To minimize costs in the storage and retrieval of information, it is desirable to place the information in such a way as to minimize read/write head movement. Although a cost function exists, no general formula exist...
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To minimize costs in the storage and retrieval of information, it is desirable to place the information in such a way as to minimize read/write head movement. Although a cost function exists, no general formula exists as a guide for placement of records under all circumstances. Optimal solutions are available in 2 special cases: independent access probabilities and purely sequential accesses. Although a specially derived algorithm supplies the optimal placements in the 2 special cases of independent and sequential accesses, the standard placement sequence conforms to the arrangement of Markov transition matrices.
A feedback vertex set of a graph is a subset of vertices that contains at least one vertex from every cycle in the graph. The problem considered is that of finding a minimum feedback vertex set given a weighted and un...
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A feedback vertex set of a graph is a subset of vertices that contains at least one vertex from every cycle in the graph. The problem considered is that of finding a minimum feedback vertex set given a weighted and undirected graph. We present a simple and efficient approximation algorithm with performance ratio of at most 2, improving previous best bounds for either weighted or unweighted cases of the problem. Any further improvement on this bound, matching the best constant factor known for the vertex cover problem, is deemed challenging. The approximation principle, underlying the algorithm, is based on a generalized form of the classical local ratio theorem, originally developed for approximation of the vertex cover problem, and a more flexible style of its application.
This paper considers the integrated production and delivery scheduling on a serial batch machine,in which split is allowed in the delivery of the *** objective is to minimize the makespan,i.e.,the maximum delivery com...
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This paper considers the integrated production and delivery scheduling on a serial batch machine,in which split is allowed in the delivery of the *** objective is to minimize the makespan,i.e.,the maximum delivery completion time of the *** et al.(Theor Comput Sci 572:50–57,2015)showed that this problem is strongly NP-hard,and presented a 32-approximation *** this paper,we present an improved 43-approximation algorithm for this *** also present a polynomial-time algorithm for the special case when all jobs have the identical weight.
In this paper, we study the single machine total completion scheduling problem subject to a period of maintenance. We propose an approximation algorithm to solve the problem with a worst case error bound of 3/17. Furt...
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In this paper, we study the single machine total completion scheduling problem subject to a period of maintenance. We propose an approximation algorithm to solve the problem with a worst case error bound of 3/17. Furthermore, an example is provided to show that the bound is tight. Computational experiments and an analysis are given afterwards. (C) 2003 Elsevier B.V. All rights reserved.
The probabilistic analysis of an approximation algorithm for the minimum-weight m-peripatetic salesman problem with different weight functions of their routes (Hamiltonian cycles) is presented. The time complexity of ...
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The probabilistic analysis of an approximation algorithm for the minimum-weight m-peripatetic salesman problem with different weight functions of their routes (Hamiltonian cycles) is presented. The time complexity of the algorithm is O(mn(2)). It is assumed that the elements of the distance matrix are independent equally distributed random variables with values in an upper unbounded domain [a(n),infinity), where a(n) > 0. The analysis is carried out for the example of truncated normal and exponential distributions. Estimates for the relative error and failure probability, as well as conditions for the asymptotic exactness of the algorithm, are found.
We study the generalizedk-median version of the warehouse-retailer network design problem(kWRND).We formulate the k-WRND as a binary integer program and propose a 6-approximation randomized algorithm based on Lagrangi...
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We study the generalizedk-median version of the warehouse-retailer network design problem(kWRND).We formulate the k-WRND as a binary integer program and propose a 6-approximation randomized algorithm based on Lagrangian relaxation.
The longest path problem is a well-known NP-hard problem which can be used to model and solve some optimization problems. There are only a few classes of graphs for which this problem can be solved polynomially. In ad...
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The longest path problem is a well-known NP-hard problem which can be used to model and solve some optimization problems. There are only a few classes of graphs for which this problem can be solved polynomially. In addition, the results show that the problem is hard to approximate within any reasonable factor for general graphs. We introduce a polynomial-time 2/3-approximation algorithm for the longest path problem in solid grid graphs. Our algorithm can also approximate the longest path between any two given boundary vertices of a solid grid graph within the same approximation factor.
We consider the following packing problem. Let alpha be a fixed real in (0, 1]. We are given a bounding rectangle rho and a set R of n possibly intersecting unit disks whose centers lie in rho. The task is to pack a s...
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We consider the following packing problem. Let alpha be a fixed real in (0, 1]. We are given a bounding rectangle rho and a set R of n possibly intersecting unit disks whose centers lie in rho. The task is to pack a set B of m disjoint disks of radius alpha into rho such that no disk in B intersects a disk in R, where m is the maximum number of unit disks that can be packed. In this paper we present a polynomial-time algorithm for alpha = 2/3. So far only the case of packing squares has been considered. For that case, Baur and Fekete have given a polynomial-time algorithm for alpha = 2/3 and have shown that the problem cannot be solved in polynomial time for any alpha > 13/14 unless P = NP.
Self-stabilization is a theoretical framework of non-masking fault-tolerant distributed algorithms. A self-stabilizing system tolerates any kind and any finite number of transient faults, such as message loss, memory ...
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Self-stabilization is a theoretical framework of non-masking fault-tolerant distributed algorithms. A self-stabilizing system tolerates any kind and any finite number of transient faults, such as message loss, memory corruption, and topology change. Because such transient faults occur so frequently in mobile ad hoc networks, distributed algorithms on them should tolerate such events. In this paper, we propose a self-stabilizing distributed approximation algorithm for the minimum connected dominating set, which can be used, for example, as a virtual backbone or routing in mobile ad hoc networks. The size of the solution by our algorithm is at most 7.6 vertical bar D-opt vertical bar + 1.4, where D-opt is the minimum connected dominating set. The time complexity is O(k) rounds, where k is the depth of input BFS tree.
Localization is a fundamental problem in robotics. The "kidnapped robot" possesses a compass and map of its environment;it must determine its location at a minimum cost of travel distance. The problem is NP-...
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Localization is a fundamental problem in robotics. The "kidnapped robot" possesses a compass and map of its environment;it must determine its location at a minimum cost of travel distance. The problem is NP-hard [G. Dudek, K. Romanik, and S. Whitesides, SIAM J. Comput., 27 (1998), pp. 583-604] even to minimize within factor c log n [C. Tovey and S. Koenig, Proceedings of the National Conference on Artificial Intelligence, Austin, TX, 2000, pp. 819-824], where n is the map size. No approximation algorithm has been known. We give an O(log(3) n)-factor algorithm. The key idea is to plan travel in a "majority-rule" map, which eliminates uncertainty and permits a link to the 1/2-Group Steiner (not Group Steiner) problem. The approximation factor is not far from optimal: we prove a c log(2-epsilon) n lower bound, assuming NP not subset of ZTIME(n(polylog(n))), for the grid graphs commonly used in practice. We also extend the algorithm to polygonal maps by discretizing the problem using novel geometric techniques.
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