In the relay placement problem, the input is a set of sensors and a number <i>r</i> ⩾ 1, the communication range of a relay. In the <i>one-tier</i> version of the problem, the objective is to place a minimum number of relays so that between every pair of sensors there is a path <i>through sensors and/or relays</i> such that the consecutive vertices of… (More)
We show that the ratio of matched individuals to blocking pairs grows linearly with the number of propose–accept rounds executed by the Gale–Shapley algorithm for the stable marriage problem. Consequently , the participants can arrive at an almost stable matching even without full information about the problem instance; for each participant , knowing only… (More)
We present a distributed 2-approximation algorithm for the minimum vertex cover problem. The algorithm is deterministic, and it runs in (∆ + 1) 2 synchronous communication rounds, where ∆ is the maximum degree of the graph. For ∆ = 3, we give a 2-approximation algorithm also for the weighted version of the problem.
In this paper, we study the robust and stochastic versions of the two-stage min-cut and shortest path problems introduced in Dhamdhere et al. , and give approximation algorithms with improved approximation factors. Specifically, we give a 2-approximation for the robust min-cut problem and a 4-approximation for the stochastic version. For the two-stage… (More)
In this paper, we study strategies for allocating and managing friendly jammers, so as to create virtual barriers that would prevent hostile eavesdroppers from tapping sensitive wireless communication. Our scheme precludes the use of any encryption technique. Applications include domains such as (i) protecting the privacy of storage locations where RFID… (More)
We study the problem of finding shortest non-crossing thick paths in a polygonal domain, where a thick path is the Min-kowski sum of a usual (zero-thickness, or thin) path and a disk. Given K pairs of terminals on the boundary of a simple n-gon, we compute in O(n + K) time a representation of the set of K shortest non-crossing thick paths joining the… (More)
We consider the problem of finding a maximum number of disjoint paths for unit disks moving amidst static or dynamic obstacles. For the static case we give efficient exact algorithms, based on adapting the "continuous uppermost path" paradigm. As a by-product, we establish a continuous analogue of Menger's Theorem. (In this extended abstract we only state… (More)
a r t i c l e i n f o a b s t r a c t We present a local algorithm (constant-time distributed algorithm) for finding a 3-approximate vertex cover in bounded-degree graphs. The algorithm is deterministic, and no auxiliary information besides port numbering is required.
We consider instances of the Stable Roommates problem that arise from geometric representation of participants preferences: a participant is a point in a metric space, and his preference list is given by sorted distances to the other participants. We observe that, unlike in the general case, if there are no ties in the preference lists, there always exists… (More)
In boundary labeling, features on a map are connected to a stack of labels on the map boundary, using simple polylines called <i>leaders</i>. We consider the setting that the labels are axis-aligned non-overlapping rectangles placed on one side of the map, and leaders are rectilinear polylines with at most one bend. The goal is to find a labeling that… (More)