semiregular group

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• Semiregular k 21 polytope — In geometry, a semiregular k21 polytope is a polytope in (k+4) dimensions constructed from the En Coxeter group, and having only regular polytope facets. The family was named by Coxeter as k21 by its bifurcating Coxeter Dynkin diagram, with a… …   Wikipedia

• Semiregular polyhedron — A semiregular polyhedron is a polyhedron with regular faces and a symmetry group which is transitive on its vertices. Or at least, that is what follows from Thorold Gosset s 1900 definition of the more general semiregular polytope. [Thorold… …   Wikipedia

• Semiregular 4-polytope — In geometry, a semiregular 4 polytope (or polychoron) is a 4 dimensional polytope which is vertex transitive (i.e. the symmetry group of the polytope acts transitively on the vertices) and whose cells are regular polyhedra. These represent a… …   Wikipedia

• Group action — This article is about the mathematical concept. For the sociology term, see group action (sociology). Given an equilateral triangle, the counterclockwise rotation by 120° around the center of the triangle acts on the set of vertices of the… …   Wikipedia

• Coxeter group — In mathematics, a Coxeter group, named after H.S.M. Coxeter, is an abstract group that admits a formal description in terms of mirror symmetries. Indeed, the finite Coxeter groups are precisely the finite Euclidean reflection groups; the symmetry …   Wikipedia

• Uniform polychoron — In geometry, a uniform polychoron (plural: uniform polychora) is a polychoron or 4 polytope which is vertex transitive and whose cells are uniform polyhedra.This article contains the complete list of 64 non prismatic convex uniform polychora, and …   Wikipedia

• Variable star — A star is classified as variable if its apparent brightness as seen from Earth changes over time, whether the changes are due to variations in the star s actual luminosity, or to variations in the amount of the star s light that is blocked from… …   Wikipedia

• List of mathematics articles (S) — NOTOC S S duality S matrix S plane S transform S unit S.O.S. Mathematics SA subgroup Saccheri quadrilateral Sacks spiral Sacred geometry Saddle node bifurcation Saddle point Saddle surface Sadleirian Professor of Pure Mathematics Safe prime Safe… …   Wikipedia

• Convex uniform honeycomb — The alternated cubic honeycomb is one of 28 space filling uniform tessellations in Euclidean 3 space, composed of alternating yellow tetrahedra and red octahedra. In geometry, a convex uniform honeycomb is a uniform tessellation which fills three …   Wikipedia

• Uniform polytope — A uniform polytope is a vertex transitive polytope made from uniform polytope facets. A uniform polytope must also have only regular polygon faces.Uniformity is a generalization of the older category semiregular, but also includes the regular… …   Wikipedia

• star — starless, adj. /stahr/, n., adj., v., starred, starring. n. 1. any of the heavenly bodies, except the moon, appearing as fixed luminous points in the sky at night. 2. Astron. any of the large, self luminous, heavenly bodies, as the sun, Polaris,… …   Universalium