We consider multiagent decision making where each agent optimizes its convex cost function subject to individual and coupling constraints. The constraint sets are compact convex subsets of a Euclidean space. To learn ...
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We consider multiagent decision making where each agent optimizes its convex cost function subject to individual and coupling constraints. The constraint sets are compact convex subsets of a Euclidean space. To learn Nash equilibria, we propose a novel distributed payoff-based algorithm, where each agent uses information only about its cost value and the constraint value with its associated dual multiplier. We prove convergence of this algorithm to a Nash equilibrium, under the assumption that the game admits a strictly convex potential function. In the absence of coupling constraints, we prove convergence to Nash equilibria under significantly weaker assumptions, not requiring a potential function. Namely, strict monotonicity of the game mapping is sufficient for convergence. We also derive the convergence rate of the algorithm for strongly monotone game maps.
Subgraph pattern matching is a basic building block for many applications. Where to commence the pattern matching task and how to proceed are fundamental issues in massive graphs. In this paper, we propose the most im...
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Subgraph pattern matching is a basic building block for many applications. Where to commence the pattern matching task and how to proceed are fundamental issues in massive graphs. In this paper, we propose the most impact vertices in view of a query graph and diffusion walk on data graph. We present a novel impact vertices-aware diffusion walk algorithm, a distributed algorithm named DiffWalk, for subgraph pattern matching. Our algorithm employs the most impact vertices from a query graph to locate the initial search position and then proceeds to traverse a large-scale data graph by diffusion walk. We give theoretical analyses based on probability inference and spectral graph, which prove that graph pattern matching beginning at the most impact vertices could prevent comparison overhead by low-probability events first, also prove that diffusion walk could traverse graph efficiently. We have performed a range of experiments that demonstrate our algorithm efficiency both in running time and communication size.
This paper considers the distributed localization problem for multi-robot systems in the plane with bearing measurements. A necessary and sufficient condition for individual robot to check triangular localizability is...
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ISBN:
(数字)9781728174471
ISBN:
(纸本)9781728174488
This paper considers the distributed localization problem for multi-robot systems in the plane with bearing measurements. A necessary and sufficient condition for individual robot to check triangular localizability is provided in terms of a geometric condition. Then a distributed orthogonal algorithm is presented for verifying whether a robot is triangularly localizable. In addition, this paper develops a distributed conjugate residual algorithm, which can solve the localization problem in a more efficient manner. Numerical simulations demonstrate the effectiveness of the approach.
This work derives and analyzes an online learning strategy for tracking the average of time-varying distributed signals by relying on randomized coordinate-descent updates. During each iteration, each agent selects or...
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This work derives and analyzes an online learning strategy for tracking the average of time-varying distributed signals by relying on randomized coordinate-descent updates. During each iteration, each agent selects or observes a random entry of the observation vector, and different agents may select different entries of their observations before engaging in a consultation step. Careful coordination of the interactions among agents is necessary to avoid bias and ensure convergence. We provide a convergence analysis for the proposed methods, and illustrate the results by means of simulations.
The complexity of distributed edge coloring depends heavily on the palette size as a function of the maximum degree Delta. In this article, we explore the complexity of edge coloring in the LOCAL model in different pa...
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The complexity of distributed edge coloring depends heavily on the palette size as a function of the maximum degree Delta. In this article, we explore the complexity of edge coloring in the LOCAL model in different palette size regimes. Our results are as follows. Lower Bounds: First, we simplify the round elimination technique of Brandt et al. [16] and prove that (2 Delta -2)-edge coloring requires Omega (log(Delta) log n) time with high probability and Omega (log(Delta) n) time deterministically, even on trees. Second, we show that a natural approach to computing (Delta + 1)-edge colorings (Vizing's theorem), namely, extending an arbitrary partial coloring by iteratively recoloring subgraphs, requires Omega (Delta log n) time. Upper Bounds on General Graphs: We give a randomized edge coloring algorithm that can use palette sizes as small as Delta + (O) over tilde(root Delta), which is a natural barrier for randomized approaches. The running time of our (1 + is an element of)Delta-edge coloring algorithm is usually dominated by O(log is an element of(-)(1)) calls to a distributed Lovasz local lemma (LLL) algorithm. For example, using the Chung-Pettie-Su LLL algorithm, we compute a (1 + is an element of)Delta-edge coloring in O(log n) time when is an element of >= (log(3) Delta)/root Delta, or O(log(Delta) n) + (log log n)(3+o(1)) time when is an element of = Omega(1). When Delta is sublogarithmic in n the performance is improved with the Ghaffari-Harris-Kuhn LLL algorithm. Upper Bounds on Trees: We show that the Omega (log(Delta) log n) lower bound can be nearly matched on trees. To establish this result, we develop a new distributed Lovasz local lemma algorithm for tree-structured dependency graphs, which arise naturally from O(1)-round probabilistic algorithms run on trees. Specifically, our (1 + is an element of)Delta-edge coloring algorithm for trees takes O(log(1/is an element of)). max {log log n/log log log n, log(log Delta) log n} time when is an element of
We study the problem of maximizing a submodular function, subject to a cardinality constraint, with a set of agents communicating over a connected graph. We propose a distributed greedy algorithm that allows all the a...
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ISBN:
(数字)9781728174471
ISBN:
(纸本)9781728174488
We study the problem of maximizing a submodular function, subject to a cardinality constraint, with a set of agents communicating over a connected graph. We propose a distributed greedy algorithm that allows all the agents to converge to a near-optimal solution to the global maximization problem using only local information and communication with neighbors in the graph. The near-optimal solution approaches the (1-1/e) approximation of the optimal solution to the global maximization problem with an additive factor that depends on the number of communication steps in the algorithm. We then analyze convergence guarantees of the proposed algorithm. This analysis reveals a tradeoff between the number of communication steps and the performance of the algorithm. Finally, we extend our analysis to nonsubmodular settings, using the notion of approximate submodularity.
Accurately tracking dynamic targets relies on robots accounting for uncertainties in their own states to share information and maintain safety. The problem becomes even more challenging when there is an unknown and ti...
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ISBN:
(数字)9781728162126
ISBN:
(纸本)9781728162133
Accurately tracking dynamic targets relies on robots accounting for uncertainties in their own states to share information and maintain safety. The problem becomes even more challenging when there is an unknown and time-varying number of targets in the environment. In this paper we address this problem by introducing four new distributed algorithms that allow large teams of robots to: i) run the prediction and ii) update steps of a distributed recursive Bayesian multi- target tracker, iii) determine the set of local neighbors that must exchange data, and iv) exchange data in a consistent manner. All of these algorithms account for a bounded level of localization uncertainty in the robots by leveraging our recent introduction of the convex uncertainty Voronoi (CUV) diagram, which extends the traditional Voronoi diagram to account for localization uncertainty. The CUV diagram introduces a tessellation over the environment, which we use in this work both to distribute the multi-target tracker and to make control decisions about where to search next. We examine the efficacy of our method via a series of simulations and compare them to our previous work which assumed perfect localization.
This paper considers distributed vertex-coloring in broadcast/receive networks suffering from conflicts and collisions. (A collision occurs when, during the same round, messages are sent to the same process by too man...
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This paper considers distributed vertex-coloring in broadcast/receive networks suffering from conflicts and collisions. (A collision occurs when, during the same round, messages are sent to the same process by too many neighbors;a conflict occurs when a process and one of its neighbors broadcast during the same round.) More specifically, the paper focuses on multi-channel networks, in which a process may either broadcast a message to its neighbors or receive a message from at most gamma of them. The paper first provides a new upper bound on the corresponding graph coloring problem (known as frugal coloring) in general graphs, proposes an exact bound for the problem in trees, and presents a deterministic, parallel, color-optimal, collision-and conflict-free distributed coloring algorithm for trees, and proves its correctness.
Large-scale optimization problems abound in data mining and machine learning applications, and the computational challenges they pose are often addressed through parallelization. We identify structural properties unde...
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Large-scale optimization problems abound in data mining and machine learning applications, and the computational challenges they pose are often addressed through parallelization. We identify structural properties under which a convex optimization problem can be massively parallelized via map-reduce operations using the Frank-Wolfe (FW) algorithm. The class of problems that can be tackled this way is quite broad and includes experimental design, AdaBoost, and projection to a convex hull. Implementing FW via map-reduce eases parallelization and deployment via commercial distributed computing frameworks. We demonstrate this by implementing FW over Spark, an engine for parallel data processing, and establish that parallelization through map-reduce yields significant performance improvements: We solve problems with 20 million variables using 350 cores in 79 min;the same operation takes 48 h when executed serially.
In the classical firing squad problem, an unknown number of nodes represented by identical finite states machines is arranged on a line and in each time unit each node may change its state according to its neighbors...
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In the classical firing squad problem, an unknown number of nodes represented by identical finite states machines is arranged on a line and in each time unit each node may change its state according to its neighbors' states. Initially all nodes are passive, except one specific node located at an end of the line, which issues a fire command. This command needs to be propagated to all other nodes, so that eventually all nodes simultaneously enter some designated "firing" state. A natural extension of the firing squad problem, introduced in this paper, allows each node to postpone its participation in the squad for an arbitrary time, possibly forever, and firing is allowed only after all nodes decided to participate. This variant is highly relevant in the context of decentralized distributed computing, where processes have to coordinate for initiating various tasks simultaneously. The main goal of this paper is to study the above variant of the firing squad problem under the assumptions that the nodes are infinite state machines, and that the internode communication links can be changed arbitrarily in each time unit, i.e., are defined by a dynamic graph. In this setting, we study the following fundamental question: what connectivity requirements enable a solution to the firing squad problem? Our main result is an exact characterization of the dynamic graphs for which the firing squad problem can be solved. When restricted to static directed graphs, this characterization implies that the problem can be solved if and only if the graph is strongly connected. We also discuss how information on the number of nodes or on the diameter of the network, and the use of randomization, can improve the solutions to the problem. (C) 2019 Elsevier B.V. All rights reserved.
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