identity permutation
41Eulerian number — This page discusses a topic in combinatorics. For Euler numbers in number theory see Euler number. In combinatorics the Eulerian number E ( n , m ), or :left langle {natop m} ight angle,is the number of permutations of the numbers 1 to n in which …
42Equivalence relation — In mathematics, an equivalence relation is a binary relation between two elements of a set which groups them together as being equivalent in some way. Let a , b , and c be arbitrary elements of some set X . Then a b or a ≡ b denotes that a is… …
43Cayley table — A Cayley table, after the 19th century British mathematician Arthur Cayley, describes the structure of a finite group by arranging all the possible products of all the group s elements in a square table reminiscent of an addition or… …
44Transformation semigroup — In algebra, a transformation semigroup (or composition semigroup) is a collection of functions from a set to itself which is closed under function composition. If it includes the identity function, it is a transformation (or composition) monoid.… …
45Sequent calculus — In proof theory and mathematical logic, sequent calculus is a family of formal systems sharing a certain style of inference and certain formal properties. The first sequent calculi, systems LK and LJ, were introduced by Gerhard Gentzen in 1934 as …
46Fano plane — In finite geometry, the Fano plane (after Gino Fano) is the projective plane with the least number of points and lines: 7 each. GeometryPerhaps the best way to view the plane is via linear algebra. Using the standard construction via homogeneous… …
47Curvilinear coordinates — Curvilinear, affine, and Cartesian coordinates in two dimensional space Curvilinear coordinates are a coordinate system for Euclidean space in which the coordinate lines may be curved. These coordinates may be derived from a set of Cartesian… …
48Orientation (vector space) — See also: orientation (geometry) The left handed orientation is shown on the left, and the right handed on the right. In mathematics, orientation is a notion that in two dimensions allows one to say when a cycle goes around clockwise or… …
49Operad theory — is a field of abstract algebra concerned with prototypical algebras that model properties such as commutativity or anticommutativity as well as various amounts of associativity. Operads generalize the various associativity properties already… …
50Newton's identities — In mathematics, Newton s identities, also known as the Newton–Girard formulae, give relations between two types of symmetric polynomials, namely between power sums and elementary symmetric polynomials. Evaluated at the roots of a monic polynomial …
