Serge A. Plotkin

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Wireless sensor networks (WSNs) are emerging as an effective means for environment monitoring. This paper investigates a strategy for energy efficient monitoring in WSNs that partitions the sensors into covers, and then activates the covers iteratively in a round-robin fashion. This approach takes advantage of the overlap created when many sensors monitor a(More)
In this paper we show that, given a graph and parameters 6 and r, we can find either a K,,. minor or an edge-cut of size O(mT/6) whose removal yields components of weak diameter O(T-26); i.e., every pair of nodes in such a component are at distance 0(r26) in the original graph. Using this lemma, we improve the best known bounds for the rein-cut max-flow(More)
In this paper we study the problem of on-line allocation of routes to virtual circuits (both <italic>point-to-point</italic> and <italic>multicast</italic>) where the goal is to route all requests while minimizing the required bandwidth. We concentrate on the case of <italic>Permanent</italic> virtual circuits (i.e., once a circuit is established it exists(More)
We describe efficient deterministic techniques for breaking symmetry in parallel. The techniques work well on rooted trees and graphs of constant degree or genus. Our primary technique allows us to 3-color a rooted tree in <italic>&Ogr;</italic>(lg<supscrpt>*</supscrpt><italic>n</italic>) time on an EREW PRAM using a linear number of processors. We apply(More)
We introduce a concept of network decomposition, a partitioning of an arbitrary graph into small-diameter connected components, such that the graph created by contracting each component into a single node has low chromatic number and low arboricity. We present an eecient distributed algorithm for constructing such a decomposition, and demonstrate its use(More)
We consider a class of network design problems in which one needs to nd a minimum-cost network satisfying certain connectivity requirements. For example, in the sur-vivable network design problem, the requirements specify that there should be at least r(v; w) edge-disjoint paths between each pair of vertices v and w. We present an approximation algorithm(More)
In this paper we study an idealized problem of on-line allocation of routes to virtual circuits where the goal is to minimize the required bandwidth. For the case where virtual circuits continue to exist forever, we describe an algorithm that achieves an O (log n) competitive ratio, where n is the number of nodes in the network. Informally, our results show(More)
In this paper we introduce the notion of the limited-depth minor exclusion and show that graphs that exclude small limited-depth minors have relatively small separators. In particular, we prove that for any graph that excludes Kh as a depth l minor, we can find a separator of size O(lh2 logn + n=l). This, in turn, implies that any graph that excludes Kh as(More)