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In this paper we present new randomized and deterministic algorithms for the classical problem of broadcasting in radio networks with unknown topology. We consider directed n-node radio networks with specified eccentricity D (maximum distance from the source node to any other node). BarYehuda et al. presented an algorithm that for any n-node radio network(More)
We study the problem of traffic routing in noncooperative networks. In such networks, users may follow selfish strategies to optimize their own performance measure and therefore, their behavior does not have to lead to optimal performance of the entire network. In this article we investigate the worst-case coordination ratio, which is a game-theoretic(More)
We investigate load balancing processes based on the multiplechoice paradigm. In these randomized processes balls are inserted into bins. In the classical single-choice variant each ball is placed simply into a randomly selected bin. In a multiple-choice process each ball can be placed into one out of randomly selected bins. It is well known that having(More)
We show how to speed up two string-matching algorithms: the Boyer-Moore algorithm (BM algorithm), and its version called here the reverse factor algorithm (RF algorithm). The RF algorithm is based on factor graphs for the reverse of the pattern. The main feature of both algorithms is that they scan the text right-to-left from the supposed right position of(More)
We present two new results about vertex and edge fault-tolerant spanners in Euclidean spaces.We describe the first construction of vertex and edge fault-tolerant spanners having optimal bounds for maximum degree and total cost. We present a greedy algorithm that for any <i>t &gt; 1</i> and any non-negative integer <i>k</i>, constructs a(More)
Many dynamic resource allocation and on-line load balancing problems can be modeled by processes that sequentially allocate balls into bins. The balls arrive one by one and are to be placed into bins on-line without using a centralized controller. If n balls are sequentially placed into n bins by placing each ball in a randomly chosen bin, then it is widely(More)
We give almost tight bounds for the online reordering buffer management problem on the uniform metric. Specifically, we present the first non-trivial lower bounds for this problem by showing that deterministic online algorithms have a competitive ratio of at least &#937;(&#8730;{log k/log log k}) and randomized online algorithms have a competitive ratio of(More)
We consider the problem of testing expansion in bounded degree graphs. We focus on the notion of vertex-expansion: an α-expander is a graph G = (V, E) in which every subset U ⊆ V of at most |V |/2 vertices has a neighborhood of size at least α · |U|. Our main result is that one can distinguish good expanders from graphs that are far from being weak(More)
We present the rst truly polynomial-time approximation scheme (PTAS) for the minimum-cost k-vertex-(or, k-edge-) connected spanning subgraph problem for complete Euclidean graphs in R d : Previously it was known for every positive constant " how to construct in a polynomial time a graph on a superset of the input points which is k-vertex connected with(More)
We present two new methods for finding a lowest common ancestor (LCA) for each pair of vertices of a directed acyclic graph (dag) on n vertices and m edges. The first method is surprisingly natural and solves the all-pairs LCA problem for the input dag on n vertices and m edges in time O(nm). The second method relies on a novel reduction of the all-pairs(More)