Response time variability

This paper presents a work-in-progress on the response time variability problem. This problem occurs whenever events, jobs, clients or products need to be sequenced so as to minimize the variability of time they wait for their next turn in obtaining the necessary resources. The problem has numerous real-life applications, which will be briefly reviewed. The problem has distinctive number theoretic flavor. We study its computational complexity, present efficient, polynomial time algorithms for some cases and the NP-completeness proof for a general problem. We then propose a position exchange heuristic and apply it to improve the response time variability of an initial sequence. The latter is obtained in various ways: the optimum bottleneck sequence, Webster and Jefferson sequences of the apportionment, or randomly. We report on computational experiments with the heuristic.