In our present investigation, we first introduce several new subclasses of analytic and bi-univalent functions by using a certain q-integral operator in the open unit disk U = {z : z ∈ Cand |z| < 1}. By applying the Faber polynomial expansion method as well as the q-analysis, we then determine bounds for the nth coefficient in the Taylor-Maclaurin series expansion for functions in each of these newly-defined analytic and bi-univalent function classes subject to a gap series condition. We also highlight some known consequences of our main results.

In this manuscript, we adopt a novel approach to present a new bound for the Jensen gap for functions whose double derivatives in absolute function, are convex. We demonstrate two numerical experiments to verify the main result and to discuss the tightness of the bound. Then we utilize the bound for deriving two new converses of the Hölder inequality and a bound for the Hermite-Hadamard gap. Finally, we demonstrate applications of the main result for various divergences in information theory. Also, we present a numerical example to verify the bound for Shannon entropy.

Jensen integral inequality has got much importance regarding their applications in different fields of mathematics. In this paper, two converses of Jensen integral inequality for convex function are obtained. The results are applied to establish converses of Hölder and Hermite‐Hadamard inequalities as well. At the end, some useful applications in information theory of the obtained results are given. The idea used in this paper may inculcate further research.

In this paper, we present a new bound for the Jensen gap with the help of a Green function. Using the bound, we deduce a converse of the Hölder inequality as well. Finally, we present some applications of the main result in information theory.

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