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On the Maximum of a Branching Process Conditioned on the Total Progeny

Kerbashev, Tzvetozar (1999)

Serdica Mathematical Journal

The maximum M of a critical Bienaymé-Galton-Watson process conditioned on the total progeny N is studied. Imbedding of the process in a random walk is used. A limit theorem for the distribution of M as N → ∞ is proved. The result is trasferred to the non-critical processes. A corollary for the maximal strata of a random rooted labeled tree is obtained.

On the minus domination number of graphs

Hailong Liu, Liang Sun (2004)

Czechoslovak Mathematical Journal

Let G = ( V , E ) be a simple graph. A 3 -valued function f V ( G ) { - 1 , 0 , 1 } is said to be a minus dominating function if for every vertex v V , f ( N [ v ] ) = u N [ v ] f ( u ) 1 , where N [ v ] is the closed neighborhood of v . The weight of a minus dominating function f on G is f ( V ) = v V f ( v ) . The minus domination number of a graph G , denoted by γ - ( G ) , equals the minimum weight of a minus dominating function on G . In this paper, the following two results are obtained. (1) If G is a bipartite graph of order n , then γ - ( G ) 4 n + 1 - 1 - n . (2) For any negative integer k and any positive integer m 3 , there exists...

On the multiplicity of Laplacian eigenvalues for unicyclic graphs

Fei Wen, Qiongxiang Huang (2022)

Czechoslovak Mathematical Journal

Let G be a connected graph of order n and U a unicyclic graph with the same order. We firstly give a sharp bound for m G ( μ ) , the multiplicity of a Laplacian eigenvalue μ of G . As a straightforward result, m U ( 1 ) n - 2 . We then provide two graph operations (i.e., grafting and shifting) on graph G for which the value of m G ( 1 ) is nondecreasing. As applications, we get the distribution of m U ( 1 ) for unicyclic graphs on n vertices. Moreover, for the two largest possible values of m U ( 1 ) { n - 5 , n - 3 } , the corresponding graphs U are completely...

On the multiplicity of Laplacian eigenvalues of graphs

Ji-Ming Guo, Lin Feng, Jiong-Ming Zhang (2010)

Czechoslovak Mathematical Journal

In this paper we investigate the effect on the multiplicity of Laplacian eigenvalues of two disjoint connected graphs when adding an edge between them. As an application of the result, the multiplicity of 1 as a Laplacian eigenvalue of trees is also considered.

On the Non-(p−1)-Partite Kp-Free Graphs

Kinnari Amin, Jill Faudree, Ronald J. Gould, Elżbieta Sidorowicz (2013)

Discussiones Mathematicae Graph Theory

We say that a graph G is maximal Kp-free if G does not contain Kp but if we add any new edge e ∈ E(G) to G, then the graph G + e contains Kp. We study the minimum and maximum size of non-(p − 1)-partite maximal Kp-free graphs with n vertices. We also answer the interpolation question: for which values of n and m are there any n-vertex maximal Kp-free graphs of size m?

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