New oscillation theorems for a class of even-order neutral delay differential equations

摘要

In this work, we study the oscillatory behavior of even-order neutral delay differential equations $upsilon ^{n}(l)+b(l)u(eta (l))=0$ , where $lgeq l_{0}$ , $ngeq 4$ is an even integer and $upsilon =u+a ( ucirc mu ) $ . By deducing a new iterative relationship between the solution and the corresponding function, new oscillation criteria are established that improve those reported in (T. Li, Yu.V. Rogovchenko in Appl. Math. Lett. 61:35–41, 2016).