作者:
Gottlieb, Elsie SterbinCUNY
Baruch Coll Dept Stat & Comp Informat Syst Zicklin Sch Business New York NY 10021 USA
The generalized assignment problem is that of finding an optimal assignment of agents to tasks, where each agent may be assigned multiple tasks and each task is performed exactly once. This is an NP-complete problem. ...
详细信息
The generalized assignment problem is that of finding an optimal assignment of agents to tasks, where each agent may be assigned multiple tasks and each task is performed exactly once. This is an NP-complete problem. Algorithms that employ information about the polyhedral structure of the associated polytope are typically more effective for large instances than those that ignore the structure. A class of generalized cover facet-defining inequalities for the generalized assignment problem is derived. These inequalities are based upon multiple knapsack constraints and are derived from generalized cover inequalities.
Three classes of valid inequalities based upon multiple knapsack constraints are derived for the generalized assignment problem. General properties of the facet defining inequalities are discussed and, for a special c...
详细信息
Three classes of valid inequalities based upon multiple knapsack constraints are derived for the generalized assignment problem. General properties of the facet defining inequalities are discussed and, for a special case, the convex hull is completely characterized. In addition, we prove that a basic fractional solution to the linear programming relaxation can be eliminated by a facet defining inequality associated with an individual knapsack constraint.
The emergence of GPU-CPU heterogeneous architecture has led to a significant paradigm shift in parallel programming. How to effectively implement Parallel Genetic Algorithm (GA) in these environments has become one of...
详细信息
The emergence of GPU-CPU heterogeneous architecture has led to a significant paradigm shift in parallel programming. How to effectively implement Parallel Genetic Algorithm (GA) in these environments has become one of the current hot issues. GA's calculation and operators are closely related to specific problems, thereby significantly affecting the acceleration method of GA algorithms. The generalized assignment problem (GAP) is a classic NP-hard combinatorial optimization problem. The more widely used genetic algorithms to solve the GAP in the CPU are difficult to be parallelized in a GPU environment due to severe data dependencies. To address this problem, two algorithms suitable for the implementation on the GPU are proposed, namely RPE algorithm and NNE algorithm, which obtain significant performance speedup by alleviating data dependencies and mutually exclusive synchronization overheads. At the same time, considering the new GPU architecture features and programming models, three different granular implementations of parallel genetic algorithms to solve the GAP are proposed, namely GPGA(thread), GPGA(warpsp) and GPGA(cgroup), by utilizing the warp-specialization technology and the cooperative group mechanism. GPGA series algorithms obtain better solution quality and very significant performance improvements compared with Serial GA, GTS (the GPU-CPU hybrid implementation of Scatter Search with Tabu lists) and Lagrange Relaxation algorithm on a CPU by solving 16 typical large-scale GAP instances.
The multilevel generalized assignment problem (MGAP) differs from the classical GAP in that agents can perform tasks at more than one efficiency level. Important manufacturing problems, such as lot sizing, can be form...
详细信息
The multilevel generalized assignment problem (MGAP) differs from the classical GAP in that agents can perform tasks at more than one efficiency level. Important manufacturing problems, such as lot sizing, can be formulated as MGAPs;however, the large number of variables in the related 0-1 integer program makes the use of commercial optimization packages impractical. In this paper, we present a heuristic approach to the solution of the MGAP, which consists of a novel application of tabu search (TS). Our TS method employs neighborhoods defined by ejection chains, that produce moves of greater power without significantly increasing the computational effort.
This paper discusses a heuristic for the generalized assignment problem (GAP). The objective of GAP is to minimize the costs of assigning J jobs to M capacity constrained machines, such that each job is assigned to ex...
详细信息
This paper discusses a heuristic for the generalized assignment problem (GAP). The objective of GAP is to minimize the costs of assigning J jobs to M capacity constrained machines, such that each job is assigned to exactly one machine. The problem is known to be NP-Hard, and it is hard from a computational point of view as well. The heuristic proposed here is based on column generation techniques, and yields both upper and lower bounds. On a set of relatively hard test problems the heuristic is able to find solutions that are on average within 0.13% from optimality.
The multi-resource generalized assignment problem is encountered when a set of tasks have to be assigned to a set of agents in a way that permits assignment of multiple tasks to an agent subject to the availability of...
详细信息
The multi-resource generalized assignment problem is encountered when a set of tasks have to be assigned to a set of agents in a way that permits assignment of multiple tasks to an agent subject to the availability of a set of multiple resources consumed by that agent. This problem differs from the generalized assignment problem in that an agent consumes not just one but a variety of resources in performing the tasks assigned to him. This paper develops effective solution procedures for the multi-resource generalized assignment problem. Various relaxations of the problem are studied and theoretical relations among these relaxations are pointed out. Rules for reducing problem size are discussed and are shown to be effective through computational experiments. Heuristic solution procedures and an efficient branch and bound procedure are developed. Results of computational experiments testing these procedures are reported.
Many real life optimization problems do not have accurate estimates of the problem parameters at the optimization phase. For this reason, the min-max regret criteria are widely used to obtain robust solutions. In this...
详细信息
ISBN:
(纸本)9781479964109
Many real life optimization problems do not have accurate estimates of the problem parameters at the optimization phase. For this reason, the min-max regret criteria are widely used to obtain robust solutions. In this paper we consider the generalized assignment problem (GAP) with min-max regret criterion under interval costs. We show that the decision version of this problem is Sigma(p)(2)-complete. We present two heuristic methods: a fixed-scenario approach and a dual substitution algorithm. For the fixed-scenario approach, we show that solving the classical GAP under a median-cost scenario leads to a solution of the min-max regret GAP whose objective function value is within twice the optimal value. We also propose exact algorithms, including a Benders' decomposition approach and branch-and-cut methods which incorporate various methodologies, including Lagrangian relaxation and variable fixing. The resulting Lagrangian-based branch-and-cut algorithm performs satisfactorily on benchmark instances.
This paper proposes a solution for active measurement of the Available Transfer Rate needed in a multi-tunnel architecture with a smart mobile router offering uninterrupted services for its wireless customers. It simu...
详细信息
ISBN:
(纸本)9781479972678
This paper proposes a solution for active measurement of the Available Transfer Rate needed in a multi-tunnel architecture with a smart mobile router offering uninterrupted services for its wireless customers. It simultaneously uses several wireless/mobile access networks to the Internet in order to reach the service continuity gateway located somewhere in a broadband network. This customer-oriented approach uses the measurements to select the tunnels between the router and the gateway. Furthermore an algorithm for solving the generalized assignment problem minimizes the costs. The allocation decision must be taken once every second in order to obtain the minimum possible cost.
The generalized assignment problem is a classical combinatorial optimization problem known to be NP-hard. It can model a variety of real world applications in location, allocation, machine assignment, and so forth. In...
详细信息
ISBN:
(纸本)0769521509
The generalized assignment problem is a classical combinatorial optimization problem known to be NP-hard. It can model a variety of real world applications in location, allocation, machine assignment, and so forth. In this paper we review recent metaheuristic algorithms we developed for this problem. The algorithms use the ejection chain approach, which is embedded in a neighborhood construction to create more complex and powerful moves. We also incorporate an automatic mechanism for adjusting search parameters, to maintain a balance between visits to the feasible and infeasible regions. Computational comparisons on benchmark instances show that the methods are very effective compared to other existing metaheuristic algorithms.
We consider a variant of the generalized assignment problem (GAP) where the items have unit size and the amount of space used in each bin is restricted to be either zero (if the bin is not opened) or above a given low...
详细信息
ISBN:
(纸本)9783642403132;9783642403125
We consider a variant of the generalized assignment problem (GAP) where the items have unit size and the amount of space used in each bin is restricted to be either zero (if the bin is not opened) or above a given lower bound (a minimum quantity). This problem is known to be strongly NP-complete and does not admit a polynomial time approximation scheme (PTAS). By using randomized rounding, we obtain a randomized 3.93-approximation algorithm, thereby providing the first nontrivial approximation result for this problem.
暂无评论