Nonlocal and Nonvariational Elliptic Problems: Existence and Multiplicity Results

This paper addresses a nonlocal elliptic problem using the Adomian decomposition method alongside the differential transform method. We establish relationships between strict upper and lower solutions of this problem and the topological degree, regardless of whether these solutions are oppositely ordered or well ordered. Furthermore, we demonstrate existence and multiplicity results. To illustrate the practical application of our theoretical results, we present two comprehensive examples.