The influence of lookahead in competitive paging algorithms

Abstract

We introduce a new model of lookahead for on-line paging algorithms and study several algorithms using this model. A paging algorithm is on-line with strong lookahead l if it sees the present request and a sequence of future requests that contains I pairwise distinct pages. These pages also differ from the page requested by the present request. We show that strong look head has practical as well as theoreticM importance and significantly improves the competitive factors of on-line paging algorithms. This is the first model of lookahead having such properties. In addition to lower bounds we present a number of deterministic and randomized on-line paging algorithms with strong lookahead which are optimal or nearly optimal.