Abstract/Summary

We report on the development of Reprobate, a tool for solving sports timetabling problems in a subset of the RobinX format. Our tool is based around a monolithic translation of a sports timetabling instance into a pseudoboolean (PB) optimisation problem; this instance can be solved using existing pseudoboolean solvers. Once the tool has found a feasible solution, it can improve it using a second encoding that alters only the home/away pattern of games. We entered our tool into the International Timetabling Competition 2021. While it was effective on many instances, it struggled to cope with schedules involving large break constraints. However, among instances for which it could initially find a feasible solution, the combination of use of a portfolio of solvers, a range of variations on the encoding and the aforementioned local improvement process yielded an average reduction in solution cost of 23%.