symmetric elements
71Simplex — For other uses, see Simplex (disambiguation). A regular 3 simplex or tetrahedron In geometry, a simplex (plural simplexes or simplices) is a generalization of the notion of a triangle or tetrahedron to arbitrary dimension. Specifically, an n… …
72Adjoint functors — Adjunction redirects here. For the construction in field theory, see Adjunction (field theory). For the construction in topology, see Adjunction space. In mathematics, adjoint functors are pairs of functors which stand in a particular… …
73Orbifold — This terminology should not be blamed on me. It was obtained by a democratic process in my course of 1976 77. An orbifold is something with many folds; unfortunately, the word “manifold” already has a different definition. I tried “foldamani”,… …
74Cross-ratio — D is the harmonic conjugate of C with respect to A and B In geometry, the cross ratio, also called double ratio and anharmonic ratio, is a special number associated with an ordered quadruple of collinear points, particularly points on a… …
75Cycle (mathematics) — This article is about group theory. For cycles in homological algebra, see Chain complex#Fundamental terminology. For cycles in graph theory, see Cycle (graph theory). In mathematics, and in particular in group theory, a cycle is a permutation of …
76Mathematics of Sudoku — The class of Sudoku puzzles consists of a partially completed row column grid of cells partitioned into N regions each of size N cells, to be filled in using a prescribed set of N distinct symbols (typically the numbers {1, ..., N}), so that each …
77Differential geometry of surfaces — Carl Friedrich Gauss in 1828 In mathematics, the differential geometry of surfaces deals with smooth surfaces with various additional structures, most often, a Riemannian metric. Surfaces have been extensively studied from various perspectives:… …
78cryptology — cryptologist, n. cryptologic /krip tl oj ik/, cryptological, adj. /krip tol euh jee/, n. 1. cryptography. 2. the science and study of cryptanalysis and cryptography. [1635 45; < NL cryptologia. See CRYPTO , LOGY] * * * Introduction …
79Nonomino — A nonomino (enneomino or 9 omino) is a polyomino of order 9, that is, a polygon in the plane made of 9 equal sized squares connected edge to edge.[1] The name of this type of figure is formed with the prefix non(a) . When rotations and… …
80Binary relation — Relation (mathematics) redirects here. For a more general notion of relation, see Finitary relation. For a more combinatorial viewpoint, see Theory of relations. In mathematics, a binary relation on a set A is a collection of ordered pairs of… …
