Oscillation of a class of second-order delay differential equation with impulses. (Q1412471)

The paper deals with the second-order linear delay differential equation with impulses \[ x''(t)+r(t)x'(t)+[p(t)-q(t)]x(t-\tau )=0,\;t\geq t_0,\;t\neq t_k,\text{ for }k=1,2,3,\dots,\tag{1} \] where \(0\leq t_0<t_1<t_2< \dots\), and \(\lim_{k\to\infty}t_k=\infty\). The authors establish sufficient conditions for all solutions of equation (1) to be oscillatory.