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Random access to highly compressed strings -- represented by straight-line programs or Lempel-Ziv parses, for example -- is a well-studied topic. Random access to such strings in strongly sublogarithmic time is impossible in the worst case,…

Data Structures and Algorithms · Computer Science 2026-02-05 Ferdinando Cicalese , Zsuzsanna Lipták , Travis Gagie , Gonzalo Navarro , Nicola Prezza , Cristian Urbina

Order-preserving pattern matching was introduced recently but it has already attracted much attention. Given a reference sequence and a pattern, we want to locate all substrings of the reference sequence whose elements have the same…

Data Structures and Algorithms · Computer Science 2018-12-11 Gianni Decaroli , Travis Gagie , Giovanni Manzini

We develop a family of techniques to align word embeddings which are derived from different source datasets or created using different mechanisms (e.g., GloVe or word2vec). Our methods are simple and have a closed form to optimally rotate,…

Computation and Language · Computer Science 2020-11-19 Sunipa Dev , Safia Hassan , Jeff M. Phillips

The paper introduces a new lossless, highly robust compression algorithm that similar with LZW algorithm, yet the algorithm discards dictionary processing and uses irregular sequences with massive, random information instead. Then the paper…

Signal Processing · Electrical Eng. & Systems 2020-06-24 Rui Zhu

Constrained codes are used to prevent errors from occurring in various data storage and data transmission systems. They can help in increasing the storage density of magnetic storage devices, in managing the lifetime of electronic storage…

Information Theory · Computer Science 2022-09-07 Ahmed Hareedy , Beyza Dabak , Robert Calderbank

Information Retrieval (IR) methods aim to identify documents relevant to a query, which have been widely applied in various natural language tasks. However, existing approaches typically consider only the textual content within documents,…

Computation and Language · Computer Science 2026-01-26 Jaewoo Lee , Joonho Ko , Jinheon Baek , Soyeong Jeong , Sung Ju Hwang

As large language models increasingly gain popularity in real-world applications, processing extremely long contexts, often exceeding the model's pre-trained context limits, has emerged as a critical challenge. While existing approaches to…

Repository-level code intelligence tasks require large language models (LLMs) to process long, multi-file contexts. Such inputs introduce three challenges: crucial context can be obscured by noise, truncated due to limited windows, and…

Software Engineering · Computer Science 2026-04-16 Jia Feng , Zhanyue Qin , Cuiyun Gao , Ruiqi Wang , Chaozheng Wang , Yingwei Ma , Xiaoyuan Xie

Indexed languages are a classical notion in formal language theory, which has attracted attention in recent decades due to its role in higher-order model checking: They are precisely the languages accepted by order-2 pushdown automata. The…

Formal Languages and Automata Theory · Computer Science 2026-05-28 Richard Mandel , Corto Mascle , Georg Zetzsche

Iterative hybrid projection methods have proven to be very effective for solving large linear inverse problems due to their inherent regularizing properties as well as the added flexibility to select regularization parameters adaptively. In…

Numerical Analysis · Mathematics 2020-07-02 Julianne Chung , Eric de Sturler , Jiahua Jiang

Suffix trees are one of the most versatile data structures in stringology, with many applications in bioinformatics. Their main drawback is their size, which can be tens of times larger than the input sequence. Much effort has been put into…

Data Structures and Algorithms · Computer Science 2017-12-18 Andrea Farruggia , Travis Gagie , Gonzalo Navarro , Simon J. Puglisi , Jouni Sirén

The Lempel--Ziv 78 (LZ78) factorization is a well-studied technique for data compression. It and its derivatives are used in compression formats such as "compress" or "gif". Although most research focuses on the factorization of plain data,…

Data Structures and Algorithms · Computer Science 2025-12-22 Hiroki Shibata , Dominik Köppl

We consider universal variable-to-fixed length compression of memoryless sources with a fidelity criterion. We design a dictionary codebook over the reproduction alphabet which is used to parse the source stream. Once a source subsequence…

Information Theory · Computer Science 2022-11-24 Nematollah Iri

Learned indices using neural networks have been shown to outperform traditional indices such as B-trees in both query time and memory. However, learning the distribution of a large dataset can be expensive, and updating learned indices is…

Databases · Computer Science 2021-02-19 Guanli Liu , Lars Kulik , Xingjun Ma , Jianzhong Qi

Ranked document retrieval is a fundamental task in search engines. Such queries are solved with inverted indexes that require additional 45%-80% of the compressed text space, and take tens to hundreds of microseconds per query. In this…

Information Retrieval · Computer Science 2015-03-20 Nieves R. Brisaboa , Ana Cerdeira-Pena , Gonzalo Navarro , Oscar Pedreira

In a distributed information application an encoder compresses an arbitrary vector while a similar reference vector is available to the decoder as side information. For the Hamming-distance similarity measure, and when guaranteed perfect…

Information Theory · Computer Science 2020-09-08 Yuval Cassuto , Jacob Ziv

The ubiquitous Variable-Byte encoding is one of the fastest compressed representation for integer sequences. However, its compression ratio is usually not competitive with other more sophisticated encoders, especially when the integers to…

Information Retrieval · Computer Science 2022-02-08 Giulio Ermanno Pibiri , Rossano Venturini

The rise of large language models (LLMs) is revolutionizing information retrieval, question answering, summarization, and code generation tasks. However, in addition to confidently presenting factually inaccurate information at times (known…

Artificial Intelligence · Computer Science 2023-04-26 Henry Gilbert , Michael Sandborn , Douglas C. Schmidt , Jesse Spencer-Smith , Jules White

One of the most famous and investigated lossless data-compression scheme is the one introduced by Lempel and Ziv about 40 years ago. This compression scheme is known as "dictionary-based compression" and consists of squeezing an input…

Data Structures and Algorithms · Computer Science 2008-02-07 Paolo Ferragina , Igor Nitto , Rossano Venturini

Compressed bitmap indexes are used in databases and search engines. Many bitmap compression techniques have been proposed, almost all relying primarily on run-length encoding (RLE). However, on unsorted data, we can get superior performance…

Databases · Computer Science 2018-03-05 Daniel Lemire , Gregory Ssi-Yan-Kai , Owen Kaser