Scheduling to minimize the coefficient of variation

Abstract

In this paper, we address the problem of uninterruptedly scheduling a set of independent jobs that are ready at time zero with the objective of minimizing the coefficient of variation (CV) of their completion times. We first show that, for high processing time values of the longest job, a variance (V) minimizing schedule also minimizes CV. Using this equivalence, we next demonstrate the invalidity of an earlier conjecture about the structure of a CV-optimal schedule and proceed to establish the NP-hardness of the CV problem. Finally, drawing from our prior work on the V problem, we provide a pseudo-polynomial dynamic programming algorithm for the solution of the CV problem.