Abstract

Effective heuristic algorithmsfor combinatorial problems are based on integrating local neighborhood search with history-sensitive schemes, where the information collected during the previous search phase is used to direct the future effort. In particular, some algorithms (like Strict Tabu Search and Reactive Tabu Search) need to detect whether a configuration has already been encountered during the previous phase of the search, either to prohibit repetitions or to determine a prohibition parameter in an adaptive way. This paper analyzes the use of persistent dynamic sets for storing and retrieving states and discusses the advantages of this option with respect to popular but less efficient realizations. If the search space is given by L-bit binary strings, the method complexity is O(L) average-case time per search iteration when hashing is used, while the total space for a sequence of t iterations is O(t).

Citations