24,712 research outputs found
The Roots and Links in a Class of -Matrices
In this paper, we discuss exiting roots of sub-kernel transient matrices
associated with a class of matrices which are related to generalized
ultrametric matrices. Then the results are used to describe completely all
links of the class of matrices in terms of structure of the supporting tree.Comment: 11 pages, 1 figur
Laplacian coefficients of unicyclic graphs with the number of leaves and girth
Let be a graph of order and let be the characteristic polynomial of its
Laplacian matrix. Motivated by Ili\'{c} and Ili\'{c}'s conjecture [A. Ili\'{c},
M. Ili\'{c}, Laplacian coefficients of trees with given number of leaves or
vertices of degree two, Linear Algebra and its Applications
431(2009)2195-2202.] on all extremal graphs which minimize all the Laplacian
coefficients in the set of all -vertex unicyclic graphs
with the number of leaves , we investigate properties of the minimal
elements in the partial set of the Laplacian
coefficients, where denote the set of -vertex
unicyclic graphs with the number of leaves and girth . These results are
used to disprove their conjecture. Moreover, the graphs with minimum
Laplacian-like energy in are also studied.Comment: 19 page, 4figure
The Minimum Spectral Radius of Graphs with the Independence Number
In this paper, we investigate some properties of the Perron vector of
connected graphs. These results are used to characterize that all extremal
connected graphs with having the minimum (maximum) spectra radius among all
connected graphs of order with the independence number ,
respectively.Comment: 28 pages, 3 figure
The Wiener and Terminal Wiener indices of trees
Heydari \cite{heydari2013} presented very nice formulae for the Wiener and
terminal Wiener indices of generalized Bethe trees. It is pity that there are
some errors for the formulae. In this paper, we correct these errors and
characterize all trees with the minimum terminal Wiener index among all the
trees of order and with maximum degree .Comment: 13 page
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