Volume
LIPIcs, Volume 103
17th International Symposium on Experimental Algorithms (SEA 2018)
-
Part of:
Series:
Leibniz International Proceedings in Informatics (LIPIcs)
Conference: International Symposium on Experimental Algorithms (SEA)
Event
SEA 2018, June 27-29, 2018, L'Aquila, ItalyEditor
Publication Details
- published at: 2018-06-19
- Publisher: Schloss Dagstuhl – Leibniz-Zentrum für Informatik
- ISBN: 978-3-95977-070-5
- DBLP: db/conf/wea/sea2018
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Document
Complete Volume
LIPIcs, Volume 103, SEA'18, Complete Volume
Abstract
LIPIcs, Volume 103, SEA'18, Complete Volume
Cite as
17th International Symposium on Experimental Algorithms (SEA 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 103, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)
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@Proceedings{dangelo:LIPIcs.SEA.2018,
title = {{LIPIcs, Volume 103, SEA'18, Complete Volume}},
booktitle = {17th International Symposium on Experimental Algorithms (SEA 2018)},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-070-5},
ISSN = {1868-8969},
year = {2018},
volume = {103},
editor = {D'Angelo, Gianlorenzo},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2018},
URN = {urn:nbn:de:0030-drops-92438},
doi = {10.4230/LIPIcs.SEA.2018},
annote = {Keywords: Theory of computation, Design and analysis of algorithms}
}
Document
Front Matter
Front Matter, Table of Contents, Preface, Conference Organization
Abstract
Gianlorenzo
Cite as
17th International Symposium on Experimental Algorithms (SEA 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 103, pp. 0:i-0:xi, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)
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@InProceedings{dangelo:LIPIcs.SEA.2018.0,
author = {D'Angelo, Gianlorenzo},
title = {{Front Matter, Table of Contents, Preface, Conference Organization}},
booktitle = {17th International Symposium on Experimental Algorithms (SEA 2018)},
pages = {0:i--0:xi},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-070-5},
ISSN = {1868-8969},
year = {2018},
volume = {103},
editor = {D'Angelo, Gianlorenzo},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2018.0},
URN = {urn:nbn:de:0030-drops-89357},
doi = {10.4230/LIPIcs.SEA.2018.0},
annote = {Keywords: Front Matter, Table of Contents, Preface, Conference Organization}
}
Document
Network Flow-Based Refinement for Multilevel Hypergraph Partitioning
Abstract
We present a refinement framework for multilevel hypergraph partitioning that uses max-flow computations on pairs of blocks to improve the solution quality of a k-way partition. The framework generalizes the flow-based improvement algorithm of KaFFPa from graphs to hypergraphs and is integrated into the hypergraph partitioner KaHyPar. By reducing the size of hypergraph flow networks, improving the flow model used in KaFFPa, and developing techniques to improve the running time of our algorithm, we obtain a partitioner that computes the best solutions for a wide range of benchmark hypergraphs from different application areas while still having a running time comparable to that of hMetis.
Cite as
Tobias Heuer, Peter Sanders, and Sebastian Schlag. Network Flow-Based Refinement for Multilevel Hypergraph Partitioning. In 17th International Symposium on Experimental Algorithms (SEA 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 103, pp. 1:1-1:19, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)
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@InProceedings{heuer_et_al:LIPIcs.SEA.2018.1,
author = {Heuer, Tobias and Sanders, Peter and Schlag, Sebastian},
title = {{Network Flow-Based Refinement for Multilevel Hypergraph Partitioning}},
booktitle = {17th International Symposium on Experimental Algorithms (SEA 2018)},
pages = {1:1--1:19},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-070-5},
ISSN = {1868-8969},
year = {2018},
volume = {103},
editor = {D'Angelo, Gianlorenzo},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2018.1},
URN = {urn:nbn:de:0030-drops-89368},
doi = {10.4230/LIPIcs.SEA.2018.1},
annote = {Keywords: Multilevel Hypergraph Partitioning, Network Flows, Refinement}
}
Document
Aggregative Coarsening for Multilevel Hypergraph Partitioning
Abstract
Algorithms for many hypergraph problems, including partitioning, utilize multilevel frameworks to achieve a good trade-off between the performance and the quality of results. In this paper we introduce two novel aggregative coarsening schemes and incorporate them within state-of-the-art hypergraph partitioner Zoltan. Our coarsening schemes are inspired by the algebraic multigrid and stable matching approaches. We demonstrate the effectiveness of the developed schemes as a part of multilevel hypergraph partitioning framework on a wide range of problems.
Cite as
Ruslan Shaydulin and Ilya Safro. Aggregative Coarsening for Multilevel Hypergraph Partitioning. In 17th International Symposium on Experimental Algorithms (SEA 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 103, pp. 2:1-2:15, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)
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@InProceedings{shaydulin_et_al:LIPIcs.SEA.2018.2,
author = {Shaydulin, Ruslan and Safro, Ilya},
title = {{Aggregative Coarsening for Multilevel Hypergraph Partitioning}},
booktitle = {17th International Symposium on Experimental Algorithms (SEA 2018)},
pages = {2:1--2:15},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-070-5},
ISSN = {1868-8969},
year = {2018},
volume = {103},
editor = {D'Angelo, Gianlorenzo},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2018.2},
URN = {urn:nbn:de:0030-drops-89371},
doi = {10.4230/LIPIcs.SEA.2018.2},
annote = {Keywords: hypergraph partitioning, multilevel algorithms, coarsening, matching, combinatorial scientific computing}
}
Document
Memetic Graph Clustering
Abstract
It is common knowledge that there is no single best strategy for graph clustering, which justifies a plethora of existing approaches. In this paper, we present a general memetic algorithm, VieClus, to tackle the graph clustering problem. This algorithm can be adapted to optimize different objective functions. A key component of our contribution are natural recombine operators that employ ensemble clusterings as well as multi-level techniques. Lastly, we combine these techniques with a scalable communication protocol, producing a system that is able to compute high-quality solutions in a short amount of time. We instantiate our scheme with local search for modularity and show that our algorithm successfully improves or reproduces all entries of the 10th DIMACS implementation challenge under consideration using a small amount of time.
Cite as
Sonja Biedermann, Monika Henzinger, Christian Schulz, and Bernhard Schuster. Memetic Graph Clustering. In 17th International Symposium on Experimental Algorithms (SEA 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 103, pp. 3:1-3:15, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)
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@InProceedings{biedermann_et_al:LIPIcs.SEA.2018.3,
author = {Biedermann, Sonja and Henzinger, Monika and Schulz, Christian and Schuster, Bernhard},
title = {{Memetic Graph Clustering}},
booktitle = {17th International Symposium on Experimental Algorithms (SEA 2018)},
pages = {3:1--3:15},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-070-5},
ISSN = {1868-8969},
year = {2018},
volume = {103},
editor = {D'Angelo, Gianlorenzo},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2018.3},
URN = {urn:nbn:de:0030-drops-89389},
doi = {10.4230/LIPIcs.SEA.2018.3},
annote = {Keywords: Graph Clustering, Evolutionary Algorithms}
}
Document
ILP-based Local Search for Graph Partitioning
Abstract
Computing high-quality graph partitions is a challenging problem with numerous applications. In this paper, we present a novel meta-heuristic for the balanced graph partitioning problem. Our approach is based on integer linear programs that solve the partitioning problem to optimality. However, since those programs typically do not scale to large inputs, we adapt them to heuristically improve a given partition. We do so by defining a much smaller model that allows us to use symmetry breaking and other techniques that make the approach scalable. For example, in Walshaw's well-known benchmark tables we are able to improve roughly half of all entries when the number of blocks is high.
Cite as
Alexandra Henzinger, Alexander Noe, and Christian Schulz. ILP-based Local Search for Graph Partitioning. In 17th International Symposium on Experimental Algorithms (SEA 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 103, pp. 4:1-4:15, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)
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@InProceedings{henzinger_et_al:LIPIcs.SEA.2018.4,
author = {Henzinger, Alexandra and Noe, Alexander and Schulz, Christian},
title = {{ILP-based Local Search for Graph Partitioning}},
booktitle = {17th International Symposium on Experimental Algorithms (SEA 2018)},
pages = {4:1--4:15},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-070-5},
ISSN = {1868-8969},
year = {2018},
volume = {103},
editor = {D'Angelo, Gianlorenzo},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2018.4},
URN = {urn:nbn:de:0030-drops-89399},
doi = {10.4230/LIPIcs.SEA.2018.4},
annote = {Keywords: Graph Partitioning, Integer Linear Programming}
}
Document
Decision Diagrams for Solving a Job Scheduling Problem Under Precedence Constraints
Abstract
We consider a job scheduling problem under precedence constraints, a classical problem for a single processor and multiple jobs to be done. The goal is, given processing time of n fixed jobs and precedence constraints over jobs, to find a permutation of n jobs that minimizes the total flow time, i.e., the sum of total wait time and processing times of all jobs, while satisfying the precedence constraints. The problem is an integer program and is NP-hard in general. We propose a decision diagram pi-MDD, for solving the scheduling problem exactly. Our diagram is suitable for solving linear optimization over permutations with precedence constraints. We show the effectiveness of our approach on the experiments on large scale artificial scheduling problems.
Cite as
Kosuke Matsumoto, Kohei Hatano, and Eiji Takimoto. Decision Diagrams for Solving a Job Scheduling Problem Under Precedence Constraints. In 17th International Symposium on Experimental Algorithms (SEA 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 103, pp. 5:1-5:12, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)
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@InProceedings{matsumoto_et_al:LIPIcs.SEA.2018.5,
author = {Matsumoto, Kosuke and Hatano, Kohei and Takimoto, Eiji},
title = {{Decision Diagrams for Solving a Job Scheduling Problem Under Precedence Constraints}},
booktitle = {17th International Symposium on Experimental Algorithms (SEA 2018)},
pages = {5:1--5:12},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-070-5},
ISSN = {1868-8969},
year = {2018},
volume = {103},
editor = {D'Angelo, Gianlorenzo},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2018.5},
URN = {urn:nbn:de:0030-drops-89402},
doi = {10.4230/LIPIcs.SEA.2018.5},
annote = {Keywords: decision diagram, permutation, scheduling, NP-hardness, precedence constraints, MDD}
}
Document
Speeding up Dualization in the Fredman-Khachiyan Algorithm B
Abstract
The problem of computing the dual of a monotone Boolean function f is a fundamental problem in theoretical computer science with numerous applications. The related problem of duality testing (given two monotone Boolean functions f and g, declare that they are dual or provide a certificate that shows they are not) has a complexity that is not yet known. However, two quasi-polynomial time algorithms for it, often referred to as FK-A and FK-B, were proposed by Fredman and Khachiyan in 1996, with the latter having a better complexity guarantee. These can be naturally used as a subroutine in computing the dual of f.
In this paper, we investigate this use of the FK-B algorithm for the computation of the dual of a monotone Boolean function, and present practical improvements to its performance. First, we show how FK-B can be modified to produce multiple certificates (Boolean vectors on which the functions defined by the original f and the current dual g do not provide outputs consistent with duality). Second, we show how the number of redundancy tests - one of the more costly and time-consuming steps of FK-B - can be substantially reduced in this context. Lastly, we describe a simple memoization technique that avoids the solution of multiple identical subproblems.
We test our approach on a number of inputs coming from computational biology as well as combinatorics. These modifications provide a substantial speed-up, as much as an order of magnitude, for FK-B dualization relative to a naive implementation. Although other methods may end up being faster in practice, our work paves the way for a principled optimization process for the generation of monotone Boolean functions and their duals from an oracle.
Cite as
Nafiseh Sedaghat, Tamon Stephen, and Leonid Chindelevitch. Speeding up Dualization in the Fredman-Khachiyan Algorithm B. In 17th International Symposium on Experimental Algorithms (SEA 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 103, pp. 6:1-6:13, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)
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@InProceedings{sedaghat_et_al:LIPIcs.SEA.2018.6,
author = {Sedaghat, Nafiseh and Stephen, Tamon and Chindelevitch, Leonid},
title = {{Speeding up Dualization in the Fredman-Khachiyan Algorithm B}},
booktitle = {17th International Symposium on Experimental Algorithms (SEA 2018)},
pages = {6:1--6:13},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-070-5},
ISSN = {1868-8969},
year = {2018},
volume = {103},
editor = {D'Angelo, Gianlorenzo},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2018.6},
URN = {urn:nbn:de:0030-drops-89413},
doi = {10.4230/LIPIcs.SEA.2018.6},
annote = {Keywords: Monotone boolean functions, dualization, Fredman-Khachiyan algorithm, algorithm engineering, metabolic networks}
}
Document
An Ambiguous Coding Scheme for Selective Encryption of High Entropy Volumes
Abstract
This study concentrates on the security of high-entropy volumes, where entropy-encoded multimedia files or compressed text sequences are the most typical sources. We consider a system in which the cost of encryption is hefty in terms of some metric (e.g., time, memory, energy, or bandwidth), and thus, creates a bottleneck. With the aim of reducing the encryption cost on such a system, we propose a data coding scheme to achieve the data security by encrypting significantly less data than the original size without sacrifice in secrecy. The main idea of the proposed technique is to represent the input sequence by not uniquely-decodable codewords. The proposed coding scheme splits a given input into two partitions as the payload, which consists of the ambiguous codeword sequence, and the disambiguation information, which is the necessary knowledge to properly decode the payload. Under the assumed condition that the input data is the output of an entropy-encoder, and thus, on ideal case independently and identically distributed, the payload occupies ~~ (d-2)/d, and the disambiguation information takes ~~ 2/d of the encoded stream, where d>2 denotes a chosen parameter typically between 6 to 20. We propose to encrypt the payload and keep the disambiguation information in plain to reduce the amount of data to be encrypted, where recursive representation of the payload with the proposed coding can decrease the to-be-encrypted volume further. When 2 * 2^d <= n <= tau * d * 2^d, for tau = (d-1.44)/2, we show that the contraction of the possible message space 2^n due to the public disambiguation information is accommodated by keeping the codeword set secret. We discuss possible applications of the proposed scheme in practice.
Cite as
M. Oguzhan Külekci. An Ambiguous Coding Scheme for Selective Encryption of High Entropy Volumes. In 17th International Symposium on Experimental Algorithms (SEA 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 103, pp. 7:1-7:13, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)
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@InProceedings{kulekci:LIPIcs.SEA.2018.7,
author = {K\"{u}lekci, M. Oguzhan},
title = {{An Ambiguous Coding Scheme for Selective Encryption of High Entropy Volumes}},
booktitle = {17th International Symposium on Experimental Algorithms (SEA 2018)},
pages = {7:1--7:13},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-070-5},
ISSN = {1868-8969},
year = {2018},
volume = {103},
editor = {D'Angelo, Gianlorenzo},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2018.7},
URN = {urn:nbn:de:0030-drops-89424},
doi = {10.4230/LIPIcs.SEA.2018.7},
annote = {Keywords: Non-prefix-free codes, selective encryption, massive data security, multimedia data security, high-entropy data security, source coding, security in resource-limited environments}
}
Document
A 3/2-Approximation Algorithm for the Student-Project Allocation Problem
Abstract
The Student-Project Allocation problem with lecturer preferences over Students (SPA-S) comprises three sets of agents, namely students, projects and lecturers, where students have preferences over projects and lecturers have preferences over students. In this scenario we seek a stable matching, that is, an assignment of students to projects such that there is no student and lecturer who have an incentive to deviate from their assignee/s. We study SPA-ST, the extension of SPA-S in which the preference lists of students and lecturers need not be strictly ordered, and may contain ties. In this scenario, stable matchings may be of different sizes, and it is known that MAX SPA-ST, the problem of finding a maximum stable matching in SPA-ST, is NP-hard. We present a linear-time 3/2-approximation algorithm for MAX SPA-ST and an Integer Programming (IP) model to solve MAX SPA-ST optimally. We compare the approximation algorithm with the IP model experimentally using randomly-generated data. We find that the performance of the approximation algorithm easily surpassed the 3/2 bound, constructing a stable matching within 92% of optimal in all cases, with the percentage being far higher for many instances.
Cite as
Frances Cooper and David Manlove. A 3/2-Approximation Algorithm for the Student-Project Allocation Problem. In 17th International Symposium on Experimental Algorithms (SEA 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 103, pp. 8:1-8:13, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)
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@InProceedings{cooper_et_al:LIPIcs.SEA.2018.8,
author = {Cooper, Frances and Manlove, David},
title = {{A 3/2-Approximation Algorithm for the Student-Project Allocation Problem}},
booktitle = {17th International Symposium on Experimental Algorithms (SEA 2018)},
pages = {8:1--8:13},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-070-5},
ISSN = {1868-8969},
year = {2018},
volume = {103},
editor = {D'Angelo, Gianlorenzo},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2018.8},
URN = {urn:nbn:de:0030-drops-89439},
doi = {10.4230/LIPIcs.SEA.2018.8},
annote = {Keywords: Matching problems, Approximation, Algorithms, Stability}
}
Document
How Good Are Popular Matchings?
Abstract
In this paper, we consider the Hospital Residents problem (HR) and the Hospital Residents problem with Lower Quotas (HRLQ). In this model with two sided preferences, stability is a well accepted notion of optimality. However, in the presence of lower quotas, a stable and feasible matching need not exist. For the HRLQ problem, our goal therefore is to output a good feasible matching assuming that a feasible matching exists. Computing matchings with minimum number of blocking pairs (Min-BP) and minimum number of blocking residents (Min-BR) are known to be NP-Complete. The only approximation algorithms for these problems work under severe restrictions on the preference lists. We present an algorithm which circumvents this restriction and computes a popular matching in the HRLQ instance. We show that on data-sets generated using various generators, our algorithm performs very well in terms of blocking pairs and blocking residents. Yokoi [Yokoi, 2017] recently studied envy-free matchings for the HRLQ problem. We propose a simple modification to Yokoi's algorithm to output a maximal envy-free matching. We observe that popular matchings outperform envy-free matchings on several parameters of practical importance, like size, number of blocking pairs, number of blocking residents.
In the absence of lower quotas, that is, in the Hospital Residents (HR) problem, stable matchings are guaranteed to exist. Even in this case, we show that popularity is a practical alternative to stability. For instance, on synthetic data-sets generated using a particular model, as well as on real world data-sets, a popular matching is on an average 8-10% larger in size, matches more number of residents to their top-choice, and more residents prefer the popular matching as compared to a stable matching. Our comprehensive study reveals the practical appeal of popular matchings for the HR and HRLQ problems. To the best of our knowledge, this is the first study on the empirical evaluation of popular matchings in this setting.
Cite as
Krishnapriya A M, Meghana Nasre, Prajakta Nimbhorkar, and Amit Rawat. How Good Are Popular Matchings?. In 17th International Symposium on Experimental Algorithms (SEA 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 103, pp. 9:1-9:14, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)
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@InProceedings{am_et_al:LIPIcs.SEA.2018.9,
author = {A M, Krishnapriya and Nasre, Meghana and Nimbhorkar, Prajakta and Rawat, Amit},
title = {{How Good Are Popular Matchings?}},
booktitle = {17th International Symposium on Experimental Algorithms (SEA 2018)},
pages = {9:1--9:14},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-070-5},
ISSN = {1868-8969},
year = {2018},
volume = {103},
editor = {D'Angelo, Gianlorenzo},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2018.9},
URN = {urn:nbn:de:0030-drops-89440},
doi = {10.4230/LIPIcs.SEA.2018.9},
annote = {Keywords: bipartite graphs, hospital residents, lower-quotas, popular matchings}
}
Document
Evaluating and Tuning n-fold Integer Programming
Abstract
In recent years, algorithmic breakthroughs in stringology, computational social choice, scheduling, etc., were achieved by applying the theory of so-called n-fold integer programming. An n-fold integer program (IP) has a highly uniform block structured constraint matrix. Hemmecke, Onn, and Romanchuk [Math. Programming, 2013] showed an algorithm with runtime a^{O(rst + r^2s)} n^3, where a is the largest coefficient, r,s, and t are dimensions of blocks of the constraint matrix and n is the total dimension of the IP; thus, an algorithm efficient if the blocks are of small size and with small coefficients. The algorithm works by iteratively improving a feasible solution with augmenting steps, and n-fold IPs have the special property that augmenting steps are guaranteed to exist in a not-too-large neighborhood. However, this algorithm has never been implemented and evaluated.
We have implemented the algorithm and learned the following along the way. The original algorithm is practically unusable, but we discover a series of improvements which make its evaluation possible. Crucially, we observe that a certain constant in the algorithm can be treated as a tuning parameter, which yields an efficient heuristic (essentially searching in a smaller-than-guaranteed neighborhood). Furthermore, the algorithm uses an overly expensive strategy to find a "best" step, while finding only an "approximatelly best" step is much cheaper, yet sufficient for quick convergence. Using this insight, we improve the asymptotic dependence on n from n^3 to n^2 log n which yields the currently asymptotically fastest algorithm for n-fold IP.
Finally, we tested the behavior of the algorithm with various values of the tuning parameter and different strategies of finding improving steps. First, we show that decreasing the tuning parameter initially leads to an increased number of iterations needed for convergence and eventually to getting stuck in local optima, as expected. However, surprisingly small values of the parameter already exhibit good behavior. Second, our new strategy for finding "approximatelly best" steps wildly outperforms the original construction.
Cite as
Katerina Altmanová, Dusan Knop, and Martin Koutecký. Evaluating and Tuning n-fold Integer Programming. In 17th International Symposium on Experimental Algorithms (SEA 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 103, pp. 10:1-10:14, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)
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@InProceedings{altmanova_et_al:LIPIcs.SEA.2018.10,
author = {Altmanov\'{a}, Katerina and Knop, Dusan and Kouteck\'{y}, Martin},
title = {{Evaluating and Tuning n-fold Integer Programming}},
booktitle = {17th International Symposium on Experimental Algorithms (SEA 2018)},
pages = {10:1--10:14},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-070-5},
ISSN = {1868-8969},
year = {2018},
volume = {103},
editor = {D'Angelo, Gianlorenzo},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2018.10},
URN = {urn:nbn:de:0030-drops-89454},
doi = {10.4230/LIPIcs.SEA.2018.10},
annote = {Keywords: n-fold integer programming, integer programming, analysis of algorithms, primal heuristic, local search}
}
Document
A Computational Investigation on the Strength of Dantzig-Wolfe Reformulations
Abstract
In Dantzig-Wolfe reformulation of an integer program one convexifies a subset of the constraints, leading to potentially stronger dual bounds from the respective linear programming relaxation. As the subset can be chosen arbitrarily, this includes the trivial cases of convexifying no and all constraints, resulting in a weakest and strongest reformulation, respectively. Our computational study aims at better understanding of what happens in between these extremes. For a collection of integer programs with few constraints we compute, optimally solve, and evaluate the relaxations of all possible (exponentially many) Dantzig-Wolfe reformulations (with mild extensions to larger models from the MIPLIBs). We observe that only a tiny number of different dual bounds actually occur and that only a few inclusion-wise minimal representatives exist for each. This aligns with considerably different impacts of individual constraints on the strengthening the relaxation, some of which have almost no influence. In contrast, types of constraints that are convexified in textbook reformulations have a larger effect. We relate our experiments to what could be called a hierarchy of Dantzig-Wolfe reformulations.
Cite as
Michael Bastubbe, Marco E. Lübbecke, and Jonas T. Witt. A Computational Investigation on the Strength of Dantzig-Wolfe Reformulations. In 17th International Symposium on Experimental Algorithms (SEA 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 103, pp. 11:1-11:12, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)
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@InProceedings{bastubbe_et_al:LIPIcs.SEA.2018.11,
author = {Bastubbe, Michael and L\"{u}bbecke, Marco E. and Witt, Jonas T.},
title = {{A Computational Investigation on the Strength of Dantzig-Wolfe Reformulations}},
booktitle = {17th International Symposium on Experimental Algorithms (SEA 2018)},
pages = {11:1--11:12},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-070-5},
ISSN = {1868-8969},
year = {2018},
volume = {103},
editor = {D'Angelo, Gianlorenzo},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2018.11},
URN = {urn:nbn:de:0030-drops-89464},
doi = {10.4230/LIPIcs.SEA.2018.11},
annote = {Keywords: Dantzig-Wolfe reformulation, strength of reformulations, Lagrangean relaxation, partial convexification, column generation, hierarchy of relaxations}
}
Document
Experimental Evaluation of Parameterized Algorithms for Feedback Vertex Set
Abstract
Feedback Vertex Set is a classic combinatorial optimization problem that asks for a minimum set of vertices in a given graph whose deletion makes the graph acyclic. From the point of view of parameterized algorithms and fixed-parameter tractability, Feedback Vertex Set is one of the landmark problems: a long line of study resulted in multiple algorithmic approaches and deep understanding of the combinatorics of the problem. Because of its central role in parameterized complexity, the first edition of the Parameterized Algorithms and Computational Experiments Challenge (PACE) in 2016 featured Feedback Vertex Set as the problem of choice in one of its tracks. The results of PACE 2016 on one hand showed large discrepancy between performance of different classic approaches to the problem, and on the other hand indicated a new approach based on half-integral relaxations of the problem as probably the most efficient approach to the problem. In this paper we provide an exhaustive experimental evaluation of fixed-parameter and branching algorithms for Feedback Vertex Set.
Cite as
Krzysztof Kiljan and Marcin Pilipczuk. Experimental Evaluation of Parameterized Algorithms for Feedback Vertex Set. In 17th International Symposium on Experimental Algorithms (SEA 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 103, pp. 12:1-12:12, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)
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@InProceedings{kiljan_et_al:LIPIcs.SEA.2018.12,
author = {Kiljan, Krzysztof and Pilipczuk, Marcin},
title = {{Experimental Evaluation of Parameterized Algorithms for Feedback Vertex Set}},
booktitle = {17th International Symposium on Experimental Algorithms (SEA 2018)},
pages = {12:1--12:12},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-070-5},
ISSN = {1868-8969},
year = {2018},
volume = {103},
editor = {D'Angelo, Gianlorenzo},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2018.12},
URN = {urn:nbn:de:0030-drops-89477},
doi = {10.4230/LIPIcs.SEA.2018.12},
annote = {Keywords: Empirical Evaluation of Algorithms, Feedback Vertex Set}
}
Document
An Efficient Local Search for the Minimum Independent Dominating Set Problem
Abstract
In the present paper, we propose an efficient local search for the minimum independent dominating set problem. We consider a local search that uses k-swap as the neighborhood operation. Given a feasible solution S, it is the operation of obtaining another feasible solution by dropping exactly k vertices from S and then by adding any number of vertices to it. We show that, when k=2, (resp., k=3 and a given solution is minimal with respect to 2-swap), we can find an improved solution in the neighborhood or conclude that no such solution exists in O(n Delta) (resp., O(n Delta^3)) time, where n denotes the number of vertices and Delta denotes the maximum degree. We develop a metaheuristic algorithm that repeats the proposed local search and the plateau search iteratively, where the plateau search examines solutions of the same size as the current solution that are obtainable by exchanging a solution vertex and a non-solution vertex. The algorithm is so effective that, among 80 DIMACS graphs, it updates the best-known solution size for five graphs and performs as well as existing methods for the remaining graphs.
Cite as
Kazuya Haraguchi. An Efficient Local Search for the Minimum Independent Dominating Set Problem. In 17th International Symposium on Experimental Algorithms (SEA 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 103, pp. 13:1-13:13, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)
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@InProceedings{haraguchi:LIPIcs.SEA.2018.13,
author = {Haraguchi, Kazuya},
title = {{An Efficient Local Search for the Minimum Independent Dominating Set Problem}},
booktitle = {17th International Symposium on Experimental Algorithms (SEA 2018)},
pages = {13:1--13:13},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-070-5},
ISSN = {1868-8969},
year = {2018},
volume = {103},
editor = {D'Angelo, Gianlorenzo},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2018.13},
URN = {urn:nbn:de:0030-drops-89484},
doi = {10.4230/LIPIcs.SEA.2018.13},
annote = {Keywords: Minimum independent dominating set problem, local search, plateau search, metaheuristics}
}
Document
Empirical Evaluation of Approximation Algorithms for Generalized Graph Coloring and Uniform Quasi-Wideness
Abstract
The notions of bounded expansion and nowhere denseness not only offer robust and general definitions of uniform sparseness of graphs, they also describe the tractability boundary for several important algorithmic questions. In this paper we study two structural properties of these graph classes that are of particular importance in this context, namely the property of having bounded generalized coloring numbers and the property of being uniformly quasi-wide. We provide experimental evaluations of several algorithms that approximate these parameters on real-world graphs. On the theoretical side, we provide a new algorithm for uniform quasi-wideness with polynomial size guarantees in graph classes of bounded expansion and show a lower bound indicating that the guarantees of this algorithm are close to optimal in graph classes with fixed excluded minor.
Cite as
Wojciech Nadara, Marcin Pilipczuk, Roman Rabinovich, Felix Reidl, and Sebastian Siebertz. Empirical Evaluation of Approximation Algorithms for Generalized Graph Coloring and Uniform Quasi-Wideness. In 17th International Symposium on Experimental Algorithms (SEA 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 103, pp. 14:1-14:16, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)
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@InProceedings{nadara_et_al:LIPIcs.SEA.2018.14,
author = {Nadara, Wojciech and Pilipczuk, Marcin and Rabinovich, Roman and Reidl, Felix and Siebertz, Sebastian},
title = {{Empirical Evaluation of Approximation Algorithms for Generalized Graph Coloring and Uniform Quasi-Wideness}},
booktitle = {17th International Symposium on Experimental Algorithms (SEA 2018)},
pages = {14:1--14:16},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-070-5},
ISSN = {1868-8969},
year = {2018},
volume = {103},
editor = {D'Angelo, Gianlorenzo},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2018.14},
URN = {urn:nbn:de:0030-drops-89493},
doi = {10.4230/LIPIcs.SEA.2018.14},
annote = {Keywords: Empirical Evaluation of Algorithms, Sparse Graph Classes, Generalized Coloring Numbers, Uniform Quasi-Wideness}
}
Document
Multi-Level Steiner Trees
Abstract
In the classical Steiner tree problem, one is given an undirected, connected graph G=(V,E) with non-negative edge costs and a set of terminals T subseteq V. The objective is to find a minimum-cost edge set E' subseteq E that spans the terminals. The problem is APX-hard; the best known approximation algorithm has a ratio of rho = ln(4)+epsilon < 1.39. In this paper, we study a natural generalization, the multi-level Steiner tree (MLST) problem: given a nested sequence of terminals T_1 subset ... subset T_k subseteq V, compute nested edge sets E_1 subseteq ... subseteq E_k subseteq E that span the corresponding terminal sets with minimum total cost.
The MLST problem and variants thereof have been studied under names such as Quality-of-Service Multicast tree, Grade-of-Service Steiner tree, and Multi-Tier tree. Several approximation results are known. We first present two natural heuristics with approximation factor O(k). Based on these, we introduce a composite algorithm that requires 2^k Steiner tree computations. We determine its approximation ratio by solving a linear program. We then present a method that guarantees the same approximation ratio and needs at most 2k Steiner tree computations. We compare five algorithms experimentally on several classes of graphs using four types of graph generators. We also implemented an integer linear program for MLST to provide ground truth. Our combined algorithm outperforms the others both in theory and in practice when the number of levels is small (k <= 22), which works well for applications such as designing multi-level infrastructure or network visualization.
Cite as
Reyan Ahmed, Patrizio Angelini, Faryad Darabi Sahneh, Alon Efrat, David Glickenstein, Martin Gronemann, Niklas Heinsohn, Stephen G. Kobourov, Richard Spence, Joseph Watkins, and Alexander Wolff. Multi-Level Steiner Trees. In 17th International Symposium on Experimental Algorithms (SEA 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 103, pp. 15:1-15:14, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)
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@InProceedings{ahmed_et_al:LIPIcs.SEA.2018.15,
author = {Ahmed, Reyan and Angelini, Patrizio and Sahneh, Faryad Darabi and Efrat, Alon and Glickenstein, David and Gronemann, Martin and Heinsohn, Niklas and Kobourov, Stephen G. and Spence, Richard and Watkins, Joseph and Wolff, Alexander},
title = {{Multi-Level Steiner Trees}},
booktitle = {17th International Symposium on Experimental Algorithms (SEA 2018)},
pages = {15:1--15:14},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-070-5},
ISSN = {1868-8969},
year = {2018},
volume = {103},
editor = {D'Angelo, Gianlorenzo},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2018.15},
URN = {urn:nbn:de:0030-drops-89506},
doi = {10.4230/LIPIcs.SEA.2018.15},
annote = {Keywords: Approximation algorithm, Steiner tree, multi-level graph representation}
}
Document
Dictionary Matching in Elastic-Degenerate Texts with Applications in Searching VCF Files On-line
Abstract
An elastic-degenerate string is a sequence of n sets of strings of total length N. It has been introduced to represent multiple sequence alignments of closely-related sequences in a compact form. For a standard pattern of length m, pattern matching in an elastic-degenerate text can be solved on-line in time O(nm^2+N) with pre-processing time and space O(m) (Grossi et al., CPM 2017). A fast bit-vector algorithm requiring time O(N * ceil[m/w]) with pre-processing time and space O(m * ceil[m/w]), where w is the size of the computer word, was also presented. In this paper we consider the same problem for a set of patterns of total length M. A straightforward generalization of the existing bit-vector algorithm would require time O(N * ceil[M/w]) with pre-processing time and space O(M * ceil[M/w]), which is prohibitive in practice. We present a new on-line O(N * ceil[M/w])-time algorithm with pre-processing time and space O(M). We present experimental results using both synthetic and real data demonstrating the performance of the algorithm. We further demonstrate a real application of our algorithm in a pipeline for discovery and verification of minimal absent words (MAWs) in the human genome showing that a significant number of previously discovered MAWs are in fact false-positives when a population's variants are considered.
Cite as
Solon P. Pissis and Ahmad Retha. Dictionary Matching in Elastic-Degenerate Texts with Applications in Searching VCF Files On-line. In 17th International Symposium on Experimental Algorithms (SEA 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 103, pp. 16:1-16:14, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)
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@InProceedings{pissis_et_al:LIPIcs.SEA.2018.16,
author = {Pissis, Solon P. and Retha, Ahmad},
title = {{Dictionary Matching in Elastic-Degenerate Texts with Applications in Searching VCF Files On-line}},
booktitle = {17th International Symposium on Experimental Algorithms (SEA 2018)},
pages = {16:1--16:14},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-070-5},
ISSN = {1868-8969},
year = {2018},
volume = {103},
editor = {D'Angelo, Gianlorenzo},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2018.16},
URN = {urn:nbn:de:0030-drops-89515},
doi = {10.4230/LIPIcs.SEA.2018.16},
annote = {Keywords: on-line algorithms, algorithms on strings, dictionary matching, elastic-degenerate string, Variant Call Format}
}
Document
Fast matching statistics in small space
Abstract
Computing the matching statistics of a string S with respect to a string T on an alphabet of size sigma is a fundamental primitive for a number of large-scale string analysis applications, including the comparison of entire genomes, for which space is a pressing issue. This paper takes from theory to practice an existing algorithm that uses just O(|T|log{sigma}) bits of space, and that computes a compact encoding of the matching statistics array in O(|S|log{sigma}) time. The techniques used to speed up the algorithm are of general interest, since they optimize queries on the existence of a Weiner link from a node of the suffix tree, and parent operations after unsuccessful Weiner links. Thus, they can be applied to other matching statistics algorithms, as well as to any suffix tree traversal that relies on such calls. Some of our optimizations yield a matching statistics implementation that is up to three times faster than a plain version of the algorithm, depending on the similarity between S and T. In genomic datasets of practical significance we achieve speedups of up to 1.8, but our fastest implementations take on average twice the time of an existing code based on the LCP array. The key advantage is that our implementations need between one half and one fifth of the competitor's memory, and they approach comparable running times when S and T are very similar.
Cite as
Djamal Belazzougui, Fabio Cunial, and Olgert Denas. Fast matching statistics in small space. In 17th International Symposium on Experimental Algorithms (SEA 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 103, pp. 17:1-17:14, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)
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@InProceedings{belazzougui_et_al:LIPIcs.SEA.2018.17,
author = {Belazzougui, Djamal and Cunial, Fabio and Denas, Olgert},
title = {{Fast matching statistics in small space}},
booktitle = {17th International Symposium on Experimental Algorithms (SEA 2018)},
pages = {17:1--17:14},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-070-5},
ISSN = {1868-8969},
year = {2018},
volume = {103},
editor = {D'Angelo, Gianlorenzo},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2018.17},
URN = {urn:nbn:de:0030-drops-89528},
doi = {10.4230/LIPIcs.SEA.2018.17},
annote = {Keywords: Matching statistics, maximal repeat, Burrows-Wheeler transform, wavelet tree, suffix tree topology}
}
Document
Practical lower and upper bounds for the Shortest Linear Superstring
Abstract
Given a set P of words, the Shortest Linear Superstring (SLS) problem is an optimisation problem that asks for a superstring of P of minimal length. SLS has applications in data compression, where a superstring is a compact representation of P, and in bioinformatics where it models the first step of genome assembly. Unfortunately SLS is hard to solve (NP-hard) and to closely approximate (MAX-SNP-hard). If numerous polynomial time approximation algorithms have been devised, few articles report on their practical performance. We lack knowledge about how closely an approximate superstring can be from an optimal one in practice. Here, we exhibit a linear time algorithm that reports an upper and a lower bound on the length of an optimal superstring. The upper bound is the length of an approximate superstring. This algorithm can be used to evaluate beforehand whether one can get an approximate superstring whose length is close to the optimum for a given instance. Experimental results suggest that its approximation performance is orders of magnitude better than previously reported practical values. Moreover, the proposed algorithm remainso efficient even on large instances and can serve to explore in practice the approximability of SLS.
Cite as
Bastien Cazaux, Samuel Juhel, and Eric Rivals. Practical lower and upper bounds for the Shortest Linear Superstring. In 17th International Symposium on Experimental Algorithms (SEA 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 103, pp. 18:1-18:14, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)
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@InProceedings{cazaux_et_al:LIPIcs.SEA.2018.18,
author = {Cazaux, Bastien and Juhel, Samuel and Rivals, Eric},
title = {{Practical lower and upper bounds for the Shortest Linear Superstring}},
booktitle = {17th International Symposium on Experimental Algorithms (SEA 2018)},
pages = {18:1--18:14},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-070-5},
ISSN = {1868-8969},
year = {2018},
volume = {103},
editor = {D'Angelo, Gianlorenzo},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2018.18},
URN = {urn:nbn:de:0030-drops-89530},
doi = {10.4230/LIPIcs.SEA.2018.18},
annote = {Keywords: greedy, approximation, overlap, Concat-Cycles, cyclic cover, linear time, text compression}
}
Document
Experimental Study of Compressed Stack Algorithms in Limited Memory Environments
Abstract
The compressed stack is a data structure designed by Barba et al. (Algorithmica 2015) that allows to reduce the amount of memory needed by a certain class of algorithms at the cost of increasing its runtime. In this paper we introduce the first implementation of this data structure and make its source code publicly available.
Together with the implementation we analyse the performance of the compressed stack. In our synthetic experiments, considering different test scenarios and using data sizes ranging up to 2^{30} elements, we compare it with the classic (uncompressed) stack, both in terms of runtime and memory used.
Our experiments show that the compressed stack needs significantly less memory than the usual stack (this difference is significant for inputs containing 2000 or more elements). Overall, with a proper choice of parameters, we can save a significant amount of space (from two to four orders of magnitude) with a small increase in the runtime (2.32 times slower on average than the classic stack). These results hold even in test scenarios specifically designed to be challenging for the compressed stack.
Cite as
Jean-François Baffier, Yago Diez, and Matias Korman. Experimental Study of Compressed Stack Algorithms in Limited Memory Environments. In 17th International Symposium on Experimental Algorithms (SEA 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 103, pp. 19:1-19:13, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)
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@InProceedings{baffier_et_al:LIPIcs.SEA.2018.19,
author = {Baffier, Jean-Fran\c{c}ois and Diez, Yago and Korman, Matias},
title = {{Experimental Study of Compressed Stack Algorithms in Limited Memory Environments}},
booktitle = {17th International Symposium on Experimental Algorithms (SEA 2018)},
pages = {19:1--19:13},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-070-5},
ISSN = {1868-8969},
year = {2018},
volume = {103},
editor = {D'Angelo, Gianlorenzo},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2018.19},
URN = {urn:nbn:de:0030-drops-89549},
doi = {10.4230/LIPIcs.SEA.2018.19},
annote = {Keywords: Stack algorithms, time-space trade-off, convex hull, implementation}
}
Document
Restructuring Expression Dags for Efficient Parallelization
Abstract
In the field of robust geometric computation it is often necessary to make exact decisions based on inexact floating-point arithmetic. One common approach is to store the computation history in an arithmetic expression dag and to re-evaluate the expression with increasing precision until an exact decision can be made. We show that exact-decisions number types based on expression dags can be evaluated faster in practice through parallelization on multiple cores. We compare the impact of several restructuring methods for the expression dag on its running time in a parallel environment.
Cite as
Martin Wilhelm. Restructuring Expression Dags for Efficient Parallelization. In 17th International Symposium on Experimental Algorithms (SEA 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 103, pp. 20:1-20:13, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)
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@InProceedings{wilhelm:LIPIcs.SEA.2018.20,
author = {Wilhelm, Martin},
title = {{Restructuring Expression Dags for Efficient Parallelization}},
booktitle = {17th International Symposium on Experimental Algorithms (SEA 2018)},
pages = {20:1--20:13},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-070-5},
ISSN = {1868-8969},
year = {2018},
volume = {103},
editor = {D'Angelo, Gianlorenzo},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2018.20},
URN = {urn:nbn:de:0030-drops-89551},
doi = {10.4230/LIPIcs.SEA.2018.20},
annote = {Keywords: exact computation, expression dag, parallel evaluation, restructuring}
}
Document
Enumerating Graph Partitions Without Too Small Connected Components Using Zero-suppressed Binary and Ternary Decision Diagrams
Abstract
Partitioning a graph into balanced components is important for several applications. For multi-objective problems, it is useful not only to find one solution but also to enumerate all the solutions with good values of objectives. However, there are a vast number of graph partitions in a graph, and thus it is difficult to enumerate desired graph partitions efficiently. In this paper, an algorithm to enumerate all the graph partitions such that all the weights of the connected components are at least a specified value is proposed. To deal with a large search space, we use zero-suppressed binary decision diagrams (ZDDs) to represent sets of graph partitions and we design a new algorithm based on frontier-based search, which is a framework to directly construct a ZDD. Our algorithm utilizes not only ZDDs but also ternary decision diagrams (TDDs) and realizes an operation which seems difficult to be designed only by ZDDs. Experimental results show that the proposed algorithm runs up to tens of times faster than an existing state-of-the-art algorithm.
Cite as
Yu Nakahata, Jun Kawahara, and Shoji Kasahara. Enumerating Graph Partitions Without Too Small Connected Components Using Zero-suppressed Binary and Ternary Decision Diagrams. In 17th International Symposium on Experimental Algorithms (SEA 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 103, pp. 21:1-21:13, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)
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@InProceedings{nakahata_et_al:LIPIcs.SEA.2018.21,
author = {Nakahata, Yu and Kawahara, Jun and Kasahara, Shoji},
title = {{Enumerating Graph Partitions Without Too Small Connected Components Using Zero-suppressed Binary and Ternary Decision Diagrams}},
booktitle = {17th International Symposium on Experimental Algorithms (SEA 2018)},
pages = {21:1--21:13},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-070-5},
ISSN = {1868-8969},
year = {2018},
volume = {103},
editor = {D'Angelo, Gianlorenzo},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2018.21},
URN = {urn:nbn:de:0030-drops-89560},
doi = {10.4230/LIPIcs.SEA.2018.21},
annote = {Keywords: Graph algorithm, Graph partitioning, Decision diagram, Frontier-based search, Enumeration problem}
}
Document
Exact Algorithms for the Maximum Planar Subgraph Problem: New Models and Experiments
Abstract
Given a graph G, the NP-hard Maximum Planar Subgraph problem asks for a planar subgraph of G with the maximum number of edges. The only known non-trivial exact algorithm utilizes Kuratowski's famous planarity criterion and can be formulated as an integer linear program (ILP) or a pseudo-boolean satisfiability problem (PBS). We examine three alternative characterizations of planarity regarding their applicability to model maximum planar subgraphs. For each, we consider both ILP and PBS variants, investigate diverse formulation aspects, and evaluate their practical performance.
Cite as
Markus Chimani, Ivo Hedtke, and Tilo Wiedera. Exact Algorithms for the Maximum Planar Subgraph Problem: New Models and Experiments. In 17th International Symposium on Experimental Algorithms (SEA 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 103, pp. 22:1-22:15, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)
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@InProceedings{chimani_et_al:LIPIcs.SEA.2018.22,
author = {Chimani, Markus and Hedtke, Ivo and Wiedera, Tilo},
title = {{Exact Algorithms for the Maximum Planar Subgraph Problem: New Models and Experiments}},
booktitle = {17th International Symposium on Experimental Algorithms (SEA 2018)},
pages = {22:1--22:15},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-070-5},
ISSN = {1868-8969},
year = {2018},
volume = {103},
editor = {D'Angelo, Gianlorenzo},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2018.22},
URN = {urn:nbn:de:0030-drops-89572},
doi = {10.4230/LIPIcs.SEA.2018.22},
annote = {Keywords: maximum planar subgraph, integer linear programming, pseudo boolean satisfiability, graph drawing, algorithm engineering}
}
Document
A Linear-Time Algorithm for Finding Induced Planar Subgraphs
Abstract
In this paper we study the problem of efficiently and effectively extracting induced planar subgraphs. Edwards and Farr proposed an algorithm with O(mn) time complexity to find an induced planar subgraph of at least 3n/(d+1) vertices in a graph of maximum degree d. They also proposed an alternative algorithm with O(mn) time complexity to find an induced planar subgraph graph of at least 3n/(bar{d}+1) vertices, where bar{d} is the average degree of the graph. These two methods appear to be best known when d and bar{d} are small. Unfortunately, they sacrifice accuracy for lower time complexity by using indirect indicators of planarity. A limitation of those approaches is that the algorithms do not implicitly test for planarity, and the additional costs of this test can be significant in large graphs. In contrast, we propose a linear-time algorithm that finds an induced planar subgraph of n-nu vertices in a graph of n vertices, where nu denotes the total number of vertices shared by the detected Kuratowski subdivisions. An added benefit of our approach is that we are able to detect when a graph is planar, and terminate the reduction. The resulting planar subgraphs also do not have any rigid constraints on the maximum degree of the induced subgraph. The experiment results show that our method achieves better performance than current methods on graphs with small skewness.
Cite as
Shixun Huang, Zhifeng Bao, J. Shane Culpepper, Ping Zhang, and Bang Zhang. A Linear-Time Algorithm for Finding Induced Planar Subgraphs. In 17th International Symposium on Experimental Algorithms (SEA 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 103, pp. 23:1-23:15, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)
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@InProceedings{huang_et_al:LIPIcs.SEA.2018.23,
author = {Huang, Shixun and Bao, Zhifeng and Culpepper, J. Shane and Zhang, Ping and Zhang, Bang},
title = {{A Linear-Time Algorithm for Finding Induced Planar Subgraphs}},
booktitle = {17th International Symposium on Experimental Algorithms (SEA 2018)},
pages = {23:1--23:15},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-070-5},
ISSN = {1868-8969},
year = {2018},
volume = {103},
editor = {D'Angelo, Gianlorenzo},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2018.23},
URN = {urn:nbn:de:0030-drops-89589},
doi = {10.4230/LIPIcs.SEA.2018.23},
annote = {Keywords: induced planar subgraphs, experimental analysis}
}
Document
Fast Spherical Drawing of Triangulations: An Experimental Study of Graph Drawing Tools
Abstract
We consider the problem of computing a spherical crossing-free geodesic drawing of a planar graph: this problem, as well as the closely related spherical parameterization problem, has attracted a lot of attention in the last two decades both in theory and in practice, motivated by a number of applications ranging from texture mapping to mesh remeshing and morphing. Our main concern is to design and implement a linear time algorithm for the computation of spherical drawings provided with theoretical guarantees. While not being aesthetically pleasing, our method is extremely fast and can be used as initial placer for spherical iterative methods and spring embedders. We provide experimental comparison with initial placers based on planar Tutte parameterization. Finally we explore the use of spherical drawings as initial layouts for (Euclidean) spring embedders: experimental evidence shows that this greatly helps to untangle the layout and to reach better local minima.
Cite as
Luca Castelli Aleardi, Gaspard Denis, and Éric Fusy. Fast Spherical Drawing of Triangulations: An Experimental Study of Graph Drawing Tools. In 17th International Symposium on Experimental Algorithms (SEA 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 103, pp. 24:1-24:14, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)
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@InProceedings{aleardi_et_al:LIPIcs.SEA.2018.24,
author = {Aleardi, Luca Castelli and Denis, Gaspard and Fusy, \'{E}ric},
title = {{Fast Spherical Drawing of Triangulations: An Experimental Study of Graph Drawing Tools}},
booktitle = {17th International Symposium on Experimental Algorithms (SEA 2018)},
pages = {24:1--24:14},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-070-5},
ISSN = {1868-8969},
year = {2018},
volume = {103},
editor = {D'Angelo, Gianlorenzo},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2018.24},
URN = {urn:nbn:de:0030-drops-89597},
doi = {10.4230/LIPIcs.SEA.2018.24},
annote = {Keywords: Graph drawing, planar triangulations, spherical parameterizations}
}
Document
Fleet Management for Autonomous Vehicles Using Multicommodity Coupled Flows in Time-Expanded Networks
Abstract
VIPAFLEET is a framework to develop models and algorithms for managing a fleet of Individual Public Autonomous Vehicles (VIPA). We consider a homogeneous fleet of such vehicles distributed at specified stations in a closed site to supply internal transportation, where the vehicles can be used in different modes of circulation (tram mode, elevator mode, taxi mode). We treat in this paper a variant of the Online Pickup-and-Delivery Problem related to the taxi mode by means of multicommodity coupled flows in a time-expanded network and propose a corresponding integer linear programming formulation. This enables us to compute optimal offline solutions. However, to apply the well-known meta-strategy Replan to the online situation by solving a sequence of offline subproblems, the computation times turned out to be too long, so that we devise a heuristic approach h-Replan based on the flow formulation. Finally, we evaluate the performance of h-Replan in comparison with the optimal offline solution, both in terms of competitive analysis and computational experiments, showing that h-Replan computes reasonable solutions, so that it suits for the online situation.
Cite as
Sahar Bsaybes, Alain Quilliot, and Annegret K. Wagler. Fleet Management for Autonomous Vehicles Using Multicommodity Coupled Flows in Time-Expanded Networks. In 17th International Symposium on Experimental Algorithms (SEA 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 103, pp. 25:1-25:14, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)
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@InProceedings{bsaybes_et_al:LIPIcs.SEA.2018.25,
author = {Bsaybes, Sahar and Quilliot, Alain and Wagler, Annegret K.},
title = {{Fleet Management for Autonomous Vehicles Using Multicommodity Coupled Flows in Time-Expanded Networks}},
booktitle = {17th International Symposium on Experimental Algorithms (SEA 2018)},
pages = {25:1--25:14},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-070-5},
ISSN = {1868-8969},
year = {2018},
volume = {103},
editor = {D'Angelo, Gianlorenzo},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2018.25},
URN = {urn:nbn:de:0030-drops-89600},
doi = {10.4230/LIPIcs.SEA.2018.25},
annote = {Keywords: fleet management, offline and online pickup and delivery problem, multicommodity flows}
}
Document
The Steiner Multi Cycle Problem with Applications to a Collaborative Truckload Problem
Abstract
We introduce a new problem called Steiner Multi Cycle Problem that extends the Steiner Cycle problem in the same way the Steiner Forest extends the Steiner Tree problem. In this problem we are given a complete weighted graph G=(V,E), which respects the triangle inequality, a collection of terminal sets {T_1,..., T_k}, where for each a in [k] we have a subset T_a of V and these terminal sets are pairwise disjoint. The problem is to find a set of disjoint cycles of minimum cost such that for each a in [k], all vertices of T_a belong to a same cycle. Our main interest is in a restricted case where |T_a| = 2, for each a in [k], which models a collaborative less-than-truckload problem with pickup and delivery. In this problem, we have a set of agents where each agent is associated with a set T_a containing a pair of pickup and delivery vertices. This problem arises in the scenario where a company has to periodically exchange goods between two different locations, and different companies can collaborate to create a route that visits all its pairs of locations sharing the total cost of the route. We show that even the restricted problem is NP-Hard, and present some heuristics to solve it. In particular, a constructive heuristic called Refinement Search, which uses geometric properties to determine if agents are close to each other. We performed computational experiments to compare this heuristic to a GRASP based heuristic. The Refinement Search obtained the best solutions in little computational time.
Cite as
Vinicius N. G. Pereira, Mário César San Felice, Pedro Henrique D. B. Hokama, and Eduardo C. Xavier. The Steiner Multi Cycle Problem with Applications to a Collaborative Truckload Problem. In 17th International Symposium on Experimental Algorithms (SEA 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 103, pp. 26:1-26:13, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)
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@InProceedings{pereira_et_al:LIPIcs.SEA.2018.26,
author = {Pereira, Vinicius N. G. and San Felice, M\'{a}rio C\'{e}sar and Hokama, Pedro Henrique D. B. and Xavier, Eduardo C.},
title = {{The Steiner Multi Cycle Problem with Applications to a Collaborative Truckload Problem}},
booktitle = {17th International Symposium on Experimental Algorithms (SEA 2018)},
pages = {26:1--26:13},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-070-5},
ISSN = {1868-8969},
year = {2018},
volume = {103},
editor = {D'Angelo, Gianlorenzo},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2018.26},
URN = {urn:nbn:de:0030-drops-89617},
doi = {10.4230/LIPIcs.SEA.2018.26},
annote = {Keywords: Steiner Cycle, Routing, Pickup-and-Delivery, Less-than-Truckload}
}
Document
Real-Time Traffic Assignment Using Fast Queries in Customizable Contraction Hierarchies
Abstract
Given an urban road network and a set of origin-destination (OD) pairs, the traffic assignment problem asks for the traffic flow on each road segment. A common solution employs a feasible-direction method, where the direction-finding step requires many shortest-path computations. In this paper, we significantly accelerate the computation of flow patterns, enabling interactive transportation and urban planning applications. We achieve this by revisiting and carefully engineering known speedup techniques for shortest paths, and combining them with customizable contraction hierarchies. In particular, our accelerated elimination tree search is more than an order of magnitude faster for local queries than the original algorithm, and our centralized search speeds up batched point-to-point shortest paths by a factor of up to 6. These optimizations are independent of traffic assignment and can be generally used for (batched) point-to-point queries. In contrast to prior work, our evaluation uses real-world data for all parts of the problem. On a metropolitan area encompassing more than 2.7 million inhabitants, we reduce the flow-pattern computation for a typical two-hour morning peak from 76.5 to 10.5 seconds on one core, and 4.3 seconds on four cores. This represents a speedup of 18 over the state of the art, and three orders of magnitude over the Dijkstra-based baseline.
Cite as
Valentin Buchhold, Peter Sanders, and Dorothea Wagner. Real-Time Traffic Assignment Using Fast Queries in Customizable Contraction Hierarchies. In 17th International Symposium on Experimental Algorithms (SEA 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 103, pp. 27:1-27:15, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)
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@InProceedings{buchhold_et_al:LIPIcs.SEA.2018.27,
author = {Buchhold, Valentin and Sanders, Peter and Wagner, Dorothea},
title = {{Real-Time Traffic Assignment Using Fast Queries in Customizable Contraction Hierarchies}},
booktitle = {17th International Symposium on Experimental Algorithms (SEA 2018)},
pages = {27:1--27:15},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-070-5},
ISSN = {1868-8969},
year = {2018},
volume = {103},
editor = {D'Angelo, Gianlorenzo},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2018.27},
URN = {urn:nbn:de:0030-drops-89623},
doi = {10.4230/LIPIcs.SEA.2018.27},
annote = {Keywords: traffic assignment, equilibrium flow pattern, customizable contraction hierarchies, batched shortest paths}
}
Document
Engineering Motif Search for Large Motifs
Abstract
Given a vertex-colored graph H and a multiset M of colors as input, the graph motif problem asks us to decide whether H has a connected induced subgraph whose multiset of colors agrees with M. The graph motif problem is NP-complete but known to admit randomized algorithms based on constrained multilinear sieving over GF(2^b) that run in time O(2^kk^2m {M({2^b})}) and with a false-negative probability of at most k/2^{b-1} for a connected m-edge input and a motif of size k. On modern CPU microarchitectures such algorithms have practical edge-linear scalability to inputs with billions of edges for small motif sizes, as demonstrated by Björklund, Kaski, Kowalik, and Lauri [ALENEX'15]. This scalability to large graphs prompts the dual question whether it is possible to scale to large motif sizes.
We present a vertex-localized variant of the constrained multilinear sieve that enables us to obtain, in time O(2^kk^2m{M({2^b})}) and for every vertex simultaneously, whether the vertex participates in at least one match with the motif, with a per-vertex probability of at most k/2^{b-1} for a false negative. Furthermore, the algorithm is easily vector-parallelizable for up to 2^k threads, and parallelizable for up to 2^kn threads, where n is the number of vertices in H. Here {M({2^b})} is the time complexity to multiply in GF(2^b).
We demonstrate with an open-source implementation that our variant of constrained multilinear sieving can be engineered for vector-parallel microarchitectures to yield hardware utilization that is bound by the available memory bandwidth.
Our main engineering contributions are (a) a version of the recurrence for tightly labeled arborescences that can be executed as a sequence of memory-and-arithmetic coalescent parallel workloads on multiple GPUs, and (b) a bit-sliced low-level implementation for arithmetic in characteristic 2 to support (a).
Cite as
Petteri Kaski, Juho Lauri, and Suhas Thejaswi. Engineering Motif Search for Large Motifs. In 17th International Symposium on Experimental Algorithms (SEA 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 103, pp. 28:1-28:19, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)
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@InProceedings{kaski_et_al:LIPIcs.SEA.2018.28,
author = {Kaski, Petteri and Lauri, Juho and Thejaswi, Suhas},
title = {{Engineering Motif Search for Large Motifs}},
booktitle = {17th International Symposium on Experimental Algorithms (SEA 2018)},
pages = {28:1--28:19},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-070-5},
ISSN = {1868-8969},
year = {2018},
volume = {103},
editor = {D'Angelo, Gianlorenzo},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2018.28},
URN = {urn:nbn:de:0030-drops-89631},
doi = {10.4230/LIPIcs.SEA.2018.28},
annote = {Keywords: algorithm engineering, constrained multilinear sieving, graph motif problem, multi-GPU, vector-parallel, vertex-localization}
}
Document
Finding Hamiltonian Cycle in Graphs of Bounded Treewidth: Experimental Evaluation
Abstract
The notion of treewidth, introduced by Robertson and Seymour in their seminal Graph Minors series, turned out to have tremendous impact on graph algorithmics. Many hard computational problems on graphs turn out to be efficiently solvable in graphs of bounded treewidth: graphs that can be sweeped with separators of bounded size. These efficient algorithms usually follow the dynamic programming paradigm.
In the recent years, we have seen a rapid and quite unexpected development of involved techniques for solving various computational problems in graphs of bounded treewidth. One of the most surprising directions is the development of algorithms for connectivity problems that have only single-exponential dependency (i.e., 2^{{O}(t)}) on the treewidth in the running time bound, as opposed to slightly superexponential (i.e., 2^{{O}(t log t)}) stemming from more naive approaches. In this work, we perform a thorough experimental evaluation of these approaches in the context of one of the most classic connectivity problem, namely Hamiltonian Cycle.
Cite as
Michal Ziobro and Marcin Pilipczuk. Finding Hamiltonian Cycle in Graphs of Bounded Treewidth: Experimental Evaluation. In 17th International Symposium on Experimental Algorithms (SEA 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 103, pp. 29:1-29:14, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)
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@InProceedings{ziobro_et_al:LIPIcs.SEA.2018.29,
author = {Ziobro, Michal and Pilipczuk, Marcin},
title = {{Finding Hamiltonian Cycle in Graphs of Bounded Treewidth: Experimental Evaluation}},
booktitle = {17th International Symposium on Experimental Algorithms (SEA 2018)},
pages = {29:1--29:14},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-070-5},
ISSN = {1868-8969},
year = {2018},
volume = {103},
editor = {D'Angelo, Gianlorenzo},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2018.29},
URN = {urn:nbn:de:0030-drops-89648},
doi = {10.4230/LIPIcs.SEA.2018.29},
annote = {Keywords: Empirical Evaluation of Algorithms, Treewidth, Hamiltonian Cycle}
}
Document
Isomorphism Test for Digraphs with Weighted Edges
Abstract
Colour refinement is at the heart of all the most efficient graph isomorphism software packages. In this paper we present a method for extending the applicability of refinement algorithms to directed graphs with weighted edges. We use {Traces} as a reference software, but the proposed solution is easily transferrable to any other refinement-based graph isomorphism tool in the literature. We substantiate the claim that the performances of the original algorithm remain substantially unchanged by showing experiments for some classes of benchmark graphs.
Cite as
Adolfo Piperno. Isomorphism Test for Digraphs with Weighted Edges. In 17th International Symposium on Experimental Algorithms (SEA 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 103, pp. 30:1-30:13, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)
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@InProceedings{piperno:LIPIcs.SEA.2018.30,
author = {Piperno, Adolfo},
title = {{Isomorphism Test for Digraphs with Weighted Edges}},
booktitle = {17th International Symposium on Experimental Algorithms (SEA 2018)},
pages = {30:1--30:13},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-070-5},
ISSN = {1868-8969},
year = {2018},
volume = {103},
editor = {D'Angelo, Gianlorenzo},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2018.30},
URN = {urn:nbn:de:0030-drops-89659},
doi = {10.4230/LIPIcs.SEA.2018.30},
annote = {Keywords: Practical Graph Isomorphism, Weighted Directed Graphs, Partition Refinement}
}