orientable surface
31Rotation system — In combinatorial mathematics, rotation systems encode embeddings of graphs onto orientable surfaces, by describing the circular ordering of a graph s edges around each vertex.A more formal definition of a rotation system involves pairs of… …
32Dehn twist — A positive Dehn twist applied to a cylinder about the red curve c modifies the green curve as shown. In geometric topology, a branch of mathematics, a Dehn twist is a certain type of self homeomorphism of a surface (two dimensional manifold).… …
33Y-homeomorfismo — En la topología geométrica o la topología de dimensiones bajas, el y homeomorfismo es un auto homeomorfismo de superficies no orientables de género mayor que uno. Él y homeomorfismo se define a partir de superficies non orientables de género dos …
34Four color theorem — Example of a four colored map A four colori …
35Edge coloring — A 3 edge coloring of the Desargues graph. In graph theory, an edge coloring of a graph is an assignment of “colors” to the edges of the graph so that no two adjacent edges have the same color. For example, the figure to the right shows an edge… …
36Algebraic curve — In algebraic geometry, an algebraic curve is an algebraic variety of dimension one. The theory of these curves in general was quite fully developed in the nineteenth century, after many particular examples had been considered, starting with… …
37Aspherical space — In topology, an aspherical space is a topological space with all higher homotopy groups equal to {0}. If one works with CW complexes, one can reformulate this condition: an aspherical CW complex is a CW complex whose universal cover is… …
38Allen Hatcher — Allen Edward Hatcher is an American topologist and also a noted author. His book Algebraic Topology , which is the first in a series, is considered by many to be one of the best introductions to the subject.He received his Ph.D. under the… …
39Petersen graph — Infobox graph name = Petersen graph image caption = The Petersen graph is most commonly drawn as a pentagon with a pentagram inside, with five spokes. namesake = Julius Petersen vertices = 10 edges = 15 radius = 2 diameter = 2 girth = 5 chromatic …
40Complex manifold — In differential geometry, a complex manifold is a manifold with an atlas of charts to the open unit disk[1] in Cn, such that the transition maps are holomorphic. The term complex manifold is variously used to mean a complex manifold in the sense… …
