Fischer, D., Györgyi, P. Approximation algorithms for coupled task scheduling minimizing the sum of completion times. Ann Oper Res (2023).

In this paper we consider the coupled task scheduling problem with exact delay times on a single machine with the objective of minimizing the total completion time of the jobs. We provide constant-factor approximation algorithms for several variants of this problem that are known to be NP hard, while also proving NP-hardness for two variants whose complexity was unknown before. Using these results, together with constant-factor approximations for the makespan objective from the literature, we also introduce the first results on bi-objective approximation in the coupled task setting.