particular, several examples that dwell upon the sharp conditions of our results are also included. (C) 2003 Elsevier Ltd. All rights reserved.
criteria oscillation neutral differential equation