Autor: Li, Hong - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: An upper bound on the Laplacian spectral radius of the signed graphs
Autorzy:: Li, Hong-Hai
Li, Jiong-Sheng
Powiązania:: https://bibliotekanauki.pl/articles/743035.pdf
Data publikacji:: 2008
Wydawca:: Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:: Laplacian matrix
signed graph
mixed graph
largest Laplacian eigenvalue
upper bound
Opis:: In this paper, we established a connection between the Laplacian eigenvalues of a signed graph and those of a mixed graph, gave a new upper bound for the largest Laplacian eigenvalue of a signed graph and characterized the extremal graph whose largest Laplacian eigenvalue achieved the upper bound. In addition, an example showed that the upper bound is the best in known upper bounds for some cases.
Źródło:: Discussiones Mathematicae Graph Theory; 2008, 28, 2; 345-359
2083-5892
Pojawia się w:: Discussiones Mathematicae Graph Theory
Dostawca treści:: Biblioteka Nauki

Artykuł

Skocz do pozycji: 2.

Tytuł:: On the Determinant of q-Distance Matrix of a Graph
Autorzy:: Li, Hong-Hai
Su, Li
Zhang, Jing
Powiązania:: https://bibliotekanauki.pl/articles/30147229.pdf
Data publikacji:: 2014-02-01
Wydawca:: Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:: q-distance matrix
determinant
weighted graph
directed graph
Opis:: In this note, we show how the determinant of the q-distance matrix D_q(T) of a weighted directed graph G can be expressed in terms of the corresponding determinants for the blocks of G, and thus generalize the results obtained by Graham et al. [R.L. Graham, A.J. Hoffman and H. Hosoya, On the distance matrix of a directed graph, J. Graph Theory 1 (1977) 85-88]. Further, by means of the result, we determine the determinant of the q-distance matrix of the graph obtained from a connected weighted graph G by adding the weighted branches to G, and so generalize in part the results obtained by Bapat et al. [R.B. Bapat, S. Kirkland and M. Neumann, On distance matrices and Laplacians, Linear Algebra Appl. 401 (2005) 193- 209]. In particular, as a consequence, determinantal formulae of q-distance matrices for unicyclic graphs and one class of bicyclic graphs are presented.
Źródło:: Discussiones Mathematicae Graph Theory; 2014, 34, 1; 103-111
2083-5892
Pojawia się w:: Discussiones Mathematicae Graph Theory
Dostawca treści:: Biblioteka Nauki

Artykuł

Skocz do pozycji: 3.

Tytuł:: The Minimum Spectral Radius of Signless Laplacian of Graphs with a Given Clique Number
Autorzy:: Su, Li
Li, Hong-Hai
Zhang, Jing
Powiązania:: https://bibliotekanauki.pl/articles/30148000.pdf
Data publikacji:: 2014-02-01
Wydawca:: Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:: clique number
kite graph
signless Laplacian
spectral radius
Opis:: In this paper we observe that the minimal signless Laplacian spectral radius is obtained uniquely at the kite graph $PK_{n-\omega,\omega}$ among all connected graphs with $n$ vertices and clique number $\omega$. In addition, we show that the spectral radius $\mu$ of $PK_{m,\omega}$ $(m\geq1)$ satisfies $$\frac{1}{2}(2\omega-1+\sqrt{4\omega^{2}-12\omega+17})\leq\mu\leq 2\omega-1.$$ More precisely, for $m>1$, $\mu$ satisfies the equation \[ \mu-\omega-\frac{\omega-1}{\mu-2\omega+3}=a_m\sqrt{\mu^2-4\mu}+\frac{1}{t_1}, \] where $a_m=\frac{1}{1-t_1^{2m+3}}$ and $t_{1}=\frac{\mu-2+\sqrt{(\mu-2)^{2}-4}}{2}$. At last the spectral radius $\mu(PK_{\infty,\omega})$ of the infinite graph $PK_{\infty,\omega}$ is also discussed.
Źródło:: Discussiones Mathematicae Graph Theory; 2014, 34, 1; 95-102
2083-5892
Pojawia się w:: Discussiones Mathematicae Graph Theory
Dostawca treści:: Biblioteka Nauki

Artykuł

Skocz do pozycji: 4.

Tytuł:: The Laplacian spectrum of some digraphs obtained from the wheel
Autorzy:: Su, Li
Li, Hong-Hai
Zheng, Liu-Rong
Powiązania:: https://bibliotekanauki.pl/articles/743220.pdf
Data publikacji:: 2012
Wydawca:: Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:: digraph
Laplacian matrix
eigenvalue
wheel
Opis:: The problem of distinguishing, in terms of graph topology, digraphs with real and partially non-real Laplacian spectra is important for applications. Motivated by the question posed in [R. Agaev, P. Chebotarev, Which digraphs with rings structure are essentially cyclic?, Adv. in Appl. Math. 45 (2010), 232-251], in this paper we completely list the Laplacian eigenvalues of some digraphs obtained from the wheel digraph by deleting some arcs.
Źródło:: Discussiones Mathematicae Graph Theory; 2012, 32, 2; 255-261
2083-5892
Pojawia się w:: Discussiones Mathematicae Graph Theory
Dostawca treści:: Biblioteka Nauki

Artykuł

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