6 Search Results for "All�aume, Romain"


Document
Collective Tree Exploration via Potential Function Method

Authors: Romain Cosson and Laurent Massoulié

Published in: LIPIcs, Volume 287, 15th Innovations in Theoretical Computer Science Conference (ITCS 2024)


Abstract
We study the problem of collective tree exploration (CTE) in which a team of k agents is tasked to traverse all the edges of an unknown tree as fast as possible, assuming complete communication between the agents [FGKP06]. In this paper, we present an algorithm performing collective tree exploration in 2n/k+𝒪(kD) rounds, where n is the number of nodes in the tree, and D is the tree depth. This leads to a competitive ratio of 𝒪(√k), the first polynomial improvement over the 𝒪(k) ratio of depth-first search. Our analysis holds for an asynchronous generalization of collective tree exploration. It relies on a game with robots at the leaves of a continuously growing tree extending the "tree-mining game" of [C23] and resembling the "evolving tree game" of [BCR22]. Another surprising consequence of our results is the existence of algorithms {𝒜_k}_{k ∈ ℕ} for layered tree traversal (LTT) with cost at most 2L/k+𝒪(kD), where L is the sum of all edge lengths. For the case of layered trees of width w and unit edge lengths, our guarantee is thus in 𝒪(√wD).

Cite as

Romain Cosson and Laurent Massoulié. Collective Tree Exploration via Potential Function Method. In 15th Innovations in Theoretical Computer Science Conference (ITCS 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 287, pp. 35:1-35:22, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)


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@InProceedings{cosson_et_al:LIPIcs.ITCS.2024.35,
  author =	{Cosson, Romain and Massouli\'{e}, Laurent},
  title =	{{Collective Tree Exploration via Potential Function Method}},
  booktitle =	{15th Innovations in Theoretical Computer Science Conference (ITCS 2024)},
  pages =	{35:1--35:22},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-309-6},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{287},
  editor =	{Guruswami, Venkatesan},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.ITCS.2024.35},
  URN =		{urn:nbn:de:0030-drops-195638},
  doi =		{10.4230/LIPIcs.ITCS.2024.35},
  annote =	{Keywords: collective exploration, online algorithms, evolving tree, competitive analysis}
}
Document
Efficient Collaborative Tree Exploration with Breadth-First Depth-Next

Authors: Romain Cosson, Laurent Massoulié, and Laurent Viennot

Published in: LIPIcs, Volume 281, 37th International Symposium on Distributed Computing (DISC 2023)


Abstract
We study the problem of collaborative tree exploration introduced by Fraigniaud, Gasieniec, Kowalski, and Pelc [Pierre Fraigniaud et al., 2006] where a team of k agents is tasked to collectively go through all the edges of an unknown tree as fast as possible and return to the root. Denoting by n the total number of nodes and by D the tree depth, the 𝒪(n/log(k)+D) algorithm of [Pierre Fraigniaud et al., 2006] achieves a 𝒪(k/log(k)) competitive ratio with respect to the cost of offline exploration which is at least max{{2n/k,2D}}. Brass, Cabrera-Mora, Gasparri, and Xiao [Peter Brass et al., 2011] study an alternative performance criterion, the competitive overhead with respect to the cost of offline exploration, with their 2n/k+𝒪((D+k)^k) guarantee. In this paper, we introduce "Breadth-First Depth-Next" (BFDN), a novel and simple algorithm that performs collaborative tree exploration in 2n/k+𝒪(D²log(k)) rounds, thus outperforming [Peter Brass et al., 2011] for all values of (n,D,k) and being order-optimal for trees of depth D = o(√n). Our analysis relies on a two-player game reflecting a problem of online resource allocation that could be of independent interest. We extend the guarantees of BFDN to: scenarios with limited memory and communication, adversarial setups where robots can be blocked, and exploration of classes of non-tree graphs. Finally, we provide a recursive version of BFDN with a runtime of 𝒪_𝓁(n/k^{1/𝓁}+log(k) D^{1+1/𝓁}) for parameter 𝓁 ≥ 1, thereby improving performance for trees with large depth.

Cite as

Romain Cosson, Laurent Massoulié, and Laurent Viennot. Efficient Collaborative Tree Exploration with Breadth-First Depth-Next. In 37th International Symposium on Distributed Computing (DISC 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 281, pp. 14:1-14:21, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)


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@InProceedings{cosson_et_al:LIPIcs.DISC.2023.14,
  author =	{Cosson, Romain and Massouli\'{e}, Laurent and Viennot, Laurent},
  title =	{{Efficient Collaborative Tree Exploration with Breadth-First Depth-Next}},
  booktitle =	{37th International Symposium on Distributed Computing (DISC 2023)},
  pages =	{14:1--14:21},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-301-0},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{281},
  editor =	{Oshman, Rotem},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.DISC.2023.14},
  URN =		{urn:nbn:de:0030-drops-191409},
  doi =		{10.4230/LIPIcs.DISC.2023.14},
  annote =	{Keywords: collaborative exploration, online algorithms, trees, adversarial game, competitive analysis, robot swarms}
}
Document
Artifact
The Time-Triggered Wireless Architecture (Artifact)

Authors: Romain Jacob, Licong Zhang, Marco Zimmerling, Jan Beutel, Samarjit Chakraborty, and Lothar Thiele

Published in: DARTS, Volume 6, Issue 1, Special Issue of the 32nd Euromicro Conference on Real-Time Systems (ECRTS 2020)


Abstract
This artifact contains a stable version of all the data and source code required to reproduce or replicate the results presented in The Time-Triggered Wireless Architecture. One GitHub repository serves as main hub for all information related to the artifact. The README file contains detailed instructions for - Running the TTnet model - Compiling and running TTnet - Running the TTW scheduler - Reproducing the data processing - Reproducing the plots

Cite as

Romain Jacob, Licong Zhang, Marco Zimmerling, Jan Beutel, Samarjit Chakraborty, and Lothar Thiele. The Time-Triggered Wireless Architecture (Artifact). In Special Issue of the 32nd Euromicro Conference on Real-Time Systems (ECRTS 2020). Dagstuhl Artifacts Series (DARTS), Volume 6, Issue 1, pp. 5:1-5:3, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)


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@Article{jacob_et_al:DARTS.6.1.5,
  author =	{Jacob, Romain and Zhang, Licong and Zimmerling, Marco and Beutel, Jan and Chakraborty, Samarjit and Thiele, Lothar},
  title =	{{The Time-Triggered Wireless Architecture (Artifact)}},
  pages =	{5:1--5:3},
  journal =	{Dagstuhl Artifacts Series},
  ISSN =	{2509-8195},
  year =	{2020},
  volume =	{6},
  number =	{1},
  editor =	{Jacob, Romain and Zhang, Licong and Zimmerling, Marco and Beutel, Jan and Chakraborty, Samarjit and Thiele, Lothar},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/DARTS.6.1.5},
  URN =		{urn:nbn:de:0030-drops-123952},
  doi =		{10.4230/DARTS.6.1.5},
  annote =	{Keywords: Time-triggered architecture, wireless bus, synchronous transmissions}
}
Document
Ad Hoc Multi-Input Functional Encryption

Authors: Shweta Agrawal, Michael Clear, Ophir Frieder, Sanjam Garg, Adam O'Neill, and Justin Thaler

Published in: LIPIcs, Volume 151, 11th Innovations in Theoretical Computer Science Conference (ITCS 2020)


Abstract
Consider sources that supply sensitive data to an aggregator. Standard encryption only hides the data from eavesdroppers, but using specialized encryption one can hope to hide the data (to the extent possible) from the aggregator itself. For flexibility and security, we envision schemes that allow sources to supply encrypted data, such that at any point a dynamically-chosen subset of sources can allow an agreed-upon joint function of their data to be computed by the aggregator. A primitive called multi-input functional encryption (MIFE), due to Goldwasser et al. (EUROCRYPT 2014), comes close, but has two main limitations: - it requires trust in a third party, who is able to decrypt all the data, and - it requires function arity to be fixed at setup time and to be equal to the number of parties. To drop these limitations, we introduce a new notion of ad hoc MIFE. In our setting, each source generates its own public key and issues individual, function-specific secret keys to an aggregator. For successful decryption, an aggregator must obtain a separate key from each source whose ciphertext is being computed upon. The aggregator could obtain multiple such secret-keys from a user corresponding to functions of varying arity. For this primitive, we obtain the following results: - We show that standard MIFE for general functions can be bootstrapped to ad hoc MIFE for free, i.e. without making any additional assumption. - We provide a direct construction of ad hoc MIFE for the inner product functionality based on the Learning with Errors (LWE) assumption. This yields the first construction of this natural primitive based on a standard assumption. At a technical level, our results are obtained by combining standard MIFE schemes and two-round secure multiparty computation (MPC) protocols in novel ways highlighting an interesting interplay between MIFE and two-round MPC.

Cite as

Shweta Agrawal, Michael Clear, Ophir Frieder, Sanjam Garg, Adam O'Neill, and Justin Thaler. Ad Hoc Multi-Input Functional Encryption. In 11th Innovations in Theoretical Computer Science Conference (ITCS 2020). Leibniz International Proceedings in Informatics (LIPIcs), Volume 151, pp. 40:1-40:41, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)


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@InProceedings{agrawal_et_al:LIPIcs.ITCS.2020.40,
  author =	{Agrawal, Shweta and Clear, Michael and Frieder, Ophir and Garg, Sanjam and O'Neill, Adam and Thaler, Justin},
  title =	{{Ad Hoc Multi-Input Functional Encryption}},
  booktitle =	{11th Innovations in Theoretical Computer Science Conference (ITCS 2020)},
  pages =	{40:1--40:41},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-134-4},
  ISSN =	{1868-8969},
  year =	{2020},
  volume =	{151},
  editor =	{Vidick, Thomas},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.ITCS.2020.40},
  URN =		{urn:nbn:de:0030-drops-117258},
  doi =		{10.4230/LIPIcs.ITCS.2020.40},
  annote =	{Keywords: Multi-Input Functional Encryption}
}
Document
Invited Talk
On the Computation of Nash Equilibria in Games on Graphs (Invited Talk)

Authors: Patricia Bouyer

Published in: LIPIcs, Volume 147, 26th International Symposium on Temporal Representation and Reasoning (TIME 2019)


Abstract
In this talk, I will show how one can characterize and compute Nash equilibria in multiplayer games played on graphs. I will present in particular a construction, called the suspect game construction, which allows to reduce the computation of Nash equilibria to the computation of winning strategies in a two-player zero-sum game.

Cite as

Patricia Bouyer. On the Computation of Nash Equilibria in Games on Graphs (Invited Talk). In 26th International Symposium on Temporal Representation and Reasoning (TIME 2019). Leibniz International Proceedings in Informatics (LIPIcs), Volume 147, pp. 3:1-3:3, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2019)


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@InProceedings{bouyer:LIPIcs.TIME.2019.3,
  author =	{Bouyer, Patricia},
  title =	{{On the Computation of Nash Equilibria in Games on Graphs}},
  booktitle =	{26th International Symposium on Temporal Representation and Reasoning (TIME 2019)},
  pages =	{3:1--3:3},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-127-6},
  ISSN =	{1868-8969},
  year =	{2019},
  volume =	{147},
  editor =	{Gamper, Johann and Pinchinat, Sophie and Sciavicco, Guido},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.TIME.2019.3},
  URN =		{urn:nbn:de:0030-drops-113616},
  doi =		{10.4230/LIPIcs.TIME.2019.3},
  annote =	{Keywords: Multiplayer games, Nash equilibria}
}
Document
Quantum key distribution and cryptography: a survey

Authors: Romain Alléaume, Norbert Lütkenhaus, Renato Renner, Philippe Grangier, Thierry Debuisschert, Gregoire Ribordy, Nicolas Gisin, Philippe Painchault, Thomas Pornin, Louis Slavail, Michel Riguidel, Andrew Shilds, Thomas Länger, Momtchil Peev, Mehrdad Dianati, Anthony Leverrier, Andreas Poppe, Jan Bouda, Cyril Branciard, Mark Godfrey, John Rarity, Harald Weinfurter, Anton Zeilinger, and Christian Monyk

Published in: Dagstuhl Seminar Proceedings, Volume 9311, Classical and Quantum Information Assurance Foundations and Practice (2010)


Abstract
I will try to partially answer, based on a review on recent work, the following question: Can QKD and more generally quantum information be useful to cover some practical security requirements in current (and future) IT infrastructures ? I will in particular cover the following topics - practical performances of QKD - QKD network deployment - SECOQC project - Capabilities of QKD as a cryptographic primitive - comparative advantage with other solution, in order to cover practical security requirements - Quantum information and Side-channels - QKD security assurance - Thoughts about "real" Post-Quantum Cryptography

Cite as

Romain Alléaume, Norbert Lütkenhaus, Renato Renner, Philippe Grangier, Thierry Debuisschert, Gregoire Ribordy, Nicolas Gisin, Philippe Painchault, Thomas Pornin, Louis Slavail, Michel Riguidel, Andrew Shilds, Thomas Länger, Momtchil Peev, Mehrdad Dianati, Anthony Leverrier, Andreas Poppe, Jan Bouda, Cyril Branciard, Mark Godfrey, John Rarity, Harald Weinfurter, Anton Zeilinger, and Christian Monyk. Quantum key distribution and cryptography: a survey. In Classical and Quantum Information Assurance Foundations and Practice. Dagstuhl Seminar Proceedings, Volume 9311, pp. 1-29, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2010)


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@InProceedings{alleaume_et_al:DagSemProc.09311.3,
  author =	{All\'{e}aume, Romain and L\"{u}tkenhaus, Norbert and Renner, Renato and Grangier, Philippe and Debuisschert, Thierry and Ribordy, Gregoire and Gisin, Nicolas and Painchault, Philippe and Pornin, Thomas and Slavail, Louis and Riguidel, Michel and Shilds, Andrew and L\"{a}nger, Thomas and Peev, Momtchil and Dianati, Mehrdad and Leverrier, Anthony and Poppe, Andreas and Bouda, Jan and Branciard, Cyril and Godfrey, Mark and Rarity, John and Weinfurter, Harald and Zeilinger, Anton and Monyk, Christian},
  title =	{{Quantum key distribution and cryptography: a survey}},
  booktitle =	{Classical and Quantum Information Assurance Foundations and Practice},
  pages =	{1--29},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2010},
  volume =	{9311},
  editor =	{Samual L. Braunstein and Hoi-Kwong Lo and Kenny Paterson and Peter Ryan},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/DagSemProc.09311.3},
  URN =		{urn:nbn:de:0030-drops-23618},
  doi =		{10.4230/DagSemProc.09311.3},
  annote =	{Keywords: QKD, QKD networks, Security assurance, Post-Quantum Cryptography}
}
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