Monotonicity Results for Nabla Riemann–Liouville Fractional Differences

Abstract

Positivity analysis is used with some basic conditions to analyse monotonicity across all discrete fractional disciplines. This article addresses the monotonicity of the discrete nabla fractional differences of the Riemann–Liouville type by considering the positivity of ∇b0RLθg(z) combined with a condition on g(b0+2), g(b0+3) and g(b0+4), successively. The article ends with a relationship between the discrete nabla fractional and integer differences of the Riemann–Liouville type, which serves to show the monotonicity of the discrete fractional difference ∇b0RLθg(z).

Keywords

• discrete fractional calculus
• discrete nabla Riemann–Liouville fractional differences
• monotonicity analysis