Oscillation of second-order functional differential equations with mixed nonlinearities and oscillatory potentials

In this paper, we study oscillation of second-order functional differential equations with mixed nonlinearities (p(t)x'(t))' + q(t)x(t - tau) + Sigma(n)(i=1)q(i)(t)vertical bar x(t - tau)vertical bar(alpha i)sgnx(t - tau) = e(t), where tau >= 0, p(t) is an element of C-1 [0, infinity), q(t); q(i)(t), e(t) is an element of C[0, infinity), p(t) > 0, alpha(1) > ... > alpha(m) > 1 > alpha(m+1) > ... > alpha(n) > 0 (n > m >= 1). Without assuming that q(t), q(i)(t) and e(t) are nonnegative, the results given in [Y.G. Sun, F. W. Meng, Interval criteria for oscillation of second-order differential equations with mixed nonlinearities, Appl. Math. Comput. 198 (2008) 375-381] have been extended to the aforementioned functional differential equation. (c) 2009 Elsevier Inc. All rights reserved.