In geometry, chamfering or edge-truncation is a topological operator that modifies one polyhedron into another. It is similar to expansion: it moves the faces apart (outward), and adds a new face between each two adjacent faces; but contrary to expansion, it maintains the original vertices. (Equivalently: it separates the faces by reducing them, and adds a new face between each two adjacent faces; but it only moves the vertices inward.) For a polyhedron, this operation adds a new hexagonal face in place of each original edge.
In Conway polyhedron notation, chamfering is represented by the letter "c". A polyhedron with e edges will have a chamfered form containing 2e new vertices, 3e new edges, and e new hexagonal faces.
In the chapters below, the chamfers of the five Platonic solids are described in detail. Each is shown in an equilateral version where all edges have the same length, and in a canonical version where all edges touch the same midsphere. (They look noticeably different only for solids containing triangles.) The shown dual polyhedra are dual to the canonical versions.
Seed Platonic solid | {3,3} | {4,3} | {3,4} | {5,3} | {3,5} |
---|---|---|---|---|---|
Chamfered Platonic solid (equilateral form) |
Chamfered tetrahedron | |
---|---|
(equilateral form) | |
Conway notation | cT |
Goldberg polyhedron | GPIII(2,0) = {3+,3}2,0 |
Faces | 4 congruent equilateral triangles 6 congruent equilateral* hexagons |
Edges | 24 (2 types: triangle-hexagon, hexagon-hexagon) |
Vertices | 16 (2 types) |
Vertex configuration | (12) 3.6.6 (4) 6.6.6 |
Symmetry group | Tetrahedral (Td) |
Dual polyhedron | Alternate-triakis tetratetrahedron |
Properties | convex, equilateral* |
Net | |
*for a certain chamfering/truncating depth |
The chamfered tetrahedron or alternate truncated cube is a convex polyhedron constructed:
For a certain depth of chamfering/truncation, all (final) edges of the cT have the same length; then, the hexagons are equilateral, but not regular.
The dual of the chamfered tetrahedron is the alternate-triakis tetratetrahedron.
The cT is the Goldberg polyhedron GPIII(2,0) or {3+,3}2,0, containing triangular and hexagonal faces.
chamfered tetrahedron (canonical form) | dual of the tetratetrahedron | chamfered tetrahedron (canonical form) |
alternate-triakis tetratetrahedron | tetratetrahedron | alternate-triakis tetratetrahedron |
Chamfered cube | |
---|---|
(equilateral form) | |
Conway notation | cC = t4daC |
Goldberg polyhedron | GPIV(2,0) = {4+,3}2,0 |
Faces | 6 congruent squares 12 congruent equilateral* hexagons |
Edges | 48 (2 types: square-hexagon, hexagon-hexagon) |
Vertices | 32 (2 types) |
Vertex configuration | (24) 4.6.6 (8) 6.6.6 |
Symmetry | Oh, [4,3], (*432) Th, [4,3+], (3*2) |
Dual polyhedron | Tetrakis cuboctahedron |
Properties | convex, equilateral* |
Net (3 zones are shown by 3 colors for their hexagons — each square is in 2 zones —.) | |
*for a certain chamfering depth |
The chamfered cube is constructed as a chamfer of a cube: the squares are reduced in size and new faces, hexagons, are added in place of all the original edges. The cC is a convex polyhedron with 32 vertices, 48 edges, and 18 faces: 6 congruent (and regular) squares, and 12 congruent flattened hexagons.
For a certain depth of chamfering, all (final) edges of the chamfered cube have the same length; then, the hexagons are equilateral, but not regular. They are congruent alternately truncated rhombi, have 2 internal angles of and 4 internal angles of while a regular hexagon would have all internal angles.
The cC is also inaccurately called a truncated rhombic dodecahedron, although that name rather suggests a rhombicuboctahedron. The cC can more accurately be called a tetratruncated rhombic dodecahedron, because only the (6) order-4 vertices of the rhombic dodecahedron are truncated.
The dual of the chamfered cube is the tetrakis cuboctahedron.
Because all the faces of the cC have an even number of sides and are centrally symmetric, it is a zonohedron:
The chamfered cube is also the Goldberg polyhedron GPIV(2,0) or {4+,3}2,0, containing square and hexagonal faces.
The cC is the Minkowski sum of a rhombic dodecahedron and a cube of edge length 1 when the eight order-3 vertices of the rhombic dodecahedron are at and its six order-4 vertices are at the permutations of
A topological equivalent to the chamfered cube, but with pyritohedral symmetry and rectangular faces, can be constructed by chamfering the axial edges of a pyritohedron. This occurs in pyrite crystals.
chamfered cube (canonical form) | rhombic dodecahedron | chamfered octahedron (canonical form) |
tetrakis cuboctahedron | cuboctahedron | triakis cuboctahedron |
Chamfered octahedron | |
---|---|
(equilateral form) | |
Conway notation | cO = t3daO |
Faces | 8 congruent equilateral triangles 12 congruent equilateral* hexagons |
Edges | 48 (2 types: triangle-hexagon, hexagon-hexagon) |
Vertices | 30 (2 types) |
Vertex configuration | (24) 3.6.6 (6) 6.6.6.6 |
Symmetry | Oh, [4,3], (*432) |
Dual polyhedron | Triakis cuboctahedron |
Properties | convex, equilateral* |
*for a certain truncating depth |
In geometry, the chamfered octahedron is a convex polyhedron constructed by truncating the 8 order-3 vertices of the rhombic dodecahedron. These truncated vertices become congruent equilateral triangles, and the original 12 rhombic faces become congruent flattened hexagons.
For a certain depth of truncation, all (final) edges of the cO have the same length; then, the hexagons are equilateral, but not regular.
The chamfered octahedron can also be called a tritruncated rhombic dodecahedron.
The dual of the cO is the triakis cuboctahedron.
Chamfered dodecahedron | |
---|---|
(equilateral form) | |
Conway notation | cD = t5daD = dk5aD |
Goldberg polyhedron | GPV(2,0) = {5+,3}2,0 |
Fullerene | C80 [2] |
Faces | 12 congruent regular pentagons 30 congruent equilateral* hexagons |
Edges | 120 (2 types: pentagon-hexagon, hexagon-hexagon) |
Vertices | 80 (2 types) |
Vertex configuration | (60) 5.6.6 (20) 6.6.6 |
Symmetry group | Icosahedral (Ih) |
Dual polyhedron | Pentakis icosidodecahedron |
Properties | convex, equilateral* |
*for a certain chamfering depth |
The chamfered dodecahedron is a convex polyhedron with 80 vertices, 120 edges, and 42 faces: 12 congruent regular pentagons and 30 congruent flattened hexagons.
It is constructed as a chamfer of a regular dodecahedron. The pentagons are reduced in size and new faces, flattened hexagons, are added in place of all the original edges. For a certain depth of chamfering, all (final) edges of the cD have the same length; then, the hexagons are equilateral, but not regular.
The cD is also inaccurately called a truncated rhombic triacontahedron, although that name rather suggests a rhombicosidodecahedron. The cD can more accurately be called a pentatruncated rhombic triacontahedron, because only the (12) order-5 vertices of the rhombic triacontahedron are truncated.
The dual of the chamfered dodecahedron is the pentakis icosidodecahedron.
The cD is the Goldberg polyhedron GPV(2,0) or {5+,3}2,0, containing pentagonal and hexagonal faces.
chamfered dodecahedron (canonical form) | rhombic triacontahedron | chamfered icosahedron (canonical form) |
pentakis icosidodecahedron | icosidodecahedron | triakis icosidodecahedron |
Chamfered icosahedron | |
---|---|
(equilateral form) | |
Conway notation | cI = t3daI |
Faces | 20 congruent equilateral triangles 30 congruent equilateral* hexagons |
Edges | 120 (2 types: triangle-hexagon, hexagon-hexagon) |
Vertices | 72 (2 types) |
Vertex configuration | (24) 3.6.6 (12) 6.6.6.6.6 |
Symmetry | Ih, [5,3], (*532) |
Dual polyhedron | Triakis icosidodecahedron |
Properties | convex, equilateral* |
*for a certain truncating depth |
In geometry, the chamfered icosahedron is a convex polyhedron constructed by truncating the 20 order-3 vertices of the rhombic triacontahedron. The hexagonal faces of the cI can be made equilateral, but not regular, with a certain depth of truncation.
The chamfered icosahedron can also be called a tritruncated rhombic triacontahedron.
The dual of the cI is the triakis icosidodecahedron.
Square tiling, Q {4,4} | Triangular tiling, Δ {3,6} | Hexagonal tiling, H {6,3} | Rhombille, daH dr{6,3} |
cQ | cΔ | cH | cdaH |
The chamfer operation applied in series creates progressively larger polyhedra with new faces, hexagonal, replacing the edges of the current one. The chamfer operator transforms GP(m,n) to GP(2m,2n).
A regular polyhedron, GP(1,0), creates a Goldberg polyhedra sequence: GP(1,0), GP(2,0), GP(4,0), GP(8,0), GP(16,0)...
GP(1,0) | GP(2,0) | GP(4,0) | GP(8,0) | GP(16,0) | ... | |
---|---|---|---|---|---|---|
GPIV {4+,3} | C | cC | ccC | cccC | ccccC | ... |
GPV {5+,3} | D | cD | ccD | cccD | ccccD | ... |
GPVI {6+,3} | H | cH | ccH | cccH | ccccH | ... |
The truncated octahedron or truncated icosahedron, GP(1,1), creates a Goldberg sequence: GP(1,1), GP(2,2), GP(4,4), GP(8,8)...
GP(1,1) | GP(2,2) | GP(4,4) | ... | |
---|---|---|---|---|
GPIV {4+,3} | tO | ctO | cctO | ... |
GPV {5+,3} | tI | ctI | cctI | ... |
GPVI {6+,3} | tΔ | ctΔ | cctΔ | ... |
A truncated tetrakis hexahedron or pentakis dodecahedron, GP(3,0), creates a Goldberg sequence: GP(3,0), GP(6,0), GP(12,0)...
GP(3,0) | GP(6,0) | GP(12,0) | ... | |
---|---|---|---|---|
GPIV {4+,3} | tkC | ctkC | cctkC | ... |
GPV {5+,3} | tkD | ctkD | cctkD | ... |
GPVI {6+,3} | tkH | ctkH | cctkH | ... |
Like the expansion operation, chamfer can be applied to any dimension.
For polygons, it triples the number of vertices. Example:
For polychora, new cells are created around the original edges. The cells are prisms, containing two copies of the original face, with pyramids augmented onto the prism sides.[something may be wrong in this passage]
A cuboctahedron is a polyhedron with 8 triangular faces and 6 square faces. A cuboctahedron has 12 identical vertices, with 2 triangles and 2 squares meeting at each, and 24 identical edges, each separating a triangle from a square. As such, it is a quasiregular polyhedron, i.e., an Archimedean solid that is not only vertex-transitive but also edge-transitive. It is radially equilateral. Its dual polyhedron is the rhombic dodecahedron.
In geometry, a dodecahedron or duodecahedron is any polyhedron with twelve flat faces. The most familiar dodecahedron is the regular dodecahedron with regular pentagons as faces, which is a Platonic solid. There are also three regular star dodecahedra, which are constructed as stellations of the convex form. All of these have icosahedral symmetry, order 120.
In geometry, the truncated tetrahedron is an Archimedean solid. It has 4 regular hexagonal faces, 4 equilateral triangle faces, 12 vertices and 18 edges. It can be constructed by truncating all 4 vertices of a regular tetrahedron.
In geometry, the rhombic dodecahedron is a convex polyhedron with 12 congruent rhombic faces. It has 24 edges, and 14 vertices of 2 types. As a Catalan solid, it is the dual polyhedron of the cuboctahedron. As a parallelohedron, the rhombic dodecahedron can be used to tesselate its copies in space creating a rhombic dodecahedral honeycomb. There are some variations of the rhombic dodecahedron, one of which is the Bilinski dodecahedron. There are some stellations of the rhombic dodecahedron, one of which is the Escher's solid. The rhombic dodecahedron may also appearances in the garnet crystal, the architectural philosophies, practical usages, and toys.
The rhombic triacontahedron, sometimes simply called the triacontahedron as it is the most common thirty-faced polyhedron, is a convex polyhedron with 30 rhombic faces. It has 60 edges and 32 vertices of two types. It is a Catalan solid, and the dual polyhedron of the icosidodecahedron. It is a zonohedron.
In geometry, a zonohedron is a convex polyhedron that is centrally symmetric, every face of which is a polygon that is centrally symmetric. Any zonohedron may equivalently be described as the Minkowski sum of a set of line segments in three-dimensional space, or as a three-dimensional projection of a hypercube. Zonohedra were originally defined and studied by E. S. Fedorove, a Russian crystallographer. More generally, in any dimension, the Minkowski sum of line segments forms a polytope known as a zonotope.
In geometry, an n-gonaltrapezohedron, n-trapezohedron, n-antidipyramid, n-antibipyramid, or n-deltohedron, is the dual polyhedron of an n-gonal antiprism. The 2n faces of an n-trapezohedron are congruent and symmetrically staggered; they are called twisted kites. With a higher symmetry, its 2n faces are kites.
In geometry, a disdyakis dodecahedron,, is a Catalan solid with 48 faces and the dual to the Archimedean truncated cuboctahedron. As such it is face-transitive but with irregular face polygons. It resembles an augmented rhombic dodecahedron. Replacing each face of the rhombic dodecahedron with a flat pyramid creates a polyhedron that looks almost like the disdyakis dodecahedron, and is topologically equivalent to it.
In geometry, the chamfered dodecahedron is a convex polyhedron with 80 vertices, 120 edges, and 42 faces: 30 hexagons and 12 pentagons. It is constructed as a chamfer (edge-truncation) of a regular dodecahedron. The pentagons are reduced in size and new hexagonal faces are added in place of all the original edges. Its dual is the pentakis icosidodecahedron.
In geometry and topology, Conway polyhedron notation, invented by John Horton Conway and promoted by George W. Hart, is used to describe polyhedra based on a seed polyhedron modified by various prefix operations.
A regular dodecahedron or pentagonal dodecahedron is a dodecahedron composed of regular pentagonal faces, three meeting at each vertex. It is an example of Platonic solids, described as cosmic stellation by Plato in his dialogues, and it was used as part of Solar System proposed by Johannes Kepler. However, the regular dodecahedron, including the other Platonic solids, has already been described by other philosophers since antiquity.
In geometry, a quasiregular polyhedron is a uniform polyhedron that has exactly two kinds of regular faces, which alternate around each vertex. They are vertex-transitive and edge-transitive, hence a step closer to regular polyhedra than the semiregular, which are merely vertex-transitive.
In geometry, a d-dimensional simple polytope is a d-dimensional polytope each of whose vertices are adjacent to exactly d edges (also d facets). The vertex figure of a simple d-polytope is a (d – 1)-simplex.
In geometry, the pentakis icosidodecahedron or subdivided icosahedron is a convex polyhedron with 80 triangular faces, 120 edges, and 42 vertices. It is a dual of the truncated rhombic triacontahedron.
In geometry and polyhedral combinatorics, the Kleetope of a polyhedron or higher-dimensional convex polytope P is another polyhedron or polytope PK formed by replacing each facet of P with a pyramid. In some cases, the pyramid is chosen to have regular sides, often producing a non-convex polytope; alternatively, by using sufficiently shallow pyramids, the results may remain convex. Kleetopes are named after Victor Klee, although the same concept was known under other names long before the work of Klee.
In mathematics, and more specifically in polyhedral combinatorics, a Goldberg polyhedron is a convex polyhedron made from hexagons and pentagons. They were first described in 1937 by Michael Goldberg (1902–1990). They are defined by three properties: each face is either a pentagon or hexagon, exactly three faces meet at each vertex, and they have rotational icosahedral symmetry. They are not necessarily mirror-symmetric; e.g. GP(5,3) and GP(3,5) are enantiomorphs of each other. A Goldberg polyhedron is a dual polyhedron of a geodesic polyhedron.
In geometry, an icosahedron is a polyhedron with 20 faces. The name comes from Ancient Greek εἴκοσι (eíkosi) 'twenty' and ἕδρα (hédra) 'seat'. The plural can be either "icosahedra" or "icosahedrons".
A geodesic polyhedron is a convex polyhedron made from triangles. They usually have icosahedral symmetry, such that they have 6 triangles at a vertex, except 12 vertices which have 5 triangles. They are the dual of corresponding Goldberg polyhedra, of which all but the smallest one have mostly hexagonal faces.
The order-5 truncated pentagonal hexecontahedron is a convex polyhedron with 72 faces: 60 hexagons and 12 pentagons triangular, with 210 edges, and 140 vertices. Its dual is the pentakis snub dodecahedron.