TL;DR: This article gives a proof of the classical honeycomb conjecture: any partition of the plane into regions of equal area has perimeter at least that of the regular hexagonal honeycomb tiling.
Abstract: This article gives a proof of the classical honeycomb conjecture: any partition of the plane into regions of equal area has perimeter at least that of the regular hexagonal honeycomb tiling.
TL;DR: The necessary conditions for the existence of such tilings using boundary invariants are given, which are combinatorial group-theoretic invariants associated to the boundaries of the tile shapes and the regions to be tiled.
TL;DR: A molecular network that exhibits critical correlations in the spatial order that is characteristic of a random, entropically stabilized, rhombus tiling is described and a topological defect can propagate through the network, giving rise to a local reordering of molecular tiles and thus to transitions between quasi-degenerate local minima of a complex energy landscape.
Abstract: A molecular network that exhibits critical correlations in the spatial order that is characteristic of a random, entropically stabilized, rhombus tiling is described. Specifically, we report a random tiling formed in a two-dimensional molecular network of p-terphenyl-3,5,3',5'-tetracarboxylic acid adsorbed on graphite. The network is stabilized by hexagonal junctions of three, four, five, or six molecules and may be mapped onto a rhombus tiling in which an ordered array of vertices is embedded within a nonperiodic framework with spatial fluctuations in a local order characteristic of an entropically stabilized phase. We identified a topological defect that can propagate through the network, giving rise to a local reordering of molecular tiles and thus to transitions between quasi-degenerate local minima of a complex energy landscape. We draw parallels between the molecular tiling and dynamically arrested systems, such as glasses.
TL;DR: The notion of tilings spaces and inverse limits was introduced in this article, where the authors propose a relaxation of the rules for tilings without finite local complexity, based on the notion of inverse limits.
Abstract: Basic notions Tiling spaces and inverse limits Cohomology of tilings spaces Relaxing the rules I: Rotations Pattern-equivariant cohomology Tricks of the trade Relaxing the rules II: Tilings without finite local complexity Solutions to selected exercises Bibliography.
TL;DR: In this paper, Minkowski's conjecture and Redei's theorem were proved for packing and covering by the semicross and cross, and by triangles of equal areas, respectively.
Abstract: 1. Minkowski's conjecture 2. Cubical clusters 3. Tiling by the semicross and cross 4. Packing and covering by the semicross and cross 5. Tiling by triangles of equal areas 6. Tiling by similar triangles 7. Redei's theorem 8. Epilogue Appendices References.