Results 31 to 40 of about 110,880 (163)
On Extremal Spectral Radii of Uniform Supertrees with Given Independence Number
Discrete Dynamics in Nature and Society, Volume 2022, Issue 1, 2022., 2022 A supertree is a connected and acyclic hypergraph. Denote by Tm,n,α the set of m‐uniform supertrees of order n with independent number α. Focusing on the spectral radius in Tm,n,α, this present completely determines the hypergraphs with maximum spectral radius among all the supertrees with n vertices and independence number α for [m − 1/mn] ≤ α ≤ n − 1,
Lei Zhang +2 more
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Locating Eigenvalues of a Symmetric Matrix whose Graph is Unicyclic
Trends in Computational and Applied Mathematics, 2021 We present a linear-time algorithm that computes in a given real interval the number of eigenvalues of any symmetric matrix whose underlying graph is unicyclic.
R. O. Braga +2 more
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New Bounds for the Generalized Distance Spectral Radius/Energy of Graphs
Mathematical Problems in Engineering, Volume 2022, Issue 1, 2022., 2022 Let G be a simple connected graph with vertex set V(G) = {v1, v2, …, vn} and dvi be the degree of the vertex vi. Let D(G) be the distance matrix and Tr(G) be the diagonal matrix of the vertex transmissions of G. The generalized distance matrix of G is defined as Dα(G) = αTr(G) + (1 − α)D(G), where 0 ≤ α ≤ 1. If λ1, λ2, …, λn are the eigenvalues of Dα(G)
Yuzheng Ma +3 more
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Spectral Sufficient Conditions on Pancyclic Graphs
Complexity, Volume 2021, Issue 1, 2021., 2021 A pancyclic graph of order n is a graph with cycles of all possible lengths from 3 to n. In fact, it is NP‐complete that deciding whether a graph is pancyclic. Because the spectrum of graphs is convenient to be calculated, in this study, we try to use the spectral theory of graphs to study this problem and give some sufficient conditions for a graph to
Guidong Yu +4 more
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Nordhaus-Gaddum Type Inequalities for Laplacian and Signless Laplacian Eigenvalues [PDF]
The Electronic Journal of Combinatorics, 2014 Let $G$ be a graph with $n$ vertices. We denote the largest signless Laplacian eigenvalue of $G$ by $q_1(G)$ and Laplacian eigenvalues of $G$ by $\mu_1(G)\ge\cdots\ge\mu_{n-1}(G)\ge\mu_n(G)=0$. It is a conjecture on Laplacian spread of graphs that $\mu_1(G)-\mu_{n-1}(G)\le n-1$ or equivalently $\mu_1(G)+\mu_1(\overline G)\le2n-1$.
F. Ashraf, Behruz Tayfeh-Rezaie
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On Laplacian Equienergetic Signed Graphs
Journal of Mathematics, Volume 2021, Issue 1, 2021., 2021 The Laplacian energy of a signed graph is defined as the sum of the distance of its Laplacian eigenvalues from its average degree. Two signed graphs of the same order are said to be Laplacian equienergetic if their Laplacian energies are equal. In this paper, we present several infinite families of Laplacian equienergetic signed graphs.
Qingyun Tao, Lixin Tao, Yongqiang Fu
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Communications in Advanced Mathematical Sciences, 2018 The signless Laplacian eigenvalues of a graph $G$ are eigenvalues of the matrix $Q(G) = D(G) + A(G)$, where $D(G)$ is the diagonal matrix of the degrees of the vertices in $G$ and $A(G)$ is the adjacency matrix of $G$.
Rao Li
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Sufficient Conditions for Graphs to Be k‐Connected, Maximally Connected, and Super‐Connected
Complexity, Volume 2021, Issue 1, 2021., 2021 Let G be a connected graph with minimum degree δ(G) and vertex‐connectivity κ(G). The graph G is k‐connected if κ(G) ≥ k, maximally connected if κ(G) = δ(G), and super‐connected if every minimum vertex‐cut isolates a vertex of minimum degree. In this paper, we present sufficient conditions for a graph with given minimum degree to be k‐connected ...
Zhen-Mu Hong +4 more
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On the sum of signless Laplacian spectra of graphs
Karpatsʹkì Matematičnì Publìkacìï, 2019 For a simple graph $G(V,E)$ with $n$ vertices, $m$ edges, vertex set $V(G)=\{v_1, v_2, \dots, v_n\}$ and edge set $E(G)=\{e_1, e_2,\dots, e_m\}$, the adjacency matrix $A=(a_{ij})$ of $G$ is a $(0, 1)$-square matrix of order $n$ whose $(i,j)$-entry is ...
S. Pirzada, H.A. Ganie, A.M. Alghamdi
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Distance (signless) Laplacian spectrum of dumbbell graphs [PDF]
Transactions on Combinatorics, 2023 In this paper, we determine the distance Laplacian and distance signless Laplacian spectrum of generalized wheel graphs and a new class of graphs called dumbbell graphs.
Sakthidevi Kaliyaperumal +1 more
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