Mikael Zayenz Lagerkvist on constraint programming, software, and research.https://zayenz.se/https://zayenz.se/blog/post/constraint-generated-puzzle-games/https://zayenz.se/blog/post/constraint-generated-puzzle-games/I wanted to play some puzzles produced by my constraint-programming experiments. That small wish grew into nine games.Fri, 07 Aug 2026 00:00:00 GMThttps://zayenz.se/blog/post/gecode-6-3-and-6-4-released/https://zayenz.se/blog/post/gecode-6-3-and-6-4-released/Gecode 6.3.0 collects seven years of solver and MiniZinc integration work, while 6.4.0 modernizes the build, adds new propagation functionality, and starts a more active release line.Thu, 16 Jul 2026 00:00:00 GMThttps://zayenz.se/blog/post/minimum-distance-propagation-modref2026-paper/https://zayenz.se/blog/post/minimum-distance-propagation-modref2026-paper/Selecting well-spaced points looks simple, but the usual decomposition creates quadratically many auxiliary variables. This post compares direct Gecode propagators and shows how a matching bound can strengthen them.Thu, 16 Jul 2026 00:00:00 GMThttps://zayenz.se/blog/post/scaling-sudoku-modref2026-paper/https://zayenz.se/blog/post/scaling-sudoku-modref2026-paper/The main result is a public collection of 434,201 generated Sudoku instances, ranging from 6×6 to 36×36. The paper's experiments provide a map of how their propagation-based hardness changes with size.Thu, 16 Jul 2026 00:00:00 GMThttps://zayenz.se/blog/post/table-talk-tuning-modref2026-paper/https://zayenz.se/blog/post/table-talk-tuning-modref2026-paper/A real wedding seating plan led to a MiniZinc model that balances practical requests with the chance of finding something to talk about. The post shows the central constraints and the mixed-radix objective.Thu, 16 Jul 2026 00:00:00 GMThttps://zayenz.se/blog/post/partridge-packing/https://zayenz.se/blog/post/partridge-packing/A MiniZinc walk-through of the Partridge Packing Problem: pack one 1×1 square, two 2×2 squares, and so on into a square with exactly the same total area.Wed, 26 Nov 2025 00:00:00 GMThttps://zayenz.se/blog/post/rotating-workforce-scheduling/https://zayenz.se/blog/post/rotating-workforce-scheduling/Solving the Rotating Workforce Scheduling problem using MiniZinc.Fri, 31 Oct 2025 00:00:00 GMThttps://zayenz.se/blog/post/how-to-check-for-overlapping-intervals/https://zayenz.se/blog/post/how-to-check-for-overlapping-intervals/Understanding intervals, their overlaps, and how to write effective conditions for interval-based problemsFri, 10 Oct 2025 00:00:00 GMThttps://zayenz.se/blog/post/work-task-variation-cp2025-paper/https://zayenz.se/blog/post/work-task-variation-cp2025-paper/The Work Task Variation Problem, a paper by Mikael Z. Lagerkvist and Magnus Rattfeldt at CP 2025.Fri, 22 Aug 2025 00:00:00 GMThttps://zayenz.se/blog/post/benchmarking-linkedin-queens/https://zayenz.se/blog/post/benchmarking-linkedin-queens/On Benchmarking MiniZinc and the LinkedIn Queens ProblemThu, 21 Aug 2025 00:00:00 GMThttps://zayenz.se/blog/post/linkedin-queens/https://zayenz.se/blog/post/linkedin-queens/Solving LinkedIn Queens using MiniZincThu, 19 Jun 2025 00:00:00 GMThttps://zayenz.se/blog/post/rewritten-site/https://zayenz.se/blog/post/rewritten-site/The blog and site has been rewrittenWed, 18 Jun 2025 00:00:00 GMThttps://zayenz.se/blog/post/half-checking-propagators-2020-modref-paper/https://zayenz.se/blog/post/half-checking-propagators-2020-modref-paper/Half-checking propagators, a paper by Mikael Z. Lagerkvist and Magnus Rattfeldt at ModRef 2020Mon, 07 Sep 2020 00:00:00 GMThttps://zayenz.se/blog/post/half-checking-propagators-2020-arxiv-paper/https://zayenz.se/blog/post/half-checking-propagators-2020-arxiv-paper/Half-checking propagators, a paper by Mikael Z. Lagerkvist and Magnus RattfeldtSun, 12 Jul 2020 00:00:00 GMThttps://zayenz.se/blog/post/conferences/cp2019/https://zayenz.se/blog/post/conferences/cp2019/Trip report on CP 2019 in Stamford, CT, USA.Mon, 30 Sep 2019 00:00:00 GMThttps://zayenz.se/blog/post/nmbr9-cp2019-abstract/https://zayenz.se/blog/post/nmbr9-cp2019-abstract/Nmbr9 as a Constraint Programming Challenge, a paper by Mikael Z. LagerkvistSat, 28 Sep 2019 00:00:00 GMThttps://zayenz.se/blog/post/patchwork-modref2019-paper/https://zayenz.se/blog/post/patchwork-modref2019-paper/State Representation and Polyomino Placement for the Game Patchwork, a paper by Mikael Z. LagerkvistFri, 27 Sep 2019 00:00:00 GMThttps://zayenz.se/blog/post/rust-2019/https://zayenz.se/blog/post/rust-2019/Rust in 2019Tue, 15 Jan 2019 00:00:00 GMThttps://zayenz.se/blog/post/conferences/rust-fest-2018-paris/https://zayenz.se/blog/post/conferences/rust-fest-2018-paris/Summary and some notes on RustFest 2018 in ParisThu, 16 Aug 2018 00:00:00 GMThttps://zayenz.se/blog/post/kingdomino-cig2018-paper/https://zayenz.se/blog/post/kingdomino-cig2018-paper/Monte Carlo Methods for the Game Kingdomino, a paper by Magnus Gedda, Mikael Z. Lagerkvist and Martin ButlerMon, 13 Aug 2018 00:00:00 GMThttps://zayenz.se/blog/post/conferences/ijcai2018-7/https://zayenz.se/blog/post/conferences/ijcai2018-7/IJCAI 2018 fourth and final conference dayThu, 19 Jul 2018 09:00:00 GMThttps://zayenz.se/blog/post/conferences/ijcai2018-summary/https://zayenz.se/blog/post/conferences/ijcai2018-summary/International Joint Conference on AI and Symposium on combinatorial search 2018 summaryThu, 19 Jul 2018 00:00:00 GMThttps://zayenz.se/blog/post/conferences/ijcai2018-6/https://zayenz.se/blog/post/conferences/ijcai2018-6/IJCAI 2018 third conference dayWed, 18 Jul 2018 00:00:00 GMThttps://zayenz.se/blog/post/conferences/ijcai2018-5/https://zayenz.se/blog/post/conferences/ijcai2018-5/IJCAI 2018 is being held in Stockholm from July the 13th to July the 19th as a part of the Federated AI Meeting. In this and other posts I will give some short comments on interesting things I've heard. If anything is wrong or misrepresented, please don't hesitate to get in touch with me. On the fifth day the main IJCAI conference continued. The conference has many parallel tracks, comments here are from sessions that I thought might be interesting for me.Tue, 17 Jul 2018 00:00:00 GMThttps://zayenz.se/blog/post/conferences/ijcai2018-4/https://zayenz.se/blog/post/conferences/ijcai2018-4/IJCAI 2018 is being held in Stockholm from July the 13th to July the 19th as a part of the Federated AI Meeting. In this and other posts I will give some short comments on interesting things I've heard. If anything is wrong or misrepresented, please don't hesitate to get in touch with me. On the fourth day the main IJCAI conference started. The conference has many parallel tracks, comments here are from sessions that I thought might be interesting for me.Mon, 16 Jul 2018 00:00:00 GMThttps://zayenz.se/blog/post/conferences/ijcai2018-3/https://zayenz.se/blog/post/conferences/ijcai2018-3/IJCAI 2018 and SOCS 2018 is being held in Stockholm from July the 13th to July the 19th as a part of the Federated AI Meeting. In this and other posts I will give some short comments on interesting things I've heard. If anything is wrong or misrepresented, please don't hesitate to get in touch with me. The third day I attended the second day of SOCS 2018, the 11th Symposium on Combinatorial Search. The proceedings for SOCS 2018 are available here.Sun, 15 Jul 2018 00:00:00 GMThttps://zayenz.se/blog/post/conferences/ijcai2018-2/https://zayenz.se/blog/post/conferences/ijcai2018-2/IJCAI 2018 and SOCS 2018 is being held in Stockholm from July the 13th to July the 19th as a part of the Federated AI Meeting. In this and other posts I will give some short comments on interesting things I've heard. If anything is wrong or misrepresented, please don't hesitate to get in touch with me. The second day I attended SOCS 2018, the 11th Symposium on Combinatorial Search. The proceedings for SOCS 2018 are available here.Sat, 14 Jul 2018 00:00:00 GMThttps://zayenz.se/blog/post/conferences/ijcai2018-1/https://zayenz.se/blog/post/conferences/ijcai2018-1/IJCAI 2018 first workshop dayFri, 13 Jul 2018 00:00:00 GMThttps://zayenz.se/blog/post/rust-2018/https://zayenz.se/blog/post/rust-2018/Rust in 2018Tue, 23 Jan 2018 00:00:00 GMT