Revisiting the Folklore Algorithm for Random Access to Grammar-Compressed Strings

Fuente: arXiv
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Autori principali: Cleary, Alan M., Winjum, Joseph, Dood, Jordan, Inenaga, Shunsuke
Natura: Preprint
Pubblicazione: 2024
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author Cleary, Alan M.
Winjum, Joseph
Dood, Jordan
Inenaga, Shunsuke
author_facet Cleary, Alan M.
Winjum, Joseph
Dood, Jordan
Inenaga, Shunsuke
contents Grammar-based compression is a widely-accepted model of string compression that allows for efficient and direct manipulations on the compressed data. Most, if not all, such manipulations rely on the primitive \emph{random access} queries, a task of quickly returning the character at a specified position of the original uncompressed string without explicit decompression. While there are advanced data structures for random access to grammar-compressed strings that guarantee theoretical query time and space bounds, little has been done for the \emph{practical} perspective of this important problem. In this paper, we revisit a well-known folklore random access algorithm for grammars in the Chomsky normal form, modify it to work directly on general grammars, and show that this modified version is fast and memory efficient in practice.
format Preprint
id arxiv_https___arxiv_org_abs_2407_08190
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Revisiting the Folklore Algorithm for Random Access to Grammar-Compressed Strings
Cleary, Alan M.
Winjum, Joseph
Dood, Jordan
Inenaga, Shunsuke
Data Structures and Algorithms
Grammar-based compression is a widely-accepted model of string compression that allows for efficient and direct manipulations on the compressed data. Most, if not all, such manipulations rely on the primitive \emph{random access} queries, a task of quickly returning the character at a specified position of the original uncompressed string without explicit decompression. While there are advanced data structures for random access to grammar-compressed strings that guarantee theoretical query time and space bounds, little has been done for the \emph{practical} perspective of this important problem. In this paper, we revisit a well-known folklore random access algorithm for grammars in the Chomsky normal form, modify it to work directly on general grammars, and show that this modified version is fast and memory efficient in practice.
title Revisiting the Folklore Algorithm for Random Access to Grammar-Compressed Strings
topic Data Structures and Algorithms
url https://arxiv.org/abs/2407.08190