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Sparse Partitions (Extended Abstract)
 In IEEE Symposium on Foundations of Computer Science
, 1990
"... 1 ) Baruch Awerbuch David Peleg y Abstract: This abstract presents a collection of clustering and decomposition techniques enabling the construction of sparse and locality preserving representations for arbitrary networks. These new clustering techniques have already found several powerful appl ..."
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1 ) Baruch Awerbuch David Peleg y Abstract: This abstract presents a collection of clustering and decomposition techniques enabling the construction of sparse and locality preserving representations for arbitrary networks. These new clustering techniques have already found several powerful applications in the area of distributed network algorithms. Two of these applications are described in this abstract, namely, routing with polynomial communicationspace tradeoff and online tracking of mobile users. 1 Introduction 1.1 Motivation As networks grow larger, various control and management functions become increasingly more complex and expensive. Traditional protocols, based on a global approach, require all sites to participate in their activities, and to maintain considerable amounts of global information (e.g. topological data, status tables etc). This becomes problematic due to space considerations, the complexity of maintaining and updating this global information and the incre...
NearLinear Cost Sequential and Distributed Constructions of Sparse Neighborhood Covers
 in Proceedings of the 34th Annual Symposium on Foundations of Computer Science (FOCS
, 1993
"... This paper introduces the first nearlinear (specifically, O(E log n + n log 2 n)) time algorithm for constructing a sparse neighborhood cover in sequential and distributed environments. This automatically implies analogous improvements (from quadratic to nearlinear) to all the results in the li ..."
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This paper introduces the first nearlinear (specifically, O(E log n + n log 2 n)) time algorithm for constructing a sparse neighborhood cover in sequential and distributed environments. This automatically implies analogous improvements (from quadratic to nearlinear) to all the results in the literature that rely on network decompositions, both in sequential and distributed domains, including adaptive routing schemes with ~ O (1) 1 stretch and memory, small edge cuts in planar graphs, sequential algorithms for dynamic approximate shortest paths with ~ O (E) cost for edge insertion/deletion and ~ O (1) time to answer shortestpath queries, weight and distancepreserving graph spanners with ~ O (E) running time and space, and distributed asynchronous "fromscratch" BreadthFirstSearch and network synchronizer constructions with ~ O (1) message and space overhead (down from O(n)). Lab. for Computer Science, MIT, Cambridge, MA 02139. Supported by Air Force Contract AFOSR F4962092 ...
Distributed Data Location in a Dynamic Network
 IN PROC. OF ACM SPAA
, 2002
"... Modern networking applications replicate data and services widely, leading to a need for locationindependent routing  the ability to route queries directly to objects using names that are independent of the objects' physical locations. Two important properties of a routing infrastructure are routi ..."
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Cited by 18 (4 self)
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Modern networking applications replicate data and services widely, leading to a need for locationindependent routing  the ability to route queries directly to objects using names that are independent of the objects' physical locations. Two important properties of a routing infrastructure are routing locality and rapid adaptation to arriving and departing nodes. We show how these two properties can be achieved with an efficient solution to the nearestneighbor problem. We present a new distributed algorithm that can solve the nearestneighbor problem for a restricted metric space. We describe our solution in the context of Tapestry, an overlay network infrastructure that employs techniques proposed by Plaxton, Rajaraman, and Richa [16].
The Hardness of Approximating Spanner Problems
"... This paper examines a number of variants of the sparse kspanner problem, and presents hardness results concerning their approximability. Previously, it was known that most kspanner problems are weakly inapproximable, namely, are NPhard to approximate with ratio O(log n), for every k * 2, and that ..."
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Cited by 11 (2 self)
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This paper examines a number of variants of the sparse kspanner problem, and presents hardness results concerning their approximability. Previously, it was known that most kspanner problems are weakly inapproximable, namely, are NPhard to approximate with ratio O(log n), for every k * 2, and that the unitlength kspanner problem for constant stretch requirement k * 5 is strongly inapproximable, namely, is NPhard to approximate with ratio O(2log ffln) [19].
Streaming and fully dynamic centralized algorithms for constructing and maintaining sparse spanners
 In International Colloquium on Automata, Languages and Programming
, 2007
"... Abstract. We present a streaming algorithm for constructing sparse spanners and show that our algorithm outperforms significantly the stateoftheart algorithm for this task [20]. Specifically, the processing timeperedge of our algorithm is drastically smaller than that of the algorithm of [20], ..."
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Cited by 10 (2 self)
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Abstract. We present a streaming algorithm for constructing sparse spanners and show that our algorithm outperforms significantly the stateoftheart algorithm for this task [20]. Specifically, the processing timeperedge of our algorithm is drastically smaller than that of the algorithm of [20], and all other efficiency parameters of our algorithm are no greater (and some of them are strictly smaller) than the respective parameters for the stateoftheart algorithm. We also devise a fully dynamic centralized algorithm maintaining sparse spanners. This algorithm has a very small incremental update time, and a nontrivial decremental update time. To our knowledge, this is the first fully dynamic centralized algorithm for maintaining sparse spanners that provides nontrivial bounds on both incremental and decremental update time for a wide range of stretch parameter t. 1
A nearoptimal distributed fully dynamic algorithm for maintaining sparse spanners
 Proceedings of the twentysixth annual ACM symposium on Principles of distributed computing
, 2006
"... Currently, there are no known explicit algorithms for the great majority of graph problems in the dynamic distributed messagepassing model. Instead, most stateoftheart dynamic distributed algorithms are constructed by composing a static algorithm for the problem at hand with a simulation techniq ..."
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Cited by 5 (1 self)
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Currently, there are no known explicit algorithms for the great majority of graph problems in the dynamic distributed messagepassing model. Instead, most stateoftheart dynamic distributed algorithms are constructed by composing a static algorithm for the problem at hand with a simulation technique that converts static algorithms to dynamic ones. We argue that this powerful methodology does not provide satisfactory solutions for many important dynamic distributed problems, and this necessitates developing algorithms for these problems from scratch. In this paper we develop a fully dynamic distributed algorithm for maintaining sparse spanners. Our algorithm improves drastically the quiescence time of the stateoftheart algorithm for the problem. Moreover, we show that the quiescence time of our algorithm is optimal up to a small constant factor. In addition, our algorithm improves significantly upon the stateoftheart algorithm in all efficiency parameters, specifically, it has smaller quiescence message and space complexities, and smaller local processing time. Finally, our algorithm is selfcontained and fairly simple, and is, consequently, amenable to implementation on unsophisticated network devices.
Compact Roundtrip Routing for Digraphs
 In Proceedings of the 10th Annual ACMSIAM Symposium on Discrete Algorithms
, 1999
"... The first sublinear space universal compact routing schemes for directed graphs are presented. The first scheme uses O( p n log 2 n)sized routing tables on average at each node, and the second achieves O(n 2=3 log 4=3 n)sized routing tables maximum space at every node. Both schemes use O( ..."
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Cited by 4 (1 self)
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The first sublinear space universal compact routing schemes for directed graphs are presented. The first scheme uses O( p n log 2 n)sized routing tables on average at each node, and the second achieves O(n 2=3 log 4=3 n)sized routing tables maximum space at every node. Both schemes use O(logn) bit vertex addresses and achieve roundtrip routes of stretch at most 3 compared to the optimal roundtrip shortest paths in any strongly connected weighted or unweighted digraph. 1 Introduction The approximate shortest path problem is concerned with computing short routes between pairs of nodes in a network faster than the time it would take to find the shortest paths exactly, although the length of the route may be longer that the shortest path between the nodes. The compact routing problem instead considers a tradeoff of route lengths for space, in the setting where each node locally stores its own routing tables. Much recent work has been done on fast constructions of approximate sh...
Active Robust Resource Management in Cluster Computing Using Policies
 Journal of Network and Systems Management , Special Issue on Policy Based Management of Networks and Services
, 2003
"... We present an implementation of a policybased management architecture for emerging communications and computing paradigms such as Active Networks and the Grid. To manage such open, highly distributed and decentralized environments, an approach based on policy concepts is adopted, allowing support f ..."
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We present an implementation of a policybased management architecture for emerging communications and computing paradigms such as Active Networks and the Grid. To manage such open, highly distributed and decentralized environments, an approach based on policy concepts is adopted, allowing support for active, dynamic adaptability in network elements, services and enduser applications, as well as achieving decentralization and distribution. We present our flexible, extensible policy and event specifications in XML, and describe our management architecture. One key feature of our approach is the distributed infrastructure: the Directory and the Management Information Distribution system. The second feature is the Resource and Security Management elements residing on the multinode managed systems. These combine to provide a lightweight, selforganizing management architecture. As an applications example, we describe the implementation of our management system applied to the Application Level Active Networking (ALAN) environment, implemented in the European Commission Information Society Technologies (IST) project ANDROID.
Dynamic Routing Schemes for Graphs with Low Local Density
, 2007
"... This paper studies approximate distributed routing schemes on dynamic communication networks. The paper focuses on dynamic weighted general graphs where the vertices of the graph are fixed but the weights of the edges may change. Our main contribution concerns bounding the cost of adapting to dynam ..."
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This paper studies approximate distributed routing schemes on dynamic communication networks. The paper focuses on dynamic weighted general graphs where the vertices of the graph are fixed but the weights of the edges may change. Our main contribution concerns bounding the cost of adapting to dynamic changes. The update efficiency of a routing scheme is measured by the time needed in order to update the routing scheme following a weight change. A naive dynamic routing scheme, which updates all vertices following a weight change, requires Ω(Diam) time in order to perform the updates after every weight change, where Diam is the diameter of the underlying graph. In contrast, this paper presents approximate dynamic routing schemes with average time complexity ˜Θ(D), per topological change, where D is the local density parameter of the underlying graph. Following a weight change, our scheme never incurs more than Diam time, thus, our scheme is particularly efficient on graphs which have low local density and large diameter. The paper also establishes upper and lower bounds on the size of the databases required by the scheme at each site.
Independent Spanning Trees with Small Stretch Factors
, 1996
"... A pair of spanning trees rooted at a vertex r are independent if for every vertex v the pair of unique tree paths from v to the root r are disjoint. This paper presents the first analysis of the path lengths involved in independent spanning trees in 2edgeconnected and 2vertexconnected graphs. We ..."
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A pair of spanning trees rooted at a vertex r are independent if for every vertex v the pair of unique tree paths from v to the root r are disjoint. This paper presents the first analysis of the path lengths involved in independent spanning trees in 2edgeconnected and 2vertexconnected graphs. We present upper and lower bounds on the stretch factors of pairs of independent spanning trees, where the stretch factor of a spanning tree is defined to be the maximum ratio between the length of paths in the tree to the root to the length of the shortest path in the graph to the root. We prove that if G is a 2edgeconnected graph with the property that every edge lies on a cycle of size at most h than we can construct in linear time a pair of edgeindependent spanning trees whose stretch factors are bounded by O(h). In fact, we prove a more general result, namely that the stretch factor of both independent trees can be bounded by a minimax length of ears with respect to a certain class of ...