16 Search Results for "Richa, Andréa W."


Document
Deterministic Self-Stabilising Leader Election for Programmable Matter with Constant Memory

Authors: Jérémie Chalopin, Shantanu Das, and Maria Kokkou

Published in: LIPIcs, Volume 319, 38th International Symposium on Distributed Computing (DISC 2024)


Abstract
The problem of electing a unique leader is central to all distributed systems, including programmable matter systems where particles have constant size memory. In this paper, we present a silent self-stabilising, deterministic, stationary, election algorithm for particles having constant memory, assuming that the system is simply connected. Our algorithm is elegant and simple, and requires constant memory per particle. We prove that our algorithm always stabilises to a configuration with a unique leader, under a daemon satisfying some fairness guarantees (Gouda fairness [Mohamed G. Gouda, 2001]). We use the special geometric properties of programmable matter in 2D triangular grids to obtain the first self-stabilising algorithm for such systems. This result is surprising since it is known that silent self-stabilising algorithms for election in general distributed networks require Ω(log n) bits of memory per node, even for ring topologies [Shlomi Dolev et al., 1999].

Cite as

Jérémie Chalopin, Shantanu Das, and Maria Kokkou. Deterministic Self-Stabilising Leader Election for Programmable Matter with Constant Memory. In 38th International Symposium on Distributed Computing (DISC 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 319, pp. 13:1-13:17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)


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@InProceedings{chalopin_et_al:LIPIcs.DISC.2024.13,
  author =	{Chalopin, J\'{e}r\'{e}mie and Das, Shantanu and Kokkou, Maria},
  title =	{{Deterministic Self-Stabilising Leader Election for Programmable Matter with Constant Memory}},
  booktitle =	{38th International Symposium on Distributed Computing (DISC 2024)},
  pages =	{13:1--13:17},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-352-2},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{319},
  editor =	{Alistarh, Dan},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.DISC.2024.13},
  URN =		{urn:nbn:de:0030-drops-212395},
  doi =		{10.4230/LIPIcs.DISC.2024.13},
  annote =	{Keywords: Leader Election, Programmable Matter, Self-Stabilisation, Silent, Deterministic, Unique Leader, Simply Connected, Gouda fair Daemon, Constant Memory}
}
Document
Decentralized Distributed Graph Coloring II: Degree+1-Coloring Virtual Graphs

Authors: Maxime Flin, Magnús M. Halldórsson, and Alexandre Nolin

Published in: LIPIcs, Volume 319, 38th International Symposium on Distributed Computing (DISC 2024)


Abstract
Graph coloring is fundamental to distributed computing. We give the first general treatment of the coloring of virtual graphs, where the graph H to be colored is locally embedded within the communication graph G. Besides generalizing classical distributed graph coloring (where H = G), this captures other previously studied settings, including cluster graphs and power graphs. We find that the complexity of coloring a virtual graph depends linearly on the edge congestion of its embedding. The main question of interest is how fast we can color virtual graphs of constant congestion. We find that, surprisingly, these graphs can be colored nearly as fast as ordinary graphs. Namely, we give a O(log⁴log n)-round algorithm for the deg+1-coloring problem, where each node is assigned more colors than its degree. This can be viewed as a case where a distributed graph problem can be solved even when the operation of each node is decentralized.

Cite as

Maxime Flin, Magnús M. Halldórsson, and Alexandre Nolin. Decentralized Distributed Graph Coloring II: Degree+1-Coloring Virtual Graphs. In 38th International Symposium on Distributed Computing (DISC 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 319, pp. 24:1-24:22, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)


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@InProceedings{flin_et_al:LIPIcs.DISC.2024.24,
  author =	{Flin, Maxime and Halld\'{o}rsson, Magn\'{u}s M. and Nolin, Alexandre},
  title =	{{Decentralized Distributed Graph Coloring II: Degree+1-Coloring Virtual Graphs}},
  booktitle =	{38th International Symposium on Distributed Computing (DISC 2024)},
  pages =	{24:1--24:22},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-352-2},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{319},
  editor =	{Alistarh, Dan},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.DISC.2024.24},
  URN =		{urn:nbn:de:0030-drops-212502},
  doi =		{10.4230/LIPIcs.DISC.2024.24},
  annote =	{Keywords: Graph Coloring, Distributed Algorithms, Virtual Graphs, Congestion, Dilation}
}
Document
Distributed Delta-Coloring Under Bandwidth Limitations

Authors: Magnús M. Halldórsson and Yannic Maus

Published in: LIPIcs, Volume 319, 38th International Symposium on Distributed Computing (DISC 2024)


Abstract
We consider the problem of coloring graphs of maximum degree Δ with Δ colors in the distributed setting with limited bandwidth. Specifically, we give a polylog log n-round randomized algorithm in the CONGEST model. This is close to the lower bound of Ω(log log n) rounds from [Brandt et al., STOC '16], which holds also in the more powerful LOCAL model. The core of our algorithm is a reduction to several special instances of the constructive Lovász local lemma (LLL) and the deg+1-list coloring problem.

Cite as

Magnús M. Halldórsson and Yannic Maus. Distributed Delta-Coloring Under Bandwidth Limitations. In 38th International Symposium on Distributed Computing (DISC 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 319, pp. 31:1-31:22, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)


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@InProceedings{halldorsson_et_al:LIPIcs.DISC.2024.31,
  author =	{Halld\'{o}rsson, Magn\'{u}s M. and Maus, Yannic},
  title =	{{Distributed Delta-Coloring Under Bandwidth Limitations}},
  booktitle =	{38th International Symposium on Distributed Computing (DISC 2024)},
  pages =	{31:1--31:22},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-352-2},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{319},
  editor =	{Alistarh, Dan},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.DISC.2024.31},
  URN =		{urn:nbn:de:0030-drops-212572},
  doi =		{10.4230/LIPIcs.DISC.2024.31},
  annote =	{Keywords: Graph problems, Graph coloring, Lov\'{a}sz local lemma, LOCAL model, CONGEST model, Distributed computing}
}
Document
Single Bridge Formation in Self-Organizing Particle Systems

Authors: Shunhao Oh, Joseph L. Briones, Jacob Calvert, Noah Egan, Dana Randall, and Andréa W. Richa

Published in: LIPIcs, Volume 319, 38th International Symposium on Distributed Computing (DISC 2024)


Abstract
Local interactions of uncoordinated individuals produce the collective behaviors of many biological systems, inspiring much of the current research in programmable matter. A striking example is the spontaneous assembly of fire ants into "bridges" comprising their own bodies to traverse obstacles and reach sources of food. Experiments and simulations suggest that, remarkably, these ants always form one bridge - instead of multiple, competing bridges - despite a lack of central coordination. We argue that the reliable formation of a single bridge does not require sophistication on behalf of the individuals by provably reproducing this behavior in a self-organizing particle system. We show that the formation of a single bridge by the particles is a statistical inevitability of their preferences to move in a particular direction, such as toward a food source, and their preference for more neighbors. Two parameters, η and β, reflect the strengths of these preferences and determine the Gibbs stationary measure of the corresponding particle system’s Markov chain dynamics. We show that a single bridge almost certainly forms when η and β are sufficiently large. Our proof introduces an auxiliary Markov chain, called an "occupancy chain," that captures only the significant, global changes to the system. Through the occupancy chain, we abstract away information about the motion of individual particles, but we gain a more direct means of analyzing their collective behavior. Such abstractions provide a promising new direction for understanding many other systems of programmable matter.

Cite as

Shunhao Oh, Joseph L. Briones, Jacob Calvert, Noah Egan, Dana Randall, and Andréa W. Richa. Single Bridge Formation in Self-Organizing Particle Systems. In 38th International Symposium on Distributed Computing (DISC 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 319, pp. 34:1-34:22, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)


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@InProceedings{oh_et_al:LIPIcs.DISC.2024.34,
  author =	{Oh, Shunhao and Briones, Joseph L. and Calvert, Jacob and Egan, Noah and Randall, Dana and Richa, Andr\'{e}a W.},
  title =	{{Single Bridge Formation in Self-Organizing Particle Systems}},
  booktitle =	{38th International Symposium on Distributed Computing (DISC 2024)},
  pages =	{34:1--34:22},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-352-2},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{319},
  editor =	{Alistarh, Dan},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.DISC.2024.34},
  URN =		{urn:nbn:de:0030-drops-212606},
  doi =		{10.4230/LIPIcs.DISC.2024.34},
  annote =	{Keywords: Self-organizing particle systems, programmable matter, bridging, jump chain}
}
Document
Memory Lower Bounds and Impossibility Results for Anonymous Dynamic Broadcast

Authors: Garrett Parzych and Joshua J. Daymude

Published in: LIPIcs, Volume 319, 38th International Symposium on Distributed Computing (DISC 2024)


Abstract
Broadcast is a ubiquitous distributed computing problem that underpins many other system tasks. In static, connected networks, it was recently shown that broadcast is solvable without any node memory and only constant-size messages in worst-case asymptotically optimal time (Hussak and Trehan, PODC'19/STACS'20/DC'23). In the dynamic setting of adversarial topology changes, however, existing algorithms rely on identifiers, port labels, or polynomial memory to solve broadcast and compute functions over node inputs. We investigate space-efficient, terminating broadcast algorithms for anonymous, synchronous, 1-interval connected dynamic networks and introduce the first memory lower bounds in this setting. Specifically, we prove that broadcast with termination detection is impossible for idle-start algorithms (where only the broadcaster can initially send messages) and otherwise requires Ω(log n) memory per node, where n is the number of nodes in the network. Even if the termination condition is relaxed to stabilizing termination (eventually no additional messages are sent), we show that any idle-start algorithm must use ω(1) memory per node, separating the static and dynamic settings for anonymous broadcast. This lower bound is not far from optimal, as we present an algorithm that solves broadcast with stabilizing termination using 𝒪(log n) memory per node in worst-case asymptotically optimal time. In sum, these results reveal the necessity of non-constant memory for nontrivial terminating computation in anonymous dynamic networks.

Cite as

Garrett Parzych and Joshua J. Daymude. Memory Lower Bounds and Impossibility Results for Anonymous Dynamic Broadcast. In 38th International Symposium on Distributed Computing (DISC 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 319, pp. 35:1-35:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)


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@InProceedings{parzych_et_al:LIPIcs.DISC.2024.35,
  author =	{Parzych, Garrett and Daymude, Joshua J.},
  title =	{{Memory Lower Bounds and Impossibility Results for Anonymous Dynamic Broadcast}},
  booktitle =	{38th International Symposium on Distributed Computing (DISC 2024)},
  pages =	{35:1--35:18},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-352-2},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{319},
  editor =	{Alistarh, Dan},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.DISC.2024.35},
  URN =		{urn:nbn:de:0030-drops-212615},
  doi =		{10.4230/LIPIcs.DISC.2024.35},
  annote =	{Keywords: Dynamic networks, anonymity, broadcast, space complexity, lower bounds, termination detection, stabilizing termination}
}
Document
Towards Communication-Efficient Peer-To-Peer Networks

Authors: Khalid Hourani, William K. Moses Jr., and Gopal Pandurangan

Published in: LIPIcs, Volume 308, 32nd Annual European Symposium on Algorithms (ESA 2024)


Abstract
We focus on designing Peer-to-Peer (P2P) networks that enable efficient communication. Over the last two decades, there has been substantial algorithmic research on distributed protocols for building P2P networks with various desirable properties such as high expansion, low diameter, and robustness to a large number of deletions. A key underlying theme in all of these works is to distributively build a random graph topology that guarantees the above properties. Moreover, the random connectivity topology is widely deployed in many P2P systems today, including those that implement blockchains and cryptocurrencies. However, a major drawback of using a random graph topology for a P2P network is that the random topology does not respect the underlying (Internet) communication topology. This creates a large propagation delay, which is a major communication bottleneck in modern P2P networks. In this paper, we work towards designing P2P networks that are communication-efficient (having small propagation delay) with provable guarantees. Our main contribution is an efficient, decentralized protocol, Close-Weaver, that transforms a random graph topology embedded in an underlying Euclidean space into a topology that also respects the underlying metric. We then present efficient point-to-point routing and broadcast protocols that achieve essentially optimal performance with respect to the underlying space.

Cite as

Khalid Hourani, William K. Moses Jr., and Gopal Pandurangan. Towards Communication-Efficient Peer-To-Peer Networks. In 32nd Annual European Symposium on Algorithms (ESA 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 308, pp. 71:1-71:15, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)


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@InProceedings{hourani_et_al:LIPIcs.ESA.2024.71,
  author =	{Hourani, Khalid and Moses Jr., William K. and Pandurangan, Gopal},
  title =	{{Towards Communication-Efficient Peer-To-Peer Networks}},
  booktitle =	{32nd Annual European Symposium on Algorithms (ESA 2024)},
  pages =	{71:1--71:15},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-338-6},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{308},
  editor =	{Chan, Timothy and Fischer, Johannes and Iacono, John and Herman, Grzegorz},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ESA.2024.71},
  URN =		{urn:nbn:de:0030-drops-211428},
  doi =		{10.4230/LIPIcs.ESA.2024.71},
  annote =	{Keywords: Peer-to-Peer Networks, Overlay Construction Protocol, Expanders, Broadcast, Geometric Routing}
}
Document
APPROX
The Telephone k-Multicast Problem

Authors: Daniel Hathcock, Guy Kortsarz, and R. Ravi

Published in: LIPIcs, Volume 317, Approximation, Randomization, and Combinatorial Optimization. Algorithms and Techniques (APPROX/RANDOM 2024)


Abstract
We consider minimum time multicasting problems in directed and undirected graphs: given a root node and a subset of t terminal nodes, multicasting seeks to find the minimum number of rounds within which all terminals can be informed with a message originating at the root. In each round, the telephone model we study allows the information to move via a matching from the informed nodes to the uninformed nodes. Since minimum time multicasting in digraphs is poorly understood compared to the undirected variant, we study an intermediate problem in undirected graphs that specifies a target k < t, and requires the only k of the terminals be informed in the minimum number of rounds. For this problem, we improve implications of prior results and obtain an Õ(t^{1/3}) multiplicative approximation. For the directed version, we obtain an additive Õ(k^{1/2}) approximation algorithm (with a poly-logarithmic multiplicative factor). Our algorithms are based on reductions to the related problems of finding k-trees of minimum poise (sum of maximum degree and diameter) and applying a combination of greedy network decomposition techniques and set covering under partition matroid constraints.

Cite as

Daniel Hathcock, Guy Kortsarz, and R. Ravi. The Telephone k-Multicast Problem. In Approximation, Randomization, and Combinatorial Optimization. Algorithms and Techniques (APPROX/RANDOM 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 317, pp. 21:1-21:16, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)


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@InProceedings{hathcock_et_al:LIPIcs.APPROX/RANDOM.2024.21,
  author =	{Hathcock, Daniel and Kortsarz, Guy and Ravi, R.},
  title =	{{The Telephone k-Multicast Problem}},
  booktitle =	{Approximation, Randomization, and Combinatorial Optimization. Algorithms and Techniques (APPROX/RANDOM 2024)},
  pages =	{21:1--21:16},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-348-5},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{317},
  editor =	{Kumar, Amit and Ron-Zewi, Noga},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.APPROX/RANDOM.2024.21},
  URN =		{urn:nbn:de:0030-drops-210148},
  doi =		{10.4230/LIPIcs.APPROX/RANDOM.2024.21},
  annote =	{Keywords: Network Design, Multicast, Steiner Poise}
}
Document
Energy-Constrained Programmable Matter Under Unfair Adversaries

Authors: Jamison W. Weber, Tishya Chhabra, Andréa W. Richa, and Joshua J. Daymude

Published in: LIPIcs, Volume 286, 27th International Conference on Principles of Distributed Systems (OPODIS 2023)


Abstract
Individual modules of programmable matter participate in their system’s collective behavior by expending energy to perform actions. However, not all modules may have access to the external energy source powering the system, necessitating a local and distributed strategy for supplying energy to modules. In this work, we present a general energy distribution framework for the canonical amoebot model of programmable matter that transforms energy-agnostic algorithms into energy-constrained ones with equivalent behavior and an 𝒪(n²)-round runtime overhead - even under an unfair adversary - provided the original algorithms satisfy certain conventions. We then prove that existing amoebot algorithms for leader election (ICDCN 2023) and shape formation (Distributed Computing, 2023) are compatible with this framework and show simulations of their energy-constrained counterparts, demonstrating how other unfair algorithms can be generalized to the energy-constrained setting with relatively little effort. Finally, we show that our energy distribution framework can be composed with the concurrency control framework for amoebot algorithms (Distributed Computing, 2023), allowing algorithm designers to focus on the simpler energy-agnostic, sequential setting but gain the general applicability of energy-constrained, asynchronous correctness.

Cite as

Jamison W. Weber, Tishya Chhabra, Andréa W. Richa, and Joshua J. Daymude. Energy-Constrained Programmable Matter Under Unfair Adversaries. In 27th International Conference on Principles of Distributed Systems (OPODIS 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 286, pp. 7:1-7:21, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)


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@InProceedings{weber_et_al:LIPIcs.OPODIS.2023.7,
  author =	{Weber, Jamison W. and Chhabra, Tishya and Richa, Andr\'{e}a W. and Daymude, Joshua J.},
  title =	{{Energy-Constrained Programmable Matter Under Unfair Adversaries}},
  booktitle =	{27th International Conference on Principles of Distributed Systems (OPODIS 2023)},
  pages =	{7:1--7:21},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-308-9},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{286},
  editor =	{Bessani, Alysson and D\'{e}fago, Xavier and Nakamura, Junya and Wada, Koichi and Yamauchi, Yukiko},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.OPODIS.2023.7},
  URN =		{urn:nbn:de:0030-drops-194971},
  doi =		{10.4230/LIPIcs.OPODIS.2023.7},
  annote =	{Keywords: Programmable matter, amoebot model, energy distribution, concurrency}
}
Document
Adaptive Collective Responses to Local Stimuli in Anonymous Dynamic Networks

Authors: Shunhao Oh, Dana Randall, and Andréa W. Richa

Published in: LIPIcs, Volume 257, 2nd Symposium on Algorithmic Foundations of Dynamic Networks (SAND 2023)


Abstract
We develop a framework for self-induced phase changes in programmable matter in which a collection of agents with limited computational and communication capabilities can collectively perform appropriate global tasks in response to local stimuli that dynamically appear and disappear. Agents reside on graph vertices, where each stimulus is only recognized locally, and agents communicate via token passing along edges to alert other agents to transition to an Aware state when stimuli are present and an Unaware state when the stimuli disappear. We present an Adaptive Stimuli Algorithm that is robust to competing waves of messages as multiple stimuli change, possibly adversarially. Moreover, in addition to handling arbitrary stimulus dynamics, the algorithm can handle agents reconfiguring the connections (edges) of the graph over time in a controlled way. As an application, we show how this Adaptive Stimuli Algorithm on reconfigurable graphs can be used to solve the foraging problem, where food sources may be discovered, removed, or shifted at arbitrary times. We would like the agents to consistently self-organize, using only local interactions, such that if the food remains in a position long enough, the agents transition to a gather phase in which many collectively form a single large component with small perimeter around the food. Alternatively, if no food source has existed recently, the agents should undergo a self-induced phase change and switch to a search phase in which they distribute themselves randomly throughout the lattice region to search for food. Unlike previous approaches to foraging, this process is indefinitely repeatable, withstanding competing waves of messages that may interfere with each other. Like a physical phase change, microscopic changes such as the deletion or addition of a single food source trigger these macroscopic, system-wide transitions as agents share information about the environment and respond locally to get the desired collective response.

Cite as

Shunhao Oh, Dana Randall, and Andréa W. Richa. Adaptive Collective Responses to Local Stimuli in Anonymous Dynamic Networks. In 2nd Symposium on Algorithmic Foundations of Dynamic Networks (SAND 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 257, pp. 6:1-6:23, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)


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@InProceedings{oh_et_al:LIPIcs.SAND.2023.6,
  author =	{Oh, Shunhao and Randall, Dana and Richa, Andr\'{e}a W.},
  title =	{{Adaptive Collective Responses to Local Stimuli in Anonymous Dynamic Networks}},
  booktitle =	{2nd Symposium on Algorithmic Foundations of Dynamic Networks (SAND 2023)},
  pages =	{6:1--6:23},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-275-4},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{257},
  editor =	{Doty, David and Spirakis, Paul},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SAND.2023.6},
  URN =		{urn:nbn:de:0030-drops-179424},
  doi =		{10.4230/LIPIcs.SAND.2023.6},
  annote =	{Keywords: Dynamic networks, adaptive stimuli, foraging, self-organizing particle systems, programmable matter}
}
Document
Brief Announcement
Brief Announcement: Foraging in Particle Systems via Self-Induced Phase Changes

Authors: Shunhao Oh, Dana Randall, and Andréa W. Richa

Published in: LIPIcs, Volume 246, 36th International Symposium on Distributed Computing (DISC 2022)


Abstract
The foraging problem asks how a collective of particles with limited computational, communication and movement capabilities can autonomously compress around a food source and disperse when the food is depleted or shifted, which may occur at arbitrary times. We would like the particles to iteratively self-organize, using only local interactions, to correctly gather whenever a food particle remains in a position long enough and search if no food particle has existed recently. Unlike previous approaches, these search and gather phases should be self-induced so as to be indefinitely repeatable as the food evolves, with microscopic changes to the food triggering macroscopic, system-wide phase transitions. We present a stochastic foraging algorithm based on a phase change in the fixed magnetization Ising model from statistical physics: Our algorithm is the first to leverage self-induced phase changes as an algorithmic tool. A key component of our algorithm is a careful token passing mechanism ensuring a dispersion broadcast wave will always outpace a compression wave.

Cite as

Shunhao Oh, Dana Randall, and Andréa W. Richa. Brief Announcement: Foraging in Particle Systems via Self-Induced Phase Changes. In 36th International Symposium on Distributed Computing (DISC 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 246, pp. 51:1-51:3, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)


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@InProceedings{oh_et_al:LIPIcs.DISC.2022.51,
  author =	{Oh, Shunhao and Randall, Dana and Richa, Andr\'{e}a W.},
  title =	{{Brief Announcement: Foraging in Particle Systems via Self-Induced Phase Changes}},
  booktitle =	{36th International Symposium on Distributed Computing (DISC 2022)},
  pages =	{51:1--51:3},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-255-6},
  ISSN =	{1868-8969},
  year =	{2022},
  volume =	{246},
  editor =	{Scheideler, Christian},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.DISC.2022.51},
  URN =		{urn:nbn:de:0030-drops-172423},
  doi =		{10.4230/LIPIcs.DISC.2022.51},
  annote =	{Keywords: Foraging, self-organized particle systems, compression, phase changes}
}
Document
Local Mutual Exclusion for Dynamic, Anonymous, Bounded Memory Message Passing Systems

Authors: Joshua J. Daymude, Andréa W. Richa, and Christian Scheideler

Published in: LIPIcs, Volume 221, 1st Symposium on Algorithmic Foundations of Dynamic Networks (SAND 2022)


Abstract
Mutual exclusion is a classical problem in distributed computing that provides isolation among concurrent action executions that may require access to the same shared resources. Inspired by algorithmic research on distributed systems of weakly capable entities whose connections change over time, we address the local mutual exclusion problem that tasks each node with acquiring exclusive locks for itself and the maximal subset of its "persistent" neighbors that remain connected to it over the time interval of the lock request. Using the established time-varying graphs model to capture adversarial topological changes, we propose and rigorously analyze a local mutual exclusion algorithm for nodes that are anonymous and communicate via asynchronous message passing. The algorithm satisfies mutual exclusion (non-intersecting lock sets) and lockout freedom (eventual success with probability 1) under both semi-synchronous and asynchronous concurrency. It requires 𝒪(Δ) memory per node and messages of size Θ(1), where Δ is the maximum number of connections per node. We conclude by describing how our algorithm can implement the pairwise interactions assumed by population protocols and the concurrency control operations assumed by the canonical amoebot model, demonstrating its utility in both passively and actively dynamic distributed systems.

Cite as

Joshua J. Daymude, Andréa W. Richa, and Christian Scheideler. Local Mutual Exclusion for Dynamic, Anonymous, Bounded Memory Message Passing Systems. In 1st Symposium on Algorithmic Foundations of Dynamic Networks (SAND 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 221, pp. 12:1-12:19, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)


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@InProceedings{daymude_et_al:LIPIcs.SAND.2022.12,
  author =	{Daymude, Joshua J. and Richa, Andr\'{e}a W. and Scheideler, Christian},
  title =	{{Local Mutual Exclusion for Dynamic, Anonymous, Bounded Memory Message Passing Systems}},
  booktitle =	{1st Symposium on Algorithmic Foundations of Dynamic Networks (SAND 2022)},
  pages =	{12:1--12:19},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-224-2},
  ISSN =	{1868-8969},
  year =	{2022},
  volume =	{221},
  editor =	{Aspnes, James and Michail, Othon},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SAND.2022.12},
  URN =		{urn:nbn:de:0030-drops-159545},
  doi =		{10.4230/LIPIcs.SAND.2022.12},
  annote =	{Keywords: Mutual exclusion, dynamic networks, message passing, concurrency}
}
Document
The Canonical Amoebot Model: Algorithms and Concurrency Control

Authors: Joshua J. Daymude, Andréa W. Richa, and Christian Scheideler

Published in: LIPIcs, Volume 209, 35th International Symposium on Distributed Computing (DISC 2021)


Abstract
The amoebot model abstracts active programmable matter as a collection of simple computational elements called amoebots that interact locally to collectively achieve tasks of coordination and movement. Since its introduction (SPAA 2014), a growing body of literature has adapted its assumptions for a variety of problems; however, without a standardized hierarchy of assumptions, precise systematic comparison of results under the amoebot model is difficult. We propose the canonical amoebot model, an updated formalization that distinguishes between core model features and families of assumption variants. A key improvement addressed by the canonical amoebot model is concurrency. Much of the existing literature implicitly assumes amoebot actions are isolated and reliable, reducing analysis to the sequential setting where at most one amoebot is active at a time. However, real programmable matter systems are concurrent. The canonical amoebot model formalizes all amoebot communication as message passing, leveraging adversarial activation models of concurrent executions. Under this granular treatment of time, we take two complementary approaches to concurrent algorithm design. Using hexagon formation as a case study, we first establish a set of sufficient conditions for algorithm correctness under any concurrent execution, embedding concurrency control directly in algorithm design. We then present a concurrency control framework that uses locks to convert amoebot algorithms that terminate in the sequential setting and satisfy certain conventions into algorithms that exhibit equivalent behavior in the concurrent setting. Together, the canonical amoebot model and these complementary approaches to concurrent algorithm design open new directions for distributed computing research on programmable matter.

Cite as

Joshua J. Daymude, Andréa W. Richa, and Christian Scheideler. The Canonical Amoebot Model: Algorithms and Concurrency Control. In 35th International Symposium on Distributed Computing (DISC 2021). Leibniz International Proceedings in Informatics (LIPIcs), Volume 209, pp. 20:1-20:19, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2021)


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@InProceedings{daymude_et_al:LIPIcs.DISC.2021.20,
  author =	{Daymude, Joshua J. and Richa, Andr\'{e}a W. and Scheideler, Christian},
  title =	{{The Canonical Amoebot Model: Algorithms and Concurrency Control}},
  booktitle =	{35th International Symposium on Distributed Computing (DISC 2021)},
  pages =	{20:1--20:19},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-210-5},
  ISSN =	{1868-8969},
  year =	{2021},
  volume =	{209},
  editor =	{Gilbert, Seth},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.DISC.2021.20},
  URN =		{urn:nbn:de:0030-drops-148227},
  doi =		{10.4230/LIPIcs.DISC.2021.20},
  annote =	{Keywords: Programmable matter, self-organization, distributed algorithms, concurrency}
}
Document
RANDOM
A Local Stochastic Algorithm for Separation in Heterogeneous Self-Organizing Particle Systems

Authors: Sarah Cannon, Joshua J. Daymude, Cem Gökmen, Dana Randall, and Andréa W. Richa

Published in: LIPIcs, Volume 145, Approximation, Randomization, and Combinatorial Optimization. Algorithms and Techniques (APPROX/RANDOM 2019)


Abstract
We present and rigorously analyze the behavior of a distributed, stochastic algorithm for separation and integration in self-organizing particle systems, an abstraction of programmable matter. Such systems are composed of individual computational particles with limited memory, strictly local communication abilities, and modest computational power. We consider heterogeneous particle systems of two different colors and prove that these systems can collectively separate into different color classes or integrate, indifferent to color. We accomplish both behaviors with the same fully distributed, local, stochastic algorithm. Achieving separation or integration depends only on a single global parameter determining whether particles prefer to be next to other particles of the same color or not; this parameter is meant to represent external, environmental influences on the particle system. The algorithm is a generalization of a previous distributed, stochastic algorithm for compression (PODC '16) that can be viewed as a special case of separation where all particles have the same color. It is significantly more challenging to prove that the desired behavior is achieved in the heterogeneous setting, however, even in the bichromatic case we focus on. This requires combining several new techniques, including the cluster expansion from statistical physics, a new variant of the bridging argument of Miracle, Pascoe and Randall (RANDOM '11), the high-temperature expansion of the Ising model, and careful probabilistic arguments.

Cite as

Sarah Cannon, Joshua J. Daymude, Cem Gökmen, Dana Randall, and Andréa W. Richa. A Local Stochastic Algorithm for Separation in Heterogeneous Self-Organizing Particle Systems. In Approximation, Randomization, and Combinatorial Optimization. Algorithms and Techniques (APPROX/RANDOM 2019). Leibniz International Proceedings in Informatics (LIPIcs), Volume 145, pp. 54:1-54:22, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2019)


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@InProceedings{cannon_et_al:LIPIcs.APPROX-RANDOM.2019.54,
  author =	{Cannon, Sarah and Daymude, Joshua J. and G\"{o}kmen, Cem and Randall, Dana and Richa, Andr\'{e}a W.},
  title =	{{A Local Stochastic Algorithm for Separation in Heterogeneous Self-Organizing Particle Systems}},
  booktitle =	{Approximation, Randomization, and Combinatorial Optimization. Algorithms and Techniques (APPROX/RANDOM 2019)},
  pages =	{54:1--54:22},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-125-2},
  ISSN =	{1868-8969},
  year =	{2019},
  volume =	{145},
  editor =	{Achlioptas, Dimitris and V\'{e}gh, L\'{a}szl\'{o} A.},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.APPROX-RANDOM.2019.54},
  URN =		{urn:nbn:de:0030-drops-112696},
  doi =		{10.4230/LIPIcs.APPROX-RANDOM.2019.54},
  annote =	{Keywords: Markov chains, Programmable matter, Cluster expansion}
}
Document
Complete Volume
LIPIcs, Volume 91, DISC'17, Complete Volume

Authors: Andréa W. Richa

Published in: LIPIcs, Volume 91, 31st International Symposium on Distributed Computing (DISC 2017)


Abstract
LIPIcs, Volume 91, DISC'17, Complete Volume

Cite as

31st International Symposium on Distributed Computing (DISC 2017). Leibniz International Proceedings in Informatics (LIPIcs), Volume 91, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2017)


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@Proceedings{richa:LIPIcs.DISC.2017,
  title =	{{LIPIcs, Volume 91, DISC'17, Complete Volume}},
  booktitle =	{31st International Symposium on Distributed Computing (DISC 2017)},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-053-8},
  ISSN =	{1868-8969},
  year =	{2017},
  volume =	{91},
  editor =	{Richa, Andr\'{e}a},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.DISC.2017},
  URN =		{urn:nbn:de:0030-drops-80247},
  doi =		{10.4230/LIPIcs.DISC.2017},
  annote =	{Keywords: Computer-Communication Networks, Distributed Systems, Concurrent Programming, Data Structures, Theory of Computation, Models of Computation, Modes of Computation}
}
Document
Front Matter
Front Matter, Table of Contents, Preface, Symposium Organization, Awards

Authors: Andréa Richa

Published in: LIPIcs, Volume 91, 31st International Symposium on Distributed Computing (DISC 2017)


Abstract
Front Matter, Table of Contents, Preface, Symposium Organization, 2017 Edsger W. Dijkstra Prize in Distributed Computing, and 2017 Principles of Distributed Computing Doctoral Dissertation Award.

Cite as

31st International Symposium on Distributed Computing (DISC 2017). Leibniz International Proceedings in Informatics (LIPIcs), Volume 91, pp. 0:i-0:xviii, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2017)


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@InProceedings{richa:LIPIcs.DISC.2017.0,
  author =	{Richa, Andr\'{e}a},
  title =	{{Front Matter, Table of Contents, Preface, Symposium Organization, Awards}},
  booktitle =	{31st International Symposium on Distributed Computing (DISC 2017)},
  pages =	{0:i--0:xviii},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-053-8},
  ISSN =	{1868-8969},
  year =	{2017},
  volume =	{91},
  editor =	{Richa, Andr\'{e}a},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.DISC.2017.0},
  URN =		{urn:nbn:de:0030-drops-79629},
  doi =		{10.4230/LIPIcs.DISC.2017.0},
  annote =	{Keywords: Front Matter, Table of Contents, Preface, Symposium Organization, Edsger W. Dijkstra Prize in Distributed Computing, Principles of Distributed Computi}
}
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