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14
Network Synchronization With Polylogarithmic Overhead
 In Proc. 31st IEEE Symp. on Foundations of Computer Science
, 1990
"... The synchronizer is a simulation methodology for simulating a synchronous network by an asynchronous one, thus enabling the execution of a synchronous algorithm on an asynchronous network. Previously known synchronizers require each processor in the entire network G(V; E) to participate in each puls ..."
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Cited by 54 (14 self)
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The synchronizer is a simulation methodology for simulating a synchronous network by an asynchronous one, thus enabling the execution of a synchronous algorithm on an asynchronous network. Previously known synchronizers require each processor in the entire network G(V; E) to participate in each pulse of the synchronization process. As a result, the communication overhead of existing synchronizers depends linearly on the number n of the network nodes. This paper presents a novel type of synchronizer, whose overhead is only polylogarithmically dependent on n. This synchronizer can also be realized with polylog(n) space. This polylogoverhead synchronizer is based on involving only the "relevant" portions of the network in the synchronization process. 1 Introduction 1.1 Motivation The synchronizer is a simulation methodology introduced in [Awe85a] for simulating a synchronous network by an asynchronous one, thus enabling the execution of a synchronous algorithm on an asynchronous netwo...
Piecemeal Graph Exploration by a Mobile Robot
, 1995
"... We study how a mobile robot can piecemeal learn an unknown environment. The robot's goal is to learn a complete map of its environment, while satisfying the constraint that it must return every so often to its starting position s #for refueling, say#. ..."
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Cited by 28 (3 self)
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We study how a mobile robot can piecemeal learn an unknown environment. The robot's goal is to learn a complete map of its environment, while satisfying the constraint that it must return every so often to its starting position s #for refueling, say#.
Sparser: A paradigm for running distributed algorithms
, 1990
"... This paper introduces a transformer for improving the communication complexity of several classes of distributed algorithms. The transformer takes a distributed algorithm whose message complexity is O(f \Delta m) and produces a new distributed algorithm to solve the same problem with O(f \Delta n lo ..."
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Cited by 25 (0 self)
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This paper introduces a transformer for improving the communication complexity of several classes of distributed algorithms. The transformer takes a distributed algorithm whose message complexity is O(f \Delta m) and produces a new distributed algorithm to solve the same problem with O(f \Delta n log n+m log n) message complexity, where n and m are the total number of nodes and links in the network, and f is an arbitrary function of n and m. Applying our paradigm to the standard all shortest paths algorithm [Gal76, Gal82, Seg83] yields a new algorithm which solves the problem in O(n 2 log n) messages (The previous best that we know of is O(m \Delta n) messages). When applied to the O(m \Delta log 3 n) breadthfirst search algorithm of Awerbuch and Peleg [AP90a] our paradigm yields an O(m+ n \Delta log 4 n) messages algorithm. 1 introduction One way to run a distributed algorithm is to collect all its inputs to one node, run a sequential algorithm on all the inputs at this ...
Dynamic Networks are as fast as static networks
 In 29th Annual Symposium on Foundations of Computer Science
, 1988
"... This paper gives an efficient simulation to show that dynamic networks are as fast as static ones up to a constant multiplicative factor. That is, any task can be performed in a dynamic asynchronous network essentially as fast as in a static synchronous network. The simulation protocol is based on a ..."
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Cited by 24 (8 self)
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This paper gives an efficient simulation to show that dynamic networks are as fast as static ones up to a constant multiplicative factor. That is, any task can be performed in a dynamic asynchronous network essentially as fast as in a static synchronous network. The simulation protocol is based on a new approach, perceiving "locality " as the key to fast adaptation to changes in network topology. The heart of our simulation is a new technique, called a dynamic synchronizer which achieves "local" simulation of a global "clock" in a dynamic asynchronous network. Using this result we obtain improved solutions to a number of well known problems on dynamic networks. It can also be used to improve the solution to certain static network problems. 1 Introduction The Dynamic Asynchronous network, where links may repeatedly fail and recover, is a realistic model of existing commercial communication networks, such the ARPANET [23]. Design and analysis of protocols for such networks is much more...
A LatticeStructured Proof Technique Applied to a Minimum Spanning Tree Algorithm (Extended Abstract)
 Laboratory for Computer Science, Massachusetts Institute of Technology
, 1988
"... Jennifer Lundelius Welch Leslie Lamport Digital Equipment Corporation, Systems Research Center Abstract: rithms are often hard to prove correct because they have no natural decomposition into separately provable parts. This paper presents a proof technique for the modular verification of su ..."
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Cited by 12 (3 self)
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Jennifer Lundelius Welch Leslie Lamport Digital Equipment Corporation, Systems Research Center Abstract: rithms are often hard to prove correct because they have no natural decomposition into separately provable parts. This paper presents a proof technique for the modular verification of such nonmodular algorithms. It generalizes existing verification techniques based on a totallyordered hierarchy of refinements to allow a partiallyordered hierarchythat is; a lattice of different views of the algorithm. The technique is applied to the wellknown distributed minimum spanning tree algorithm of Gallager, Humblet and Spira, which has until recently lacked a rigorous proof. 1.
Distributed network monitoring and multicommodity flows: a primaldual approach
, 2007
"... A canonical distributed optimization problem is solving a Covering/Packing Linear Program in a distributed environment with fast convergence and low communication and space overheads. In this paper, we consider the following covering and packing problems, which are the dual of each other: • Passive ..."
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Cited by 6 (2 self)
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A canonical distributed optimization problem is solving a Covering/Packing Linear Program in a distributed environment with fast convergence and low communication and space overheads. In this paper, we consider the following covering and packing problems, which are the dual of each other: • Passive Commodity Monitoring: minimize the total cost of monitoring devices used to measure the network traffic on all paths. • Maximum Throughput Multicommodity flow: maximize the total value of the flow with bounded edge capacities. We present the first known distributed algorithms for both of these problems that converge to (1 + ɛ)approximate solutions in polylogarithmic time with communication and space overheads that depend on the maximal path length but are almost independent of the size of the entire network. Previous distributed solutions achieving similar approximations required convergence time, communication, or space overheads that depend polynomially on the size of the entire network. The sequential simulation of our algorithm is more efficient than the fastest known approximation algorithms for multicommodity flows, e.g., GargKönemann [14], when the maximal path length is small.
Learning and Vision Algorithms for Robot Navigation
, 1992
"... through its environment. The robot either explores an unknown environment or navigates through a somewhat familiar environment. The thesis addresses the design of algorithms for 1. environment learning, 2. position estimation using landmarks, 3. visual landmark recognition. ..."
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Cited by 3 (0 self)
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through its environment. The robot either explores an unknown environment or navigates through a somewhat familiar environment. The thesis addresses the design of algorithms for 1. environment learning, 2. position estimation using landmarks, 3. visual landmark recognition.
Piecemeal Graph Exploration by a Mobile Robot (Extended Abstract)
, 1995
"... We study how a mobile robot can piecemeal learn an unknown environment. The robot's goal is to learn a complete map of its environment, while satisfying the constraint that it must return every so often to its starting position (for refueling, say). The environment is modelled as an arbitrary, undi ..."
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Cited by 2 (0 self)
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We study how a mobile robot can piecemeal learn an unknown environment. The robot's goal is to learn a complete map of its environment, while satisfying the constraint that it must return every so often to its starting position (for refueling, say). The environment is modelled as an arbitrary, undirected graph, which is initially unknown to the robot. We assume that the robot can distinguish vertices and edges that it has already explored. We present a surprisingly efficient algorithm for piecemeal learning an unknown undirected graph G = (V; E) in which the robot explores every vertex and edge in the graph by traversing at most O(E + V 1+o(1)) edges. This nearly linear algorithm improves on the best previous algorithm, in which the robot traverses at most O(E + V²) edges. We also give an application of piecemeal learning to the problem of searching a graph for a "treasure".
Dynamic Structures for Routing and Loadbalancing in Wireless Sensor Networks
, 2008
"... Loadbalancing is a fundamental problem in wireless sensor networks (WSNs), essential for maximizing lifetime and throughput, and for minimizing delay. Although the WSN architecture usually imposes restrictions on the network topology, utilizing dynamic network structures allows for better loadbala ..."
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Cited by 1 (1 self)
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Loadbalancing is a fundamental problem in wireless sensor networks (WSNs), essential for maximizing lifetime and throughput, and for minimizing delay. Although the WSN architecture usually imposes restrictions on the network topology, utilizing dynamic network structures allows for better loadbalancing than could be achieved by any particular static structure. In this thesis, we propose a study of dynamic network structures and associated algorithms and protocols, to achieve optimal loadbalancing in the network. In our current work, we consider the problem of dynamically routing the sensed data from source nodes to the sink nodes. The distanceDAG is a natural model for data gather in a WSN, since by defining parent nodes for each sensor node, the DAG not only represents the direction of data flow but also encapsulates the shortest paths (in minimum number of hops) to the sink. There are two approaches for routing in the distanceDAG — using dynamic paths where the source node forwards the data along one of the several different paths to the sink, and, using dynamic forests where a new spanning tree rooted at the sink is constructed periodically and used for data gather.
Tradeoff between Redundancy and Feedbacks in Wireless Network Communication," accepted to appear
 in AdHoc & Sensor Wireless Networks, 2013. � � � � Onehop
"... Feedback is an important control mechanism that provides reliability in most wireless network protocols. However, feedback incurs some overhead, especially in lossy network environments. Many previous works on reliable communication neglect the cost of the feedback messages. In this paper, we study ..."
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Cited by 1 (1 self)
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Feedback is an important control mechanism that provides reliability in most wireless network protocols. However, feedback incurs some overhead, especially in lossy network environments. Many previous works on reliable communication neglect the cost of the feedback messages. In this paper, we study the problem of minimumcost reliable transmission over errorprone wireless networks by considering the cost of feedback. We address two cases: the case where we have a finite number of packets to send and the case where we have infinite packets. In both cases, we provide a solution to the problem with onehop broadcast transmission. After that, we study the case where network coding is used in our proposed methods. In addition to that, we extend our approaches to address the problem of minimumcost reliable broadcasting in multihop wireless networks. Our simulation results show that the cost of our proposed method is about 40 % less than that of the traditional Automatic Repeat reQuest (ARQ) method. Also, the cost of our proposed method with network coding is about 40 % less than that of the traditional ARQ