MiniZinc Challenge 2020

The Challenge

The aim of the challenge is to start to compare various constraint solving technology on the same problems sets. The focus is on finite domain propagation solvers. An auxiliary aim is to build up a library of interesting problem models, which can be used to compare solvers and solving technologies.

Entrants to the challenge provide a FlatZinc or MiniZinc solver and global constraint definitions specialized for their solver. Each solver is run on 100 MiniZinc model instances. For FlatZinc solvers, we run the minizinc compiler on the MiniZinc model and instance using the provided global constraint definitions to create a FlatZinc file. The FlatZinc file is input to the provided FlatZinc solver. For MiniZinc solvers, the MiniZinc model and instance are input to the provided solver. Points are awarded for solving problems, speed of solution, and goodness of solutions (for optimization problems).


  • 2020-09-08 Announcements of the results are here.
  • 2020-06-23 Official Call for Participation for the MiniZinc Challenge.


  • Registration opens: Now.
  • Problem submission deadline: Fri, 24 July 2020.
  • Initial submission round begins: Wed, 24 June 2020.
  • Initial submission round ends: Fri, 24 July 2020.
  • Final submissions: Fri, 14 August 2020.
  • Announcement of results at CP2020: 7-11 September (Louvain-la-Neuve, Belgium).


Entrants must register their intention to enter the contest before the final submission round.
The first submission round is an opportunity for us to provide feedback concerning your entry; it does not count towards the final result.
Feel free to register and later withdraw.

To register send an email with the following subject line

    [MZNC20] registration


    mzn-challenge 'at'

In the body of the email please include an email address at which we can contact you and the name of your solver.


All entrants need to extend the MiniZinc docker image (available at, tag latest) with their solver. Detailed information how to prepare the docker image are available here. The entrant will upload the extended image to Docker Hub and send the location of the extenstion to the MiniZinc organisers. Please read the rules before submission.

Problem Submission

We strongly encourage all entrants to submit one or two MiniZinc models satisfying the contest requirements, together with instances for these models. They can be submitted as tarballs to:

    mzn-challenge 'at'

The sooner they are submitted the better, the deadline is Fri, 24 July 2020. The call for problem submission is available here. Please feel free to distribute it.


The rules for the MiniZinc Challenge 2020 are available here.
If we need to make changes to the rules, all registered entrants will be informed by email.


The judges will be responsible for selecting the tested instances, vetting the results, and ruling on any questions that arise during the competition.

  • Jimmy H.M. Lee. Chinese University of Hong Kong.
  • Barry O'Sullivan, University College Cork, Ireland.
  • Roland Yap, National University of Singapore.


This is the 12th time this challenge is run, and there are many possibilities for comparing CP solvers. The rules try to make a sensible set of choices for the comparison. We would welcome any comments or suggestions regarding the running of this challenge.

We can be contacted with the subject starting with [MZNC20] at:

    mzn-challenge 'at'

MiniZinc forums

The MiniZinc forum is for beginners, users, and developers to discuss MiniZinc. If you would like to join then sign up for the MiniZinc forums.


The MiniZinc page includes a list of resources related to MiniZinc and FlatZinc.

The MiniZinc 2.4.3 Distribution includes a MiniZinc-to-FlatZinc converter and a large suite of MiniZinc examples and benchmarks.

The MiniZinc Challenges 2008-2019 webpage, includes the results from each MiniZinc Challenge.