694 research outputs found

    Upper bounds for domination related parameters in graphs on surfaces

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    AbstractIn this paper we give tight upper bounds on the total domination number, the weakly connected domination number and the connected domination number of a graph in terms of order and Euler characteristic. We also present upper bounds for the restrained bondage number, the total restrained bondage number and the restricted edge connectivity of graphs in terms of the orientable/nonorientable genus and maximum degree

    Bondage number of grid graphs

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    The bondage number b(G)b(G) of a nonempty graph GG is the cardinality of a smallest set of edges whose removal from GG results in a graph with domination number greater than the domination number of GG. Here we study the bondage number of some grid-like graphs. In this sense, we obtain some bounds or exact values of the bondage number of some strong product and direct product of two paths.Comment: 13 pages. Discrete Applied Mathematics, 201

    Weak and Strong Reinforcement Number For a Graph

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    Introducing the weak reinforcement number which is the minimum number of added edges to reduce the weak dominating number, and giving some boundary of this new parameter and trees

    A bound on the size of a graph with given order and bondage number

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    AbstractThe domination number of a graph is the minimum number of vertices in a set S such that every vertex of the graph is either in S or adjacent to a member of S. The bondage number of a graph G is the cardinality of a smallest set of edges whose removal results in a graph with domination number greater than that of G. We prove that a graph with p vertices and bondage number b has at least p(b + 1)/4 edges, and for each b there is at least one p for which this bound is sharp. © 1999 Elsevier Science B.V. All rights reserve

    A Study on Set-Graphs

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    A \textit{primitive hole} of a graph GG is a cycle of length 33 in GG. The number of primitive holes in a given graph GG is called the primitive hole number of that graph GG. The primitive degree of a vertex vv of a given graph GG is the number of primitive holes incident on the vertex vv. In this paper, we introduce the notion of set-graphs and study the properties and characteristics of set-graphs. We also check the primitive hole number and primitive degree of set-graphs. Interesting introductory results on the nature of order of set-graphs, degree of the vertices corresponding to subsets of equal cardinality, the number of largest complete subgraphs in a set-graph etc. are discussed in this study. A recursive formula to determine the primitive hole number of a set-graph is also derived in this paper.Comment: 11 pages, 1 figure, submitte
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