Note on oscillation of neutral differential equations with multiple delays

Abstract

This note is a reaction on a recently published sufficient condition for oscillation of all solutions of a neutral delay differential equation. It is shown by a counterexample that the result is not correct and the problem is explained in details. Several, more general, classes of neutral differential equations with time-dependent discrete, distributed as well as mixed delays are considered. New sufficient conditions for oscillation of all their solutions are proved. Applications are given for illustration.

Keywords

• oscillatory solution
• discrete delay
• distributed delay
• mixed delay