Existence of periodic solutions for a fourth-order pp-Laplacian equation with a deviating argument

In this paper, we study the existence of periodic solutions for a fourth-order pp-Laplacian differential equation with a deviating argument as follows: [φp(u″(t))]″+f(u″(t))+g(u(t−τ(t)))=e(t).[φp(u″(t))]″+f(u″(t))+g(u(t−τ(t)))=e(t). Under various assumptions, the existence of periodic solutions of the problem is obtained by applying Mawhin’s continuation theorem.