Results 31 to 40 of about 272 (159)

Graphic and Cographic Г-Extensions of Binary Matroids

Discussiones Mathematicae Graph Theory, 2018
Slater introduced the point-addition operation on graphs to characterize 4-connected graphs. The Г-extension operation on binary matroids is a generalization of the point-addition operation. In general, under the Г-extension operation the properties like
Borse Y.M., Mundhe Ganesh
doaj   +1 more source

Turán’s Theorem Implies Stanley’s Bound

Discussiones Mathematicae Graph Theory, 2020
Let G be a graph with m edges and let ρ be the largest eigenvalue of its adjacency matrix.
Nikiforov V.
doaj   +1 more source

The Maximum Order of Adjacency Matrices With a Given Rank [PDF]

, 2010
AMS Subject Classification: 05B20 ...
Peeters, M.J.P., Haemers, W.H.; id_orcid, Haemers, W.H.   +2 more
core  

On the Eccentric Spectra of the Line Graph of Starlike Trees

Discrete Dynamics in Nature and Society, Volume 2025, Issue 1, 2025.
A tree is called starlike if it has exactly one vertex with a degree greater than two. In this paper, we determine the eccentricity spectrum of the line graphs of starlike trees and compute their eccentric energy. Furthermore, we establish that the eccentricity matrix of the line graph of any starlike tree is irreducible.
S. Balamoorthy, S. V. Bharanedhar, Yilun Shang, R. Gurusamy, Palanivel M   +4 more
wiley   +1 more source

Graphs whose Laplacian eigenvalues are almost all 1 or 2

Special Matrices
We explicitly determine all connected graphs whose Laplacian matrices have at most four eigenvalues different from 1 and 2.
Mohammadian Ali, Xu Shanshan
doaj   +1 more source

On Singular Signed Graphs with Nullspace Spanned by a Full Vector: Signed Nut Graphs

Discussiones Mathematicae Graph Theory, 2022
A signed graph has edge weights drawn from the set {+1, −1}, and is sign-balanced if it is equivalent to an unsigned graph under the operation of sign switching; otherwise it is sign-unbalanced.
Bašić Nino, Fowler Patrick W., Pisanski Tomaž, Sciriha Irene   +3 more
doaj   +1 more source

On the Sum of Laplacian Eigenvalues of Graphs [PDF]

, 2008
AMS Subject Classification: 05C50 ...
Haemers, W.H.; id_orcid, Mohammadian, A., A. Mohammadian, Haemers, W.H., Tayfeh-Rezaie, B., W. H. Haemers, B. Tayfeh-rezaie   +6 more
core  

Prime Graphs of Polynomials and Power Series Over Noncommutative Rings

International Journal of Mathematics and Mathematical Sciences, Volume 2025, Issue 1, 2025.
The prime graph PG(R) of a ring R is a graph whose vertex set consists of all elements of R. Two elements x, y ∈ R are adjacent in the graph if and only if xRy = 0 or yRx = 0. An element a ∈ R is called a strong zero divisor in R if 〈a〉〈b〉 = 0 or 〈b〉〈a〉 = 0 for some nonzero element b ∈ R. The set of all strong zero divisors is denoted by S(R).
Walaa Obaidallah Alqarafi, Wafaa Mohammed Fakieh, Alaa Abdullah Altassan, Shikha Binwal   +3 more
wiley   +1 more source

On the α-Spectral Radius of Uniform Hypergraphs

Discussiones Mathematicae Graph Theory, 2020
For 0 ≤ α ---lt--- 1 and a uniform hypergraph G, the α-spectral radius of G is the largest H-eigenvalue of αD(G)+(1−α)A(G), where D(G) and A(G) are the diagonal tensor of degrees and the adjacency tensor of G, respectively. We give upper bounds for the α-
Guo Haiyan, Zhou Bo
doaj   +1 more source

On the Maximum SC Index of Chemical Unicyclic Graphs

Journal of Mathematics, Volume 2025, Issue 1, 2025.
The sum‐connectivity (SC) index of a graph G is defined as SCG=∑μν∈EG1/Θμ+Θν, where Θμ denotes the vertex degree of μ in G. In this paper, the fourth largest value of SC index for the chemical unicyclic graphs of order n ≥ 7 is determined.
Hui-Yan Cheng, Lei Chen, Sattar Alyar, Guo Zhong   +3 more
wiley   +1 more source