Wikipedia

Common net

In geometry, a common net is a net that can be folded onto several polyhedra. To be a valid common net, there shouldn't exist any non-overlapping sides and the resulting polyhedra must be connected through faces. The research of examples of this particular nets dates back to the end of the 20th century, despite that, not many examples have been found. Two classes, however, have been deeply explored, regular polyhedra and cuboids. The search of common nets is usually made by either extensive search or the overlapping of nets that tile the plane.

Common net for both a octahedron and a Tritetrahedron.

Demaine et al. proved that every convex polyhedron can be unfolded and refolded to a different convex polyhedron.[1]

There can be types of common nets, strict edge unfoldings and free unfoldings. Strict edge unfoldings refers to common nets where the different polyhedra that can be folded use the same folds, that is, to fold one polyhedra from the net of another there is no need to make new folds. Free unfoldings refer to the opposite case, when we can create as many folds as needed to enable the folding of different polyhedra.

Multiplicity of common nets refers to the number of common nets for the same set of polyhedra.

Regular polyhedra

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Open problem 25.31 in Geometric Folding Algorithm by Rourke and Demaine reads:

"Can any Platonic solid be cut open and unfolded to a polygon that may be refolded to a different Platonic solid? For example, may a cube be so dissected to a tetrahedron?"[2]

This problem has been partially solved by Shirakawa et al. with a fractal net that is conjectured to fold to a tetrahedron and a cube.

Multiplicity Polyhedra 1 Polyhedra 2 Reference
Tetrahedron Cube [3]
Tetrahedron Cuboid (1x1x1.232) [4]
87 Tetrahedron Jonhson Solid J17 [5]
37 Tetrahedron Jonhson Solid J84 [5]
Cube Tetramonohedron [6]
Cube 1x1x7 and 1x3x3 Cuboids [7]
Cube Octahedron (non-Regular) [3]
Octahedron Tetramonohedron [8]
Octahedron tetramonohedron [6]
Octahedron Tritetrahedron [9]
Icosahedron Tetramonohedron [6]

Non-regular polyhedra

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Cuboids

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Common net of a 1x1x5 and 1x2x3 cuboid

Common nets of cuboids have been deeply researched, mainly by Uehara and coworkers. To the moment, common nets of up to three cuboids have been found, It has, however, been proven that there exist infinitely many examples of nets that can be folded into more than one polyhedra.[10]

Area Multiplicity Cuboid 1 Cuboid 2 Cuboid 3 Reference
22 6495 1x1x5 1x2x3 [11]
22 3 1x1x5 1x2x3 0x1x11 [12]
28 1x2x4 √2x√2x3√2 [12]
30 30 1x1x7 1x3x3 √5x√5x√5 [13]
30 1080 1x1x7 1x3x3 [13]
34 11291 1x1x8 1x2x5 [11]
38 2334 1x1x9 1x3x4 [11]
46 568 1x1x11 1x3x5 [11]
46 92 1x2x7 1x3x5 [11]
54 1735 1x1x13 3x3x3 [11]
54 1806 1x1x13 1x3x6 [11]
54 387 1x3x6 3x3x3 [11]
58 37 1x1x14 1x4x5 [11]
62 5 1x3x7 2x3x5 [11]
64 50 2x2x7 1x2x10 [11]
64 6 2x2x7 2x4x4 [11]
70 3 1x1x17 1x5x5 [11]
70 11 1x2x11 1x3x8 [11]
88 218 2x2x10 1x4x8 [11]
88 86 2x2x10 2x4x6 [11]
160 4x4x8 √10x2√10x2√10 [12]
532 7x8x14 2x4x43 2x13x16 [14]
1792 7x8x56 7x14x38 2x13x58 [14]

*Non-orthogonal foldings

Polycubes

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The first cases of common nets of polycubes found was the work by George Miller, with a later contribution of Donald Knuth, that culminated in the Cubigami puzzle.[15] It’s composed of a net that can fold to all 7 tree-like tetracubes. All possible common nets up to pentacubes were found. All the nets follow strict orthogonal folding despite still being considered free unfoldings.

Area Multiplicity Polyhedra Reference
14 29026 All tricubes [16]
14 All tricubes [11]
18 68 All tree-like tetracubes[15] [17]
22 23 pentacubes [18]
22 3 22 tree-like pentacubes [18]
22 1 Non-planar pentacubes [18]

Deltahedra

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3D Simplicial polytope

Area Multiplicity Polyhedra Reference
8 1 Both 8 face deltahedra [9]
10 4 7-vertex deltahedra [19]

References

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  1. ^ Demaine, Erik D.; Demaine, Martin L.; Itoh, Jin-ichi; Lubiw, Anna; Nara, Chie; OʼRourke, Joseph (2013-10-01). "Refold rigidity of convex polyhedra". Computational Geometry. 46 (8): 979–989. doi:10.1016/j.comgeo.2013.05.002. hdl:1721.1/99989. ISSN 0925-7721.
  2. ^ Demaine, Erik D.; O'Rourke, Joseph (2007). Geometric folding algorithms: linkages, origami, polyhedra. Cambridge: Cambridge university press. ISBN 978-0-521-85757-4.
  3. ^ a b Toshihiro Shirakawa, Takashi Horiyama, and Ryuhei Uehara, 27th European Workshop on Computational Geometry (EuroCG 2011), 2011, 47-50.
  4. ^ Koichi Hirata, Personal communication, December 2000
  5. ^ a b Araki, Y., Horiyama, T., Uehara, R. (2015). Common Unfolding of Regular Tetrahedron and Johnson-Zalgaller Solid. In: Rahman, M.S., Tomita, E. (eds) WALCOM: Algorithms and Computation. WALCOM 2015. Lecture Notes in Computer Science, vol 8973. Springer, Cham. https://doi.org/10.1007/978-3-319-15612-5_26
  6. ^ a b c "Ryuuhei Uehara - Nonexistence of Common Edge Developments of Regular Tetrahedron and Other Platonic Solids - Papers - researchmap". researchmap.jp. Retrieved 2024-08-01.
  7. ^ Xu D., Horiyama T., Shirakawa T., Uehara R., Common developments of three incongruent boxes of area 30, Computational Geometry, 64, 8 2017
  8. ^ Demaine, Erik; O'Rourke (July 2007). Geometric Folding Algorithms: Linkages, Origami, Polyhedra. Cambridge University Press. ISBN 978-0-521-85757-4.{{cite book}}: CS1 maint: date and year (link)
  9. ^ a b Weisstein, Eric. "Net".
  10. ^ Shirakawa, Toshihiro; Uehara, Ryuhei (February 2013). "Common Developments of Three Incongruent Orthogonal Boxes". International Journal of Computational Geometry & Applications. 23 (1): 65–71. doi:10.1142/S0218195913500040. ISSN 0218-1959.
  11. ^ a b c d e f g h i j k l m n o p q Mitani, Jun; Uehara, Ryuhei (2008). "Polygons Folding to Plural Incongruent Orthogonal Boxes" (PDF). Canadian Conference on Computational Geometry.
  12. ^ a b c Abel, Zachary; Demaine, Erik; Demaine, Martin; Matsui, Hiroaki; Rote, Günter; Uehara, Ryuhei. "Common Developments of Several Different Orthogonal Boxes". The 23rd Canadian Conference on Computational Geometr: 77–82. hdl:10119/10308.
  13. ^ a b Xu, Dawei; Horiyama, Takashi; Shirakawa, Toshihiro; Uehara, Ryuhei (August 2017). "Common developments of three incongruent boxes of area 30". Computational Geometry. 64: 1–12. doi:10.1016/j.comgeo.2017.03.001. ISSN 0925-7721.
  14. ^ a b Shirakawa, Toshihiro; Uehara, Ryuhei (February 2013). "Common Developments of Three Incongruent Orthogonal Boxes". International Journal of Computational Geometry & Applications. 23 (1): 65–71. doi:10.1142/S0218195913500040. ISSN 0218-1959.
  15. ^ a b Miller, George; Knuth, Donald. "Cubigami".
  16. ^ Mabry, Rick. "Ambiguous unfoldings of polycubes".
  17. ^ Miller, George. "Cubigami".
  18. ^ a b c Aloupis, Greg; Bose, Prosenjit K.; Collette, Sébastien; Demaine, Erik D.; Demaine, Martin L.; Douïeb, Karim; Dujmović, Vida; Iacono, John; Langerman, Stefan; Morin, Pat (2011). "Common Unfoldings of Polyominoes and Polycubes". In Akiyama, Jin; Bo, Jiang; Kano, Mikio; Tan, Xuehou (eds.). Computational Geometry, Graphs and Applications. Lecture Notes in Computer Science. Vol. 7033. Berlin, Heidelberg: Springer. pp. 44–54. doi:10.1007/978-3-642-24983-9_5. ISBN 978-3-642-24983-9.
  19. ^ Mabry, Rick. "The four common nets of the five 7-vertex deltahedra".
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