Imbalance in Random Digital Trees

Abstract

The imbalance factor of the nodes containing keys in a trie (a sort of digital trees) is investigated. Accurate asymptotics for the mean are derived for a randomly chosen key in the trie via poissonization and the Mellin transform, and the inverse of the two operations. It is also shown from an analysis of the moving poles of the Mellin transform of the poissonized moment generating function that the imbalance factor (under appropriate centering and scaling) follows a Gaussian limit law.