Necessary and sufficient conditions for the oscillation of certain delay differential equations Original Research Article

Consider the following equations: ξ(t)+aξ(t)+bξ(t − τ)+cξ(t − σ) = 0 where a, b, c, τ, σ are constants, and τ, σ > 0. In this paper, we establish sufficient and necessary conditions for all solutions of equation (∗) to oscillate, which is easy to verify and apply.