Existence of positive periodic solutions of a neutral delay Lotka-Volterra system with impulses

Sufficient conditions are obtained for the existence of periodic positive solutions of a class of neutral impulsive delay Lotka-Volterra systems by using some techniques of Mawhin coincidence degree theory. My results generalize some known results. It is shown that under the appropriate linear periodic impulsive perturbations, the neutral impulsive delay Lotka-Volterra system preserves the original periodicity of the neutral nonimpulsive delay Lotka-Volterra system.