extremal graph

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• Extremal graph theory — is a branch of mathematics. In the narrow sense, extremal graph theory studies the graphs which are extremal among graphs with a certain property. There are various meanings for the word extremal : with the largest number of edges, the largest… …   Wikipedia

• Graph theory — In mathematics and computer science, graph theory is the study of graphs : mathematical structures used to model pairwise relations between objects from a certain collection. A graph in this context refers to a collection of vertices or nodes and …   Wikipedia

• Extremal optimization — (EO) is an optimization heuristic inspired by the Bak Sneppen model of self organized criticality from the field of statistical physics. This heuristic was designed initially to address combinatorial optimization problems such as the travelling… …   Wikipedia

• Extremal length — In the mathematical theory of conformal and quasiconformal mappings, the extremal length of a collection of curves Gamma is a conformal invariant of Gamma. More specifically, suppose thatD is an open set in the complex plane and Gamma is a… …   Wikipedia

• Turán graph — The Turán graph T(13,4) Named after Pál Turán v · …   Wikipedia

• List of graph theory topics — This is a list of graph theory topics, by Wikipedia page. See glossary of graph theory for basic terminology Contents 1 Examples and types of graphs 2 Graph coloring 3 Paths and cycles 4 …   Wikipedia

• Triangle-free graph — In the mathematical area of graph theory, a triangle free graph is an undirected graph in which no three vertices form a triangle of edges. Triangle free graphs may be equivalently defined as graphs with clique number ≤ 2, graphs with girth ≥ 4,… …   Wikipedia

• Grötzsch graph — infobox graph name = Grötzsch graph namesake = Herbert Grötzsch vertices = 11 edges = 20 chromatic number = 4 chromatic index = girth = 4 properties = The Grötzsch graph is a triangle free graph with 11 vertices, 20 edges, and chromatic number 4 …   Wikipedia

• Uniquely colorable graph — In graph theory, a uniquely colorable graph is a k chromatic graph that has only one possible (proper) k coloring up to permutation of the colors. Example 1 . A minimal imperfect graph is a graph in which every subgraph is perfect. The deletion… …   Wikipedia

• Ramanujan graph — A Ramanujan graph, named after Srinivasa Ramanujan, is a regular graph whose spectral gap is almost as large as possible (see extremal graph theory). Such graphs are excellent spectral expanders.Examples of Ramanujan graphs include the clique,… …   Wikipedia

• Petersen 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 …   Wikipedia