共查询到20条相似文献,搜索用时 0 毫秒
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On general sum-connectivity index 总被引:1,自引:0,他引:1
We report some properties of the reverse degree distance of a connected (molecular) graph, and, in particular, its relationship
with the first Zagreb index and Wiener index. We also show that the reverse degree distance satisfies the basic requirement
for a branching index. 相似文献
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Suppose G is a chemical graph with vertex set V(G). Define D(G) = {{u, v} ⊆ V (G) | d G (u, v) = 3}, where d G (u, v) denotes the length of the shortest path between u and v. The Wiener polarity index of G, W p (G), is defined as the size of D(G). In this article, an ordering of chemical unicyclic graphs of order n with respect to the Wiener polarity index is given. 相似文献
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Hongbo Hua 《Journal of mathematical chemistry》2008,43(2):831-844
The Hosoya index z(G) of a (molecular) graph G is defined as the total number of subsets of the edge set, in which any two edges are mutually independent, i.e., the total
number of independent-edge sets of G. By G(n, l, k) we denote the set of unicyclic graphs on n vertices with girth and pendent vertices being resp. l and k. Let be the graph obtained by identifying the center of the star S
n-l+1 with any vertex of C
l
. By we denote the graph obtained by identifying one pendent vertex of the path P
n-l-k+1 with one pendent vertex of . In this paper, we show that is the unique unicyclic graph with minimal Hosoya index among all graphs in G(n, l, k).
相似文献
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The energy of a graph is defined as the sum of the absolute values of all the eigenvalues of the graph. For a given positive
integer d with , we characterize the graphs with minimal energy in the class of unicyclic graphs with n vertices and a given diameter d.
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The spread s(G) of a graph G is defined as s(G) = max
i,j
|λ
i
− λ
j
|, where the maximum is taken over all pairs of eigenvalues of G. Let U(n,k) denote the set of all unicyclic graphs on n vertices with a maximum matching of cardinality k, and U
*(n,k) the set of triangle-free graphs in U(n,k). In this paper, we determine the graphs with the largest and second largest spectral radius in U
*(n,k), and the graph with the largest spread in U(n,k).
相似文献
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Ying Liu 《Journal of mathematical chemistry》2010,47(1):1-10
A unicyclic graph is a connected graph whose number of edges is equal to the number of vertices. Hou (J Math Chem 29:163–168,
2001) first considered the minimal energy for general unicyclic graphs. In this paper, we determine the unicyclic graphs with
the minimal energy in Unl{\mathcal {U}_n^l} and the unicyclic graphs with the first forth smallest energy in Un (n 3 13){\mathcal {U}_n\,(n\geq 13)} vertices. 相似文献
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The Wiener index of a connected k-uniform hypergraph is defined as the summation of distances between all pairs of vertices. We determine the unique k-uniform unicyclic hypergraphs with maximum and second maximum, minimum and second minimum Wiener indices, respectively. 相似文献
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Journal of Mathematical Chemistry - The Harary index of a connected (molecular) graph is defined as the sum of reciprocals of distances between all its pairs of vertices. In this paper, we... 相似文献
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Jos Luis Palacios 《International journal of quantum chemistry》2010,110(7):1307-1309
Using probabilistic tools, we give a compact formula for the Kirchhoff index of any d‐regular N‐vertex graph in terms of d, N, and Kemeny's constant, as well as general upper and lower bounds in terms of d and N. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010 相似文献
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José M. Rodríguez José L. Sánchez José M. Sigarreta 《Journal of mathematical chemistry》2018,56(7):1849-1864
The aim of this paper is to obtain new inequalities involving the first general Zagreb index, and characterize graphs which are extremal with respect to them. We also obtain inequalities involving the forgotten and second general Zagreb indices. 相似文献
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On the Harary index for the characterization of chemical graphs 总被引:1,自引:0,他引:1
Dejan Plavšić Sonja Nikolić Nenad Trinajstić Zlatko Mihalić 《Journal of mathematical chemistry》1993,12(1):235-250
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Cash G Klavzar S Petkovsek M 《Journal of chemical information and computer sciences》2002,42(3):571-576
The hyper-Wiener index WW of a graph G is defined as WW(G) = (summation operator d (u, v)(2) + summation operator d (u, v))/2, where d (u, v) denotes the distance between the vertices u and v in the graph G and the summations run over all (unordered) pairs of vertices of G. We consider three different methods for calculating the hyper-Wiener index of molecular graphs: the cut method, the method of Hosoya polynomials, and the interpolation method. Along the way we obtain new closed-form expressions for the WW of linear phenylenes, cyclic phenylenes, poly(azulenes), and several families of periodic hexagonal chains. We also verify some previously known (but not mathematically proved) formulas. 相似文献
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Xiu-Mei Zhang Yu-Qin Sun Hua Wang Xiao-Dong Zhang 《Journal of mathematical chemistry》2018,56(2):568-582
The atom-bond connectivity (ABC) index of a graph G is defined to be \(ABC(G)=\sum _{uv\in E(G)}\sqrt{\frac{d(u)+d(v)-2}{d(u)d(v)}}\) where d(u) is the degree of a vertex u. The ABC index plays a key role in correlating the physical–chemical properties and the molecular structures of some families of compounds. In this paper, we describe the structural properties of graphs which have the minimum ABC index among all connected graphs with a given degree sequence. Moreover, these results are used to characterize the extremal graphs which have the minimum ABC index among all unicyclic and bicyclic graphs with a given degree sequence. 相似文献
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Hosoya H 《Journal of chemical information and modeling》2007,47(3):744-750
Mathematical importance of the topological index, ZG, or the so-called Hosoya index is stressed by presenting and giving supporting evidence for the proposed conjecture. That is, for a given pair of positive integers (n1or=3), with Z(G1) = n1 and Z(G2) = n2. 相似文献
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