Succinct representation of labeled trees

TL;DR

This paper introduces a space-efficient representation for labeled ordered trees that enables fast label-based queries, improving upon previous succinct representations especially when label entropy is low.

Contribution

It presents a novel succinct tree representation supporting label queries, reducing redundancy compared to prior methods, especially in low-entropy label scenarios.

Findings

Supports labeled queries like ancestor retrieval

Achieves small-o redundancy relative to optimal space

Improves upon He et al.'s representation in low-entropy cases

Abstract

We give a representation for labeled ordered trees that supports labeled queries such as finding the i-th ancestor of a node with a given label. Our representation is succinct, namely the redundancy is small-o of the optimal space for storing the tree. This improves the representation of He et al. which is succinct unless the entropy of the labels is small.