Rc. Brown et Db. Hinton, OPIAL INEQUALITY AND OSCILLATION OF 2ND-ORDER EQUATIONS, Proceedings of the American Mathematical Society, 125(4), 1997, pp. 1123-1129
For a second-order differential equation, we obtain from Opial's inequ
ality lower bounds for the spacing between two zeros of a solution or
between a zero of a solution and a zero of its derivative. These bound
s are expressed in terms of antiderivatives of the potential, and in p
articular we derive some new Liapunov type inequalities from them.