A Constant Update Time Finger Search Tree

Levcopolous and Overmars [L088] described a search tree in which the time to insert or delete a key was O( 1) once the position of the key to be inserted or deleted was known. Their data structure did not support fingers, pointers to points of high access or update activity in the set such that access and update operations in the vicinity of a finger are particularly efficient [GMPR77, BT80, Kos81, HM82, Tsa85]. Levcopolous and Overrnars left open the question of whether a data structure could be designed which allowed updates in constant time and supported fingers. We answer the question in the affirmative by giving an algorithm in the RAM with logarithmic word size. CR Classification Number: [F.2.2 Sorting and Searching]