A converse to the neo-classical inequality with an application to the Mittag-Leffler function

Abstract

We prove two inequalities for the Mittag-Leffler function, namely that the function $\log E_\alpha(x^\alpha)$ is sub-additive for $0<\alpha<1,$ and super-additive for $\alpha>1.$ These assertions follow from two new binomial inequalities, one of which is a converse to the neo-classical inequality. The proofs use a generalization of the binomial theorem due to Hara and Hino (Bull. London Math. Soc. 2010). For $0<\alpha<2,$ we also show that $E_\alpha(x^\alpha)$ is log-concave resp. log-convex, using analytic as well as probabilistic arguments.