PERIODIC SOLUTION OF CERTAIN NONLINEAR DIFFERENTIAL EQUATIONS: VIA TOPOLOGICAL DEGREE THEORY AND MATRIX SPECTRAL THEORY
The main purpose of this article is to establish the existence and stability of a periodic solution of nonlinear differential equation connected with a problem from mathematical biology. The existence and stability conditions are given in terms of spectral radius of explicit matrices, which are better than conditions obtained by using classic norms. The approaches are based on Mawhin's coincidence degree theory, matrix spectral theory and Lyapunov functional. It should be noted that the new problem appears due to the introduction of Gilpin–Ayala effect. The standard methods used in the previous literature cannot be used to analyze the asymptotic stability of such systems. To handle this problem, two novel techniques should be employed. One is to rescale the system by [Formula: see text], not [Formula: see text]. The other is to analyze the maximal eigenvalue of matrix. In fact, the analytic technique is nontrivial. It is original and very interesting. Finally, some examples and their simulations show the feasibility of our results.