Concept
Rectified 6-simplexes
Concepts associés (4)
2 51 honeycomb
DISPLAYTITLE:2 51 honeycomb In 8-dimensional geometry, the 251 honeycomb is a space-filling uniform tessellation. It is composed of 241 polytope and 8-simplex facets arranged in an 8-demicube vertex figure. It is the final figure in the 2k1 family. It is created by a Wythoff construction upon a set of 9 hyperplane mirrors in 8-dimensional space. The facet information can be extracted from its Coxeter-Dynkin diagram. Removing the node on the short branch leaves the 8-simplex.
2 31 polytope
DISPLAYTITLE:2 31 polytope In 7-dimensional geometry, 231 is a uniform polytope, constructed from the E7 group. Its Coxeter symbol is 231, describing its bifurcating Coxeter-Dynkin diagram, with a single ring on the end of the 2-node branch. The rectified 231 is constructed by points at the mid-edges of the 231. These polytopes are part of a family of 127 (or 27−1) convex uniform polytopes in 7-dimensions, made of uniform polytope facets and vertex figures, defined by all permutations of rings in this Coxeter-Dynkin diagram: .
1 42 polytope
DISPLAYTITLE:1 42 polytope In 8-dimensional geometry, the 142 is a uniform 8-polytope, constructed within the symmetry of the E8 group. Its Coxeter symbol is 142, describing its bifurcating Coxeter-Dynkin diagram, with a single ring on the end of the 1-node sequences. The rectified 142 is constructed by points at the mid-edges of the 142 and is the same as the birectified 241, and the quadrirectified 421.
Groupe de Coxeter
Un groupe de Coxeter est un groupe engendré par des réflexions sur un espace. Les groupes de Coxeter se retrouvent dans de nombreux domaines des mathématiques et de la géométrie. En particulier, les groupes diédraux, ou les groupes d'isométries de polyèdres réguliers, sont des groupes de Coxeter. Les groupes de Weyl sont d'autres exemples de groupes de Coxeter. Ces groupes sont nommés d'après le mathématicien H.S.M. Coxeter. Un groupe de Coxeter est un groupe W ayant une présentation du type: où est à valeurs dans , est symétrique () et vérifie , si .