Displaying similar documents to “A characterization of diameter-2-critical graphs with no antihole of length four”

A maximum degree theorem for diameter-2-critical graphs

Teresa Haynes, Michael Henning, Lucas Merwe, Anders Yeo (2014)

Open Mathematics

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A graph is diameter-2-critical if its diameter is two and the deletion of any edge increases the diameter. Let G be a diameter-2-critical graph of order n. Murty and Simon conjectured that the number of edges in G is at most ⌊n 2/4⌋ and that the extremal graphs are the complete bipartite graphs K ⌊n/2⌋,⌊n/2⌉. Fan [Discrete Math. 67 (1987), 235–240] proved the conjecture for n ≤ 24 and for n = 26, while Füredi [J. Graph Theory 16 (1992), 81–98] proved the conjecture for n > n 0 where...

On the Independence Number of Edge Chromatic Critical Graphs

Shiyou Pang, Lianying Miao, Wenyao Song, Zhengke Miao (2014)

Discussiones Mathematicae Graph Theory

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In 1968, Vizing conjectured that for any edge chromatic critical graph G = (V,E) with maximum degree △ and independence number α (G), α (G) ≤ [...] . It is known that α (G) < [...] |V |. In this paper we improve this bound when △≥ 4. Our precise result depends on the number n2 of 2-vertices in G, but in particular we prove that α (G) ≤ [...] |V | when △ ≥ 5 and n2 ≤ 2(△− 1)

The Connectivity Of Domination Dot-Critical Graphs With No Critical Vertices

Michitaka Furuya (2014)

Discussiones Mathematicae Graph Theory

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An edge of a graph is called dot-critical if its contraction decreases the domination number. A graph is said to be dot-critical if all of its edges are dot-critical. A vertex of a graph is called critical if its deletion decreases the domination number. In A note on the domination dot-critical graphs, Discrete Appl. Math. 157 (2009) 3743-3745, Chen and Shiu constructed for each even integer k ≥ 4 infinitely many k-dot-critical graphs G with no critical vertices and k(G) = 1. In this...

Generalized matrix graphs and completely independent critical cliques in any dimension

John J. Lattanzio, Quan Zheng (2012)

Discussiones Mathematicae Graph Theory

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For natural numbers k and n, where 2 ≤ k ≤ n, the vertices of a graph are labeled using the elements of the k-fold Cartesian product Iₙ × Iₙ × ... × Iₙ. Two particular graph constructions will be given and the graphs so constructed are called generalized matrix graphs. Properties of generalized matrix graphs are determined and their application to completely independent critical cliques is investigated. It is shown that there exists a vertex critical graph which admits a family of k...