Johnson solid

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Template:Short description Template:Pp-sock

In geometry, a Johnson solid, sometimes also known as a Johnson–Zalgaller solid,[1] is a convex polyhedron whose faces[2] are regular polygons and that is not a uniform polyhedron.Template:R 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

Template:Multiple image A convex polyhedron is the convex hull of a finite set of points in 3-dimensional space, not all in a plane.Template:R 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,Template:R but not a uniform polyhedron;Template:R the last condition excludes the Platonic solids, Archimedean solids, prisms, and antiprisms.

The solids are named after Norman Johnson and Victor Zalgaller.Template:R Template:Harvtxt published a list of 92 such solids and assigned them their names and numbers. Template:Harvtxt proved Johnson's conjectureTemplate:R that there were none beyond these 92.Template:Secondary 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.Template:R

Naming and construction of solids

Template:Wide image

Template:Color box - invalid, Template:Color box - Platonic, Template:Color box - Archimedean, Template:Color box - 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:Template:R

  • 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: Template:Color box - coplanar, Template:Color box - Platonic, Template:Color box - 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

Template:Multiple image

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:Template:R

  • 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.Template:R

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:Template:R

  • 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

Template:Further 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:[3]

Chiral solids

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

Circumscribable solids

Template:Further 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.[4]

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.Template:Sfnp A volume is a measurement of a region in three-dimensional space.Template:Sfnp 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.[5]

A polygon that is rotated symmetrically by 360∘n is denoted by Cn, a cyclic group of order n; combining this with the reflection symmetry results in the symmetry of dihedral group Dn of order 2n.[6] 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 Cnv of order 2n. The transformation that preserves a polyhedron's symmetry by reflecting it across a horizontal plane is known as the prismatic symmetry Dnh of order 4n. The antiprismatic symmetry Dnd of order 4n preserves the symmetry by rotating its half bottom and reflection across the horizontal plane.Template:Sfnp The symmetry group Cnh of order 2n 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 C1h of order 2, often denoted as Cs.[7] Template:Mw-datatableTemplate:Sticky-headerTemplate:Sort-under

The table below lists the properties of the 92 (non-uniform) Johnson solids. The table includes each solid's enumeration (denoted as Jn).Template:Sfnp 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 α=5+25.

Table of the 92 Johnson solids
Jn Solid name Image Vertices Edges Faces Symmetry group and orderTemplate:Sfnp Surface area, exactTemplate:Sfnp Surface area,
approx.Template:Sfnp
Volume, exactTemplate:Sfnp Volume,
approx.Template:Sfnp
1 Square pyramid 5 8 5 C4v of order 8 1+3 2.7321 26 0.2357
2 Pentagonal pyramid 6 10 6 C5v of order 10 1252(10+5+15α) 3.8855 5+524 0.3015
3 Triangular cupola 9 15 8 C3v of order 6 3+532 7.3301 532 1.1785
4 Square cupola 12 20 10 C4v of order 8 7+22+3 11.5605 1+223 1.9428
5 Pentagonal cupola 15 25 12 C5v of order 10 5+53+155α−504 16.5798 5+456 2.3241
6 Pentagonal rotunda 20 35 17 C5v of order 10 53+145α−752 22.3472 45+17512 6.9178
7 Elongated triangular pyramid 7 12 7 C3v of order 6 3+3 4.7321 2+3312 0.5509
8 Elongated square pyramid 9 16 9 C4v of order 8 5+3 6.7321 1+26 1.2357
9 Elongated pentagonal pyramid 11 20 11 C5v of order 10 5+53+5α4 8.8855 5+5+65α24 2.022
10 Gyroelongated square pyramid 9 20 13 C4v of order 8 1+33 6.1962 2+24+326 1.1927
11 Gyroelongated pentagonal pyramid (diminished icosahedron) 11 25 16 C5v of order 10 153+5α4 8.2157 25+9524 1.8802
12 Triangular bipyramid 5 9 6 D3h of order 12 332 2.5981 26 0.2357
13 Pentagonal bipyramid 7 15 10 D5h of order 20 532 4.3301 5+512 0.6030
14 Elongated triangular bipyramid 8 15 9 D3h of order 12 3+332 5.5981 26+34 0.6687
15 Elongated square bipyramid 10 20 12 D4h of order 16 4+23 7.4641 1+23 1.4714
16 Elongated pentagonal bipyramid 12 25 15 D5h of order 20 5+523 9.3301 5+5+35α12 2.3235
17 Gyroelongated square bipyramid 10 24 16 D4d of order 16 43 6.9282 2+4+323 1.4284
18 Elongated triangular cupola 15 27 14 C3v of order 6 9+523 13.3301 52+936 3.7766
19 Elongated square cupola 20 36 18 C4v of order 8 15+22+3 19.5605 3+823 6.7712
20 Elongated pentagonal cupola 25 45 22 C5v of order 10 15+53+10α+5α4 26.5798 5+45+15α6 10.0183
21 Elongated pentagonal rotunda 30 55 27 C5v of order 10 10+53+5α+35α2 32.3472 45+175+30α12 14.612
22 Gyroelongated triangular cupola 15 33 20 C3v of order 6 3+1123 12.5263 13612+183+301+3 3.5161
23 Gyroelongated square cupola 20 44 26 C4v of order 8 7+22+53 18.4887 1+232+234+22+2146+1032 6.2108
24 Gyroelongated pentagonal cupola 25 55 32 C5v of order 10 5+253+10α+5α4 25.2400 56+235+562145α−75−25−2 9.0733
25 Gyroelongated pentagonal rotunda 30 65 37 C5v of order 10 153+(α+5)α2 31.0075 45+175+102145α−75−25−212 13.6671
26 Gyrobifastigium 8 14 8 D2d of order 8 4+3 5.7321 32 0.8660
27 Triangular orthobicupola 12 24 14 D3h of order 12 6+23 9.4641 523 2.3570
28 Square orthobicupola 16 32 18 D4h of order 16 10+23 13.4641 2+423 3.8856
29 Square gyrobicupola 16 32 18 D4d of order 16
30 Pentagonal orthobicupola 20 40 22 D5h of order 20 10+75+5α+1015α2 17.7711 5+453 4.6481
31 Pentagonal gyrobicupola 20 40 22 D5d of order 20
32 Pentagonal orthocupolarotunda 25 50 27 C5v of order 10 5+675+245α+21015α4 23.5385 55+25512 9.2418
33 Pentagonal gyrocupolarotunda 25 50 27 C5v of order 10 5+1543+745α 23.5385
34 Pentagonal orthobirotunda 30 60 32 D5h of order 20 53+35α 29.306 45+1756 13.8355
35 Elongated triangular orthobicupola 18 36 20 D3h of order 12 12+23 15.4641 523+332 4.9551
36 Elongated triangular gyrobicupola 18 36 20 D3d of order 12
37 Elongated square gyrobicupola 24 48 26 D4d of order 16 18+23 21.4641 4+1023 8.714
38 Elongated pentagonal orthobicupola 30 60 32 D5h of order 20 20+75+5α+1015α2 27.7711 10+85+15α6 12.3423
39 Elongated pentagonal gyrobicupola 30 60 32 D5d of order 20
40 Elongated pentagonal orthocupolarotunda 35 70 37 C5v of order 10 15+675+245α+21015α4 33.5385 55+255+30α12 16.936
41 Elongated pentagonal gyrocupolarotunda 35 70 37 C5v of order 10
42 Elongated pentagonal orthobirotunda 40 80 42 D5h of order 20 10+75+45α+3015α 39.306 45+175+15α6 21.5297
43 Elongated pentagonal gyrobirotunda 40 80 42 D5d of order 20
44 Gyroelongated triangular bicupola 18 42 26 D3 of order 6 6+53 14.6603 532+2+23 4.6946
45 Gyroelongated square bicupola 24 56 34 D4 of order 8 10+63 20.3923 2+432+234+22+2146+1032 8.1536
46 Gyroelongated pentagonal bicupola 30 70 42 D5 of order 10 10+1523+125α 26.4313 5+453+562145α−75−α+3 11.3974
47 Gyroelongated pentagonal cupolarotunda 35 80 47 C5 of order 5 5+74(53+5α) 32.1988 55+25512+562145α−75−α+3 15.9911
48 Gyroelongated pentagonal birotunda 40 90 52 D5 of order 10 103+35α 37.9662 45+175+52145α−75−α+36 20.5848
49 Augmented triangular prism 7 13 8 C2v of order 4 2+323 4.5981 26+34 0.6687
50 Biaugmented triangular prism 8 17 11 C2v of order 4 1+523 5.3301 59144+16 0.9044
51 Triaugmented triangular prism 9 21 14 D3h of order 12 732 6.0622 22+34 1.1401
52 Augmented pentagonal prism 11 19 10 C2v of order 4 4+3+125α 9.173 1128+45α+1210α 1.9562
53 Biaugmented pentagonal prism 12 23 13 C2v of order 4 3+23+125α 9.9051 11232+45α+2410α 2.1919
54 Augmented hexagonal prism 13 22 11 C2v of order 4 5+43 11.9282 26+332 2.8338
55 Parabiaugmented hexagonal prism 14 26 14 D2h of order 8 4+53 12.6603 23+332 3.0695
56 Metabiaugmented hexagonal prism 14 26 14 C2v of order 4
57 Triaugmented hexagonal prism 15 30 17 D3h of order 12 3+63 13.3923 12+332 3.3052
58 Augmented dodecahedron 21 35 16 C5v of order 10 53+115α4 21.0903 95+43524 7.9646
59 Parabiaugmented dodecahedron 22 40 20 D5d of order 20 52(3+5α) 21.5349 25+1156 8.2661
60 Metabiaugmented dodecahedron 22 40 20 C2v of order 4
61 Triaugmented dodecahedron 23 45 24 C3v of order 6 34(53+35α) 21.9795 58(7+35) 8.5676
62 Metabidiminished icosahedron 10 20 12 C2v of order 4 53+5α2 7.7711 α6 1.5787
63 Tridiminished icosahedron 9 15 8 C3v of order 6 53+35α4 7.3265 58+7524 1.2772
64 Augmented tridiminished icosahedron 10 18 10 C3v of order 6 73+35α4 8.1925 15+22+7524 1.3950
65 Augmented truncated tetrahedron 15 27 14 C3v of order 6 3+1323 14.2583 1122 3.8891
66 Augmented truncated cube 28 48 22 C4v of order 8 15+102+33 34.3383 8+1623 15.5425
67 Biaugmented truncated cube 32 60 30 D4h of order 16 18+82+43 36.2419 9+62 17.4853
68 Augmented truncated dodecahedron 65 105 42 C5v of order 10 5+253+110α+5α4 102.1821 50512+8154 87.3637
69 Parabiaugmented truncated dodecahedron 70 120 52 D5d of order 20 10+25α+153+5α2 103.3734 515+251512 89.6878
70 Metabiaugmented truncated dodecahedron 70 120 52 C2v of order 4
71 Triaugmented truncated dodecahedron 75 135 62 C3v of order 6 15+353+90α+35α4 104.5648 712(75+375) 92.0118
72 Gyrate rhombicosidodecahedron 60 120 62 C5v of order 10 30+53+35α 59.306 20+2953 41.6153
73 Parabigyrate rhombicosidodecahedron 60 120 62 D5d of order 20
74 Metabigyrate rhombicosidodecahedron 60 120 62 C2v of order 4
75 Trigyrate rhombicosidodecahedron 60 120 62 C3v of order 6
76 Diminished rhombicosidodecahedron 55 105 52 C5v of order 10 25+153+10α+115α4 58.1147 1156+95 39.2913
77 Paragyrate diminished rhombicosidodecahedron 55 105 52 C5v of order 10
78 Metagyrate diminished rhombicosidodecahedron 55 105 52 Cs of order 2
79 Bigyrate diminished rhombicosidodecahedron 55 105 52 Cs of order 2
80 Parabidiminished rhombicosidodecahedron 50 90 42 D5d of order 20 20+52(3+2α+5α) 56.9233 55+2553 36.9672
81 Metabidiminished rhombicosidodecahedron 50 90 42 C2v of order 4
82 Gyrate bidiminished rhombicosidodecahedron 50 90 42 Cs of order 2
83 Tridiminished rhombicosidodecahedron 45 75 32 C3v of order 6 15+53+30α+95α4 55.732 352+2353 34.6432
84 Snub disphenoid 8 18 12 D2d of order 8 33 5.1962   0.8595
85 Snub square antiprism 16 40 26 D4d of order 16 2+63 12.3923   3.6012
86 Sphenocorona 10 22 14 C2v of order 4 2+33 7.1962 121+332+13+36 1.5154
87 Augmented sphenocorona 11 26 17 Cs of order 2 1+43 7.9282 121+332+13+36+132 1.7511
88 Sphenomegacorona 12 28 18 C2v of order 4 2+43 8.9282   1.9481
89 Hebesphenomegacorona 14 33 21 C2v of order 4 3+923 10.7942   2.9129
90 Disphenocingulum 16 38 24 D2d of order 8 4+53 12.6603   3.7776
91 Bilunabirotunda 14 26 14 D2h of order 8 2+23+5α 12.346 17+9512 3.0937
92 Triangular hebesphenorotunda 18 36 20 C3v of order 6 3+193+35α4 16.3887 52+756 5.1087

See also

References

  1. ↑ Template:Cite journal Cite error: <ref> tag with name "berman" defined in <references> is not used in prior text.
  2. ↑ Template:Cite book Cite error: <ref> tag with name "bk" defined in <references> is not used in prior text.
  3. ↑ Template:Cite book Cite error: <ref> tag with name "diudea" defined in <references> is not used in prior text.
  4. ↑ Template:Cite journal Cite error: <ref> tag with name "johnson" defined in <references> is not used in prior text.
  5. ↑ Template:Cite journal Cite error: <ref> tag with name "kaplan-hart" defined in <references> is not used in prior text.
  6. ↑ Template:Cite book Cite error: <ref> tag with name "uehara" defined in <references> is not used in prior text.
  7. ↑ Template:Cite book Cite error: <ref> tag with name "todesco" defined in <references> is not used in prior text.
  8. ↑ Template:Cite book Cite error: <ref> tag with name "williams" defined in <references> is not used in prior text.
  9. ↑ Template:Cite book Cite error: <ref> tag with name "zalgaller" defined in <references> is not used in prior text.
  10. ↑ Template:Cite book
  11. ↑ 2.0 2.1 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.
  12. ↑ Template:Multiref
  13. ↑ Template:Cite web
  14. ↑ Template:Multiref
  15. ↑ Template:Multiref
  16. ↑ Template:Multiref

Bibliography

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