Infinitely many solutions for fourth-order elliptic equations with general potentials

This paper is concerned with the following fourth-order elliptic equations {Δ2u−Δu+V(x)u=f(x,u)in  RN,u∈H2(RN), where u:RN→Ru:RN→R. Under general assumption on potential V(x)V(x), and f(x,u)f(x,u) is indefinite sign and sublinear as |u|→∞|u|→∞, we establish the existence of infinitely many solutions by using the genus properties in critical point theory. Recent results from the literature are extended.