Several Functions Originating from Fisher-Rao Geometry of Dirichlet Distributions and Involving Polygamma Functions

In this paper, the authors review and survey some results published since 2020 about (complete) monotonicity, inequalities, and their necessary and sufficient conditions for several newly introduced functions involving polygamma functions and originating from the estimation of the sectional curvature of the Fisher-Rao geometry of the Dirichlet distributions in the two-dimensional case.