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39
APPROXIMATION ALGORITHMS FOR THE DISCRETE TIMECOST TRADEOFF PROBLEM
, 1998
"... Due to its obvious practical relevance, the TimeCost Tradeoff Problem has attracted the attention of many researchers over the last forty years. While the Linear TimeCost Tradeoff Problem can be solved in polynomial time, its discrete variant is known to be NPhard. We present the first approximat ..."
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Cited by 25 (0 self)
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Due to its obvious practical relevance, the TimeCost Tradeoff Problem has attracted the attention of many researchers over the last forty years. While the Linear TimeCost Tradeoff Problem can be solved in polynomial time, its discrete variant is known to be NPhard. We present the first approximation algorithms for the Discrete TimeCost Tradeoff Problem. Specifically, given a fixed budget we consider the problem of finding a shortest schedule for a project. We give an approximation algorithm with performance ratio 3/2 for the class of projects where all feasible durations of activities are either 0, 1, or 2. We extend our result by giving approximation algorithms with performance guarantee O(log l), where l is the ratio of the maximum duration of any activity to the minimum nonzero duration of any activity. Finally, we discuss bicriteria approximation algorithms which compute schedules for a given deadline or budget such that both project duration and cost are within a constant factor of the duration and cost of an optimum schedule for the given deadline or budget.
On project scheduling with irregular starting time costs
, 2001
"... Maniezzo and Mingozzi (Oper.Res Lett. 25 (1999) 175182) study a project scheduling problem with irregular starting time costs. Starting from the assumption that its computational complexity sompl is open, they develop a branchandbound procedure and they identifysentif cast that aresej7xx# in pol ..."
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Cited by 10 (0 self)
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Maniezzo and Mingozzi (Oper.Res Lett. 25 (1999) 175182) study a project scheduling problem with irregular starting time costs. Starting from the assumption that its computational complexity sompl is open, they develop a branchandbound procedure and they identifysentif cast that aresej7xx# in polynomial time. In this note, we pres;I a collection of previousk esviouskx resiou whichsic that the general problemis sblemj in polynomial time. This collection maysyjas ausExE guide to the literature, site this polynomialtimeslynomial has beenredis7E7jk7 in different contexts orus# different methods In addition, we briefly reviews vi related rested forsjxJJ7Ejk7#T#x and generalizations of the problem.
An Analysis of Several New Product Performance Metrics
, 2000
"... For most #rms, new product development is the engine for growth and pro#tability. A #rm's new product success depends on its ability to manage the product development process in a way that employs scarce resources to achieve the goal of the #rm as well as the speci#c project's objectives. ..."
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Cited by 9 (0 self)
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For most #rms, new product development is the engine for growth and pro#tability. A #rm's new product success depends on its ability to manage the product development process in a way that employs scarce resources to achieve the goal of the #rm as well as the speci#c project's objectives. Simple and measurable performance metrics have been proposed and applied in order to monitor and compensate the development teams. In this paper, we develop a modeling framework in order to analyze the implications of setting managerial priorities for three commonly used new product performance metrics: 1) timetomarket, 2) product performance, and 3) total development cost. We model new product development as a product performance production' process that requires scarce development resources. Setting a target for development teams for each of these performance metrics can constrain this performance production process and thereby aect the other performance metrics. We model the constrained process a...
New DistanceDirected Algorithms for Maximum Flow and Parametric Maximum Flow Problems
, 1987
"... ..."
Distancedirected augmenting path algorithms for maximum flow and parametric maximum flow problems
 Naval Research Logistics
, 1991
"... Until recently, fast algorithms for the maximum flow problem have typically proceeded by constructing layered networks and establishing blocking flows in these networks. However, in recent years, new distancedirected algorithms have been suggested that do not construct layered networks but instead ..."
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Cited by 5 (1 self)
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Until recently, fast algorithms for the maximum flow problem have typically proceeded by constructing layered networks and establishing blocking flows in these networks. However, in recent years, new distancedirected algorithms have been suggested that do not construct layered networks but instead maintain a distance label with each node. The distance label of a node is a lower bound on the length of the shortest augmenting path from the node to the sink. In this article we develop two distancedirected augmenting path algorithms for the maximum flow problem. Both the algorithms run in O(n 2 m) time on networks with n nodes and m arcs. We also point out the relationship between the distance labels and layered networks. Using a scaling technique, we improve the complexity of our distancedirected algorithms to O(nm log U), where U denotes the largest arc capacity. We also consider applications of these algorithms to unit capacity maximum flow problems and a class of parametric maximum flow problems. t i
Retaining flexibility to maximize quality: When the scheduler has the right to decide durations
 Proceedings of the 15Th International Conference on Automated Planning & Scheduling
"... In many resource constrained scheduling applications, the ability to vary task durations provides another degree of freedom for resolving resource conflicts. Furthermore, when each task is associated with a durationdependent quality profile, activity durations must be determined to maximize over ..."
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In many resource constrained scheduling applications, the ability to vary task durations provides another degree of freedom for resolving resource conflicts. Furthermore, when each task is associated with a durationdependent quality profile, activity durations must be determined to maximize overall quality while respecting process deadlines and resource capacity constraints. In this paper, we formulate this type of scheduling problem, which we refer to generally as quality maximization. We develop and empirically evaluate a new precedence constraint posting (PCP) algorithm, along with a number of search control heuristics for solving this class of problems. Our PCP algorithm incorporates linear optimization to set activity durations at each step, and search control heuristics direct the search toward resource feasibility. A central concept in the heuristics we define is use of a measure that combines an activity’s reducible duration with its quality profile as a basis for determining how to resolve resource conflicts. This concept is found to yield heuristics that exhibit superior performance. Surprisingly, we also find that use of a simple local estimation of quality degradation at each posting step leads to better performance than use of an exact computation at dramatically reduced computation expense. Overall, the experimental analysis indicates that a good heuristic must strike the right balance between minimizing quality loss at each step and retaining flexibility for future duration reduction.
Resourceconstrained project scheduling: Past work and new directions
 Department of Industrial and Systems Engineering, University of Florida
, 2001
"... This report summarizes past work in resourceconstrained project scheduling problems (RCPSP) and also presents a new RCPSP with a specialized minimum cost objective function. This new RCPSP model focuses on singleresource problems with resource consumption and late delivery costs. This model applie ..."
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This report summarizes past work in resourceconstrained project scheduling problems (RCPSP) and also presents a new RCPSP with a specialized minimum cost objective function. This new RCPSP model focuses on singleresource problems with resource consumption and late delivery costs. This model applies, for example, to a general contractor or subcontractor in the construction industry facing project deadlines with limited resources and penalties for late completion. We develop a new binpacking based algorithm to provide good solutions for this problem and describe some computational experience with this algorithm. This paper is separated into two distinct parts. Part 1 (Sections 1 through 5) summarizes the vast literature on RCPSPs and categorizes this literature. Part 2 (Section 6) presents our new RCPSP variant and our heuristic algorithm. 1. Introduction and Classification of RCPSP Problems Resource constrained project scheduling problems (RCPSPs) involve assigning jobs or tasks to a resource or set of resources with limited capacity in order to meet some predefined objective. As we will see, many different objectives are possible and these depend on the goals of the decision maker, but
Decision support and optimization in shutdown and turnaround scheduling
 INFORMS J. Computing
, 2010
"... informs doi 10.1287/ijoc.1100.0393 ..."
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