scholarly journals Sharp upper bounds on Zagreb indices of bicyclic graphs with a given matching number

2011 ◽  
Vol 54 (11-12) ◽  
pp. 2869-2879 ◽  
Author(s):  
Shuchao Li ◽  
Qin Zhao
Keyword(s):  
Upper Bounds ◽  
Matching Number ◽  
Zagreb Indices ◽  
Bicyclic Graphs

scholarly journals General Multiplicative Zagreb Indices of Graphs with a Small Number of Cycles

Symmetry ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 514 ◽  
Author(s):  
Monther R. Alfuraidan ◽  
Tomáš Vetrík ◽  
Selvaraj Balachandran
Keyword(s):  
Upper Bounds ◽  
Extremal Graphs ◽  
Lower And Upper Bounds ◽  
Zagreb Indices ◽  
Special Cases ◽  
Tricyclic Graphs ◽  
Bicyclic Graphs ◽  
Number Of Cycles

We present lower and upper bounds on the general multiplicative Zagreb indices for bicyclic graphs of a given order and number of pendant vertices. Then, we generalize our methods and obtain bounds for the general multiplicative Zagreb indices of tricyclic graphs, tetracyclic graphs and graphs of given order, size and number of pendant vertices. We show that all our bounds are sharp by presenting extremal graphs including graphs with symmetries. Bounds for the classical multiplicative Zagreb indices are special cases of our results.

Sharp upper bounds of F-index among bicyclic graphs

2021 ◽  
pp. 2250055
Author(s):  
R. Khoeilar ◽  
A. Jahanbani ◽  
L. Shahbazi ◽  
J. Rodríguez
Keyword(s):  
Maximum Degree ◽  
Topological Index ◽  
Upper Bounds ◽  
Degree Of A Vertex ◽  
Bicyclic Graphs

The [Formula: see text]-index of a graph [Formula: see text], denoted by [Formula: see text], is defined as the sum of weights [Formula: see text] over all edges [Formula: see text] of [Formula: see text], where [Formula: see text] denotes the degree of a vertex [Formula: see text]. In this paper, we give sharp upper bounds of the [Formula: see text]-index (forgotten topological index) over bicyclic graphs, in terms of the order and maximum degree.

scholarly journals Upper bounds on the energy of graphs in terms of matching number

2021 ◽  
pp. 16-16
Author(s):  
Saieed Akbari ◽  
Abdullah Alazemi ◽  
Milica Andjelic
Keyword(s):  
Adjacency Matrix ◽  
Connected Graph ◽  
Short Proof ◽  
Upper Bounds ◽  
Vertex Degree ◽  
Maximum Matching ◽  
Matching Number ◽  
Open Problems

The energy of a graph G, ?(G), is the sum of absolute values of the eigenvalues of its adjacency matrix. The matching number ?(G) is the number of edges in a maximum matching. In this paper, for a connected graph G of order n with largest vertex degree ? ? 6 we present two new upper bounds for the energy of a graph: ?(G) ? (n-1)?? and ?(G) ? 2?(G)??. The latter one improves recently obtained bound ?(G) ? {2?(G)?2?e + 1, if ?e is even; ?(G)(? a + 2?a + ?a-2?a), otherwise, where ?e stands for the largest edge degree and a = 2(?e + 1). We also present a short proof of this result and several open problems.

scholarly journals Regularity of bicyclic graphs and their powers

2019 ◽  
Vol 19 (03) ◽  
pp. 2050057 ◽  
Author(s):  
Yairon Cid-Ruiz ◽  
Sepehr Jafari ◽  
Navid Nemati ◽  
Beatrice Picone
Keyword(s):  
Base Case ◽  
Matching Number ◽  
Edge Ideal ◽  
Induced Matching ◽  
Base Graph ◽  
Bicyclic Graph ◽  
Bicyclic Graphs

Let [Formula: see text] be the edge ideal of a bicyclic graph [Formula: see text] with a dumbbell as the base graph. In this paper, we characterize the Castelnuovo–Mumford regularity of [Formula: see text] in terms of the induced matching number of [Formula: see text]. For the base case of this family of graphs, i.e. dumbbell graphs, we explicitly compute the induced matching number. Moreover, we prove that [Formula: see text], for all [Formula: see text], when [Formula: see text] is a dumbbell graph with a connecting path having no more than two vertices.

scholarly journals Note on the Reformulated Zagreb Indices of Two Classes of Graphs

2020 ◽  
Vol 2020 ◽  
pp. 1-4
Author(s):  
Tongkun Qu ◽  
Mengya He ◽  
Shengjin Ji ◽  
Xia Li
Keyword(s):  
Upper Bounds ◽  
Extremal Graphs ◽  
Zagreb Index ◽  
Zagreb Indices ◽  
Vertex Degrees

The reformulated Zagreb indices of a graph are obtained from the original Zagreb indices by replacing vertex degrees with edge degrees, where the degree of an edge is taken as the sum of degrees of its two end vertices minus 2. In this paper, we obtain two upper bounds of the first reformulated Zagreb index among all graphs with p pendant vertices and all graphs having key vertices for which they will become trees after deleting their one key vertex. Moreover, the corresponding extremal graphs which attained these bounds are characterized.

scholarly journals General multiplicative Zagreb indices of unicyclic graphs

2021 ◽  
Vol 37 (1) ◽  
pp. 1-11
Author(s):  
MONTHER R. ALFURAIDAN ◽  
SELVARAJ BALACHANDRAN ◽  
TOMAS VETRIK
Keyword(s):  
Upper Bounds ◽  
Lower And Upper Bounds ◽  
Unicyclic Graphs ◽  
Zagreb Indices

"General multiplicative Zagreb indices generalize well-known multiplicative Zagreb indices of graphs. We present lower and upper bounds on the general multiplicative Zagreb indices for unicyclic graphs with given number of vertices and diameter/number of pendant vertices/cycle of given length. All bounds are best possible. Bounds on the classical multiplicative Zagreb indices of unicyclic graphs are corollaries of the general results. "

Product version of reciprocal Gutman indices of composite graphs

2017 ◽  
Vol 26 (2) ◽  
pp. 211-219
Author(s):  
K. Pattabiraman
Keyword(s):  
Tensor Product ◽  
Upper Bounds ◽  
Graph Invariants ◽  
Harary Index ◽  
Connected Graphs ◽  
Zagreb Indices ◽  
Strong Product

In this paper, we present the upper bounds for the product version of reciprocal Gutman indices of the tensor product, join and strong product of two connected graphs in terms of other graph invariants including the Harary index and Zagreb indices.

scholarly journals Sharp Bounds of the Hyper-Zagreb Index on Acyclic, Unicylic, and Bicyclic Graphs

2017 ◽  
Vol 2017 ◽  
pp. 1-5 ◽  
Author(s):  
Wei Gao ◽  
Muhammad Kamran Jamil ◽  
Aisha Javed ◽  
Mohammad Reza Farahani ◽  
Shaohui Wang ◽  
...  
Keyword(s):  
Lower Bounds ◽  
Upper And Lower Bounds ◽  
Extremal Graphs ◽  
Zagreb Index ◽  
Sharp Bounds ◽  
Zagreb Indices ◽  
Graph Transformations ◽  
Mathematical Properties ◽  
Bicyclic Graphs ◽  
Important Branch

The hyper-Zagreb index is an important branch in the Zagreb indices family, which is defined as∑uv∈E(G)‍(d(u)+d(v))2, whered(v)is the degree of the vertexvin a graphG=(V(G),E(G)). In this paper, the monotonicity of the hyper-Zagreb index under some graph transformations was studied. Using these nice mathematical properties, the extremal graphs amongn-vertex trees (acyclic), unicyclic, and bicyclic graphs are determined for hyper-Zagreb index. Furthermore, the sharp upper and lower bounds on the hyper-Zagreb index of these graphs are provided.

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