OSCILLATION OF SUBLINEAR 2ND-ORDER DIFFERENTIAL-EQUATIONS WITH INTEGRABLE COEFFICIENTS

An oscillation criterion is given for the second order sublinear differential equation y″ + a(t)f(y) = 0, where a(t) ε{lunate} C[0, ∞) and f(y) ε{lunate} C(-∞, ∞) is nondecreasing with yf(y) > 0 for y ≠ 0, and also satisfies a sublinear condition which covers the special case f(y) = |y|γ sgn y, 0 < γ < 1. The coefficient a(t) is allowed to be negative for large values of t, and its integral over the nonnegative reals is finite. This result extends an earlier oscillation theorem of Kwong and Wong for the special case. © 1991.