Near-miss Johnson solid explained

In geometry, a near-miss Johnson solid is a strictly convex polyhedron whose faces are close to being regular polygons but some or all of which are not precisely regular. Thus, it fails to meet the definition of a Johnson solid, a polyhedron whose faces are all regular, though it "can often be physically constructed without noticing the discrepancy" between its regular and irregular faces.[1] The precise number of near-misses depends on how closely the faces of such a polyhedron are required to approximate regular polygons.

Some near-misses with high symmetry are also symmetrohedra with some truly regular polygon faces.

Some near-misses are also zonohedra.

Examples

Name
Conway name
ImageVertex
configurations
VEFF3F4F5F6F8F10F12Symmetry
Associahedron
t4dP3
2 (5.5.5)
12 (4.5.5)
1421936Dih3
order 12
Truncated triakis tetrahedron
t6kT
4 (5.5.5)
24 (5.5.6)
284216  124   Td, [3,3]
order 24
Pentahexagonal pyritoheptacontatetrahedron12 (3.5.3.6)
24 (3.3.5.6)
24 (3.3.3.3.5)
601327456126Th, [3<sup>+</sup>,4]
order 24
Chamfered cube
cC
24 (4.6.6)
8 (6.6.6)
324818 6 12   Oh, [4,3]
order 48
--12 (5.5.6)
6 (3.5.3.5)
12 (3.3.5.5)
30542612 122   D6h, [6,2]
order 24
--6 (5.5.5)
9 (3.5.3.5)
12 (3.3.5.5)
27512614 12    D3h, [3,2]
order 12
Tetrated dodecahedron4 (5.5.5)
12 (3.5.3.5)
12 (3.3.5.5)
28542816 12    Td, [3,3]
order 24
Chamfered dodecahedron
cD
60 (5.6.6)
20 (6.6.6)
8012042  1230   Ih, [5,3]
order 120
Rectified truncated icosahedron
atI
60 (3.5.3.6)
30 (3.6.3.6)
901809260 1220   Ih, [5,3]
order 120
Truncated truncated icosahedron
ttI
120 (3.10.12)
60 (3.12.12)
1802709260    1220Ih, [5,3]
order 120
Expanded truncated icosahedron
etI
60 (3.4.5.4)
120 (3.4.6.4)
18036018260901220   Ih, [5,3]
order 120
Snub rectified truncated icosahedron
stI
60 (3.3.3.3.5)
120 (3.3.3.3.6)
180450272240 1220   I, [5,3]+
order 60

Coplanar misses

Some failed Johnson solid candidates have coplanar faces. These polyhedra can be perturbed to become convex with faces that are arbitrarily close to regular polygons. These cases use 4.4.4.4 vertex figures of the square tiling, 3.3.3.3.3.3 vertex figure of the triangular tiling, as well as 60 degree rhombi divided double equilateral triangle faces, or a 60 degree trapezoid as three equilateral triangles. It is possible to take an infinite amount of distinct coplanar misses from sections of the cubic honeycomb (alternatively convex polycubes) or alternated cubic honeycomb, ignoring any obscured faces.

Examples:3.3.3.3.3.34.4.4.43.4.6.4:

See also

External links

Notes and References

  1. .