Distribution of zeros of solutions of functional differential equations

By improving the bracketing techniques for a functional differential inequality in a previous paper [H.W. Wu, Y.T Xu, The distribution of zeros of solutions of neutral differential equations, Appl. Math. Comput. 156 (3) (2004) 665–677], we are able to derive sharper upper bounds on the distance between zeros of solutions of a class of neutral functional differential equations with delays, and hence improve many known bounds in the literature.