Periodic solutions for a fourth-order pp-Laplacian differential equation with a deviating argument

By means of Mawhin’s continuation theorem, a kind of fourth-order pp-Laplacian differential equation with a deviating argument as follows: [φp(u″(t))]″+f(u(t))u′(t)+g(t,u(t),u(t−τ(t)))=e(t)[φp(u″(t))]″+f(u(t))u′(t)+g(t,u(t),u(t−τ(t)))=e(t) is studied. Under various assumptions, the existence of periodic solutions is obtained.