Merging RLBWTs adaptively

TL;DR

This paper presents a method for efficiently merging two run-length compressed Burrows-Wheeler Transforms into a single extended BWT, optimizing space and time complexity.

Contribution

It introduces an adaptive merging algorithm for RLBWTs that operates in linear space and logarithmic time relative to input sizes.

Findings

Merging RLBWTs can be achieved in O(r + L) log(m + n) time.

The method operates in O(r) space, making it space-efficient.

The approach improves the efficiency of combining compressed text indexes.

Abstract

We show how to merge two run-length compressed Burrows-Wheeler Transforms (RLBWTs) into a run-length compressed extended Burrows-Wheeler Transform (eBWT) in $O (r)$ space and $O ((r + L) \log (m + n))$ time, where $m$ and $n$ are the lengths of the uncompressed strings, $r$ is the number of runs in the final eBWT and $L$ is the sum of its irreducible LCP values.