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Tytuł:
Wiener and vertex PI indices of the strong product of graphs
Autorzy:
Pattabiraman, K.
Paulraja, P.
Powiązania:
https://bibliotekanauki.pl/articles/743324.pdf
Data publikacji:
2012
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
strong product
Wiener index
hyper-Wiener index
vertex PI index
Opis:
The Wiener index of a connected graph G, denoted by W(G), is defined as $½ ∑_{u,v ∈ V(G)}d_G(u,v)$. Similarly, the hyper-Wiener index of a connected graph G, denoted by WW(G), is defined as $½W(G) + ¼ ∑_{u,v ∈ V(G)} d²_G(u,v)$. The vertex Padmakar-Ivan (vertex PI) index of a graph G is the sum over all edges uv of G of the number of vertices which are not equidistant from u and v. In this paper, the exact formulae for Wiener, hyper-Wiener and vertex PI indices of the strong product $G ⊠ K_{m₀,m₁,...,m_{r -1}}$, where $K_{m₀,m₁,...,m_{r -1}}$ is the complete multipartite graph with partite sets of sizes $m₀,m₁, ...,m_{r -1}$, are obtained. Also lower bounds for Wiener and hyper-Wiener indices of strong product of graphs are established.
Źródło:
Discussiones Mathematicae Graph Theory; 2012, 32, 4; 749-769
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Gutman Index and the Edge-Wiener Index of Graphs with Given Vertex-Connectivity
Autorzy:
Mazorodze, Jaya Percival
Mukwembi, Simon
Vetrík, Tomáš
Powiązania:
https://bibliotekanauki.pl/articles/31340463.pdf
Data publikacji:
2016-11-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
Gutman index
edge-Wiener index
vertex-connectivity
Opis:
The Gutman index and the edge-Wiener index have been extensively investigated particularly in the last decade. An important stream of re- search on graph indices is to bound indices in terms of the order and other parameters of given graph. In this paper we present asymptotically sharp upper bounds on the Gutman index and the edge-Wiener index for graphs of given order and vertex-connectivity κ, where κ is a constant. Our results substantially generalize and extend known results in the area.
Źródło:
Discussiones Mathematicae Graph Theory; 2016, 36, 4; 867-876
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Power indices of trace zero symmetric Boolean matrices
Autorzy:
Zhou, Bo
Powiązania:
https://bibliotekanauki.pl/articles/728910.pdf
Data publikacji:
2004
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
power index
index of convergence
period
Boolean matrix
Opis:
The power index of a square Boolean matrix A is the least integer d such that Ad is a linear combination of previous nonnegative powers of A. We determine the maximum power indices for the class of n×n primitive symmetric Boolean matrices of trace zero, the class of n×n irreducible nonprimitive symmetric Boolean matrices, and the class of n×n reducible symmetric Boolean matrices of trace zero, and characterize the extreme matrices respectively.
Źródło:
Discussiones Mathematicae - General Algebra and Applications; 2004, 24, 1; 53-61
1509-9415
Pojawia się w:
Discussiones Mathematicae - General Algebra and Applications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Inverse Problem on the Steiner Wiener Index
Autorzy:
Li, Xueliang
Mao, Yaping
Gutman, Ivan
Powiązania:
https://bibliotekanauki.pl/articles/31342440.pdf
Data publikacji:
2018-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
distance
Steiner distance
Wiener index
Steiner Wiener index
Opis:
The Wiener index $ W(G) $ of a connected graph $G$, introduced by Wiener in 1947, is defined as $ W(G) = \Sigma_{ u,v \in V (G) } \ d_G(u, v) $, where $ d_G(u, v) $ is the distance (the length a shortest path) between the vertices $u$ and $v$ in $G$. For $ S \subseteq V (G) $, the Steiner distance $d(S)$ of the vertices of $S$, introduced by Chartrand et al. in 1989, is the minimum size of a connected subgraph of $G$ whose vertex set contains $S$. The $k$-th Steiner Wiener index $ SW_k(G) $ of $G$ is defined as $ SW_k(G)= \Sigma_{ S \subseteq V(G) \ |S|=k } \ d(S) $. We investigate the following problem: Fixed a positive integer $k$, for what kind of positive integer w does there exist a connected graph $G$ (or a tree $T$) of order $ n \ge k$ such that $ SW_k(G) = w$ (or $ SW_k(T) = w$)? In this paper, we give some solutions to this problem.
Źródło:
Discussiones Mathematicae Graph Theory; 2018, 38, 1; 83-95
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Smallest Harmonic Index of Trees with Given Maximum Degree
Autorzy:
Rasi, Reza
Sheikholeslami, Seyed Mahmoud
Powiązania:
https://bibliotekanauki.pl/articles/31342320.pdf
Data publikacji:
2018-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
harmonic index
trees
Opis:
The harmonic index of a graph G, denoted by H(G), is defined as the sum of weights 2/[d(u) + d(v)] over all edges uv of G, where d(u) denotes the degree of a vertex u. In this paper we establish a lower bound on the harmonic index of a tree T.
Źródło:
Discussiones Mathematicae Graph Theory; 2018, 38, 2; 499-513
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nordhaus-Gaddum-Type Results for Resistance Distance-Based Graph Invariants
Autorzy:
Das, Kinkar Ch.
Yang, Yujun
Xu, Kexiang
Powiązania:
https://bibliotekanauki.pl/articles/31340811.pdf
Data publikacji:
2016-08-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
resistance distance
Kirchhoff index
additive degree-Kirchhoff index
multiplicative degree-Kirchhoff index
Nordhaus-Gaddum-type result
Opis:
Two decades ago, resistance distance was introduced to characterize “chemical distance” in (molecular) graphs. In this paper, we consider three resistance distance-based graph invariants, namely, the Kirchhoff index, the additive degree-Kirchhoff index, and the multiplicative degree-Kirchhoff index. Some Nordhaus-Gaddum-type results for these three molecular structure descriptors are obtained. In addition, a relation between these Kirchhoffian indices is established.
Źródło:
Discussiones Mathematicae Graph Theory; 2016, 36, 3; 695-707
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Steiner Wiener Index of A Graph
Autorzy:
Li, Xueliang
Mao, Yaping
Gutman, Ivan
Powiązania:
https://bibliotekanauki.pl/articles/31340916.pdf
Data publikacji:
2016-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
distance
Steiner distance
Wiener index
Steiner Wiener k- index
Opis:
The Wiener index $ W(G) $ of a connected graph $G$, introduced by Wiener in 1947, is defined as $ W(G) = \Sigma_{ u,v \in V(G) } d(u, v) $ where $ d_G(u, v) $ is the distance between vertices $u$ and $v$ of $G$. The Steiner distance in a graph, introduced by Chartrand et al. in 1989, is a natural generalization of the concept of classical graph distance. For a connected graph $G$ of order at least 2 and $ S \subseteq V (G) $, the Steiner distance $d(S)$ of the vertices of $S$ is the minimum size of a connected subgraph whose vertex set is $S$. We now introduce the concept of the Steiner Wiener index of a graph. The Steiner k-Wiener index $ SW_k(G) $ of $ G $ is defined by $ \Sigma_{ S \subseteq V(G) \ |S| = k } \ d(S) $. Expressions for $ SW_k $ for some special graphs are obtained. We also give sharp upper and lower bounds of $ SW_k $ of a connected graph, and establish some of its properties in the case of trees. An application in chemistry of the Steiner Wiener index is reported in our another paper.
Źródło:
Discussiones Mathematicae Graph Theory; 2016, 36, 2; 455-465
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Product Connectivity Banhatti Index of a Graph
Autorzy:
Kulli, V.R.
Chaluvaraju, B.
Boregowda, H.S.
Powiązania:
https://bibliotekanauki.pl/articles/31343417.pdf
Data publikacji:
2019-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
Randić index
Zagreb indices
Banhatti indices
product connectivity Banhatti index
Opis:
Let $ G = (V, E) $ be a connected graph with vertex set $ V (G) $ and edge set $ E(G) $. The product connectivity Banhatti index of a graph $G$ is defined as, \( PB(G)= \sum_{ue} \tfrac{1}{ \sqrt { d_G(u) d_G(e) } } \), where $ue$ means that the vertex $u$ and edge $e$ are incident in $G$. In this paper, we determine $PB(G)$ of some standard classes of graphs. We also provide some relationship between $PB(G)$ in terms of order, size, minimum / maximum degrees and minimal non-pendant vertex degree. In addition, we obtain some bounds on $PB(G)$ in terms of Randić, Zagreb and other degree based topological indices of $G$.
Źródło:
Discussiones Mathematicae Graph Theory; 2019, 39, 2; 505-517
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Wiener index of the tensor product of a path and a cycle
Autorzy:
Pattabiraman, K.
Paulraja, P.
Powiązania:
https://bibliotekanauki.pl/articles/743591.pdf
Data publikacji:
2011
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
tensor product
Wiener index
Opis:
The Wiener index, denoted by W(G), of a connected graph G is the sum of all pairwise distances of vertices of the graph, that is, $W(G) = ½Σ_{u,v ∈ V(G)} d(u,v)$. In this paper, we obtain the Wiener index of the tensor product of a path and a cycle.
Źródło:
Discussiones Mathematicae Graph Theory; 2011, 31, 4; 737-751
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Few Examples and Counterexamples in Spectral Graph Theory
Autorzy:
Stevanović, Dragan
Milosavljević, Nikola
Vukičević, Damir
Powiązania:
https://bibliotekanauki.pl/articles/31563587.pdf
Data publikacji:
2020-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
communicability distance
spectral radius
integral graph
second Zagreb index
Wiener index
estrada index
almost cospectral graphs
NEPS of graphs
Opis:
We present a small collection of examples and counterexamples for selected problems, mostly in spectral graph theory, that have occupied our minds over a number of years without being completely resolved.
Źródło:
Discussiones Mathematicae Graph Theory; 2020, 40, 2; 637-662
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparing Eccentricity-Based Graph Invariants
Autorzy:
Hua, Hongbo
Wang, Hongzhuan
Gutman, Ivan
Powiązania:
https://bibliotekanauki.pl/articles/31348117.pdf
Data publikacji:
2020-11-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
eccentricity (of vertex)
Zagreb eccentricity index
eccentric distance sum
connective eccentricity index
Opis:
The first and second Zagreb eccentricity indices (EM1 and EM2), the eccentric distance sum (EDS), and the connective eccentricity index (CEI) are all recently conceived eccentricity-based graph invariants, some of which found applications in chemistry. We prove that EDS ≥ EM1 for any connected graph, whereas EDS > EM2 for trees. Moreover, in the case of trees, EM1 ≥ CEI, whereas EM2 > CEI for trees with at least three vertices. In addition, we compare EDS with EM2, and compare EM1, EM2 with CEI for general connected graphs under some restricted conditions.
Źródło:
Discussiones Mathematicae Graph Theory; 2020, 40, 4; 1111-1125
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Minimum Harmonic Index for Unicyclic Graphs with Given Diameter
Autorzy:
Zhong, Lingping
Powiązania:
https://bibliotekanauki.pl/articles/31342329.pdf
Data publikacji:
2018-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
harmonic index
unicyclic graphs
diameter
Opis:
The harmonic index of a graph $G$ is defined as the sum of the weights \( \tfrac{2}{d(u)+d(v)} \) of all edges uv of G, where $d(u)$ denotes the degree of a vertex $u$ in $G$. In this paper, we present the minimum harmonic index for unicyclic graphs with given diameter and characterize the corresponding extremal graphs. This answers an unsolved problem of Zhu and Chang [26].
Źródło:
Discussiones Mathematicae Graph Theory; 2018, 38, 2; 429-442
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Signed Complete Graphs with Maximum Index
Autorzy:
Akbari, Saieed
Dalvandi, Soudabeh
Heydari, Farideh
Maghasedi, Mohammad
Powiązania:
https://bibliotekanauki.pl/articles/31530379.pdf
Data publikacji:
2020-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
signed graph
complete graph
index
Opis:
Let Γ = (G, σ) be a signed graph, where G is the underlying simple graph and σ E(G) → {−, +} is the sign function on the edges of G. The adjacency matrix of a signed graph has −1 or +1 for adjacent vertices, depending on the sign of the edges. It was conjectured that if is a signed complete graph of order n with k negative edges, k < n − 1 and has maximum index, then negative edges form K1,k. In this paper, we prove this conjecture if we confine ourselves to all signed complete graphs of order n whose negative edges form a tree of order k + 1. A [1, 2]-subgraph of G is a graph whose components are paths and cycles. Let Γ be a signed complete graph whose negative edges form a [1, 2]-subgraph. We show that the eigenvalues of Γ satisfy the following inequalities: −5 ≤ λn ≤ . . . ≤ λ2 ≤ 3.
Źródło:
Discussiones Mathematicae Graph Theory; 2020, 40, 2; 393-403
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Relations between the domination parameters and the chromatic index of a graph
Autorzy:
Ulatowski, Włodzimierz
Powiązania:
https://bibliotekanauki.pl/articles/744471.pdf
Data publikacji:
2009
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
domination
domination parameters
chromatic index
Opis:
In this paper we show upper bounds for the sum and the product of the lower domination parameters and the chromatic index of a graph. We also present some families of graphs for which these upper bounds are achieved. Next, we give a lower bound for the sum of the upper domination parameters and the chromatic index. This lower bound is a function of the number of vertices of a graph and a new graph parameter which is defined here. In this case we also characterize graphs for which a respective equality holds.
Źródło:
Discussiones Mathematicae Graph Theory; 2009, 29, 3; 615-627
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Distinguishing Number and Distinguishing Index of the Lexicographic Product of Two Graphs
Autorzy:
Alikhani, Saeid
Soltani, Samaneh
Powiązania:
https://bibliotekanauki.pl/articles/31342273.pdf
Data publikacji:
2018-08-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
distinguishing index
distinguishing number
lexicographic
Opis:
The distinguishing number (index) D(G) (D′(G)) of a graph G is the least integer d such that G has a vertex labeling (edge labeling) with d labels that is preserved only by the trivial automorphism. The lexicographic product of two graphs G and H, G[H] can be obtained from G by substituting a copy Hu of H for every vertex u of G and then joining all vertices of Hu with all vertices of Hv if uv ∈ E(G). In this paper we obtain some sharp bounds for the distinguishing number and the distinguishing index of the lexicographic product of two graphs. As consequences, we prove that if G is a connected graph with Aut(G[G]) = Aut(G)[Aut(G)], then for every natural number k, D(G) ≤ D(Gk) ≤ D(G) + k − 1 and all lexicographic powers of G, Gk (k ≥ 2) can be distinguished by two edge labels, where Gk = G[G[. . . ]].
Źródło:
Discussiones Mathematicae Graph Theory; 2018, 38, 3; 853-865
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł

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