Unsuccessful Search in Self-Adjusting Data Structures

Abstract

This paper introduces a general technique for speeding up unsuccessful search using very little extra space (two bits per key). This technique is applicable to many data structures including linear lists and search trees. For linear lists we obtain on-line algorithms for processing a sequence of successful and unsuccessful searches which are competitive with strong off-line algorithms. In a virtual memory environment our self-adjusting algorithm for multiway search trees is competitive with an optimal static multiway tree and will often outperform the static tree. We are also able to extend several other results for successful search to include both successful and unsuccessful searches.