Abstract
In this paper, we establish a Lyapunov-type inequality for a fractional q-difference equation subject to Dirichlet-type boundary conditions. The obtained inequality generalizes several existing results from the literature including the standard Lyapunov inequality. We use that result to provide an interval, where a certain Mittag-Leffler function has no real zeros. We present also another application of the obtained inequality, where we prove that existence implies uniqueness for a certain class of fractional q-difference boundary value problems. (C) 2016 All rights reserved.