The sub-supersolution method for variable exponent double phase systems with nonlinear boundary conditions

In this paper, we study quasilinear elliptic systems driven by variable exponent double phase operators involving fully coupled right-hand sides and nonlinear boundary conditions. The aim of our work is to establish an enclosure and existence result for such systems by means of trapping regions formed by pairs of sub- and supersolutions. Under very general assumptions on the data, we then apply our result to get infinitely many solutions. Moreover, we discuss the case when we have homogeneous Dirichlet boundary conditions and present some existence results for this kind of problem.