Search

The problem of data representation is fundamental to the efficiency of search algorithms for the traveling salesman problem (TSP). The computational effort required to perform such tour operations as traversal and subpath reversal considerably influence algorithm design and performance. We propose a new data structure-the k-level satellite tree-for representing a TSP tour with a discussion of properties in the framework of general tour operations. The k-level satellite tree representation is shown to be significantly more efficient than its predecessors for large-scale instances. [ABSTRACT FROM AUTHOR]

This paper introduces polymorphic ejection chains, and applies them to the problem of repairing time assignments in high school timetables while preserving regularity. An ejection chain is a sequence of repairs, each of which removes a defect introduced by the previous repair. Just as the elements of a polymorphic list may have different types, so in a polymorphic ejection chain the individual repairs may have different types. Methods for the efficient realization of these ideas, implemented in the author's KHE framework, are given, and some initial experiments are presented. [ABSTRACT FROM AUTHOR]

The design of effective neighborhood structures is fundamentally important for creating better local search and metaheuristic algorithms for combinatorial optimization. Significant efforts have been made to develop larger and more powerful neighborhoods that are able to explore the solution space more effectively while keeping computation complexity within acceptable levels. The most important advances in this domain derive from dynamic and adaptive neighborhood constructions originating in ejection chain methods and a special form of a candidate list design that constitutes the core of the filter-and-fan method. The objective of this paper is to lay out the general framework of the ejection chain and filter-and-fan methods and present applications to a number of important combinatorial optimization problems. The features of the methods that make them effective in these applications are highlighted to provide insights into solving challenging problems in other settings. [ABSTRACT FROM AUTHOR]

Abstract: This paper proposes neighborhood search heuristics to optimize the planned routes of vehicles in a context where new requests, with a pick-up and a delivery location, occur in real-time. Within this framework, new solutions are explored through a neighborhood structure based on ejection chains. Numerical results show the benefits of these procedures in a real-time context. The impact of a master–slave parallelization scheme, using an increasing number of processors, is also investigated. [Copyright &y& Elsevier]