Strategies for dealing with uncertainty in time-relaxed sports timetabling.

Time-relaxed sports timetables use more time slots than strictly needed, and are particularly popular in amateur (indoor) leagues. However, due to unexpected events, a considerable number of games may not be played as initially planned before the start of the tournament, leading to a potentially very different realized timetable. This study focuses on dealing with these uncertain events in time-relaxed round-robin sports timetabling, and how to mitigate their effect on the quality of the timetable. We use three quality measures to evaluate the time-relaxed timetables, namely, the games played difference index, the rest difference index and the number of cancelled games. We present several combined proactive and reactive approaches taking into account venue and team availability. Proactive strategies determine the position of time slots that are used as a buffer, while reactive strategies reschedule matches to these buffers in terms of the quality measures.