New Inequalities of Gruss Type for the Stieltjes Integral and Applications
Sever Silvestru Dragomir
TL;DR
This work extends Grüss-type inequalities from the weighted Čebyšev framework to Stieltjes integrals by introducing the generalized Čebyšev functional $T(f,g;u)$ for $f,g$ continuous and $u\in BV[a,b]$ with $u(b)\neq u(a)$. It proves sharp, $\tfrac{1}{2}$-constant bounds under various conditions on $f$ and $u$ (including bounded, monotone, Lipschitz, and Hölder cases) and develops a quadrature rule $S_n(f,g;u,I_n)$ with a sharp remainder bound for approximating $\int_a^b f(t)g(t)\,du(t)$. The paper then specializes these results to weighted functionals $T_w$ and to $D(f;u)$, providing identities, positivity criteria, and numerous corollaries, thereby broadening the applicability to numerical integration and analysis of Stieltjes-type integrals. Overall, the results yield tight error estimates and practical quadrature schemes for Stieltjes integrals with diverse integrators, impacting numerical analysis and approximation theory in this domain.
Abstract
Sharp inequalitieis of Gruss type for Stieltjes integrals with application in numerical integration are provided.
