On bond incident degree index of chemical trees with a fixed order and a fixed number of leaves

• Published in: Applied mathematics and computation 2024-03, Vol.464, p.128390, Article 128390
• Main Authors: Du, Jianwei, Sun, Xiaoling
• Format: Article
• Language: English
• Subjects: Bond incident degree index; Chemical tree; Leaf
• ISSN: 0096-3003; 1873-5649
• DOI: 10.1016/j.amc.2023.128390

A tree in which no vertex has a degree greater than 4 is called a chemical tree. The bond incident degree index of a chemical tree T is defined as ∑xy∈ETφ(degT(x),degT(y)), where ET is the edge set of T, φ is a real-valued symmetric function, and degT(x) stands for the degree of a vertex x of T. This paper reports extremal results on bond incident degree indices of chemical trees with a fixed order and a fixed number of leaves. Furthermore, we use these results directly to some renowned topological indices, such as symmetric division deg index, Randić index, geometric-arithmetic index, sum-connectivity index, Sombor index, harmonic index, multiplicative sum Zagreb index, atom-bond connectivity index, etc. •We report extremal results on bond incident degree indices of chemical trees with a fixed order and number of leaves.•Our results can be used directly to some renowned topological indices.•The obtained results generalize many existing, provide new cases for many existing indices.•We adopt a unified technique to some type of topological indices.