The optimum execution order of queries in linear storage

Kollias, John G.; Manolopoulos, Y.; Papadimitriou, C.

doi:10.1016/0020-0190(90)90083-a

Cited by 10 publications

(11 citation statements)

References 10 publications

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“…We first note that the  −   is similar to the Rural Postman Problem on a Line, which has been solved in polynomial time by van den Berg (1996) and to the problem order execution of queries in linear storage proposed and solved by Kollias et al (1990). Here, we provide a shorter and perhaps more intuitive alternative solution procedure.…”

Section: The Single Line Problem For Deterministic Nodes ( −   )mentioning

confidence: 89%

The Traveling Salesman Problem with Flexible Coloring

2011

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This paper introduces a new generalized version of the Traveling Salesman Problem (  ) in which nodes belong to various color classes and each color class must be visited as an entity. We distinguish the cases of the problem for which the colors are either pre-assigned or can be selected from a given subset of colors. We establish computational complexity and provide concise formulations for the problems that lend themselves to derive tight lower bounds. Exact solutions for special cases and a two-phase heuristic for the general case are provided. Worst case performance and asymptotic performance of the heuristic are analyzed and the effectiveness of the proposed heuristic in solving large industrial size problems is empirically demonstrated.. . .

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Section: The Single Line Problem For Deterministic Nodes ( −   )mentioning

confidence: 89%

The Traveling Salesman Problem with Flexible Coloring

2011

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“…Another result in this direction is presented by Kollias, Manolopoulos, and Papadimitriou [69]. They investigate a TSP on a permuted right-upper-triangular Monge matrix with an additional column and show how to solve it in O(n log n) time.…”

Section: It Can Be Shown That If a Matrix D Fulfills Properties (21)-mentioning

confidence: 98%

Well-Solvable Special Cases of the Traveling Salesman Problem: A Survey

Burkard

Deı̆neko

Dal³

et al. 1998

SIAM Rev.

156

104

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Abstract. The traveling salesman problem (TSP) belongs to the most basic, most important, and most investigated problems in combinatorial optimization. Although it is an N P-hard problem, many of its special cases can be solved efficiently in polynomial time. We survey these special cases with emphasis on the results that have been obtained during the decade [1985][1986][1987][1988][1989][1990][1991][1992][1993][1994][1995]

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“…Each time, either a batch of queries (based on primary key values) or one query (based on secondary key values) is satisfied [El. If more than one such query is involved, then the system satisfies them either on a FCFS basis [2] or according to an optimization algorithm [2,16,18,261. In other words, the algorithm rules out techniques that would interleave searching for more than one query in one scanning of the disk.…”

Section: Assumptions and Definitionsmentioning

confidence: 99%

Performance of a two-headed disk system when serving database queries under the scan policy

Manolopoulos

Kollias

1989

ACM Trans. Database Syst.

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Disk drives with movable two-headed arms are now commercially available. The two heads are separated by a fixed number of cylinders. A major problem for optimizing disk head movement, when answering database requests, is the specification of the optimum number of cylinders separating the two heads. An earlier analytical study assumed a FCFS model and concluded that the optimum separation distance should be equal to 0.44657 of the number of cylinders N of the disk. This paper considers that the SCAN scheduling policy is used in file access, and it applies combinatorial analysis to derive exact formulas for the expected head movement. Furthermore, it is proven that the optimum separation distance is N/2 -1 (TN/2 -11 and LN/2 -1 J) if N is even (odd). In addition, a comparison with a single-headed disk system operating under the same scheduling policy shows that if the two heads are optimally spaced, then the mean seek distance is less than one-half of the value obtained with one head. In fact that the SCAN policy is used for many database applications (for example, batching and secondary key retrieval) demonstrates the potential of two-headed disk systems for improving the performance of database systems.

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The optimum execution order of queries in linear storage

Cited by 10 publications

References 10 publications

The Traveling Salesman Problem with Flexible Coloring

The Traveling Salesman Problem with Flexible Coloring

Well-Solvable Special Cases of the Traveling Salesman Problem: A Survey

Performance of a two-headed disk system when serving database queries under the scan policy

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