Preservation of nonoscillatory behavior of solutions to second-order delay differential equations under impulsive perturbations (Q1609455)

Here, the authors present a new criterion for the preservation of nonoscillatory behavior of solutions to the second-order delay differential equation \[ x''(t) + p(t) x(t-\tau)=0,\qquad t\geq t_0, \] under impulsive perturbations. A method of direct analysis and a technique not utilizing fixed-point theorems are developed.