摘要
In 1958, the Chinese mathematicians led by Prof. QIN Yuan-xun proposed a problem of equivalence between differential equations and differential difference equations in the stability theory. The achievements in systematic research on the problem were summarized in [2]. In this letter, by using the idea and method in [1, 2], a theorem on the equivalence between multidelay neutral differential difference equations (NDDE) and the corresponding ordinary differential equations (ODE)in the stability theory is established.
