dual snub 24-cell

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bgcolor=#e7dcc3 align=center colspan=3|Dual snub 24-cell
bgcolor=#ffffff align=center colspan=3|280px
Orthogonal projection
bgcolor=#e7dcc3|Type

|colspan=2|4-polytope

bgcolor=#e7dcc3|Cells

|colspan=2|96 60px

bgcolor=#e7dcc3|Faces

|432

|144 kites
288 Isosceles triangle

bgcolor=#e7dcc3|Edges

|colspan=2|480

bgcolor=#e7dcc3|Vertices

|colspan=2|144

bgcolor=#e7dcc3|Dual

|colspan=2|Snub 24-cell

bgcolor=#e7dcc3|Properties

|colspan=2|convex

In geometry, the dual snub 24-cell is a 144 vertex convex 4-polytope composed of 96 irregular cells. Each cell has faces of two kinds: 3 kites and 6 isosceles triangles.{{Sfn|Koca|Al-Ajmi|Ozdes Koca|2011|loc=Fig. 4|pp=986-987}} The polytope has a total of 432 faces (144 kites and 288 isosceles triangles) and 480 edges.

Geometry

The dual snub 24-cell, first described by Koca et al. in 2011,{{Sfn|Koca|Al-Ajmi|Ozdes Koca|2011}} is the dual polytope of the snub 24-cell, a semiregular polytope first described by Thorold Gosset in 1900.{{Sfn|Gosset|1900}}

Construction

The vertices of a dual snub 24-cell are obtained using quaternion simple roots (T') in the generation of the 600 vertices of the 120-cell.{{Sfn|Koca|Al-Ajmi|Ozdes Koca|2011|loc=6. Dual of the snub 24-cell|pp=986-988}} The following describe T and T' 24-cells as quaternion orbit weights of D4 under the Weyl group W(D4):

O(0100) : T = {±1,±e1,±e2,±e3,(±1±e1±e2±e3)/2}

O(1000) : V1

O(0010) : V2

O(0001) : V3

600px

With quaternions (p,q) where \bar p is the conjugate of p and [p,q]:r\rightarrow r'=prq and [p,q]^*:r\rightarrow r''=p\bar rq, then the Coxeter group W(H_4)=\lbrace[p,\bar p] \oplus [p,\bar p]^*\rbrace is the symmetry group of the 600-cell and the 120-cell of order 14400.

Given p \in T such that \bar p=\pm p^4, \bar p^2=\pm p^3, \bar p^3=\pm p^2, \bar p^4=\pm p and p^\dagger as an exchange of -1/\phi \leftrightarrow \phi within p where \phi=\frac{1+\sqrt{5}}{2} is the golden ratio, we can construct:

  • the snub 24-cell S=\sum_{i=1}^4\oplus p^i T
  • the 600-cell I=T+S=\sum_{i=0}^4\oplus p^i T
  • the 120-cell J=\sum_{i,j=0}^4\oplus p^i\bar p^{\dagger j}T'
  • the alternate snub 24-cell S'=\sum_{i=1}^4\oplus p^i\bar p^{\dagger i}T'

and finally the dual snub 24-cell can then be defined as the orbits of T \oplus T' \oplus S'.

Projections

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|+ 3D Orthogonal projections

[[File:DualSnub24Cell-2.png|400px|thumb|right|3D Visualization of the hull of the dual snub 24-cell, with vertices colored by overlap count:

The (42) yellow have no overlaps.

The (51) orange have 2 overlaps.

The (18) sets of tetrahedral surfaces are uniquely colored.]]

File:Dual_snub_24-cell_overlay_with_the_convex_hull_of_the_120-cell.svg chamfered dodecahedron. Of the 600 vertices in the 120-cell (J), 120 of the dual snub 24-cell (T'+S') are a subset of J and 24 (the T 24-cell) are not.

Some of those 24 can be seen projecting outside the convex 3D hull of the 120-cell. As itemized in the hull data of this diagram, the 8 16-cell vertices of T have 6 with unit norm and can be seen projecting outside the center of 6 hexagon faces, while 2 with a \pm1 in the 4th dimension get projected to the origin in 3D. The 16 other vertices are the 8-cell Tesseract which project to norm

\tfrac{\sqrt{3}}{2}=.866 inside the 120-cell 3D hull. Please note: the face and cell count data, along with the area and volume, within this image are from Mathematica automated tetrahedral cell analysis and are not based on the 96 kite cells of the dual snub 24-cell.]]

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|+ 2D Orthogonal projections

File:DualSnub24cell-2D-with-overlaps.png

File:DualSnub24Cell-2D-all-projections.svg

Dual

The dual polytope of this polytope is the Snub 24-cell.{{Sfn|Coxeter|1973|pp=151-153|loc=§8.4. The snub {3,4,3} }}

See also

Citations

{{Reflist}}

References

{{Refbegin}}

  • {{Cite journal|first=Thorold|last=Gosset|author-link=Thorold Gosset|title=On the Regular and Semi-Regular Figures in Space of n Dimensions|journal=Messenger of Mathematics|publisher=Macmillan|year=1900}}
  • {{Cite book | last=Coxeter | first=H.S.M. | author-link=Harold Scott MacDonald Coxeter | year=1973 | orig-year=1948 | title=Regular Polytopes | publisher=Dover | place=New York | edition=3rd | title-link=Regular Polytopes (book) }}
  • {{Cite book|author-link=John Horton Conway|first1=John|last1=Conway|first2=Heidi|last2=Burgiel|first3=Chaim|last3=Goodman-Strauss|title=The Symmetries of Things|year=2008|isbn=978-1-56881-220-5}}
  • {{Cite journal|url=http://arxiv-web3.library.cornell.edu/abs/1106.3433|title=Snub 24-Cell Derived from the Coxeter-Weyl Group W(D4)|first1=Mehmet|last1=Koca|first2=Nazife|last2=Ozdes Koca|first3=Muataz|last3=Al-Barwani|year=2012|journal=Int. J. Geom. Methods Mod. Phys.|volume=09|issue=8 |doi=10.1142/S0219887812500685 |arxiv=1106.3433 |s2cid=119288632 }}
  • {{Cite journal|title=Quaternionic representation of snub 24-cell and its dual polytope derived from E8 root system|first1=Mehmet|last1=Koca|first2= Mudhahir|last2=Al-Ajmi|first3=Nazife|last3=Ozdes Koca|journal=Linear Algebra and Its Applications|volume=434|issue=4|year=2011|pages=977–989|doi=10.1016/j.laa.2010.10.005 |s2cid=18278359 |issn=0024-3795|doi-access=free|arxiv=0906.2109}}

{{Refend}}

{{Polytopes}}

{{DEFAULTSORT:Dual snub 24-Cell}}

Category:4-polytopes