Displaying similar documents to “Coalescing Fiedler and core vertices”

Distance in stratified graphs

Gary Chartrand, Lisa Hansen, Reza Rashidi, Naveed Sherwani (2000)

Czechoslovak Mathematical Journal

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A graph G is stratified if its vertex set is partitioned into classes, called strata. If there are k strata, then G is k -stratified. These graphs were introduced to study problems in VLSI design. The strata in a stratified graph are also referred to as color classes. For a color X in a stratified graph G , the X -eccentricity e X ( v ) of a vertex v of G is the distance between v and an X -colored vertex furthest from v . The minimum X -eccentricity among the vertices of G is the X -radius r a d X G of G ...

Double domination critical and stable graphs upon vertex removal

Soufiane Khelifi, Mustapha Chellali (2012)

Discussiones Mathematicae Graph Theory

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In a graph a vertex is said to dominate itself and all its neighbors. A double dominating set of a graph G is a subset of vertices that dominates every vertex of G at least twice. The double domination number of G, denoted γ × 2 ( G ) , is the minimum cardinality among all double dominating sets of G. We consider the effects of vertex removal on the double domination number of a graph. A graph G is γ × 2 -vertex critical graph ( γ × 2 -vertex stable graph, respectively) if the removal of any vertex different...

Inequalities involving independence domination, f -domination, connected and total f -domination numbers

San Ming Zhou (2000)

Czechoslovak Mathematical Journal

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Let f be an integer-valued function defined on the vertex set V ( G ) of a graph G . A subset D of V ( G ) is an f -dominating set if each vertex x outside D is adjacent to at least f ( x ) vertices in D . The minimum number of vertices in an f -dominating set is defined to be the f -domination number, denoted by γ f ( G ) . In a similar way one can define the connected and total f -domination numbers γ c , f ( G ) and γ t , f ( G ) . If f ( x ) = 1 for all vertices x , then these are the ordinary domination number, connected domination number and total...

Wiener index of graphs with fixed number of pendant or cut-vertices

Dinesh Pandey, Kamal Lochan Patra (2022)

Czechoslovak Mathematical Journal

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The Wiener index of a connected graph is defined as the sum of the distances between all unordered pairs of its vertices. We characterize the graphs which extremize the Wiener index among all graphs on n vertices with k pendant vertices. We also characterize the graph which minimizes the Wiener index over the graphs on n vertices with s cut-vertices.

On arbitrarily vertex decomposable unicyclic graphs with dominating cycle

Sylwia Cichacz, Irmina A. Zioło (2006)

Discussiones Mathematicae Graph Theory

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A graph G of order n is called arbitrarily vertex decomposable if for each sequence (n₁,...,nₖ) of positive integers such that ∑ i = 1 k n i = n , there exists a partition (V₁,...,Vₖ) of vertex set of G such that for every i ∈ 1,...,k the set V i induces a connected subgraph of G on n i vertices. We consider arbitrarily vertex decomposable unicyclic graphs with dominating cycle. We also characterize all such graphs with at most four hanging vertices such that exactly two of them have a common neighbour. ...