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Tutorial validating files

The tutorial below explains how to validate XML solution files.

Submitting XML files

You are invited to send in new problem instances, solutions, or bounds to david dot VanBulck at Ugent dot be. Our aim is to answer your mail within a week. To avoid mistakes, please follow the following rules:

Only submit XML files, any other format will not be accepted! An interactive problem instance and solution XML file writer can be found here. C++ file converters for existing file formats can be found here.
When submitting a solution for an existing problem instance, make sure that the solution quality is strictly better than the current best found solution.
When submitting a new problem instance XML file, provide us with a short description how the instance was generated. At the very minimum this description should mention whether the instance is artificial or real-life, in which case you should also mention the country of origin, the name of the competition and the type of sport.
If you submit more than two XML files at the same time, please bundle them in a single zip file.
Run the online validator on the XML files to check that the results are as expected.

Questions or suggestions

Please send any question or suggestion to david dot VanBulck at Ugent dot be.

How to cite? View MLS publication View EJOR publication

Van Bulck, D., Goossens, D., and Schönberger, J., & Guajardo, M. (2020). RobinX: A three-field classification and unified data format for round-robin sports timetabling. European Journal of Operational Research, 280, 568-580.

Van Bulck, D., Goossens, D., Schönberger, J., & Guajardo, M. (2020). An Instance Data Repository for the Round-robin Sports Timetabling Problem. Management and Labour Studies, 45, 184–200.

What's new?

December 7, 2022 Several new solutions have been added for the TTP. See the travel minimization page for more information. Congratulations to Zhao, Xiao, and Xu! November 2, 2022 In honor of Gerhard Woeginger, a new instance has been added to the timetable constrained break-minimization problem. See the breaks minimization repository. Sept 30, 2022 An optimal solution has been added for the late 15 problem instance of the ITC2021 repository. Sept 29, 2022 Contributors of new best solutions are now explicity mentioned on the website! Sept 29, 2022 A new best solution has been added for the middle 12 problem instance of the ITC2021 repository. Sept 14, 2022. Minimum-trip ILB bounds have been computed for the LINE and INCR instances. See the travel minimization page for more information. Sept 11, 2022. No less than 13 new best solutions have been added for the TTP. See the travel minimization page for more information. Congratulations to Nikolaus Frohner, Jan Gmys, Nouredine Melab, Günther R. Raidl, and El-Ghazali Talbi! See also their source code at github. Aug 24, 2022. New problem instances from Van Bulck, D. & Goossens, D. Optimizing rest times and differences in games played: an iterative two-phase approach Journal of Scheduling, Springer, 2022, 25, 261-271 have been added to the website. See the constraint satisfaction repository. May 13, 2022. New lowerbounds are added for NL16, BRA24, NFL16, NFL28, GAL16, GAL18, GAL22, GAL28, GAL34, GAL40, NL10Mirrored, NL12Mirrored, and NFL20Mirrored. March 22, 2022. Instances which are solved to proven optimality are now shown in green, open instances in red, and instances that are solved to optimality according to some source in the literature but for which no XML file is available in orange. March 22, 2022. New best solutions are added for CON26Mirrored to CON40Mirrored. Bounds have also been updated according to the paper by Urrutia, S. & Ribeiro, C. C. Maximizing breaks and bounding solutions to the mirrored traveling tournament problem Discrete Appl. Math., Elsevier, 2006, 154, 1932-1938. See the travel minimization page for more information. March 22, 2022. New best solutions are added for CON20Mirrored, CON26Mirrored, CON18, CON24, CON26, and CON30. The solution for CON20Mirrored is now claimed to be optimal. See the travel minimization page for more information. November 1, 2021. Zhao and Xiao found a new better found solution for the Galaxy 24 problem instance. See the travel minimization page for more information. August 9, 2021. In total, 27 new problem instances have been added regarding the venue constrained travel miniminization problem (TTPV). Many thanks to Tiago Januario for providing us with the original instance files! June 1, 2021. In total, 30 problem instances have been added regarding the venue constrained break minimization problem (see Rasmussen, R. V. & Trick, M. A. A Benders approach for the constrained minimum break problem Eur. J. Oper. Res., 2007, 177, 198 - 213 ). For more information, see the break minimization page. June 1, 2021. Over 100 problem instances and several solutions have been added regarding the timetable constrained break minimization problem (see Elf, M.; Jünger, M. & Rinaldi, G. Minimizing breaks by maximizing cuts Oper. Res. Lett., 2003, 31, 343 - 349). Many thanks to Matthias Elf, Michael Jünger, and Giovanni Rinaldi for generating the instances and solutions and to Jacob Deconinck for submitting these instances and solutions to RobinX! May 28, 2021. Nine new best found solutions for the TTPV from "Januario, T. & Urrutia, S. A new neighborhood structure for round robin scheduling problems Comput. Oper. Res., 2016, 70, 127 - 139" were added to the travel minimization page. May 28, 2021. A mistake was present in the Traveling Tournament Problem with Predefined Venues instances (predefined venues were not enforced). New problem instances correcting for this mistake have been uploaded. May 28, 2021. No less than 55 new best found solutions from "Januario, T. & Urrutia, S. A new neighborhood structure for round robin scheduling problems Comput. Oper. Res., 2016, 70, 127 - 139" were added to the carryover effects minimization page. May 19, 2021. For a wide variety of problem instances we generated initial solutions to prove feasibility of the instances. Check e.g. the soft constraint repository for more information. Solutions were generated with a generic ALNS algorithm that was designed for the ITC 2021 competition. October 13, 2020. New lowerbounds and upperbounds based on existing literature where added to the carryover effects minimization page. See the carryover page for more information. October 7, 2020. New best found solutions are added for the minimum cost problem instances of Uthus, see the minimum cost repository. You are challenged to find better solutions! October 7, 2020. Twenty new problem instances have been added from A. Horbach, T. Bartsch & D. Briskorn (2010). Using a SAT-solver to schedule sports leagues. J. Sched., 2012, 15, 117-125. See the soft constraint optimization library. September 24, 2020. New best solutions are available for CIRC14 CIRC18, GAL12, GAL14, GAL16, GAL18, GAL20, and SUP12. Congratulations to Nikolaus Frohner, Bernhard Neumann, and Günther R. Raidl! See also their source code at github. April 17, 2020. The webpage on the three-field notation has been updated to resolve some ambiguity. Special thanks to Jeffrey Kingston for his valuable comments! April 17, 2020. Two new problem instances have been added regarding the National Football Competition in Iceland. See the soft constraint optimization library. February 3, 2020. New best solutions are available for CIRC14 and CIRC16. Congratulations to Nikolaus Frohner, Bernhard Neumann, and Günther R. Raidl! Many thanks to Michael Trick for informing us about the solutions. October 29, 2019. Instance B8 to B16K12P116C1 were moved from the break to the soft constraints repository as the instances essentialy minimize breaks, among others, using soft constraints. October 24, 2019. Modification to instance FIN2: changed type of BR1 from hard to soft with weight 10. Otherwise the instance is infeasble (at least four violations). October 23, 2019. Modification to instance AUS1: changed mirrored symmetry requirement to inverse symmetry requirement as there was a conflict with hard constraint BR2. Instance is now feasible. October 11, 2019. New bounds for the CON INCR and LINE traveling tournament problem instances have been added. Bounds are based on an approximation of the ILB using column generation. October 10, 2019. New bounds for the time-relaxed ttp resulting from Bandao and Pedrosso have been added. October 10, 2019. New solutions for the traveling tournament problem have been added. October 9, 2019. New upperbounds from Trick's website for the traveling tournament problem have been added. August 1, 2019. A new paper was added to the query tool: Kim, T. Optimal approach to game scheduling of multiple round-robin tournament: Korea professional baseball league in focus. Computers & Industrial Engineering, 136:95-105, 2019. July 17, 2019. The RobinX paper got accepted for publication in the European Journal of Operational Research and is available here.

Interesting web links

Euro working group "OR in Sports"
The EURO working group “OR in Sports” aims to bring together all quantitative research that is related to sports in a broad sense. This is a vast domain, covering questions that range from the theoretical (say, for instance, tournament design), to the very applied (behavioral issues). However, the common denominator of this field is that it is related to sports, and that it is quantitative. Scientific research on this subject is scattered, and dispersed over many different fields, in particular operational research, economics, statistics, health-related studies, and so on.
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An overview of literature on sports scheduling

This website collects references on different topics of sports scheduling and classifies them according to models, methods, and sport disciplines. This classification is maintained by Sigrid Knust.

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XHST: benchmarking project for (high) school timetabling

The High School Timetabling Problem is amongst the most widely used timetabling problems. This problem has varying structures in different high schools even within the same country or educational system. Due to lack of standard benchmarks and data formats this problem has been studied less than other timetabling problems in the literature. The authors of this website describe the High School Timetabling Problem in several countries in order to find a common set of constraints and objectives. Their main goal is to provide exchangeable benchmarks for this problem and to track algorithmic progress over time.

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