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LIPIcs, Volume 371
24th International Symposium on Experimental Algorithms (SEA 2026)
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Leibniz International Proceedings in Informatics (LIPIcs)
Conference: International Symposium on Experimental Algorithms (SEA)
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- published at: 2026-06-15
- Publisher: Schloss Dagstuhl – Leibniz-Zentrum für Informatik
- ISBN: 978-3-95977-422-2
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Complete Volume
LIPIcs, Volume 371, SEA 2026, Complete Volume
Abstract
LIPIcs, Volume 371, SEA 2026, Complete Volume
Cite as
24th International Symposium on Experimental Algorithms (SEA 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 371, pp. 1-548, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)
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@Proceedings{aumuller_et_al:LIPIcs.SEA.2026,
title = {{LIPIcs, Volume 371, SEA 2026, Complete Volume}},
booktitle = {24th International Symposium on Experimental Algorithms (SEA 2026)},
pages = {1--548},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-422-2},
ISSN = {1868-8969},
year = {2026},
volume = {371},
editor = {Aum\"{u}ller, Martin and Finocchi, Irene},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2026},
URN = {urn:nbn:de:0030-drops-262680},
doi = {10.4230/LIPIcs.SEA.2026},
annote = {Keywords: LIPIcs, Volume 371, SEA 2026, Complete Volume}
}
Document
Front Matter
Front Matter, Table of Contents, Preface, Conference Organization
Abstract
Front Matter, Table of Contents, Preface, Conference Organization
Cite as
24th International Symposium on Experimental Algorithms (SEA 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 371, pp. 0:i-0:xvi, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)
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@InProceedings{aumuller_et_al:LIPIcs.SEA.2026.0,
author = {Aum\"{u}ller, Martin and Finocchi, Irene},
title = {{Front Matter, Table of Contents, Preface, Conference Organization}},
booktitle = {24th International Symposium on Experimental Algorithms (SEA 2026)},
pages = {0:i--0:xvi},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-422-2},
ISSN = {1868-8969},
year = {2026},
volume = {371},
editor = {Aum\"{u}ller, Martin and Finocchi, Irene},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2026.0},
URN = {urn:nbn:de:0030-drops-262673},
doi = {10.4230/LIPIcs.SEA.2026.0},
annote = {Keywords: Front Matter, Table of Contents, Preface, Conference Organization}
}
Document
Global Polyline Simplification Under the Fréchet Distance: Theory and Practice
Abstract
Given an input polyline with n vertices, the global polyline simplification problem seeks a simplified polyline with the minimum number of vertices whose distance to the original polyline does not exceed a given bound. For the vertex-restricted variant, where the simplified polyline is required to be a subsequence of the input vertices, an algorithm with a running time of 𝒪(n³) was presented in previous work, using the Fréchet distance as the polyline similarity measure. A closely related variant is the local polyline simplification problem, in which the distance bound is required to hold for every individual shortcut segment replacing a sub-polyline. This condition implies that any locally valid simplification is also globally valid, whereas the converse does not hold. As a consequence, globally optimal simplifications may use substantially fewer vertices than locally optimal ones. Indeed, in previous work, instances were constructed in which the optimal global simplification is smaller by a constant factor. On the algorithmic side, optimal local simplifications can be computed significantly faster, namely in 𝒪(n² log n) under the Fréchet distance, and efficient heuristics are also available. This raises the question of which problem variant is more suitable for practical application.
In this paper, we first show that there exist instances for which the optimal solution sizes of global and local polyline simplification differ by a factor in Θ(n), substantially strengthening the previously known constant-factor separation. We then present the first practical implementations of existing algorithms for global polyline simplification and experimentally evaluate their performance. To this end, we introduce several engineering techniques that considerably accelerate these algorithms. Moreover, we develop an implicit Fréchet framework that allows many Fréchet-related problems to be addressed in a weaker computational model. Within this framework, explicit geometric computations can be reduced to simple comparisons, resulting in significantly more robust implementations. Somewhat surprisingly, our experimental results reveal that, despite the large worst-case gap established by our theoretical result, the difference in solution size between optimal global and local simplifications is negligible in practice. Motivated by this observation, we propose a heuristic for global polyline simplification that is guaranteed to produce solutions of size equal to or smaller than the optimal local simplification. On a benchmark consisting of one million polylines, the heuristic yields suboptimal results on only eight while being significantly faster than the optimal algorithms.
Cite as
Christian Abdullahad and Sabine Storandt. Global Polyline Simplification Under the Fréchet Distance: Theory and Practice. In 24th International Symposium on Experimental Algorithms (SEA 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 371, pp. 1:1-1:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)
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@InProceedings{abdullahad_et_al:LIPIcs.SEA.2026.1,
author = {Abdullahad, Christian and Storandt, Sabine},
title = {{Global Polyline Simplification Under the Fr\'{e}chet Distance: Theory and Practice}},
booktitle = {24th International Symposium on Experimental Algorithms (SEA 2026)},
pages = {1:1--1:20},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-422-2},
ISSN = {1868-8969},
year = {2026},
volume = {371},
editor = {Aum\"{u}ller, Martin and Finocchi, Irene},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2026.1},
URN = {urn:nbn:de:0030-drops-260055},
doi = {10.4230/LIPIcs.SEA.2026.1},
annote = {Keywords: Polyline Simplification, Shortcut Graph, Fr\'{e}chet Distance}
}
Document
Different Scales of Randomness: Empirical Mixing Times of the Edge Switching and Curveball MCMC
Abstract
The Fixed Degree Sequence Model (FDSM) asks for a uniform sample from the set of all simple graphs that match a prescribed degree sequence. It is typically implemented using Markov-Chain Monte-Carlo (MCMC) processes, such as Edge Switching or Curveball (and their variants). Yet despite decades of research, rigorous bounds on the mixing times of such processes remain impractical.
Consequently, several experimental techniques have been used to derive "empirical lower bounds" on the mixing time. We address the following research questions: (1) Which commonly studied graph-theoretic properties serve as reliable empirical predictors for mixing of FDSM MCMC processes? (2) At what structural scales do these properties operate primarily (i. e., are they predominantly local or global in nature)? (3) How can these properties be characterised and quantified most effectively?
To this end, we propose Claim, a novel systematic method to establish empirical lower bounds using learnt classifiers, and compare it to existing methods. Apart from interesting insights into the usage of machine learning for this problem, we also derive robust graph properties with respect to different randomisation algorithms. Although experimental in nature, these results may influence both theorist’s and algorithm engineer’s work on improved bounds and better algorithm respectively.
Cite as
Deepak Ajwani, Melvin Kallmayer, Alexander Leonhardt, Ulrich Meyer, Ryan O'Connor, and Manuel Penschuck. Different Scales of Randomness: Empirical Mixing Times of the Edge Switching and Curveball MCMC. In 24th International Symposium on Experimental Algorithms (SEA 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 371, pp. 2:1-2:19, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)
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@InProceedings{ajwani_et_al:LIPIcs.SEA.2026.2,
author = {Ajwani, Deepak and Kallmayer, Melvin and Leonhardt, Alexander and Meyer, Ulrich and O'Connor, Ryan and Penschuck, Manuel},
title = {{Different Scales of Randomness: Empirical Mixing Times of the Edge Switching and Curveball MCMC}},
booktitle = {24th International Symposium on Experimental Algorithms (SEA 2026)},
pages = {2:1--2:19},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-422-2},
ISSN = {1868-8969},
year = {2026},
volume = {371},
editor = {Aum\"{u}ller, Martin and Finocchi, Irene},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2026.2},
URN = {urn:nbn:de:0030-drops-260062},
doi = {10.4230/LIPIcs.SEA.2026.2},
annote = {Keywords: Mixing Time, Graph Randomization, Machine Learning, Edge Switching}
}
Document
Approximation Algorithms for Budget Splitting in Multi-Channel Influence Maximization
Abstract
How to utilize an allocated budget effectively for branding and promotion of a commercial house is an important problem, particularly when multiple advertising media are available. There exist multiple such media, and among them, two popular ones are billboards and social media advertisements. In this context, the question naturally arises: how should a budget be allocated to maximize total influence? Although there is significant literature on the effective use of budgets in individual advertising media, there are hardly any studies examining budget allocation across multiple advertising media. To bridge this gap, this paper introduces the Budget Splitting Problem in Billboard and Social Network Advertisement. We introduce the notion of interaction effect to capture the additional influence due to triggers from multiple media of advertising. Using this notion, we propose a noble influence function Φ(,) that captures the total influence and shows that this function is non-negative, monotone, and non-bisubmodular. We introduce bi-submodularity ratio (γ) and generalized curvature (α) to measure how close a function is to being bi-submodular and how far a function is from being modular, respectively. We propose the Randomized Greedy and Two-Phase Adaptive Greedy approach, where the influence function is non-bisubmodular and achieves an approximation guarantee of (1/α)(1-e^(-γα)). We conducted several experiments using real-world datasets and observed that the proposed solution approach’s budget splitting leads to a greater influence than existing approaches.
Cite as
Dildar Ali, Ansh Jasrotia, Abishek Salaria, and Suman Banerjee. Approximation Algorithms for Budget Splitting in Multi-Channel Influence Maximization. In 24th International Symposium on Experimental Algorithms (SEA 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 371, pp. 3:1-3:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)
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@InProceedings{ali_et_al:LIPIcs.SEA.2026.3,
author = {Ali, Dildar and Jasrotia, Ansh and Salaria, Abishek and Banerjee, Suman},
title = {{Approximation Algorithms for Budget Splitting in Multi-Channel Influence Maximization}},
booktitle = {24th International Symposium on Experimental Algorithms (SEA 2026)},
pages = {3:1--3:20},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-422-2},
ISSN = {1868-8969},
year = {2026},
volume = {371},
editor = {Aum\"{u}ller, Martin and Finocchi, Irene},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2026.3},
URN = {urn:nbn:de:0030-drops-260070},
doi = {10.4230/LIPIcs.SEA.2026.3},
annote = {Keywords: Advertisement, Billboard, Social Network, Bi-submodularity, Influence Maximization}
}
Document
Integer Programming Models for the Median of a 0-1 String Set Under Levenshtein Distance
Abstract
The Median String Problem calls for finding a string that minimizes the average distance from a given set of strings. Under the Levenshtein (or edit) metric, the problem is NP-hard even for binary strings. We devised two novel integer linear programming models for this case and tested them against the only formulation we are aware of in the literature. Our numerical experiments attest to the efficacy of the proposed approach.
Cite as
Claudio Arbib, Andrea D'Ascenzo, Oya E. Karaşan, and Andrea Pizzuti. Integer Programming Models for the Median of a 0-1 String Set Under Levenshtein Distance. In 24th International Symposium on Experimental Algorithms (SEA 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 371, pp. 4:1-4:15, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)
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@InProceedings{arbib_et_al:LIPIcs.SEA.2026.4,
author = {Arbib, Claudio and D'Ascenzo, Andrea and Kara\c{s}an, Oya E. and Pizzuti, Andrea},
title = {{Integer Programming Models for the Median of a 0-1 String Set Under Levenshtein Distance}},
booktitle = {24th International Symposium on Experimental Algorithms (SEA 2026)},
pages = {4:1--4:15},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-422-2},
ISSN = {1868-8969},
year = {2026},
volume = {371},
editor = {Aum\"{u}ller, Martin and Finocchi, Irene},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2026.4},
URN = {urn:nbn:de:0030-drops-260081},
doi = {10.4230/LIPIcs.SEA.2026.4},
annote = {Keywords: Levenshtein Distance, Median String Problem, Integer Programming}
}
Document
BuffCut: Prioritized Buffered Streaming Graph Partitioning
Abstract
Streaming graph partitioners enable resource-efficient and massively scalable partitioning, but one-pass assignment heuristics are highly sensitive to stream order and often yield substantially higher edge cuts than in-memory methods. We present BuffCut, a buffered streaming partitioner that narrows this quality gap, particularly when stream ordering is adversarial, by combining prioritized buffering with batch-wise multilevel assignment. BuffCut maintains a bounded priority buffer to delay poorly informed decisions and regulate the order in which nodes are considered for assignment. It incrementally constructs high-locality batches of configurable size by iteratively inserting the highest-priority nodes from the buffer into the batch, effectively recovering locality structure from the stream. Each batch is then assigned via a multilevel partitioning algorithm. Experiments on diverse real-world and synthetic graphs show that BuffCut consistently outperforms state-of-the-art buffered streaming methods. Compared to the strongest prioritized buffering baseline, BuffCut achieves 20.8% fewer edge cuts while running 2.9× faster and using 11.3× less memory. Against the next-best batched method, it reduces edge cut by 15.8% with only modest overheads of 1.8× runtime and 1.09× memory.
Cite as
Linus Baumgärtner, Adil Chhabra, Marcelo Fonseca Faraj, and Christian Schulz. BuffCut: Prioritized Buffered Streaming Graph Partitioning. In 24th International Symposium on Experimental Algorithms (SEA 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 371, pp. 5:1-5:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)
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@InProceedings{baumgartner_et_al:LIPIcs.SEA.2026.5,
author = {Baumg\"{a}rtner, Linus and Chhabra, Adil and Faraj, Marcelo Fonseca and Schulz, Christian},
title = {{BuffCut: Prioritized Buffered Streaming Graph Partitioning}},
booktitle = {24th International Symposium on Experimental Algorithms (SEA 2026)},
pages = {5:1--5:20},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-422-2},
ISSN = {1868-8969},
year = {2026},
volume = {371},
editor = {Aum\"{u}ller, Martin and Finocchi, Irene},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2026.5},
URN = {urn:nbn:de:0030-drops-260097},
doi = {10.4230/LIPIcs.SEA.2026.5},
annote = {Keywords: graph partitioning, streaming, online, buffered, prioritized partitioning}
}
Document
A Practical Algorithm for (Geometry-Aware) Interleavings Between Merge Trees
Abstract
Merge trees are a popular topological descriptor for scalar field data. A common measure to compare two merge trees is the interleaving distance, which relies on a mapping between the two merge trees, also referred to as an interleaving. Despite its desirable properties, the interleaving distance has not been used much in practice, largely due to the fact that computing the exact interleaving distance is NP-hard. In this paper, we show that the exact interleaving distance can be computed efficiently for merge trees encountered in practice: we present the first implementation of the exact fixed-parameter tractable (FPT) algorithm by Touli and Wang [Touli and Wang, 2022]. This algorithm uses a dynamic program to test if a specific interleaving distance δ is feasible. They bound the running time using a parameter τ that captures the number of mapping options between the two merge trees for the output distance δ. Our experiments show that, even though τ can become quite large for real-world merge trees, the running time of our implementation does not depend very heavily on τ. Furthermore, we modify the FPT algorithm into a sweepline algorithm that runs much faster in practice. Finally, we introduce a natural restriction for the interleaving distance capturing the geometric similarity between the underlying scalar fields. This restricted interleaving distance can be computed more efficiently and can, in some settings, also result in more meaningful interleavings. We extend our implementations to support these restrictions and demonstrate their effect on the running time of the algorithms.
Cite as
Thijs Beurskens, Emil Toftegaard Gæde, Tim Ophelders, Willem Sonke, Bettina Speckmann, and Kevin Verbeek. A Practical Algorithm for (Geometry-Aware) Interleavings Between Merge Trees. In 24th International Symposium on Experimental Algorithms (SEA 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 371, pp. 6:1-6:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)
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@InProceedings{beurskens_et_al:LIPIcs.SEA.2026.6,
author = {Beurskens, Thijs and G{\ae}de, Emil Toftegaard and Ophelders, Tim and Sonke, Willem and Speckmann, Bettina and Verbeek, Kevin},
title = {{A Practical Algorithm for (Geometry-Aware) Interleavings Between Merge Trees}},
booktitle = {24th International Symposium on Experimental Algorithms (SEA 2026)},
pages = {6:1--6:18},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-422-2},
ISSN = {1868-8969},
year = {2026},
volume = {371},
editor = {Aum\"{u}ller, Martin and Finocchi, Irene},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2026.6},
URN = {urn:nbn:de:0030-drops-260100},
doi = {10.4230/LIPIcs.SEA.2026.6},
annote = {Keywords: interleaving distance, geometry-aware, exact algorithm, implementation}
}
Document
From Relative Compression to Hierarchical Compression
Abstract
We introduce a framework to use any relative compression algorithm as a subroutine for hierarchical relative compression. In a dataset consisting of n sequences, it consists of constructing a rooted tree on the sequences, using hashing and similarity techniques, and compressing the children of a node relative to their parent. We build up on previous techniques [Bille et al., 2023], and optimize them further for computational efficiency. We test our framework with three existing relative compression algorithms on six genomic datasets, and we show that in datasets that contain heterogeneous data, hierarchical relative compression improves the compression ratio by a factor 2 or more, when compared to relative compression to a single sequence. Apart from compression ratio, we also explore the trade-offs with respect to compression speed, dataset decompression speed, and average sequence decompression speed. With two of the surveyed algorithms, dataset decompression becomes faster and sequence decompression remains practical, at the cost of compression time, which remains competitive for the datasets with highest variability.
Cite as
Philip Bille, Inge Li Gørtz, and Máximo Pérez-López. From Relative Compression to Hierarchical Compression. In 24th International Symposium on Experimental Algorithms (SEA 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 371, pp. 7:1-7:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)
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@InProceedings{bille_et_al:LIPIcs.SEA.2026.7,
author = {Bille, Philip and G{\o}rtz, Inge Li and P\'{e}rez-L\'{o}pez, M\'{a}ximo},
title = {{From Relative Compression to Hierarchical Compression}},
booktitle = {24th International Symposium on Experimental Algorithms (SEA 2026)},
pages = {7:1--7:18},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-422-2},
ISSN = {1868-8969},
year = {2026},
volume = {371},
editor = {Aum\"{u}ller, Martin and Finocchi, Irene},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2026.7},
URN = {urn:nbn:de:0030-drops-260117},
doi = {10.4230/LIPIcs.SEA.2026.7},
annote = {Keywords: Relative compression, RLZ, string collections, compressed representation, data structures, efficient algorithms}
}
Document
General Multiplicative Spanners in Practice
Abstract
Given an undirected graph G with edge weights and lengths, a minimum α-spanner is a least-weight subgraph H ⊆ G that preserves distances w.r.t. the lengths between all node pairs up to a factor of α. Literature often takes the simplifying assumption of a single (coupled) edge function for weights and lengths. For such instances, several exact and non-exact algorithms are known and have been thoroughly evaluated in practice. However, many practical instances have decoupled form, as their weights and lengths are generally independent. Due to the increased complexity, only few (and even fewer practical) algorithms are able to guarantee low-weight solutions. This prompts practitioners to force their naturally decoupled instances into a coupled format, forsaking any quality guarantee.
We implement several exact, approximative and heuristic algorithms for decoupled α-spanners, and use algorithm engineering to speed them up in practice. Our hypothesis-driven experiments evaluate their performance w.r.t. solution quality and speed. Generally, many practical instances can indeed be solved exactly within reasonable time, while LP-based approximation algorithms are not worthwhile. We find that standard greedy algorithms often yield acceptable results, but there are also practical instances for which they yield arbitrarily poor solutions. Here, augmented greedy variations offer a good compromise between solution quality and speed.
Cite as
Fritz Bökler, Markus Chimani, and Henning Jasper. General Multiplicative Spanners in Practice. In 24th International Symposium on Experimental Algorithms (SEA 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 371, pp. 8:1-8:21, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)
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@InProceedings{bokler_et_al:LIPIcs.SEA.2026.8,
author = {B\"{o}kler, Fritz and Chimani, Markus and Jasper, Henning},
title = {{General Multiplicative Spanners in Practice}},
booktitle = {24th International Symposium on Experimental Algorithms (SEA 2026)},
pages = {8:1--8:21},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-422-2},
ISSN = {1868-8969},
year = {2026},
volume = {371},
editor = {Aum\"{u}ller, Martin and Finocchi, Irene},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2026.8},
URN = {urn:nbn:de:0030-drops-260120},
doi = {10.4230/LIPIcs.SEA.2026.8},
annote = {Keywords: Graph spanners, ILP, experimental study, algorithm engineering}
}
Document
Bounding the Average Move Structure Query for Faster and Smaller RLBWT Permutations
Abstract
The move structure represents permutations with long contiguously permuted intervals in compressed space with optimal query time. They have become an important feature of compressed text indexes using space proportional to the number of Burrows-Wheeler Transform (BWT) runs, often applied in genomics. This is in thanks not only to theoretical improvements over past approaches, but great cache efficiency and average case query time in practice. This is true even without using the worst case guarantees provided by the interval splitting balancing of the original result. In this paper, we show that an even simpler type of splitting, length capping by truncating long intervals, bounds the average move structure query time to optimal whilst obtaining a superior construction time than the traditional approach. This also proves constant query time when amortized over a full traversal of a single cycle permutation from an arbitrary starting position.
Such a scheme has surprising benefits both in theory and practice. For a move structure with r runs over a domain n, we replace all O(r log n)-bit components to reduce the overall representation by O(r log r)-bits. The worst case query time is also improved to O(log n/r) without balancing. An O(r)-time and space construction lets us apply the method to run-length encoded BWT (RLBWT) permutations such as LF and ϕ to obtain optimal-time algorithms for BWT inversion and suffix array (SA) enumeration in O(r) working space. Finally, we introduce the Orbit library, providing flexible plug and play move structure support, and use it to evaluate our splitting approach. Experiments find length capping construction is faster and uses less memory than balancing, and results in faster move structure queries: up to ∼ 17 times faster when compared to an unbalanced representation of ϕ. We also see a space reduction in practice, with at least a ∼ 40% disk size decrease for LF across large repetitive genomic collections when compared to a balanced/unbalanced move structure.
Cite as
Nathaniel K. Brown and Ben Langmead. Bounding the Average Move Structure Query for Faster and Smaller RLBWT Permutations. In 24th International Symposium on Experimental Algorithms (SEA 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 371, pp. 9:1-9:15, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)
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@InProceedings{brown_et_al:LIPIcs.SEA.2026.9,
author = {Brown, Nathaniel K. and Langmead, Ben},
title = {{Bounding the Average Move Structure Query for Faster and Smaller RLBWT Permutations}},
booktitle = {24th International Symposium on Experimental Algorithms (SEA 2026)},
pages = {9:1--9:15},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-422-2},
ISSN = {1868-8969},
year = {2026},
volume = {371},
editor = {Aum\"{u}ller, Martin and Finocchi, Irene},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2026.9},
URN = {urn:nbn:de:0030-drops-260136},
doi = {10.4230/LIPIcs.SEA.2026.9},
annote = {Keywords: Move Structure, Burrows-Wheeler Transform, Permutation}
}
Document
Compressing Highly Repetitive Binary Trees with an Application to Range Minimum Queries
Abstract
Tree compression is a well-studied area that aims at reducing the size of tree representations by exploiting different forms of repetition. While the underlying theory is well understood, there is still significant room for experimental investigation, particularly in the design of compressed representations that efficiently support navigational queries.
In this work, we address the problem of designing, engineering, and experimentally evaluating a compression technique for unlabeled binary trees based on repeated subtrees, yielding the minimal Directed Acyclic Graph (DAG) of the input tree. We show how this representation can be computed in linear time and space directly from a succinct encoding of the tree, and how it can be augmented with compact auxiliary data structures to support Lowest Common Ancestor (LCA) queries.
When the input tree is the Cartesian tree of an array, LCA queries can be used to answer Range Minimum Queries (RMQs) on the underlying array. This is particularly relevant in the encoding model, where the array is not accessible at query time, and a space lower bound of 2n-O(log n) bits is known. Given the numerous applications of RMQs, we use this problem as a case study for our experimental evaluation, testing our implementation on 11 real-world datasets. Our experiments show that, on almost every dataset, our implementation is the most space-efficient, using as few as 0.11n bits, while still delivering practical query times.
Cite as
Gabriel Carmona and Filippo Lari. Compressing Highly Repetitive Binary Trees with an Application to Range Minimum Queries. In 24th International Symposium on Experimental Algorithms (SEA 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 371, pp. 10:1-10:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)
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@InProceedings{carmona_et_al:LIPIcs.SEA.2026.10,
author = {Carmona, Gabriel and Lari, Filippo},
title = {{Compressing Highly Repetitive Binary Trees with an Application to Range Minimum Queries}},
booktitle = {24th International Symposium on Experimental Algorithms (SEA 2026)},
pages = {10:1--10:20},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-422-2},
ISSN = {1868-8969},
year = {2026},
volume = {371},
editor = {Aum\"{u}ller, Martin and Finocchi, Irene},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2026.10},
URN = {urn:nbn:de:0030-drops-260140},
doi = {10.4230/LIPIcs.SEA.2026.10},
annote = {Keywords: tree compression, range minimum query, compact data structures, algorithm engineering, experimental evaluation}
}
Document
Wavelet Forests Revisited
Abstract
Rank and select queries are basic operations on sequences, with applications in compressed text indexes and other space-efficient data structures. One of the standard data structures supporting these queries is the wavelet tree. In this paper, we study wavelet forests, that is, wavelet-tree structures based on the fixed-block compression boosting technique. Such structures partition the input sequence into fixed-size blocks and build a separate wavelet tree for each block. Previous work showed that this approach yields strong practical performance for rank queries.
We extend wavelet forests to support select queries. We show that select support can be added with little additional space overhead and that the resulting structures remain practically efficient. In experiments on a range of non-repetitive and repetitive inputs, wavelet forests are competitive with, and in most cases outperform, standalone wavelet-tree implementations. We also study the effect of internal parameters, including superblock size and navigational data, on select-query performance.
Cite as
Eric Chiu and Dominik Kempa. Wavelet Forests Revisited. In 24th International Symposium on Experimental Algorithms (SEA 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 371, pp. 11:1-11:11, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)
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@InProceedings{chiu_et_al:LIPIcs.SEA.2026.11,
author = {Chiu, Eric and Kempa, Dominik},
title = {{Wavelet Forests Revisited}},
booktitle = {24th International Symposium on Experimental Algorithms (SEA 2026)},
pages = {11:1--11:11},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-422-2},
ISSN = {1868-8969},
year = {2026},
volume = {371},
editor = {Aum\"{u}ller, Martin and Finocchi, Irene},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2026.11},
URN = {urn:nbn:de:0030-drops-260152},
doi = {10.4230/LIPIcs.SEA.2026.11},
annote = {Keywords: wavelet tree, wavelet forest, select queries}
}
Document
Fast Select Queries Using Hybrid Bitvectors
Abstract
One of the central problems in the design of compressed data structures is the efficient support for rank and select queries on bitvectors. These two operations form the backbone of more complex data structures used for the compact representation of texts, trees, graphs, or grids. One effective solution is the so-called hybrid bitvector implementation, which partitions the input bitvector into blocks and adaptively selects an encoding method - such as run-length, plain, or minority encoding - based on local redundancy. Experiments have shown that hybrid bitvectors achieve excellent all-around performance on repetitive and non-repetitive inputs. Current hybrid bitvector implementations, however, support only rank queries (i.e., counting the number of ones up to a given position) and lack support for select queries (which ask for the position of a given occurrence of a given bit), which limits their applicability. In this paper, we propose a method to add support for select queries to hybrid bitvectors, and we evaluate the resulting implementation on repetitive and non-repetitive inputs. Our results show that hybrid bitvectors offer very strong all-around performance, combining high query speed with space efficiency and remaining consistently on or near the Pareto frontier.
Cite as
Eric Chiu and Dominik Kempa. Fast Select Queries Using Hybrid Bitvectors. In 24th International Symposium on Experimental Algorithms (SEA 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 371, pp. 12:1-12:11, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)
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@InProceedings{chiu_et_al:LIPIcs.SEA.2026.12,
author = {Chiu, Eric and Kempa, Dominik},
title = {{Fast Select Queries Using Hybrid Bitvectors}},
booktitle = {24th International Symposium on Experimental Algorithms (SEA 2026)},
pages = {12:1--12:11},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-422-2},
ISSN = {1868-8969},
year = {2026},
volume = {371},
editor = {Aum\"{u}ller, Martin and Finocchi, Irene},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2026.12},
URN = {urn:nbn:de:0030-drops-260168},
doi = {10.4230/LIPIcs.SEA.2026.12},
annote = {Keywords: compressed bitvectors, hybrid bitvector, select queries}
}
Document
Practical Parallel Block Tree Construction
Abstract
The block tree [Belazzougui et al., J. Comput. Syst. Sci. '21] is a compressed representation of a length-n text that supports access, rank, and select queries while requiring only O(z log n/z) words of space, where z is the number of Lempel-Ziv factors of the text. In other words, its space requirements are asymptotically comparable to those of the compressed text itself. In practice, block trees offer query performance comparable to that of state-of-the-art compressed rank and select indices. However, their construction is significantly slower, and the fastest known construction algorithms additionally require a significant amount of working memory. To address these limitations, we propose fast and lightweight parallel algorithms for the efficient construction of block trees.
Our algorithm achieves similar construction speed than the currently fastest block tree construction algorithm on a single core and is up to eight times faster using 64 cores, while requiring an order of magnitude less memory. Overall, we achieve a speedup of up to 15.5 on 64 cores, which is in line with the parallel construction of the Lempel-Ziv compression.
Cite as
Robert Clausecker, Florian Kurpicz, and Etienne Palanga. Practical Parallel Block Tree Construction. In 24th International Symposium on Experimental Algorithms (SEA 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 371, pp. 13:1-13:19, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)
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@InProceedings{clausecker_et_al:LIPIcs.SEA.2026.13,
author = {Clausecker, Robert and Kurpicz, Florian and Palanga, Etienne},
title = {{Practical Parallel Block Tree Construction}},
booktitle = {24th International Symposium on Experimental Algorithms (SEA 2026)},
pages = {13:1--13:19},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-422-2},
ISSN = {1868-8969},
year = {2026},
volume = {371},
editor = {Aum\"{u}ller, Martin and Finocchi, Irene},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2026.13},
URN = {urn:nbn:de:0030-drops-260175},
doi = {10.4230/LIPIcs.SEA.2026.13},
annote = {Keywords: block tree, shared memory, compression, SIMD, Karp-Rabin fingerprints}
}
Document
K-Hole Separation in PEO‑Based ILP Treewidth Formulation
Abstract
In this paper, we introduce a family of valid inequalities for the strongest currently known integer programming formulation of treewidth based on perfect elimination orderings. These inequalities arise from the structure of induced chordless cycles (holes) and strengthen the canonical linear relaxation by enforcing constraints that every feasible chordal completion must satisfy. To handle the exponentially many such inequalities, we develop a dedicated separation routine capable of detecting violated k-hole constraints within a cutting-plane framework. Our computational results show that incorporating these inequalities substantially improves the quality of the lower bounds across a broad range of graph classes, in some cases nearly closing the integrality gap.
Cite as
Andrea D'Ascenzo. K-Hole Separation in PEO‑Based ILP Treewidth Formulation. In 24th International Symposium on Experimental Algorithms (SEA 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 371, pp. 14:1-14:14, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)
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@InProceedings{dascenzo:LIPIcs.SEA.2026.14,
author = {D'Ascenzo, Andrea},
title = {{K-Hole Separation in PEO‑Based ILP Treewidth Formulation}},
booktitle = {24th International Symposium on Experimental Algorithms (SEA 2026)},
pages = {14:1--14:14},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-422-2},
ISSN = {1868-8969},
year = {2026},
volume = {371},
editor = {Aum\"{u}ller, Martin and Finocchi, Irene},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2026.14},
URN = {urn:nbn:de:0030-drops-260186},
doi = {10.4230/LIPIcs.SEA.2026.14},
annote = {Keywords: Treewidth, Integer Linear Programming, Polyhedral Combinatorics, Chordal Completion, Induced Cycles}
}
Document
Computational Generation of Substrate-Specific Molecular Cages
Abstract
In this paper, we propose a method to build molecular cages designed to capture a specific substrate. We model a cage as a graph of atoms with coordinates in space, and several constraints on their edges (degree, length and angle). We use a simple method to place binding patterns which are able to interact with certain parts of the substrate. We then propose an algorithm which considers all possible ways of connecting these binding patterns and try to construct the smallest possible molecular paths realizing these connections. We investigate many variants of our method in order to obtain the most efficient algorithm, able to build cages of more than a hundred atoms.
Cite as
Noé Demange, Yann Strozecki, and Sandrine Vial. Computational Generation of Substrate-Specific Molecular Cages. In 24th International Symposium on Experimental Algorithms (SEA 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 371, pp. 15:1-15:21, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)
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@InProceedings{demange_et_al:LIPIcs.SEA.2026.15,
author = {Demange, No\'{e} and Strozecki, Yann and Vial, Sandrine},
title = {{Computational Generation of Substrate-Specific Molecular Cages}},
booktitle = {24th International Symposium on Experimental Algorithms (SEA 2026)},
pages = {15:1--15:21},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-422-2},
ISSN = {1868-8969},
year = {2026},
volume = {371},
editor = {Aum\"{u}ller, Martin and Finocchi, Irene},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2026.15},
URN = {urn:nbn:de:0030-drops-260191},
doi = {10.4230/LIPIcs.SEA.2026.15},
annote = {Keywords: Enumeration, Molecular Cage, Cheminformatics, Geometric Algorithms, Experimental Algorithms}
}
Document
Efficient Large-Scale Text Precompression via Approximate LZ77 Parsings
Abstract
The LZ77 [Lempel and Ziv, 1977] compression scheme is ubiquitous: it lies at the core of everyday general-purpose standard compressors such as gzip or zstd, but also behind the scenes of many applications such as the compression of payloads transmitted in networks.
Computing the exact LZ77 parsing is largely solved in theory: it can be done in sublinear time and space, in compressed space and in external memory, to name but some scenarios. However, these approaches are often impractical for everyday use due to their intensive time or space requirements. Standard compressors tackle this issue by introducing heuristics that go hand in hand with sophisticated encoding schemes to achieve very good compression fast and in small space, however, they only have a local view (e.g., a sliding window) on the input, potentially missing out on long-range repetitions that may be located far apart from one another.
In this work, we design and implement - in C++ and leveraging shared-memory parallelism - compression pipelines that first precompress the input using an approximate LZ77 parsing taking care of long-range repetitions. This then serves as an assist to standard compressors for producing a succinct encoding of the remaining short and local repetitions. Similar approaches have been considered by [Kosolobov et al., 2020] and [Nalbach, 2024], respectively using Relative Lempel Ziv [Kuruppu et al. 2010] or the string synchronizing set [Kempa & Kociumaka, 2019].
We fill a gap taking the route via the prefix-free parsing [Boucher et al., 2019], using an intermediate result of [Hong et al., 2023]. On large repetitive inputs of tens of gigabytes, our pipelines are orders of magnitudes faster than the state of the art for computing the exact LZ77 parsing, use space less than the input size and still - despite producing more phrases - achieve the best overall compression in comparison to related work.
Cite as
Patrick Dinklage. Efficient Large-Scale Text Precompression via Approximate LZ77 Parsings. In 24th International Symposium on Experimental Algorithms (SEA 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 371, pp. 16:1-16:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)
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@InProceedings{dinklage:LIPIcs.SEA.2026.16,
author = {Dinklage, Patrick},
title = {{Efficient Large-Scale Text Precompression via Approximate LZ77 Parsings}},
booktitle = {24th International Symposium on Experimental Algorithms (SEA 2026)},
pages = {16:1--16:20},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-422-2},
ISSN = {1868-8969},
year = {2026},
volume = {371},
editor = {Aum\"{u}ller, Martin and Finocchi, Irene},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2026.16},
URN = {urn:nbn:de:0030-drops-260204},
doi = {10.4230/LIPIcs.SEA.2026.16},
annote = {Keywords: compression, algorithm engineering, parallel computation}
}
Document
Adaptive Subproblem Selection in Benders Decomposition for Survivable Network Design Problems
Abstract
Scenario-based optimization problems can be solved via Benders decomposition, which separates first-stage (master problem) decisions from second-stage (subproblem) recourse actions and iteratively refines the master problem with Benders cuts. In conventional Benders decomposition, all subproblems are solved at each iteration. For problems with many scenarios, solving only a selected subset can reduce computation. We quantify the potential in selecting only those subproblems that yield cuts, and develop subproblem scoring and selection strategies. The proposed multi-criteria scoring methods combine historical subproblem performance metrics with problem-specific features, trained online via logistic regression to adapt to the changing likelihood of subproblem usefulness. Multiple stopping criteria balance exploration and exploitation: cut limits, proportional solve limits, and score thresholds. We evaluate our approach on a variant of the survivable network design problem, which serves as a testbed due to its natural decomposition into many subproblems of varying importance.
Computational experiments on 135 test instances demonstrate the potential and practical performance of subproblem selection. Analysis reveals that 52.1% of all subproblems solved are unnecessary (they contribute no cuts and occur outside cut-free rounds). An oracle with perfect foresight reduces total solve times by 34.4%. Random selection performs significantly worse than full enumeration, showing that naive strategies can degrade performance. Our best-scoring and selection method achieves statistically significant improvements in both runtime and primal-dual integrals. These results provide empirical evidence that informed subproblem selection can improve Benders decomposition in this setting, while highlighting challenges in developing reliable prediction models. Whether these findings extend to other problem classes remains an open question for future work.
Cite as
Tim Donkiewicz. Adaptive Subproblem Selection in Benders Decomposition for Survivable Network Design Problems. In 24th International Symposium on Experimental Algorithms (SEA 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 371, pp. 17:1-17:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)
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@InProceedings{donkiewicz:LIPIcs.SEA.2026.17,
author = {Donkiewicz, Tim},
title = {{Adaptive Subproblem Selection in Benders Decomposition for Survivable Network Design Problems}},
booktitle = {24th International Symposium on Experimental Algorithms (SEA 2026)},
pages = {17:1--17:20},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-422-2},
ISSN = {1868-8969},
year = {2026},
volume = {371},
editor = {Aum\"{u}ller, Martin and Finocchi, Irene},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2026.17},
URN = {urn:nbn:de:0030-drops-260219},
doi = {10.4230/LIPIcs.SEA.2026.17},
annote = {Keywords: Integer programming, Benders decomposition, subproblem selection, survivable network design, machine learning, operations research}
}
Document
DeltaSort: Incremental Sorting of Arrays with Known Updates
Abstract
When records need to be read in a particular order, sorting at query time incurs repeated Θ(n log n) cost for an array of n records and can become a bottleneck in read-heavy workloads. A common solution is to maintain a derived sorted read-replica that is kept updated as the underlying system-of-record changes. For updating read-replicas that are stored as arrays, existing approaches rely on either full re-sorting or incremental algorithms such as binary insertion or merge-based sort. In this paper, we study incremental sorting under a new model in which the sorting routine is explicitly informed of the k indices updated since the previous sort - a setting that naturally arises in systems that track updates. Under this model, we present DeltaSort, a new algorithm that runs in O(n√k) expected time using O(k) auxiliary space under a random update model, and outperforms existing algorithms for small update batches in our experimental evaluation.
Cite as
Shubham Dwivedi. DeltaSort: Incremental Sorting of Arrays with Known Updates. In 24th International Symposium on Experimental Algorithms (SEA 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 371, pp. 18:1-18:16, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)
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@InProceedings{dwivedi:LIPIcs.SEA.2026.18,
author = {Dwivedi, Shubham},
title = {{DeltaSort: Incremental Sorting of Arrays with Known Updates}},
booktitle = {24th International Symposium on Experimental Algorithms (SEA 2026)},
pages = {18:1--18:16},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-422-2},
ISSN = {1868-8969},
year = {2026},
volume = {371},
editor = {Aum\"{u}ller, Martin and Finocchi, Irene},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2026.18},
URN = {urn:nbn:de:0030-drops-260224},
doi = {10.4230/LIPIcs.SEA.2026.18},
annote = {Keywords: Incremental sorting, Sorting algorithms, Array maintenance}
}
Document
Breaking 2-Cores for Invertible Bloom Lookup Tables by Structure Prediction
Abstract
Invertible Bloom Lookup Tables (IBLTs) provide a highly space-efficient way to reconstruct small sets resulting from a large number of insertions and deletions of elements, such as in streaming or distributed computation of the symmetric difference of similar sets. The set recovery process succeeds if the IBLT size is at least 1.22 times the size of the encoded set; otherwise, a 2-core occurs with high probability in the corresponding random hypergraph. However, the sets in practice often exhibit structure that allows for performance beyond worst-case bounds.
Here, we demonstrate that structured sets - such as the k-mers in the symmetric difference of two closely related genomes - can be recovered with an IBLT of significantly smaller size. We achieve this by employing structure-aware predictors to break the 2-core whenever the recovery process gets stuck. Importantly, this approach modifies only the decoding procedure, leaving the IBLT data structure unchanged. We prove that even a weak matching-based predictor enables the recovery of 27% more elements than the nominal IBLT size. Equipped with simple predictors for k-mers of genomic datasets, we demonstrate that recovering a symmetric difference with high probability can be done with an IBLT of size only 66% of the encoded set size for k = 31, improving the space efficiency by almost a factor of two.
Moreover, we design an improved method for k-mers with large k that combines subsampling with nearly perfect prediction via fingerprinting and achieves a scaling property, requiring only O(M log M) bits for recovering M k-mers, instead of Θ(k⋅M) bits of the standard IBLT.
Overall, our results highlight the possibility of significant space-efficiency improvements for IBLTs on datasets with predictable structure.
Cite as
Vojtěch Gaďurek and Pavel Veselý. Breaking 2-Cores for Invertible Bloom Lookup Tables by Structure Prediction. In 24th International Symposium on Experimental Algorithms (SEA 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 371, pp. 19:1-19:24, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)
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@InProceedings{gadurek_et_al:LIPIcs.SEA.2026.19,
author = {Ga\v{d}urek, Vojt\v{e}ch and Vesel\'{y}, Pavel},
title = {{Breaking 2-Cores for Invertible Bloom Lookup Tables by Structure Prediction}},
booktitle = {24th International Symposium on Experimental Algorithms (SEA 2026)},
pages = {19:1--19:24},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-422-2},
ISSN = {1868-8969},
year = {2026},
volume = {371},
editor = {Aum\"{u}ller, Martin and Finocchi, Irene},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2026.19},
URN = {urn:nbn:de:0030-drops-260237},
doi = {10.4230/LIPIcs.SEA.2026.19},
annote = {Keywords: Invertible Bloom Lookup Table, symmetric difference, k-mer sets}
}
Document
QuadRank: Engineering a High Throughput Rank
Abstract
Motivation. Given a text, a query rank(q, c) counts the number of occurrences of character c among the first q characters of the text. Space-efficient methods to answer these rank queries form an important building block in many succinct data structures. For example, the FM-index [Ferragina and Manzini, 2000] is a widely used data structure that uses rank queries to locate all occurrences of a pattern in a text.
In bioinformatics applications, the goal is usually to process large inputs as fast as possible. Thus, data structures should have high throughput when used with many threads.
Contributions. We first survey existing results on rank data structures. For the σ = 2 binary alphabet, we then develop BiRank, which has 3.28% space overhead. BiRank merges the central ideas of two recent papers: (1) we interleave (inline) offsets in each cache line of the underlying bit vector [Laws et al., 2024], reducing cache misses, and (2) these offsets are to the middle of each block so that only half of each needs popcounting [Gottlieb and Reinert, 2025]. In QuadRank (14.4% overhead), we extend these techniques to the σ = 4 (DNA) alphabet.
Both data structures typically require only a single cache miss per query, making them highly suitable for high-throughput and memory-bound settings. To enable efficient batch-processing, we support prefetching the cache lines required to answer upcoming queries.
Results. BiRank and QuadRank are around 1.5× and 2× faster than similar-overhead methods that do not use interleaving. Prefetching gives an additional 2× speedup, at which point the dual-channel DDR4 RAM bandwidth becomes a hard limit on the total throughput. With prefetching, both methods outperform all other methods apart from SPIDER [Laws et al., 2024] by 2×.
When using QuadRank with prefetching in a toy count-only FM-index, QuadFm, this results in a smaller size and up to 4× speedup over Genedex, a state-of-the-art batching FM-index implementation.
Conclusion. Optimizing data structures for high throughput, by minimizing cache misses and branch-misses and adding support for prefetching, can result in significant speedups when benchmarks are adjusted accordingly.
Cite as
Ragnar Groot Koerkamp. QuadRank: Engineering a High Throughput Rank. In 24th International Symposium on Experimental Algorithms (SEA 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 371, pp. 20:1-20:23, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)
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@InProceedings{grootkoerkamp:LIPIcs.SEA.2026.20,
author = {Groot Koerkamp, Ragnar},
title = {{QuadRank: Engineering a High Throughput Rank}},
booktitle = {24th International Symposium on Experimental Algorithms (SEA 2026)},
pages = {20:1--20:23},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-422-2},
ISSN = {1868-8969},
year = {2026},
volume = {371},
editor = {Aum\"{u}ller, Martin and Finocchi, Irene},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2026.20},
URN = {urn:nbn:de:0030-drops-260248},
doi = {10.4230/LIPIcs.SEA.2026.20},
annote = {Keywords: Rank, Succinct Data Structures, Cache Performance, Prefetching}
}
Document
An Empirical Analysis of Approximation Algorithms for the Unweighted Tree Augmentation Problem
Abstract
In this paper, we perform an experimental study of approximation algorithms for the unweighted tree augmentation problem (UTAP). Our goal is to establish a baseline performance for several existing approximation algorithms on actual instances rather than worst-case instances. In particular, we are interested in whether the algorithms' performance in practical instances is consistent with their worst-case guarantee rankings. We are also interested in whether preprocessing times, implementation difficulties, and running times justify the use of an algorithm in practice. We profile and analyze three approximation algorithms from the literature against a simple randomized algorithm. The performance of each algorithm was evaluated using metrics for space usage, running time, and solution quality. We found that the simple randomized algorithm is very competitive with the approximation algorithms and that the algorithms do not necessarily rank according to their theoretical guarantees. The randomized algorithm is easier to implement and understand, using less space than any of the more sophisticated approximation algorithms.
Cite as
Luke Hawranick, Matthew Williamson, Jacob Restanio, K. Subramani, and Cody Klingler. An Empirical Analysis of Approximation Algorithms for the Unweighted Tree Augmentation Problem. In 24th International Symposium on Experimental Algorithms (SEA 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 371, pp. 21:1-21:15, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)
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@InProceedings{hawranick_et_al:LIPIcs.SEA.2026.21,
author = {Hawranick, Luke and Williamson, Matthew and Restanio, Jacob and Subramani, K. and Klingler, Cody},
title = {{An Empirical Analysis of Approximation Algorithms for the Unweighted Tree Augmentation Problem}},
booktitle = {24th International Symposium on Experimental Algorithms (SEA 2026)},
pages = {21:1--21:15},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-422-2},
ISSN = {1868-8969},
year = {2026},
volume = {371},
editor = {Aum\"{u}ller, Martin and Finocchi, Irene},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2026.21},
URN = {urn:nbn:de:0030-drops-260259},
doi = {10.4230/LIPIcs.SEA.2026.21},
annote = {Keywords: Graphs, Networks, Tree Augmentation, Approximation Algorithms, Empirical}
}
Document
Engineering Fully Dynamic Convex Hulls
Abstract
We present a new fully dynamic algorithm for maintaining convex hulls under insertions and deletions while supporting geometric queries. Our approach combines the logarithmic method with a deletion-only convex hull data structure, achieving amortised update times of O(log n log log n) and query times of O(log² n). We provide a robust and non-trivial implementation that supports point-location queries, a challenging and non-decomposable class of convex hull queries.
We evaluate our implementation against the state of the art, including a new naive baseline that rebuilds the convex hull whenever an update affects it. On hulls that include polynomially many data points (e.g. Θ(n^ε) for some ε), such as the ones that often occur in practice, our method outperforms all other techniques. Update-heavy workloads strongly favour our approach, which is in line with our theoretical guarantees. Yet, our method remains competitive all the way down to when the update to query ratio is 1 to 10.
Experiments on real-world data sets furthermore reveal that existing fully dynamic techniques suffer from significant robustness issues. In contrast, our implementation remains stable across all tested inputs.
Cite as
Ivor van der Hoog, Henrik Reinstädtler, and Eva Rotenberg. Engineering Fully Dynamic Convex Hulls. In 24th International Symposium on Experimental Algorithms (SEA 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 371, pp. 22:1-22:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)
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@InProceedings{vanderhoog_et_al:LIPIcs.SEA.2026.22,
author = {van der Hoog, Ivor and Reinst\"{a}dtler, Henrik and Rotenberg, Eva},
title = {{Engineering Fully Dynamic Convex Hulls}},
booktitle = {24th International Symposium on Experimental Algorithms (SEA 2026)},
pages = {22:1--22:20},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-422-2},
ISSN = {1868-8969},
year = {2026},
volume = {371},
editor = {Aum\"{u}ller, Martin and Finocchi, Irene},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2026.22},
URN = {urn:nbn:de:0030-drops-260264},
doi = {10.4230/LIPIcs.SEA.2026.22},
annote = {Keywords: Convex hulls, fully-dynamic data structures, robustness}
}
Document
Exploiting Multi-Core Parallelism in Blockchain Validation and Construction
Abstract
Blockchain validators can reduce block processing time by exploiting multi-core CPUs, but deterministic execution must preserve a given total order while respecting transaction conflicts and per-block runtime limits. This paper systematically examines how validators can exploit multi-core parallelism during both block construction and execution without violating blockchain semantics. We formalize two validator-side optimization problems: (i) executing an already ordered block on p cores to minimize makespan while ensuring equivalence to sequential execution; and (ii) selecting and scheduling a subset of mempool transactions under a runtime limit B to maximize validator reward. For both, we develop exact Mixed-Integer Linear Programming (MILP) formulations that capture conflict, order, and capacity constraints, and propose fast deterministic heuristics that scale to realistic workloads.
Using Ethereum mainnet traces and including a Solana-inspired declared-access baseline (Sol) for ordered-block scheduling and a simple reward-greedy baseline (RG) for block construction, we empirically quantify the trade-offs between optimality and runtime. MILPs quickly become intractable as heterogeneity or core count increases, whereas our heuristics run in milliseconds and achieve near-optimal quality. For ordered-block execution, heuristic makespans are typically within a few percent of the MILP solutions (and can even surpass the MILP incumbent when the solver times out), yielding up to 1.5 speedup with p = 2 and 2.3 speedup with p = 8 over sequential execution, despite tight ordering constraints. For block construction, the heuristic achieves 99-100% of the MILP optimum reward on homogeneous workloads, and 74-100% of an LP-relaxation upper bound on heterogeneous workloads, where exact optimization often times out. The resulting block-construction throughput scales close to linearly with p, reaching up to 7.9 speedup with p = 8 in our experiments. These results demonstrate that lightweight, conflict-aware scheduling and selection can unlock substantial parallelism in blockchain validation, bridging the gap between sequential execution and the true potential of multi-core hardware.
Cite as
Arivarasan Karmegam, Lucianna Kiffer, and Antonio Fernández Anta. Exploiting Multi-Core Parallelism in Blockchain Validation and Construction. In 24th International Symposium on Experimental Algorithms (SEA 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 371, pp. 23:1-23:21, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)
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@InProceedings{karmegam_et_al:LIPIcs.SEA.2026.23,
author = {Karmegam, Arivarasan and Kiffer, Lucianna and Fern\'{a}ndez Anta, Antonio},
title = {{Exploiting Multi-Core Parallelism in Blockchain Validation and Construction}},
booktitle = {24th International Symposium on Experimental Algorithms (SEA 2026)},
pages = {23:1--23:21},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-422-2},
ISSN = {1868-8969},
year = {2026},
volume = {371},
editor = {Aum\"{u}ller, Martin and Finocchi, Irene},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2026.23},
URN = {urn:nbn:de:0030-drops-260271},
doi = {10.4230/LIPIcs.SEA.2026.23},
annote = {Keywords: Block construction, Block execution, Deterministic parallelism, Conflict-aware scheduling}
}
Document
ZOR Filters: Fast and Smaller Than Fuse Filters
Abstract
Probabilistic membership filters support fast approximate membership queries with controlled false-positive probability ε and are widely used across storage, analytics, networking, and bioinformatics [Chang et al., 2008; Niv Dayan et al., 2018; Broder and Mitzenmacher, 2004; Harris and Medvedev, 2020; Marchet and Limasset, 2023; Chikhi et al., 2025; Hernandez-Courbevoie et al., 2025]. In the static setting, low-overhead methods such as XOR, Fuse, and BuRR have been proposed [Graf and Lemire, 2020; Graf and Lemire, 2022; Dillinger et al., 2022; Ulrich and Renard, 2023]. Among these, Fuse filters are known for near-optimal query throughput. For XOR/Fuse-style peeling constructions, however, build success is only high probability, which complicates deterministic builds.
We introduce ZOR filters, a deterministic continuation of XOR/Fuse-style constructions that guarantees termination while preserving the same XOR-based query mechanism. ZOR replaces restart-on-failure with deterministic peeling that abandons a small fraction of keys, and restores false-positive-only semantics by storing the remainder in a compact auxiliary structure. In our experiments, the abandoned fraction drops below 1% for moderate arity (e.g., N ≥ 5), so the auxiliary handles a negligible fraction of keys. As a result, ZOR filters can be substantially more memory-efficient than Fuse filters, with overhead below 1%, while not yet matching the near-optimal overhead of BuRR (below 0.1%). In query performance, ZOR-pure is close to Fuse and faster than BuRR on positive queries, while the complete interleaved variant trades additional negative-query latency for deterministic continuation. Relative to optimised Fuse/BuRR implementations [Graf and Lemire, 2022; Dillinger et al., 2022], the current ZOR prototype remains slower in construction because deterministic peeling requires explicit incidence handling; reducing this construction gap is an important direction for future work.
Cite as
Antoine Limasset. ZOR Filters: Fast and Smaller Than Fuse Filters. In 24th International Symposium on Experimental Algorithms (SEA 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 371, pp. 24:1-24:17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)
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@InProceedings{limasset:LIPIcs.SEA.2026.24,
author = {Limasset, Antoine},
title = {{ZOR Filters: Fast and Smaller Than Fuse Filters}},
booktitle = {24th International Symposium on Experimental Algorithms (SEA 2026)},
pages = {24:1--24:17},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-422-2},
ISSN = {1868-8969},
year = {2026},
volume = {371},
editor = {Aum\"{u}ller, Martin and Finocchi, Irene},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2026.24},
URN = {urn:nbn:de:0030-drops-260281},
doi = {10.4230/LIPIcs.SEA.2026.24},
annote = {Keywords: Data structure, Approximate Set Membership, Static filter}
}
Document
Engineering Learned Heuristics to Improve Clustering for Multilevel Graph Partitioning
Abstract
Balanced Graph Partitioning is a classical optimization problem where quality guarantees are computationally infeasible, and practical solvers therefore rely on manually engineered heuristics. Yet, the problem has also proven difficult for approaches that rely heavily on machine learning - especially since applications often need to partition graphs of huge scale in a short amount of time. Instead, we demonstrate how to achieve practical improvements with a more careful approach that uses machine learning to improve heuristic decisions within the state-of-the-art solver Mt-KaHyPar.
We use a pre-trained neural network to predict a score for each edge, which then guides clustering decisions in the first phase of the partitioning (the coarsening). Combined with corresponding adjustments to the clustering algorithm and an efficient implementation of the neural network logic, we improve the overall solution quality while preserving the efficiency and scalability of the original algorithm. Our detailed evaluation on more than 180 graphs shows an average quality improvement of 2% on a class of graphs with beneficial properties, and unchanged quality on all remaining graphs. Moreover, our improvements generalize to a set of instances from the literature that are much larger than the graphs used during training.
Cite as
Simeon Schrape, Nikolai Maas, Kenneth Langedal, and Daniel Seemaier. Engineering Learned Heuristics to Improve Clustering for Multilevel Graph Partitioning. In 24th International Symposium on Experimental Algorithms (SEA 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 371, pp. 25:1-25:21, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)
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@InProceedings{schrape_et_al:LIPIcs.SEA.2026.25,
author = {Schrape, Simeon and Maas, Nikolai and Langedal, Kenneth and Seemaier, Daniel},
title = {{Engineering Learned Heuristics to Improve Clustering for Multilevel Graph Partitioning}},
booktitle = {24th International Symposium on Experimental Algorithms (SEA 2026)},
pages = {25:1--25:21},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-422-2},
ISSN = {1868-8969},
year = {2026},
volume = {371},
editor = {Aum\"{u}ller, Martin and Finocchi, Irene},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2026.25},
URN = {urn:nbn:de:0030-drops-260295},
doi = {10.4230/LIPIcs.SEA.2026.25},
annote = {Keywords: Graph Partitioning, Graph Algorithms, Machine Learning, Neural Networks}
}
Document
Engineering Algorithms for Dynamic Greedy Set Cover
Abstract
In the dynamic set cover problem, the input is a dynamic universe of elements and a fixed collection of sets. As elements are inserted or deleted, the goal is to efficiently maintain an approximate minimum set cover. While the past decade has seen significant theoretical breakthroughs for this problem, a notable gap remains between theoretical design and practical performance, as no comprehensive experimental study currently exists to validate these results.
In this paper, we bridge this gap by implementing and evaluating four greedy-based dynamic algorithms across a diverse range of real-world instances. We derive our implementations from state-of-the-art frameworks - such as [GKKP(STOC'17); SU(STOC'23); SUZ(FOCS'24)] - which we simplify by identifying and modifying intricate subroutines that optimize asymptotic bounds but hinder practical performance. We evaluate these algorithms based on solution quality (set cover size) and efficiency, which comprises update time - the time required to update the solution following each insertion/deletion - and recourse - the number of changes made to the solution per update. Each algorithm uses a parameter β to balance quality against efficiency; we investigate the influence of this tradeoff parameter on each algorithm and then perform a comparative analysis to evaluate the algorithms against each other. Our results provide the first practical insights into which algorithmic strategies provide the most value in realistic scenarios.
Cite as
Amitai Uzrad. Engineering Algorithms for Dynamic Greedy Set Cover. In 24th International Symposium on Experimental Algorithms (SEA 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 371, pp. 26:1-26:22, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)
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@InProceedings{uzrad:LIPIcs.SEA.2026.26,
author = {Uzrad, Amitai},
title = {{Engineering Algorithms for Dynamic Greedy Set Cover}},
booktitle = {24th International Symposium on Experimental Algorithms (SEA 2026)},
pages = {26:1--26:22},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-422-2},
ISSN = {1868-8969},
year = {2026},
volume = {371},
editor = {Aum\"{u}ller, Martin and Finocchi, Irene},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2026.26},
URN = {urn:nbn:de:0030-drops-260308},
doi = {10.4230/LIPIcs.SEA.2026.26},
annote = {Keywords: Dynamic graphs, set cover, recourse}
}
Document
Cycle Basis Algorithms for Reducing Maximum Edge Participation
Abstract
A cycle basis of a graph is a minimal set of cycles from which every cycle in the graph can be generated by symmetric difference. We study the problem of constructing cycle bases of graphs with low maximum edge participation, defined as the maximum number of cycles in the basis that share any single edge. This quantity, though less studied than total weight or length, plays a critical role in quantum fault tolerance, as it directly impacts the overhead of lattice surgery procedures used to implement an almost universal quantum gate set. Building on a recursive algorithm by Freedman and Hastings, we introduce a family of load-aware heuristics that adaptively select vertices and edges to minimize edge participation throughout the cycle basis construction. Our approach improves empirical performance on random regular graphs and on graphs derived from small quantum codes. We further analyze a simplified balls-into-bins process to establish lower bounds on edge participation. While the model differs from the cycle basis algorithm on real graphs, it captures what can be proven for our heuristics without using more complex graph theoretic properties related to the distribution of cycles in the graph. Our analysis suggests that the maximum load of all of our heuristics will be Ω(log² n). Our results indicate that careful cycle basis construction can yield significant practical benefits in the design of fault-tolerant quantum systems. Maximum edge participation has been studied in the graph theory literature under the name basis number, which is the minimum possible maximum edge participation over all cycle bases in a graph.
Cite as
Fan Wang and Sandy Irani. Cycle Basis Algorithms for Reducing Maximum Edge Participation. In 24th International Symposium on Experimental Algorithms (SEA 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 371, pp. 27:1-27:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)
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@InProceedings{wang_et_al:LIPIcs.SEA.2026.27,
author = {Wang, Fan and Irani, Sandy},
title = {{Cycle Basis Algorithms for Reducing Maximum Edge Participation}},
booktitle = {24th International Symposium on Experimental Algorithms (SEA 2026)},
pages = {27:1--27:20},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-422-2},
ISSN = {1868-8969},
year = {2026},
volume = {371},
editor = {Aum\"{u}ller, Martin and Finocchi, Irene},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2026.27},
URN = {urn:nbn:de:0030-drops-260311},
doi = {10.4230/LIPIcs.SEA.2026.27},
annote = {Keywords: Graph algorithms, Cycle Basis, Quantum fault tolerance}
}
Document
The Dual-Path Fixing Strategy and Its Application to the Set-Covering Problem
Abstract
We introduce the dual-path fixing strategy to exploit dual algorithms for solving relaxations of mixed-integer nonlinear-optimization problems. Such dual algorithms are naturally applied in the context of branch-and-bound, and eventual impact on the success of branch-and-bound is our strong motivation. Our fixing strategy aims to be more powerful than the common strategy of fixing variables based on a single dual-feasible solution (e.g., standard reduced-cost fixing for mixed-integer linear optimization), but to be much faster than "strong fixing", essentially requiring no more time than that of the dual algorithm that we exploit. We have successfully tested our ideas on mixed-integer linear-optimization set-covering instances from the literature, in the context of the dual-simplex method applied to the continuous relaxations.
Cite as
Paulo Michel F. Yamagishi, Marcia Fampa, and Jon Lee. The Dual-Path Fixing Strategy and Its Application to the Set-Covering Problem. In 24th International Symposium on Experimental Algorithms (SEA 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 371, pp. 28:1-28:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)
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@InProceedings{yamagishi_et_al:LIPIcs.SEA.2026.28,
author = {Yamagishi, Paulo Michel F. and Fampa, Marcia and Lee, Jon},
title = {{The Dual-Path Fixing Strategy and Its Application to the Set-Covering Problem}},
booktitle = {24th International Symposium on Experimental Algorithms (SEA 2026)},
pages = {28:1--28:18},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-422-2},
ISSN = {1868-8969},
year = {2026},
volume = {371},
editor = {Aum\"{u}ller, Martin and Finocchi, Irene},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2026.28},
URN = {urn:nbn:de:0030-drops-260329},
doi = {10.4230/LIPIcs.SEA.2026.28},
annote = {Keywords: integer programming, mixed-integer programming, variable fixing, reduced-cost fixing, strong fixing, dual-path fixing, set cover}
}