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The complexity of performing matrix computations, such as solving a linear system, inverting a nonsingular matrix or computing its rank, has received a lot of attention by both the theory and the scientiic computing communities. In this paper we address some \nonclassical" matrix problems that nd extensive applications, notably in control theory. More(More)
In this paper we study the following problem: we are given a certain region <i>R</i> to monitor and a requirement on the degree of coverage (DoC) of <i>R</i> to meet by a network of deployed sensors. The latter will be dropped by a moving vehicle, which can release sensors at arbitrary points within <i>R</i>. The node spatial distribution when sensors are(More)
—Topology control, wherein nodes adjust their transmission ranges to conserve energy and reduce interference, is an important feature in wireless ad hoc networks. Contrary to most of the literature on topology control which focuses on reducing energy consumption, in this paper we tackle the topology control problem with the goal of limiting interference as(More)
Topology Control (TC) is a well-studied technique used in wireless ad hoc networks to find energy-efficient and/or low-interference subgraphs of the maxpower communication graph. However, existing work has the following limitations: (1) the energy model adopted is quite unrealistic - only transmit power is often considered and homogeneous decay of the radio(More)
In this paper we study a variant of the bin packing problem in which the items to be packed are structured as the leaves of a tree. The problem is motivated by document organization and retrieval. We show that the problem is NP-hard and we give approximation algorithms for the general case and for the particular case in which all the items have the same(More)
Microarray technology for profiling gene expression levels is a popular tool in modern biological research. Applications range from tissue classification to the detection of metabolic networks, from drug discovery to time-critical personalized medicine. Given the increase in size and complexity of the data sets produced, their analysis is becoming(More)