Existence results for positive solutions to iterative systems of four-point fractional-order boundary value problems in a Banach space.

We investigate the eigenvalue intervals of λ 1 , λ 2 , ... , λ n for which the iterative system of four-point fractional-order boundary value problem has at least one positive solution by utilizing Guo–Krasnosel'skii fixed point theorem under suitable conditions. The obtained results in the paper are illustrated with an example for their feasibility. [ABSTRACT FROM AUTHOR]