Copyright © 2010 Feng Qi. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

By looking back at the long history of bounding the ratio Γ(x+a)/Γ(x+b) for x>-min⁡{a,b} and a,b∈ℝ, various origins of this topic are clarified, several developed courses are followed, different results are compared, useful methods are summarized, new advances are presented, some related problems are pointed out, and related references are collected.