Sharpened Oscillation Conditions for Even-Order Neutral Differential Equations Involving Distributed Deviating Arguments

The present work is devoted to the investigation of oscillatory solutions of even-order neutral differential equations with distributed deviating arguments. By developing sharper iterative inequalities, we derive a comparison framework that reduces the oscillation problem to the study of a related discrete-delay equation. The proposed approach establishes oscillation criteria for a broad range of argument configurations, including delayed, advanced, and mixed cases, while also accommodating different monotonicity assumptions with respect to the distributed argument. These features allow the analysis to be carried out within a single unified framework and substantially extend the applicability of many existing results. The effectiveness of the obtained criteria is further illustrated through applications to Euler-type differential equations, where the proposed conditions remain applicable in situations for which several related results fail to provide a conclusion.