Grammar Compressed Sequences with Rank/Select Support

TL;DR

This paper introduces grammar-based compressed sequence representations that efficiently support access, rank, and select operations, outperforming statistical methods in space and speed, especially for highly repetitive data.

Contribution

The authors present a novel grammar-based compression method for repetitive sequences that significantly reduces space and maintains fast query support.

Findings

Uses up to 6% of space compared to statistical compression.

Supports access and rank/select operations within tens of microseconds.

Effective in text indexing applications.

Abstract

Sequence representations supporting not only direct access to their symbols, but also rank/select operations, are a fundamental building block in many compressed data structures. Several recent applications need to represent highly repetitive sequences, and classical statistical compression proves ineffective. We introduce, instead, grammar-based representations for repetitive sequences, which use up to 6% of the space needed by statistically compressed representations, and support direct access and rank/select operations within tens of microseconds. We demonstrate the impact of our structures in text indexing applications.