Oscillation of neutral differential equation with positive and negative coefficients

In this paper, we provide oscillation properties of every solution of the neutral differential equation with positive and negative coefficients x(t)− R(t)x(t −r) +P(t)x(t − τ)−Q(t)x(t − σ) = 0, where R(t),P(t ), Q(t) ∈ C([t0,∞),R+), r >0, τ 0, σ 0. © 2006 Elsevier Inc. All rights reserved.