The international timetabling competition on sports timetabling (ITC2021)

The fifth International Timetabling Competition ITC2021 aims to instigate further research on automated sports timetabling. The competition's problem consists of constructing a compact double round-robin tournament with 16 to 20 teams while respecting various hard constraints and minimizing the penalties from violated soft constraints. This paper focuses on the organization of the ITC2021 competition, with a particular focus on the generation of a set of artificial though challenging, realistic, and diverse problem instances. For the latter, we present a set of features describing the structure of the problem instances, and use these features to construct the so-called instance space for sports timetabling. Several gaps in this space hint that existing problem instances from the literature are not very diverse. We therefore propose a novel integer programming approach to determine the feature values that cover these gaps, and show how to generate associated problem instances. Finally, we provide an overview of the participants and their contributions.(c) 2022 Elsevier B.V. All rights reserved.