4 Search Results for "Boria, Nicolas"

Document
DOI: 10.4230/LIPIcs.WADS.2025.31
Repairing Schedules by Removing Waiting Times: A Parameterized Complexity Analysis

Authors: Niels Grüttemeier and Klaus Heeger

Published in: LIPIcs, Volume 349, 19th International Symposium on Algorithms and Data Structures (WADS 2025)

Abstract
We consider the problem of repairing production schedules in a job-shop setting by reducing pre-planned waiting times. Herein, a schedule of all jobs is given. To compensate unforeseen disturbances, this schedule contains waiting times between the execution of two consecutive tasks of a job. Further, we assume that the schedule temporarily overloads some machines, e.g. due to reduced machine capacities because of worker sickness or (partially) broken machines. We study the problem of removing as few waiting times as possible in order to eliminate the machine overloads. After formalizing this problem, we perform an extensive analysis of its parameterized complexity with respect to several natural parameters, resulting in a detailed picture of the problem’s complexity.
Cite as

Niels Grüttemeier and Klaus Heeger. Repairing Schedules by Removing Waiting Times: A Parameterized Complexity Analysis. In 19th International Symposium on Algorithms and Data Structures (WADS 2025). Leibniz International Proceedings in Informatics (LIPIcs), Volume 349, pp. 31:1-31:14, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)

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@InProceedings{gruttemeier_et_al:LIPIcs.WADS.2025.31,
  author =	{Gr\"{u}ttemeier, Niels and Heeger, Klaus},
  title =	{{Repairing Schedules by Removing Waiting Times: A Parameterized Complexity Analysis}},
  booktitle =	{19th International Symposium on Algorithms and Data Structures (WADS 2025)},
  pages =	{31:1--31:14},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-398-0},
  ISSN =	{1868-8969},
  year =	{2025},
  volume =	{349},
  editor =	{Morin, Pat and Oh, Eunjin},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.WADS.2025.31},
  URN =		{urn:nbn:de:0030-drops-242624},
  doi =		{10.4230/LIPIcs.WADS.2025.31},
  annote =	{Keywords: Job shop, parallel machines, reactive scheduling}
}
Document
DOI: 10.4230/LIPIcs.STACS.2025.36
MaxMin Separation Problems: FPT Algorithms for st-Separator and Odd Cycle Transversal

Authors: Ajinkya Gaikwad, Hitendra Kumar, Soumen Maity, Saket Saurabh, and Roohani Sharma

Published in: LIPIcs, Volume 327, 42nd International Symposium on Theoretical Aspects of Computer Science (STACS 2025)

Abstract
In this paper, we study the parameterized complexity of the MaxMin versions of two fundamental separation problems: Maximum Minimal st-Separator and Maximum Minimal Odd Cycle Transversal (OCT), both parameterized by the solution size. In the Maximum Minimal st-Separator problem, given a graph G, two distinct vertices s and t and a positive integer k, the goal is to determine whether there exists a minimal st-separator in G of size at least k. Similarly, the Maximum Minimal OCT problem seeks to determine if there exists a minimal set of vertices whose deletion results in a bipartite graph, and whose size is at least k. We demonstrate that both problems are fixed-parameter tractable parameterized by k. Our FPT algorithm for Maximum Minimal st-Separator answers the open question by Hanaka, Bodlaender, van der Zanden & Ono [TCS 2019]. One unique insight from this work is the following. We use the meta-result of Lokshtanov, Ramanujan, Saurabh & Zehavi [ICALP 2018] that enables us to reduce our problems to highly unbreakable graphs. This is interesting, as an explicit use of the recursive understanding and randomized contractions framework of Chitnis, Cygan, Hajiaghayi, Pilipczuk & Pilipczuk [SICOMP 2016] to reduce to the highly unbreakable graphs setting (which is the result that Lokshtanov et al. tries to abstract out in their meta-theorem) does not seem obvious because certain "extension" variants of our problems are W[1]-hard.
Cite as

Ajinkya Gaikwad, Hitendra Kumar, Soumen Maity, Saket Saurabh, and Roohani Sharma. MaxMin Separation Problems: FPT Algorithms for st-Separator and Odd Cycle Transversal. In 42nd International Symposium on Theoretical Aspects of Computer Science (STACS 2025). Leibniz International Proceedings in Informatics (LIPIcs), Volume 327, pp. 36:1-36:21, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)

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@InProceedings{gaikwad_et_al:LIPIcs.STACS.2025.36,
  author =	{Gaikwad, Ajinkya and Kumar, Hitendra and Maity, Soumen and Saurabh, Saket and Sharma, Roohani},
  title =	{{MaxMin Separation Problems: FPT Algorithms for st-Separator and Odd Cycle Transversal}},
  booktitle =	{42nd International Symposium on Theoretical Aspects of Computer Science (STACS 2025)},
  pages =	{36:1--36:21},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-365-2},
  ISSN =	{1868-8969},
  year =	{2025},
  volume =	{327},
  editor =	{Beyersdorff, Olaf and Pilipczuk, Micha{\l} and Pimentel, Elaine and Thắng, Nguy\~{ê}n Kim},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.STACS.2025.36},
  URN =		{urn:nbn:de:0030-drops-228622},
  doi =		{10.4230/LIPIcs.STACS.2025.36},
  annote =	{Keywords: Parameterized Complexity, FPT, MaxMin problems, Maximum Minimal st-separator, Maximum Minimal Odd Cycle Transversal, Unbreakable Graphs, CMSO, Long Induced Odd Cycles, Sunflower Lemma}
}
Document
DOI: 10.4230/LIPIcs.WABI.2021.5
The Maximum Duo-Preservation String Mapping Problem with Bounded Alphabet

Authors: Nicolas Boria, Laurent Gourvès, Vangelis Th. Paschos, and Jérôme Monnot

Published in: LIPIcs, Volume 201, 21st International Workshop on Algorithms in Bioinformatics (WABI 2021)

Abstract
Given two strings A and B such that B is a permutation of A, the max duo-preservation string mapping (MPSM) problem asks to find a mapping π between them so as to preserve a maximum number of duos. A duo is any pair of consecutive characters in a string and it is preserved by π if its two consecutive characters in A are mapped to same two consecutive characters in B. This problem has received a growing attention in recent years, partly as an alternative way to produce approximation algorithms for its minimization counterpart, min common string partition, a widely studied problem due its applications in comparative genomics. Considering this favored field of application with short alphabet, it is surprising that MPSM^𝓁, the variant of MPSM with bounded alphabet, has received so little attention, with a single yet impressive work that provides a 2.67-approximation achieved in O(n) [Brubach, 2018], where n = |A| = |B|. Our work focuses on MPSM^𝓁, and our main contribution is the demonstration that this problem admits a Polynomial Time Approximation Scheme (PTAS) when 𝓁 = O(1). We also provide an alternate, somewhat simpler, proof of NP-hardness for this problem compared with the NP-hardness proof presented in [Haitao Jiang et al., 2012].
Cite as

Nicolas Boria, Laurent Gourvès, Vangelis Th. Paschos, and Jérôme Monnot. The Maximum Duo-Preservation String Mapping Problem with Bounded Alphabet. In 21st International Workshop on Algorithms in Bioinformatics (WABI 2021). Leibniz International Proceedings in Informatics (LIPIcs), Volume 201, pp. 5:1-5:12, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2021)

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@InProceedings{boria_et_al:LIPIcs.WABI.2021.5,
  author =	{Boria, Nicolas and Gourv\`{e}s, Laurent and Paschos, Vangelis Th. and Monnot, J\'{e}r\^{o}me},
  title =	{{The Maximum Duo-Preservation String Mapping Problem with Bounded Alphabet}},
  booktitle =	{21st International Workshop on Algorithms in Bioinformatics (WABI 2021)},
  pages =	{5:1--5:12},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-200-6},
  ISSN =	{1868-8969},
  year =	{2021},
  volume =	{201},
  editor =	{Carbone, Alessandra and El-Kebir, Mohammed},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.WABI.2021.5},
  URN =		{urn:nbn:de:0030-drops-143586},
  doi =		{10.4230/LIPIcs.WABI.2021.5},
  annote =	{Keywords: Maximum-Duo Preservation String Mapping, Bounded alphabet, Polynomial Time Approximation Scheme}
}
Document
DOI: 10.4230/LIPIcs.CPM.2016.11
A 7/2-Approximation Algorithm for the Maximum Duo-Preservation String Mapping Problem

Authors: Nicolas Boria, Gianpiero Cabodi, Paolo Camurati, Marco Palena, Paolo Pasini, and Stefano Quer

Published in: LIPIcs, Volume 54, 27th Annual Symposium on Combinatorial Pattern Matching (CPM 2016)

Abstract
This paper presents a simple 7/2-approximation algorithm for the Maximum Duo-Preservation String Mapping (MPSM) problem. This problem is complementary to the classical and well studied min common string partition problem (MCSP), that computes the minimal edit distance between two strings when the only operation allowed is to shift blocks of characters. The algorithm improves on the previously best-known 4-approximation algorithm by computing a simple local optimum.
Cite as

Nicolas Boria, Gianpiero Cabodi, Paolo Camurati, Marco Palena, Paolo Pasini, and Stefano Quer. A 7/2-Approximation Algorithm for the Maximum Duo-Preservation String Mapping Problem. In 27th Annual Symposium on Combinatorial Pattern Matching (CPM 2016). Leibniz International Proceedings in Informatics (LIPIcs), Volume 54, pp. 11:1-11:8, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2016)

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@InProceedings{boria_et_al:LIPIcs.CPM.2016.11,
  author =	{Boria, Nicolas and Cabodi, Gianpiero and Camurati, Paolo and Palena, Marco and Pasini, Paolo and Quer, Stefano},
  title =	{{A 7/2-Approximation Algorithm for the Maximum Duo-Preservation String Mapping Problem}},
  booktitle =	{27th Annual Symposium on Combinatorial Pattern Matching (CPM 2016)},
  pages =	{11:1--11:8},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-012-5},
  ISSN =	{1868-8969},
  year =	{2016},
  volume =	{54},
  editor =	{Grossi, Roberto and Lewenstein, Moshe},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CPM.2016.11},
  URN =		{urn:nbn:de:0030-drops-60875},
  doi =		{10.4230/LIPIcs.CPM.2016.11},
  annote =	{Keywords: Polynomial approximation, Max Duo-Preservation String Mapping Problem, Min Common String Partition Problem, Local Search}
}
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