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Lempel-Ziv (LZ77 or, briefly, LZ) is one of the most effective and widely-used compressors for repetitive texts. However, the existing efficient methods computing the exact LZ parsing have to use linear or close to linear space to index the…

Data Structures and Algorithms · Computer Science 2020-05-12 Dmitry Kosolobov , Daniel Valenzuela , Gonzalo Navarro , Simon J. Puglisi

For decades, computing the LZ factorization (or LZ77 parsing) of a string has been a requisite and computationally intensive step in many diverse applications, including text indexing and data compression. Many algorithms for LZ77 parsing…

Data Structures and Algorithms · Computer Science 2020-12-11 Juha Kärkkäinen , Dominik Kempa , Simon J. Puglisi

The paper proposes an improved error-resilient Lempel-Ziv'77 (LZ'77) algorithm employing an adaptive amount of parity bits for error protection. It is a modified version of error resilient algorithm LZRS'77, proposed recently, which uses a…

Information Theory · Computer Science 2008-04-21 Tomaz Korosec , Saso Tomazic

We consider the problem of {\em restructuring} compressed texts without explicit decompression. We present algorithms which allow conversions from compressed representations of a string $T$ produced by any grammar-based compression…

Data Structures and Algorithms · Computer Science 2011-07-15 Keisuke Goto , Shirou Maruyama , Shunsuke Inenaga , Hideo Bannai , Hiroshi Sakamoto , Masayuki Takeda

The Lempel-Ziv 77 (LZ77) factorization is a fundamental compression scheme widely used in text processing and data compression. In this work, we investigate the time complexity of maintaining the LZ77 factorization of a dynamic string. By…

Data Structures and Algorithms · Computer Science 2025-10-28 Itai Boneh , Shay Golan , Matan Kraus

We extend Ziv and Lempel's model of finite-state encoders to the realm of lossy compression of individual sequences. In particular, the model of the encoder includes a finite-state reconstruction codebook followed by an information lossless…

Information Theory · Computer Science 2024-01-04 Neri Merhav

The compression-complexity trade-off of lossy compression algorithms that are based on a random codebook or a random database is examined. Motivated, in part, by recent results of Gupta-Verd\'{u}-Weissman (GVW) and their underlying…

Information Theory · Computer Science 2009-04-23 Chris Gioran , Ioannis Kontoyiannis

In this report, we investigate the potential use of large language models (LLM's) in the task of data compression. Previous works have demonstrated promising results in applying LLM's towards compressing not only text, but also a wide range…

Computation and Language · Computer Science 2026-01-07 Chen-Han Tsai

We present a simple adaptation of the Lempel Ziv 78' (LZ78) compression scheme ({\em IEEE Transactions on Information Theory, 1978}) that supports efficient random access to the input string. Namely, given query access to the compressed…

Data Structures and Algorithms · Computer Science 2013-01-14 Akashnil Dutta , Reut Levi , Dana Ron , Ronitt Rubinfeld

Data used for analytics and machine learning often take the form of tables with categorical entries. We introduce a family of lossless compression algorithms for such data that proceed in four steps: $(i)$ Estimate latent variables…

Information Theory · Computer Science 2023-02-21 Andrea Montanari , Eric Weiner

We introduce the first self-index based on the Lempel-Ziv 1977 compression format (LZ77). It is particularly competitive for highly repetitive text collections such as sequence databases of genomes of related species, software repositories,…

Data Structures and Algorithms · Computer Science 2011-01-24 Sebastian Kreft , Gonzalo Navarro

The advent of massive datasets (and the consequent design of high-performing distributed storage systems) have reignited the interest of the scientific and engineering community towards the design of lossless data compressors which achieve…

Information Theory · Computer Science 2013-07-16 Andrea Farruggia , Paolo Ferragina , Antonio Frangioni , Rossano Venturini

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

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

Bidirectional compression algorithms work by substituting repeated substrings by references that, unlike in the famous LZ77-scheme, can point to either direction. We present such an algorithm that is particularly suited for an external…

Data Structures and Algorithms · Computer Science 2019-12-04 Patrick Dinklage , Jonas Ellert , Johannes Fischer , Dominik Köppl , Manuel Penschuck

As large language models (LLMs) continue to be deployed and utilized across domains, the volume of LLM-generated data is growing rapidly. This trend highlights the increasing importance of effective and lossless compression for such data in…

Machine Learning · Computer Science 2025-05-13 Yu Mao , Holger Pirk , Chun Jason Xue

We propose algorithms computing the semi-greedy Lempel-Ziv 78 (LZ78), the Lempel-Ziv Double (LZD), and the Lempel-Ziv-Miller-Wegman (LZMW) factorizations in linear time for integer alphabets. For LZD and LZMW, we additionally propose data…

Data Structures and Algorithms · Computer Science 2024-09-24 Dominik Köppl

As the demand for digital information grows in fields like medicine, remote sensing, and archival, efficient image compression becomes crucial. This paper focuses on lossless image compression, vital for managing the increasing volume of…

Information Theory · Computer Science 2024-05-01 Rustam Mamedov

We consider lossless compression based on statistical data modeling followed by prediction-based encoding, where an accurate statistical model for the input data leads to substantial improvements in compression. We propose DZip, a…

Machine Learning · Computer Science 2020-09-21 Mohit Goyal , Kedar Tatwawadi , Shubham Chandak , Idoia Ochoa

We present an algorithm that constructs the LZ-End parsing (a variation of LZ77) of a given string of length $n$ in $O(n\log\ell)$ expected time and $O(z + \ell)$ space, where $z$ is the number of phrases in the parsing and $\ell$ is the…

Data Structures and Algorithms · Computer Science 2020-12-15 Dominik Kempa , Dmitry Kosolobov