Results 11  20
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4,423
Greedy strikes back: Improved facility location algorithms
 Journal of Algorithms
, 1999
"... A fundamental facility location problem is to choose the location of facilities, such as industrial plants and warehouses, to minimize the cost of satisfying the demand for some commodity. There are associated costs for locating the facilities, as well as transportation costs for distributing the co ..."
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Cited by 210 (11 self)
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of the problem, demonstrating better approximation factors for restricted versions of the problem. We also show that the problem is Max SNPhard. However, the inapproximability constants derived from the Max SNP hardness are very close to one. By relating this problem to Set Cover, we prove a lower bound of 1
Unit Disk Graph Recognition is NPHard
 COMPUTATIONAL GEOMETRY. THEORY AND APPLICATIONS
, 1993
"... Unit disk graphs are the intersection graphs of unit diameter closed disks in the plane. This paper reduces SATISFIABILITY to the problem of recognizing unit disk graphs. Equivalently, it shows that determining if a graph has sphericity 2 or less, even if the graph is planar or is known to have s ..."
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Cited by 114 (2 self)
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Unit disk graphs are the intersection graphs of unit diameter closed disks in the plane. This paper reduces SATISFIABILITY to the problem of recognizing unit disk graphs. Equivalently, it shows that determining if a graph has sphericity 2 or less, even if the graph is planar or is known to have
Online Scheduling of Hard RealTime Tasks on Variable Voltage Processor
, 1998
"... We consider the problem of scheduling the mixed workload of both sporadic (online) and periodic (offline) tasks on variable voltage processor to optimize power consumption while ensuring that all periodic tasks meet their deadlines and to accept as many sporadic tasks, which can be guaranteed to m ..."
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Cited by 121 (7 self)
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to meet their deadlines, as possible. The proposed efficient algorithms result in the scheduling solutions, which are very close to the minimum bound achievable with the dynamically variable voltage approach. The effectiveness of the proposed algorithms is shown on extensive experiments with real
EXACT AND APPROXIMATE ALGORITHMS FOR PARTIALLY OBSERVABLE MARKOV DECISION PROCESSES
, 1998
"... Automated sequential decision making is crucial in many contexts. In the face of uncertainty, this task becomes even more important, though at the same time, computing optimal decision policies becomes more complex. The more sources of uncertainty there are, the harder the problem becomes to solve. ..."
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Cited by 186 (2 self)
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for approximate solutions. We present some improvements, analysis and empirical comparisons for some existing and some novel approaches for computing the optimal POMDP policy exactly. Since it is also hard (NPcomplete or worse) to derive close approximations to the optimal solution for POMDPs, we consider a
On the Hardness of Approximating Spanners
 Algorithmica
, 1999
"... A k\Gammaspanner of a connected graph G = (V; E) is a subgraph G 0 consisting of all the vertices of V and a subset of the edges, with the additional property that the distance between any two vertices in G 0 is larger than the distance in G by no more than a factor of k. This paper concerns ..."
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Cited by 58 (14 self)
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the hardness of finding spanners with a number of edges close to the optimum. It is proved that for every fixed k, approximating the spanner problem is at least as hard as approximating the set cover problem We also consider a weighted version of the spanner problem, and prove an essential difference
2005): “Hard and Soft Closes: A Field Experiment on Auction Closing Rules
 in Amnon Rapoport and Rami Zwick, Eds., Experimental Business Research, Vol. 2: Economic and Managerial Perspectives
, 2005
"... The growth of auctions on the Internet raises new theoretical questions, provides a wealth of data on bidding behavior in auctions, and presents new opportunities for running experiments in the field. The present paper reports the results of a field experiment on the effects of closing rules on auct ..."
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Cited by 5 (1 self)
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The growth of auctions on the Internet raises new theoretical questions, provides a wealth of data on bidding behavior in auctions, and presents new opportunities for running experiments in the field. The present paper reports the results of a field experiment on the effects of closing rules
Hardness of learning halfspaces with noise
 In Proceedings of the 47th Annual IEEE Symposium on Foundations of Computer Science
, 2006
"... Learning an unknown halfspace (also called a perceptron) from labeled examples is one of the classic problems in machine learning. In the noisefree case, when a halfspace consistent with all the training examples exists, the problem can be solved in polynomial time using linear programming. However ..."
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Cited by 44 (3 self)
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. However, under the promise that a halfspace consistent with a fraction (1 − ε) of the examples exists (for some small constant ε> 0), it was not known how to efficiently find a halfspace that is correct on even 51 % of the examples. Nor was a hardness result that ruled out getting agreement on more
Combination Can Be Hard: Approximability of the Unique Coverage Problem
 In Proceedings of the 17th Annual ACMSIAM Symposium on Discrete Algorithms
, 2006
"... Abstract We prove semilogarithmic inapproximability for a maximization problem called unique coverage:given a collection of sets, find a subcollection that maximizes the number of elements covered exactly once. Specifically, assuming that NP 6 ` BPTIME(2n " ) for an arbitrary "> ..."
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Cited by 77 (2 self)
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;quot;> 0, we prove O(1 / logoe n) inapproximability for some constant oe = oe("). We also prove O(1 / log1/3 " n) inapproximability, forany "> 0, assuming that refuting random instances of 3SAT is hard on average; and prove O(1 / log n)inapproximability under a plausible
HeavyTailed Phenomena in Satisfiability and Constraint Satisfaction Problems
 J. of Autom. Reasoning
, 2000
"... Abstract. We study the runtime distributions of backtrack procedures for propositional satisfiability and constraint satisfaction. Such procedures often exhibit a large variability in performance. Our study reveals some intriguing properties of such distributions: They are often characterized by ver ..."
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Cited by 165 (27 self)
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, statistical physics, and geophysics. They are closely related to fractal phenomena, whose study was introduced by Mandelbrot. We also show how random restarts can effectively eliminate heavytailed behavior. Furthermore, for harder problem instances, we observe long tails on the lefthand side
Engineering Design Thinking, Teaching, and Learning
 JOURNAL OF ENGINEERING EDUCATION
, 2005
"... This paper is based on the premises that the purpose of engineering education is to graduate engineers who can design, and that design thinking is complex. The paper begins by briefly reviewing the history and role of design in the engineering curriculum. Several dimensions of design thinking are th ..."
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Cited by 158 (6 self)
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are then detailed, explaining why design is hard to learn and harder still to teach, and outlining the research available on how well design thinking skills are learned. The currently mostfavored pedagogical model for teaching design, projectbased learning (PBL), is explored next, along with available assessment
Results 11  20
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4,423