Chain rule formula and generalized mean value theorem for nabla fractional differentiation on time scale
Gaddiel L. Dorado, Mark Allien D. Roble
TL;DR
The paper develops a modified framework for nabla fractional differentiation on time scales, addressing real-valuedness issues for certain orders with a carefully defined neighborhood. It then proves a nabla fractional generalized mean value theorem and two-chain-rule formulations, including an explicit integral form, expanding the calculus of compositions on time scales. A key application is a closed-form expression for the sum of finite series in terms of the nabla fractional derivative, enabling efficient summation identities and classical expansions. Collectively, these results extend backward-difference fractional calculus to unified discrete-continuous settings and provide practical tools for series evaluation and numerical analysis.
Abstract
The nabla fractional derivative, which was introduced by Gogoi et.al., generalized the ordinary derivative with non-integer order, and unifies the continuous and discrete analysis using backward operator. In this study, we proposed a modification of their definition. The main focus of this work is to introduce a chain rule formula and a generalized mean value theorem for nabla fractional differentiation on time scale. Results of this study will be applied in finding the sum of a finite series.
