Displaying similar documents to “A note on K Δ + 1 - -free precolouring with Δ colours.”

On the total domination subdivision numbers in graphs

Seyed Sheikholeslami (2010)

Open Mathematics

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A set S of vertices of a graph G = (V, E) without isolated vertex is a total dominating set if every vertex of V(G) is adjacent to some vertex in S. The total domination number γ t(G) is the minimum cardinality of a total dominating set of G. The total domination subdivision number sdγt (G) is the minimum number of edges that must be subdivided (each edge in G can be subdivided at most once) in order to increase the total domination number. Karami, Khoeilar, Sheikholeslami and Khodkar,...

On the Numbers of Cut-Vertices and End-Blocks in 4-Regular Graphs

Dingguo Wang, Erfang Shan (2014)

Discussiones Mathematicae Graph Theory

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A cut-vertex in a graph G is a vertex whose removal increases the number of connected components of G. An end-block of G is a block with a single cut-vertex. In this paper we establish upper bounds on the numbers of end-blocks and cut-vertices in a 4-regular graph G and claw-free 4-regular graphs. We characterize the extremal graphs achieving these bounds.