- Heptacross
A heptacross, is a regular
7-polytope with 14 vertices, 84 edges, 280 triangle faces, 560 octahedron cells, 6725-cell s "4-faces", 448 "5-faces", and 128 "6-faces".It is a part of an infinite family of polytopes, called
cross-polytope s or "orthoplexes". The dual polytope is the 7-hypercube , orhepteract .The name "heptacross" is derived from combining the family name "cross polytope" with "hept" for seven (dimensions) in Greek.
Construction
There are two
Coxeter group s associated with the "heptacross", one regular, dual of thehepteract with the C7 or [4,3,3,3,3,3] symmetry group, and a lower symmetry with two copies of 6-simplex facets, alternating, with the D7 or [34,1,1] symmetry group.Cartesian coordinates
Cartesian coordinates for the vertices of a heptacross, centered at the origin are: (±1,0,0,0,0,0,0), (0,±1,0,0,0,0,0), (0,0,±1,0,0,0,0), (0,0,0,±1,0,0,0), (0,0,0,0,±1,0,0), (0,0,0,0,0,±1,0), (0,0,0,0,0,0,±1)Every vertex pair is connected by an edge, except opposites.
See also
* Other
7-polytope s:
**7-simplex - {36}
**7-cube (hepteract) - {4,35}
**7-demicube (demihepteract) - {31,4,1}
** 321 polytope - {33,2,1}
** 231 polytope - {32,3,1}
** 132 polytope - {31,3,2}
* Others in thecross-polytope family
**Octahedron - {3,4}
**Hexadecachoron - {3,3,4}
**Pentacross - {33,4}
**Hexacross - {34,4}
**Heptacross - {35,4}
**Octacross - {36,4}
**Enneacross - {37,4}
**Decacross - {38,4}External links
*GlossaryForHyperspace | anchor=Cross | title=Cross polytope
* [http://members.cox.net/hedrondude/topes.htm Polytopes of Various Dimensions]
* [http://tetraspace.alkaline.org/glossary.htm Multi-dimensional Glossary]
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