orientation-preserving isomorphism
11Degree of a continuous mapping — This article is about the term degree as used in algebraic topology. For other uses, see degree (mathematics). A degree two map of a sphere onto itself. In topology, the degree is a numerical invariant that describes a continuous mapping between… …
12Discrete group — Concepts in group theory category of groups subgroups, normal subgroups group homomorphisms, kernel, image, quotient direct product, direct sum semidirect product, wreath product …
13Mapping class group — In mathematics, in the sub field of geometric topology, the mapping class group is an important algebraic invariant of a topological space. Briefly, the mapping class group is a discrete group of symmetries of the space. Contents 1 Motivation 2… …
14Hyperbolic geometry — Lines through a given point P and asymptotic to line R. A triangle immersed in a saddle shape plane (a hyperbolic paraboloid), as well as two diverging ultraparall …
15Symplectic vector space — In mathematics, a symplectic vector space is a vector space V equipped with a nondegenerate, skew symmetric, bilinear form omega; called the symplectic form. Explicitly, a symplectic form is a bilinear form omega; : V times; V rarr; R which is *… …
16SL2(R) — In mathematics, the special linear group SL2(R) is the group of all real 2 times; 2 matrices with determinant one:: mbox{SL} 2(mathbb{R}) = left{ egin{bmatrix}a b c dend{bmatrix} : a,b,c,dinmathbb{R}mbox{ and }ad bc=1 ight}.It is a real Lie… …
17Euclidean space — Every point in three dimensional Euclidean space is determined by three coordinates. In mathematics, Euclidean space is the Euclidean plane and three dimensional space of Euclidean geometry, as well as the generalizations of these notions to… …
18General linear group — Group theory Group theory …
19(2,3,7) triangle group — In the theory of Riemann surfaces and hyperbolic geometry, the triangle group (2, 3, 7) is particularly important. This importance stems from its connection to Hurwitz surfaces, namely Riemann surfaces of genus g with the largest possible order,… …
20Orbifold — 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”,… …
