5 Search Results for "Dumas, Jean-Guillaume"

Document
DOI: 10.4230/LIPIcs.SWAT.2026.39
Faster Approximate Linear Matroid Intersection

Authors: Tatsuya Terao

Published in: LIPIcs, Volume 370, 20th Scandinavian Symposium on Algorithm Theory (SWAT 2026)

Abstract
We consider a fast approximation algorithm for the linear matroid intersection problem. In this problem, we are given two r × n matrices M₁ and M₂, and the objective is to find a largest set of columns that are linearly independent in both M₁ and M₂. We design a (1 - ε)-approximation algorithm with time complexity Õ_{ε}(nnz(M₁) + nnz(M₂) + r_{*}^{ω}), where nnz(M_i) denotes the number of nonzero entries in M_i for i = 1, 2, r_{*} denotes the maximum size of a common independent set, and ω < 2.372 denotes the matrix multiplication exponent. Our approximation algorithm is faster than the exact algorithm by Harvey [FOCS'06 & SICOMP'09] and Cheung-Kwok-Lau [STOC'12 & JACM'13], which runs in Õ(nnz(M₁) + nnz(M₂) + n r_{*}^{ω - 1}) time. We also develop a fast (1 - ε)-approximation algorithm for the weighted version of the linear matroid intersection problem. In fact, we design a (1 - ε)-approximation algorithm for weighted linear matroid intersection with time complexity Õ_{ε}(nnz(M₁) + nnz(M₂) + r_{*}^{ω}). Our algorithm improves upon the (1 - ε)-approximation algorithm by Huang-Kakimura-Kamiyama [SODA'16 & Math. Program.'19], which runs in Õ_{ε}(nnz(M₁) + nnz(M₂) + nr_{*}^{ω - 1}) time. To obtain these results, we combine Quanrud’s adaptive sparsification framework [ICALP'24] with a simple yet effective method for efficiently checking whether a given vector lies in the linear span of a subset of vectors, which is of independent interest.
Cite as

Tatsuya Terao. Faster Approximate Linear Matroid Intersection. In 20th Scandinavian Symposium on Algorithm Theory (SWAT 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 370, pp. 39:1-39:19, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)

Copy BibTex To Clipboard

@InProceedings{terao:LIPIcs.SWAT.2026.39,
  author =	{Terao, Tatsuya},
  title =	{{Faster Approximate Linear Matroid Intersection}},
  booktitle =	{20th Scandinavian Symposium on Algorithm Theory (SWAT 2026)},
  pages =	{39:1--39:19},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-421-5},
  ISSN =	{1868-8969},
  year =	{2026},
  volume =	{370},
  editor =	{Fraigniaud, Pierre},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SWAT.2026.39},
  URN =		{urn:nbn:de:0030-drops-260756},
  doi =		{10.4230/LIPIcs.SWAT.2026.39},
  annote =	{Keywords: Linear matroid intersection, fast approximation algorithm}
}
Document
DOI: 10.4230/OASIcs.SpaceCHI.2025.30
A Research Framework to Develop a Real-Time Synchrony Index to Monitor Team Cohesion and Performance in Long-Duration Space Exploration

Authors: Federico Nemmi, Emma Chabani, Laure Boyer, Charlie Madier, and Daniel Lewkowicz

Published in: OASIcs, Volume 130, Advancing Human-Computer Interaction for Space Exploration (SpaceCHI 2025)

Abstract
As humanity prepares for long-distance space exploration, optimizing group performance, the ability of a group to achieve its goals efficiently, is critical. Astronaut crews will endure isolation, confinement, and operational stress, making group synchrony - the alignment of behaviors, emotions, and physiological states - a key factor in mission success. Synchrony influences team cohesion, performance, and resilience, necessitating effective crew management strategies. This paper proposes a framework for a real-time, unobtrusive index of group synchrony to support astronauts and mission control. Research indicates that team cohesion fluctuates in isolated environments, with reduced communication and interpersonal conflicts emerging over time. A system tracking synchrony could mitigate these issues, providing proactive support and improving remote management. Additionally, it could serve as a cognitive and physiological feedback tool for astronauts and a decision-making aid for mission control, enhancing well-being and efficiency. Our approach integrates behavioral and physiological synchrony measures to assess team cohesion and performance. We propose a multi-modal synchrony index combining movement coordination, communication patterns, and physiological signals such as heart rate, electrodermal activity, and EEG. This index will be validated across different tasks to ensure applicability across diverse mission scenarios. By developing a robust synchrony index, we address a fundamental challenge in space missions: sustaining team effectiveness under extreme conditions. Beyond space exploration, our findings could benefit high-risk, high-isolation teams in submarine crews, polar expeditions, and remote research groups. Our collaboration with the Centre National d'Etudes Spatiales, the Institut de Médecine et de Physiologie Spatiales, and the Toulouse University Hospital marks the first step, with experimental data collection starting this year. Ultimately, this research fosters more adaptive, responsive, and resilient teams for future space missions.
Cite as

Federico Nemmi, Emma Chabani, Laure Boyer, Charlie Madier, and Daniel Lewkowicz. A Research Framework to Develop a Real-Time Synchrony Index to Monitor Team Cohesion and Performance in Long-Duration Space Exploration. In Advancing Human-Computer Interaction for Space Exploration (SpaceCHI 2025). Open Access Series in Informatics (OASIcs), Volume 130, pp. 30:1-30:16, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)

Copy BibTex To Clipboard

@InProceedings{nemmi_et_al:OASIcs.SpaceCHI.2025.30,
  author =	{Nemmi, Federico and Chabani, Emma and Boyer, Laure and Madier, Charlie and Lewkowicz, Daniel},
  title =	{{A Research Framework to Develop a Real-Time Synchrony Index to Monitor Team Cohesion and Performance in Long-Duration Space Exploration}},
  booktitle =	{Advancing Human-Computer Interaction for Space Exploration (SpaceCHI 2025)},
  pages =	{30:1--30:16},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-384-3},
  ISSN =	{2190-6807},
  year =	{2025},
  volume =	{130},
  editor =	{Bensch, Leonie and Nilsson, Tommy and Nisser, Martin and Pataranutaporn, Pat and Schmidt, Albrecht and Sumini, Valentina},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.SpaceCHI.2025.30},
  URN =		{urn:nbn:de:0030-drops-240200},
  doi =		{10.4230/OASIcs.SpaceCHI.2025.30},
  annote =	{Keywords: Performance, Synchronie, Crew monitoring, Cohesion}
}
Document
DOI: 10.4230/LIPIcs.FUN.2018.13
A Cryptographer's Conspiracy Santa

Authors: Xavier Bultel, Jannik Dreier, Jean-Guillaume Dumas, and Pascal Lafourcade

Published in: LIPIcs, Volume 100, 9th International Conference on Fun with Algorithms (FUN 2018)

Abstract
In Conspiracy Santa, a variant of Secret Santa, a group of people offer each other Christmas gifts, where each member of the group receives a gift from the other members of the group. To that end, the members of the group form conspiracies, to decide on appropriate gifts, and usually divide the cost of each gift among all participants of that conspiracy. This requires to settle the shared expenses per conspiracy, so Conspiracy Santa can actually be seen as an aggregation of several shared expenses problems. First, we show that the problem of finding a minimal number of transaction when settling shared expenses is NP-complete. Still, there exists good greedy approximations. Second, we present a greedy distributed secure solution to Conspiracy Santa. This solution allows a group of people to share the expenses for the gifts in such a way that no participant learns the price of his gift, but at the same time notably reduces the number of transactions with respect to a naive aggregation. Furthermore, our solution does not require a trusted third party, and can either be implemented physically (the participants are in the same room and exchange money using envelopes) or, virtually, using a cryptocurrency.
Cite as

Xavier Bultel, Jannik Dreier, Jean-Guillaume Dumas, and Pascal Lafourcade. A Cryptographer's Conspiracy Santa. In 9th International Conference on Fun with Algorithms (FUN 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 100, pp. 13:1-13:13, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)

Copy BibTex To Clipboard

@InProceedings{bultel_et_al:LIPIcs.FUN.2018.13,
  author =	{Bultel, Xavier and Dreier, Jannik and Dumas, Jean-Guillaume and Lafourcade, Pascal},
  title =	{{A Cryptographer's Conspiracy Santa}},
  booktitle =	{9th International Conference on Fun with Algorithms (FUN 2018)},
  pages =	{13:1--13:13},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-067-5},
  ISSN =	{1868-8969},
  year =	{2018},
  volume =	{100},
  editor =	{Ito, Hiro and Leonardi, Stefano and Pagli, Linda and Prencipe, Giuseppe},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.FUN.2018.13},
  URN =		{urn:nbn:de:0030-drops-88047},
  doi =		{10.4230/LIPIcs.FUN.2018.13},
  annote =	{Keywords: Secret Santa, Conspiracy Santa, Secure Multi-Party Computation, Cryptocurrency, Physical Cryptography}
}
Document
DOI: 10.4230/LIPIcs.FUN.2016.8
Physical Zero-Knowledge Proofs for Akari, Takuzu, Kakuro and KenKen

Authors: Xavier Bultel, Jannik Dreier, Jean-Guillaume Dumas, and Pascal Lafourcade

Published in: LIPIcs, Volume 49, 8th International Conference on Fun with Algorithms (FUN 2016)

Abstract
Akari, Takuzu, Kakuro and KenKen are logic games similar to Sudoku. In Akari, a labyrinth on a grid has to be lit by placing lanterns, respecting various constraints. In Takuzu a grid has to be filled with 0's and 1's, while respecting certain constraints. In Kakuro a grid has to be filled with numbers such that the sums per row and column match given values; similarly in KenKen a grid has to be filled with numbers such that in given areas the product, sum, difference or quotient equals a given value. We give physical algorithms to realize zero-knowledge proofs for these games which allow a player to show that he knows a solution without revealing it. These interactive proofs can be realized with simple office material as they only rely on cards and envelopes. Moreover, we formalize our algorithms and prove their security.
Cite as

Xavier Bultel, Jannik Dreier, Jean-Guillaume Dumas, and Pascal Lafourcade. Physical Zero-Knowledge Proofs for Akari, Takuzu, Kakuro and KenKen. In 8th International Conference on Fun with Algorithms (FUN 2016). Leibniz International Proceedings in Informatics (LIPIcs), Volume 49, pp. 8:1-8:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2016)

Copy BibTex To Clipboard

@InProceedings{bultel_et_al:LIPIcs.FUN.2016.8,
  author =	{Bultel, Xavier and Dreier, Jannik and Dumas, Jean-Guillaume and Lafourcade, Pascal},
  title =	{{Physical Zero-Knowledge Proofs for Akari, Takuzu, Kakuro and  KenKen}},
  booktitle =	{8th International Conference on Fun with Algorithms (FUN 2016)},
  pages =	{8:1--8:20},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-005-7},
  ISSN =	{1868-8969},
  year =	{2016},
  volume =	{49},
  editor =	{Demaine, Erik D. and Grandoni, Fabrizio},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.FUN.2016.8},
  URN =		{urn:nbn:de:0030-drops-58693},
  doi =		{10.4230/LIPIcs.FUN.2016.8},
  annote =	{Keywords: Physical Cryptography, ZKP, Games, Akari, Kakuro, KenKen, Takuzu}
}
Document
DOI: 10.4230/DagSemProc.06271.3
Adaptive Triangular System Solving

Authors: Jean-Guillaume Dumas, Clément Pernet, and Jean-Louis Roch

Published in: Dagstuhl Seminar Proceedings, Volume 6271, Challenges in Symbolic Computation Software (2006)

Abstract
Large-scale applications and software systems are getting increasingly complex. To deal with this complexity, those systems must manage themselves in accordance with high-level guidance from humans. Adaptive and hybrid algorithms enable this self-management of resources and structured inputs. In this talk, we first propose a classification of the different notions of adaptivity. For us, an algorithm is adaptive (or a poly-algorithm) when there is a choice at a high level between at least two distinct algorithms, each of which could solve the same problem. The choice is strategic, not tactical. It is motivated by an increase of the performance of the execution, depending on both input/output data and computing resources. Then we propose a new adaptive algorithm for the exact simultaneous resolution of several triangular systems over finite fields. The resolution of such systems is e.g. one of the two main operations in block Gaussian elimination. For solving triangular systems over finite fields, the block algorithm reduces to matrix multiplication and achieves the best known algebraic complexity. Exact matrix multiplication, together with matrix factorizations, over finite fields can now be performed at the speed of the highly optimized numerical BLAS routines. This has been established by the FFLAS and FFPACK libraries. In this talk we propose several practicable variants solving these systems: a pure recursive version, a reduction to the numerical dtrsm routine and a delaying of the modulus operation. Then a cascading scheme is proposed to merge these variants into an adaptive sequential algorithm. We then propose a parallelization of this resolution. The adaptive sequential algorithm is not the best parallel algorithm since its recursion induces a dependancy. A better parallel algorithm would be to first invert the matrix and then to multiply this inverse by the right hand side. Unfortunately the latter requires more total operations than the adaptive algorithm. We thus propose a coupling of the sequential algorithm and of the parallel one in order to get the best performances on any number of processors. The resulting cascading is then an adaptation to resources. This shows that the same process has been used both for adaptation to data and to resources. We thus propose a generic framework for the automatic adaptation of algorithms using recursive cascading.
Cite as

Jean-Guillaume Dumas, Clément Pernet, and Jean-Louis Roch. Adaptive Triangular System Solving. In Challenges in Symbolic Computation Software. Dagstuhl Seminar Proceedings, Volume 6271, pp. 1-18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2006)

Copy BibTex To Clipboard

@InProceedings{dumas_et_al:DagSemProc.06271.3,
  author =	{Dumas, Jean-Guillaume and Pernet, Cl\'{e}ment and Roch, Jean-Louis},
  title =	{{Adaptive Triangular System Solving}},
  booktitle =	{Challenges in Symbolic Computation Software},
  pages =	{1--18},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2006},
  volume =	{6271},
  editor =	{Wolfram Decker and Mike Dewar and Erich Kaltofen and Stephen Watt},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagSemProc.06271.3},
  URN =		{urn:nbn:de:0030-drops-7704},
  doi =		{10.4230/DagSemProc.06271.3},
  annote =	{Keywords: Adaptive and hybrid algorithms; triangular system solving; parallel and sequential degenerations}
}
  • Refine by Type
  • 5 Document/PDF
  • 2 Document/HTML

  • Refine by Publication Year
  • 1 2026
  • 1 2025
  • 1 2018
  • 1 2016
  • 1 2006

  • Refine by Author
  • 3 Dumas, Jean-Guillaume
  • 2 Bultel, Xavier
  • 2 Dreier, Jannik
  • 2 Lafourcade, Pascal
  • 1 Boyer, Laure
  • Show More...

  • Refine by Series/Journal
  • 3 LIPIcs
  • 1 OASIcs
  • 1 DagSemProc

  • Refine by Classification
  • 1 Applied computing → Life and medical sciences
  • 1 Mathematics of computing → Matroids and greedoids
  • 1 Security and privacy → Formal security models
  • 1 Security and privacy → Privacy-preserving protocols
  • 1 Theory of computation → Algorithm design techniques
  • Show More...

  • Refine by Keyword
  • 2 Physical Cryptography
  • 1 Adaptive and hybrid algorithms; triangular system solving; parallel and sequential degenerations
  • 1 Akari
  • 1 Cohesion
  • 1 Conspiracy Santa
  • Show More...

Any Issues?
X

Feedback on the Current Page

CAPTCHA

Thanks for your feedback!

Feedback submitted to Dagstuhl Publishing

Could not send message

Please try again later or send an E-mail
© 2023-2026 Schloss Dagstuhl – LZI GmbH Schloss Dagstuhl – LZI GmbH About DROPS Imprint Privacy Contact