Stability criteria for certain high even order delay differential equations

In this paper we study the asymptotic stability of the zero solution of even order linear delay differential equations of the formy(2m)(t)=∑j=02m−1ajy(j)(t)+∑j=02m−1bjy(j)(t−τ), where ajaj and bjbj are certain constants and m⩾1m⩾1. Here τ>0τ>0 is a constant delay. In proving our results we make use of Pontryagin's theory for quasi-polynomials.