Interval oscillation of second-order functional differential equations with oscillatory potentials

Interval oscillation criteria are established for second-order differential equations of the form (k(t)x' (t))' + p(t)x(g(t)) + q (t) vertical bar x(g(t))vertical bar gamma-1x(g(t)) = e(t), t >= 0 (E gamma) where gamma > 1; k,p,q,e and g are continuous real-valued functions; k(t) > 0 is nondecreasing; g(t) is nondecreasing, lim(t ->infinity) g(t) infinity. We consider g(t) <= t and g(t) >= t, separately. Illustrative examples are included. (C) 2009 Elsevier Ltd. All rights reserved.