Tiling
A tiling in n dimensions can be thought of as an infinite n+1-dimensional polytope.
2D[edit | edit source]
Two-dimensional fillings of the plane by polygons are generally referred to as tilings or tessellations.
Regular tilings[edit | edit source]
A regular tiling in 2D space is vertex-transitive, edge-transitive, and face-transitive. There are only three such tilings in Euclidean 2D space.
Square tiling | Triangular tiling | Hexagonal tiling |
---|---|---|
The order-2 apeirogonal tiling is sometimes considered a valid regular tiling.
Semiregular tilings[edit | edit source]
Like a regular tiling, a semiregular tiling has only one type of vertex, and edges that are all of equal length. However, it can have different kinds of faces. There are eight such tilings in Euclidean 2D space, one of which does not maintain the symmetries of its "parent" regular tiling.
Semiregular tilings can also be called Archimedean tilings (because they can be derived from the regular tilings in the same way that the Archimedean solids are derived from the Platonic solids), although this name can exclude the elongated triangular tiling because it lacks the full symmetry of its "parent" regular tiling. Together, the regular and semiregular tilings make up the uniform tilings.
Duals of tilings can be constructed in the same way they are for polytopes: by "swapping" the facets and the vertices. Since the semiregular tilings are vertex-transitive, their duals are face-transitive.
k-uniform tilings[edit | edit source]
More complicated tilings called k-uniform tilings, defined as having exactly k types of vertex, are possible as well. Naturally, these become more numerous with higher values of k.
Tiling | k | Dual of tiling |
---|---|---|
2-uniform | ||
4-uniform | ||
7-uniform |
Hyperbolic tilings[edit | edit source]
In hyperbolic (non-Euclidean) space, the interior angles of faces around a vertex can add up to more than 360°, permitting tilings that would have been impossible otherwise.
Order-7 triangular tiling | Small rhombitriheptagonal tiling | Deltoidal triheptagonal tiling |
---|---|---|
regular | semiregular | semiregular dual |
3D[edit | edit source]
Three-dimensional fillings of space by polyhedra are usually referred to as honeycombs.
A polyhedron that can fill space on its own, using only more copies of itself, is regarded as space-filling. The honeycomb it forms, being made of only one type of cell, is therefore cell-transitive. The cube is the only Platonic solid that can do this; other polyhedra with this property include the hexagonal prism, truncated octahedron, and the rhombic dodecahedron. These can all fill space with only translational symmetries, while the triangular prism requires rotational symmetries to do so.
Regular honeycombs[edit | edit source]
There is only one regular honeycomb in Euclidean 3D space: the cubic honeycomb.
Uniform honeycombs[edit | edit source]
Including the cubic honeycomb, there are 28 "uniform" honeycombs in Euclidean 3D space: that is to say, vertex-transitive honeycombs made of uniform components. They can be separated into direct modifications of the cubic honeycomb, modifications of the tetrahedral-octahedral honeycomb (itself a modification of the cubic honeycomb), prisms of uniform 2D tilings, and gyrations and elongations of existing honeycombs.
Since the uniform honeycombs are vertex-transitive, their duals are cell-transitive.
Hyperbolic honeycombs[edit | edit source]
In hyperbolic 3D space, the dihedral angles of cells around an edge can add up to more than 360°. Not only does this permit conventional polyhedra (usually Platonic solids) to be packed more tightly around an edge than they could be in Euclidean space, but also allows for the use of unconventional forms that could only exist in hyperbolic space, such as packing more than 6 triangles around a vertex.
Order-4 dodecahedral honeycomb | Hexagonal tiling honeycomb | Order-5 octahedral honeycomb |
---|---|---|
{5,3,4} | {6,3,3} | {3,4,5} |
4 dodecahedra meet around an edge | 3 hexagons around a vertex tile a plane.
Here, these tilings also meet 3 to an edge. |
5 octahedra meet around an edge |
Higher dimensions[edit | edit source]
A honeycomb analog in n dimensions can be referred to as an n-honeycomb, or by one of many competing unofficial names.
1D | Sequence |
2D | Tiling |
3D | Honeycomb |
4D | Tetracomb |
5D | Pentacomb |
6D | Hexacomb |
7D | Heptacomb |
8D | Octacomb |
9D | Enneacomb |
An n-dimensional hypercube can, almost by definition, fill the space it inhabits.
External links[edit | edit source]
- Klitzing, Richard. "Euclidean Tesselations".
- Wikipedia Contributors, "Convex uniform honeycomb".
- Wikipedia Contributors. "Euclidean tilings by convex regular polygons".