New on-line algorithms for the page replication problem

Abstract

We present improved competitive on-line algorittmls for the page replication problem and concentrate on important network topologies for which algorithms with a constant competitive factor can be given. We develop an optional randomized on-line replication algorithm for trees and uniform networks; its competitive factor is approximately 1.58. Furthermore we consider on-llne replication algorithms for rings and present general techniques that transform large classes of c-competltlve algorithms for trees into 2c-competitive algorithms for rings. As a result we obtain a randomized on-line algorithm for rings that is 3.16-competitive. We also derive two 4-competitive on-line algorithms for rings which are either deterministic or memoryless.