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The Burrows-Wheeler transform (BWT) is a string transformation that enhances string indexing and compressibility. Cotumaccio and Prezza [SODA '21] extended this transformation to nondeterministic finite automata (NFAs) through…

Data Structures and Algorithms · Computer Science 2025-03-11 Ruben Becker , Nicola Cotumaccio , Sung-Hwan Kim , Nicola Prezza , Carlo Tosoni

We present a new on-line algorithm for computing the Lempel-Ziv factorization of a string that runs in $O(N\log N)$ time and uses only $O(N\log\sigma)$ bits of working space, where $N$ is the length of the string and $\sigma$ is the size of…

Data Structures and Algorithms · Computer Science 2013-05-28 Jun'ichi Yamamoto , Tomohiro I , Hideo Bannai , Shunsuke Inenaga , Masayuki Takeda

The observed frequency of the longest proper prefix, the longest proper suffix, and the longest infix of a word $w$ in a given sequence $x$ can be used for classifying $w$ as avoided or overabundant. The definitions used for the expectation…

In this paper, we show that the LZ77 factorization of a text T {\in\Sigma^n} can be computed in O(R log n) bits of working space and O(n log R) time, R being the number of runs in the Burrows-Wheeler transform of T reversed. For extremely…

Data Structures and Algorithms · Computer Science 2015-10-22 Nicola Prezza , Alberto Policriti

A compressed self-index stores a string in compressed form while supporting locate queries without decompression. For highly repetitive strings (arising in web crawls, versioned documents, and genomic collections), static self-indexes can…

Data Structures and Algorithms · Computer Science 2026-04-29 Takaaki Nishimoto , Yasuo Tabei

In this paper, we consider the problem of compressing a trie while supporting the powerful \emph{locate} queries: to return the pre-order identifiers of all nodes reached by a path labeled with a given query pattern. Our result builds on…

Data Structures and Algorithms · Computer Science 2020-12-18 Nicola Prezza

Recently, Cenzato et al.\ proposed a new text index, called the \emph{suffixient array}, which is a subset of the suffix array and supports locating a single pattern occurrence or finding its maximal exact matches (MEMs), assuming random…

Data Structures and Algorithms · Computer Science 2026-05-07 Paola Bonizzoni , Younan Gao , Brian Riccardi

An index for a finite automaton is a powerful data structure that supports locating paths labeled with a query pattern, thus solving pattern matching on the underlying regular language. In this paper, we solve the long-standing problem of…

Data Structures and Algorithms · Computer Science 2020-07-16 Nicola Cotumaccio , Nicola Prezza

The Lempel-Ziv factorization (LZ77) and the Run-Length encoded Burrows-Wheeler Transform (RLBWT) are two important tools in text compression and indexing, being their sizes $z$ and $r$ closely related to the amount of text…

Data Structures and Algorithms · Computer Science 2017-02-07 Alberto Policriti , Nicola Prezza

The suffix tree is a very important data structure in string processing, but it suffers from a huge space consumption. In large-scale applications, compressed suffix trees (CSTs) are therefore used instead. A CST consists of three…

Data Structures and Algorithms · Computer Science 2010-12-21 Simon Gog , Enno Ohlebusch

Learning the structure of Directed Acyclic Graphs (DAGs) presents a significant challenge due to the vast combinatorial search space of possible graphs, which scales exponentially with the number of nodes. Recent advancements have redefined…

Machine Learning · Computer Science 2024-11-01 Klea Ziu , Slavomír Hanzely , Loka Li , Kun Zhang , Martin Takáč , Dmitry Kamzolov

While graphs and abstract data structures can be large and complex, practical instances are often regular or highly structured. If the instance has sufficient structure, we might hope to compress the object into a more succinct…

Computational Complexity · Computer Science 2024-12-02 Shreya Gupta , Boyang Huang , Russell Impagliazzo , Stanley Woo , Christopher Ye

In this paper, we propose a new paradigm for program optimization which is based on aggressive aggregation, i.e., on a partial evaluation-based decomposition of acyclic program fragments into a pair of computationally optimal structures: an…

Programming Languages · Computer Science 2019-12-25 Frederik Gossen , Marc Jasper , Alnis Murtovi , Bernhard Steffen

Structural measures of graphs, such as treewidth, are central tools in computational complexity resulting in efficient algorithms when exploiting the parameter. It is even known that modern SAT solvers work efficiently on instances of small…

Artificial Intelligence · Computer Science 2025-11-17 Yasir Mahmood , Markus Hecher , Johanna Groven , Johannes K. Fichte

The compression of highly repetitive strings (i.e., strings with many repetitions) has been a central research topic in string processing, and quite a few compression methods for these strings have been proposed thus far. Among them, an…

Data Structures and Algorithms · Computer Science 2022-02-17 Takaaki Nishimoto , Shunsuke Kanda , Yasuo Tabei

Matching statistics were introduced to solve the approximate string matching problem, which is a recurrent subroutine in bioinformatics applications. In 2010, Ohlebusch et al. [SPIRE 2010] proposed a time and space efficient algorithm for…

Data Structures and Algorithms · Computer Science 2023-01-16 Alessio Conte , Nicola Cotumaccio , Travis Gagie , Giovanni Manzini , Nicola Prezza , Marinella Sciortino

We consider the problem of producing compact architectures for text classification, such that the full model fits in a limited amount of memory. After considering different solutions inspired by the hashing literature, we propose a method…

Computation and Language · Computer Science 2016-12-19 Armand Joulin , Edouard Grave , Piotr Bojanowski , Matthijs Douze , Hérve Jégou , Tomas Mikolov

Given a dynamic set $K$ of $k$ strings of total length $n$ whose characters are drawn from an alphabet of size $\sigma$, a keyword dictionary is a data structure built on $K$ that provides locate, prefix search, and update operations on…

Data Structures and Algorithms · Computer Science 2020-10-08 Kazuya Tsuruta , Dominik Köppl , Shunsuke Kanda , Yuto Nakashima , Shunsuke Inenaga , Hideo Bannai , Masayuki Takeda

The well-known dictionary-based algorithms of the Lempel-Ziv (LZ) 77 family are the basis of several universal lossless compression techniques. These algorithms are asymmetric regarding encoding/decoding time and memory requirements, with…

Data Structures and Algorithms · Computer Science 2009-12-31 Artur Ferreira , Arlindo Oliveira , Mario Figueiredo

Indexing very large collections of strings, such as those produced by the widespread next generation sequencing technologies, heavily relies on multistring generalization of the Burrows-Wheeler Transform (BWT): large requirements of…

Data Structures and Algorithms · Computer Science 2020-12-07 Paola Bonizzoni , Gianluca Della Vedova , Yuri Pirola , Marco Previtali , Raffaella Rizzi