The height of Dyck paths and checkerboard labellings

Abstract

Dyck paths and certain black/white labelling of nodes leads to the \emph{white-height}. Using generating functions and tricks of the trade, we establish that the average white-height among Dyck paths of half length $n$ is asymptotic to $\frac12\sqrt{πn}$ for two different models. These are appealing results that could be presented to students to learn the trade. A last section links walks with double steps and 2-Motzkin paths. For them, the white-height is the natural concept. Folks who might be offended by the notion of \emph{white-height} might choose their own colours that they like.