Nonlinear neutral delay differential equations of fourth-order: Oscillation of solutions

The objective of this paper is to study oscillation of fourth-order neutral differential equa-tion. By using Riccati substitution and comparison technique, new oscillation conditions are obtained which insure that all solutions of the studied equation are oscillatory. Our results complement some known results for neutral differential equations. An illustrative example is included. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.