Positivity of sums and integrals for $n$-convex functions via the Fink identity

Authors: ASIF R KHAN, JOSIP PECARIC, MARJAN PRALJAK, SANJA VAROSANEC

Abstract: We consider the positivity of the sum $\sum_{i=1}^n\rho_i\digamma(\xi_i)$, where $\digamma$ is a convex function of higher order, as well as analogous results involving the integral $\int_{a_0}^{b_0}\rho(\xi)\digamma(g(\xi))d\xi$. We use a representation of the function $\digamma$ via the Fink identity and the Green function that leads us to identities from which we obtain conditions for positivity of the above-mentioned sum and integral. We also obtain bounds for the integral remainders which occur in these identities, as well as corresponding mean value results.

Keywords: $n$-convex functions, Fink identity, Green function, \v{C}eby\v{s}ev functional

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