Displaying similar documents to “The classification of edges and the change in multiplicity of an eigenvalue of a real symmetric matrix resulting from the change in an edge value”

Total edge irregularity strength of trees

Jaroslav Ivančo, Stanislav Jendrol' (2006)

Discussiones Mathematicae Graph Theory

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A total edge-irregular k-labelling ξ:V(G)∪ E(G) → {1,2,...,k} of a graph G is a labelling of vertices and edges of G in such a way that for any different edges e and f their weights wt(e) and wt(f) are distinct. The weight wt(e) of an edge e = xy is the sum of the labels of vertices x and y and the label of the edge e. The minimum k for which a graph G has a total edge-irregular k-labelling is called the total edge irregularity strength of G, tes(G). In this paper we prove that...

On the energy and spectral properties of the he matrix of hexagonal systems

Faqir M. Bhatti, Kinkar Ch. Das, Syed A. Ahmed (2013)

Czechoslovak Mathematical Journal

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The He matrix, put forward by He and He in 1989, is designed as a means for uniquely representing the structure of a hexagonal system (= benzenoid graph). Observing that the He matrix is just the adjacency matrix of a pertinently weighted inner dual of the respective hexagonal system, we establish a number of its spectral properties. Afterwards, we discuss the number of eigenvalues equal to zero of the He matrix of a hexagonal system. Moreover, we obtain a relation between the number...

On Super Edge-Antimagic Total Labeling Of Subdivided Stars

Muhammad Javaid (2014)

Discussiones Mathematicae Graph Theory

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In 1980, Enomoto et al. proposed the conjecture that every tree is a super (a, 0)-edge-antimagic total graph. In this paper, we give a partial sup- port for the correctness of this conjecture by formulating some super (a, d)- edge-antimagic total labelings on a subclass of subdivided stars denoted by T(n, n + 1, 2n + 1, 4n + 2, n5, n6, . . . , nr) for different values of the edge- antimagic labeling parameter d, where n ≥ 3 is odd, nm = 2m−4(4n+1)+1, r ≥ 5 and 5 ≤ m ≤ r.

Bounds for index of a modified graph

Bo Zhou (2004)

Discussiones Mathematicae Graph Theory

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If a graph is connected then the largest eigenvalue (i.e., index) generally changes (decreases or increases) if some local modifications are performed. In this paper two types of modifications are considered: (i) for a fixed vertex, t edges incident with it are deleted, while s new edges incident with it are inserted; (ii) for two non-adjacent vertices, t edges incident with one vertex are deleted, while s new edges incident with the other vertex are...