Abstract

In this work, by using the properties of the variable sum exdeg indices and analyzing the structure of the quasi-tree graphs and unicyclic graphs, the minimum and maximum variable sum exdeg indices of quasi-tree graphs and quasi-tree graphs with perfect matchings were presented; the minimum and maximum variable sum exdeg indices of unicyclic graphs with given pendant vertices and cycle length were determined.

Highlights

  • Topological indices are mathematical descriptors reflecting some structural characteristics of organic molecules on molecular graphs, and they play an important role in pharmacology, chemistry, etc. ([1,2,3])

  • Where a ∈ (0, 1) ∪ (1, +∞) and dG(v) is the degree of vertex v. is graph invariant has a good correlation with the octanol-water partition coefficient [4] and was used to study the octane isomers given by the International Academy of Mathematical Chemistry (IAMC) [5,6,7]

  • Erefore, our results may be used to predict the extremal properties of organic molecules

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Summary

Introduction

Where a ∈ (0, 1) ∪ (1, +∞) and dG(v) is the degree of vertex v. is graph invariant has a good correlation with the octanol-water partition coefficient [4] and was used to study the octane isomers given by the International Academy of Mathematical Chemistry (IAMC) [5,6,7]. By using the technique of majorization, Ghalavand and Ashrafi [9] provided the maximal and minimal SEIa (for a > 1) of trees, bicyclic graphs, unicyclic graphs, and tricyclic graphs. We use NG(v) to denote the neighbourhood of a vertex v and ni to denote the number of vertices with degree i.

Preliminaries
Variable Sum Exdeg Indices of QuasiTree Graphs
Variable Sum Exdeg Indices of Quasi-Tree Graphs with a Perfect Matching
Variable Sum Exdeg Indices of Unicyclic Graphs with Given Cycle Length
Variable Sum Exdeg Index of Unicyclic Graphs with Given Pendant Vertex
Results and Discussion
Conclusions
Full Text
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