Tiling with Three Polygons is Undecidable
arXiv:2409.11582
Abstract
We prove that the following problem is co-RE-complete and thus undecidable: given three simple polygons, is there a tiling of the plane where every tile is an isometry of one of the three polygons (either allowing or forbidding reflections)? This result improves on the best previous construction which requires five polygons.
17 pages, 5 figures