FUN2026 - Program

Weak Binary Search Trees — Tobias Lauer
Sorting Magazines and Boxes — Gabriele Fici, Manal Mohamed, and Jakub Radoszewski
Finding Maximum and Minimum Size Matrices: The Algorithmic Complexity of Coding Challenges — Abdelrahman Abdelmonsef, Xingyu Dong, Daniel Průša, Michael Wehar, and Chen Xu
Turing Completeness of GNU find: From mkdir-assisted Loops to Standalone Computation — Keigo Oka

Ferry Cover with Connectivity Constraints — Niranjan Balachandran, Ankita Dargad, Urban Larsson, Neeldhara Misra, and Umesh Shankar
The Berlin Safe House Puzzle: Spycraft via Interval Graphs — Gennaro Cordasco, Luisa Gargano, and Adele Anna Rescigno
Sinks and Ladders: ARRIVAL and SSG with Two Vertices per Level — Bernd Gärtner, Sebastian Haslebacher, and Hung P. Hoang
Finding Shortest Walks in Kuru Kuru Kururin — Mickaël Laurent and Maher Mallem

Fun with Maps — Bettina Speckman
Abstract:The field of cartography is concerned with the design of high-quality cartographic products, most frequently maps. Cartographers have made maps for centuries, initially by hand, and now aided by computers. The automation of cartographic tasks has progressed far: smart devices help to plan routes and to use public transport in new environments, restaurants and shops are easy to find, and it has become increasingly difficult to get lost on a hike. However, beyond topographic maps, special purpose thematic maps are designed to convey targeted information. Such maps usually focus on a single theme and visualize diverse topics such as weather patterns, election results, or library holdings. There is only limited support in standard cartographic software solutions for such specialized maps and practitioners are often forced to resort to essentially handcrafted solutions. In this presentation I will introduce several thematic maps we encountered while trying to help practitioners, as well as the fun algorithmic problems (and solutions) we found on the way.

The Closed Hull Game and the Closed Interval Game — Samuel N. Araújo, Fabrício Benevides, Nicolas Martins, Nicolas Nisse, and Rudini Sampaio
Nemesis, an Escape Game in Graphs — Pierre Bergé, Antoine Dailly, and Yan Gerard
On the complexity of the Maker-Breaker happy vertex game — Mathieu Hilaire, Perig Montfort, and Nacim Oijid
Directed grabbing games or how to politely grab the maximum number of olives in a reception — Jean-Claude Bermond, Michel Cosnard, Frédéric Havet, Takako Kodate, and Stéphane Pérennes
Token positional games — Guillaume Bagan, Quentin Deschamps, Florian Galliot, Mirjana Mikalački, and Nacim Oijid
Replacing Cops with Zombies — Fengyi Liu and Avery Miller

Tetris is Hard with Just One Piece Type — Josh Brunner, Erik D. Demaine, Della Hendrickson, and Jeffery Li
Hive is PSPACE-Hard — Daniël I. Andel and Benjamin G. Rin
Completing the Complexity Classification of 2-Solo Chess: Knights and Kings are Hard — Kolja Kühn and Wendy Yi
Endgames in Fog of War Chess — Matthias Gehnen and Julius Stannat

Man, these New York Times games are hard! A computational perspective — Alessandro Giovanni Alberti, Flavio Chierichetti, Mirko Giacchini, Daniele Muscillo, Alessandro Panconesi, and Erasmo Tani
An ASP-Completeness Framework for Dynasty Puzzles — Kosuke Susukita
Permutation Match Puzzles: How Young Tanvi Learned About Computational Complexity — Kshitij Gajjar and Neeldhara Misra
Computational Complexity of Swish Is Solved — Takashi Horiyama, Takehiro Ito, Jun Kawahara, Shin-ichi Minato, Akira Suzuki, Ryuhei Uehara, and Yutaro Yamaguchi

Covering a Polyomino-Shaped Stain with Non-Overlapping Identical Stickers — Keigo Oka, Naoki Inaba, and Akira Iino
Lozenge Tiling by Computing Distances — Jean-Marie Favreau, Yan Gerard, Pascal Lafourcade, and Léo Robert
MIDTERM Is a Deterministic Technique to Exit Recursive Mazes — Charles Bouillaguet and Orel Cosseron
An Almost-Optimal Upper Bound on the Push Number of the Torus Puzzle — Matteo Caporrella and Stefano Leucci

When Locality Implies Globality: Card-based ZKP Protocol for Shakashaka Puzzle — Daiki Miyahara, Léo Robert, Pascal Lafourcade, and Shohei Kaneko
Card-Based ZKP Protocols for Connectivity-Based Puzzles: Extending to Tree Structures with Application to Nurimeizu — Daiki Miyahara, Pascal Lafourcade, and Maxime Puys
Playing President with Virtual Players: How to Play Multiple Cards of a Kind — Daiki Miyahara, Pascal Lafourcade, Takaaki Mizuki, and Kazumasa Shinagawa
77 Shades of Grey — Quentin Bramas, Stéphane Devismes, Anaïs Durand, Pascal Lafourcade, and Anissa Lamani

1038 A10s fit into one A0 — Noel Friedrich
The Careless Coupon Collector’s Problem — Emilio Cruciani and Aditi Dudeja
A Demigod’s Number for the Rubik’s Cube — Arturo Merino and Bernardo Subercaseaux
Solving Small Rubik’s Cubes as Slowly as Possible — Jenny Quan, Noah Kim, Bernardo Subercaseaux, and John Mackey
Price of Locality in Permutation Mastermind: Are TikTok influencers Chaotic Enough? — Bernardo Subercaseaux

Hexasort - The Complexity of Stacking Colors on Graphs — Linus Klocker and Simon Dominik Fink
A Bookworm Climbs Up the Polynomial Hierarchy: Meta-Restoration Complexity in Arithmetic Puzzles — Brynmor Chapman, Lily Chung, Erik D. Demaine, Yota Irino, Della Hendrickson, Tonan Kamata, and Ryuhei Uehara
Spells for Quantum Programmers: Expressive High-Level Commands in Qutes — Simone Faro, Francesco Pio Marino, and Gabriele Messina
Pyramid Schemes for Eating M&Ms: Enumeration, Generation, and Gray Codes — Elizabeth Hartung, Brett Stevens, and Aaron Williams
The Quaternary Gray Code and Ziggu Puzzles — Madeleine Goertz and Aaron Williams

13th International Conference on Fun with Algorithms