Voronoi Diagrams in L1 (L∞) Metrics with 2-Dimensional Storage Applications

TLDR: It is shown in this paper that there exists a natural isometry between the L_1 and L_\infty metrics, which implies the existence of a polynomial time algorithm for the OPP in one metric and the existence for the same problem in the other metric.

Abstract: In this paper we study the problem of scheduling the read/write head movement to handle a batch of $nI/O$ requests in a 2-dimensional secondary storage device in minimum time. Two models of storage systems are assumed in which the access time of a record (being proportional to the “distance” between the position of the record and that of the read/write head) is measured in terms of $L_1 $ and $L_\infty $ metrics, respectively. The scheduling problem, referred to as the Open Path Problem (OPP), is equivalent to finding a shortest Hamiltonian path with a specified end point in a complete graph with n vertices. We first show in this paper that there exists a natural isometry between the $L_1 $ and $L_\infty $ metrics. Consequently, the existence of a polynomial time algorithm for the OPP in one metric implies the existence of a polynomial time algorithm for the same problem in the other metric. Based on a result by Garey, Graham and Johnson, it is easy to show that the OPP in $L_1 $ (hence in $L_\infty $) me...