English

Note on Sombor index of connected graphs with given degree sequence

Combinatorics 2022-11-08 v1

Abstract

For a simple connected graph G=(V,E)G=(V,E), let d(u)d(u) be the degree of the vertex uu of GG. The general Sombor index of GG is defined as SOα(G)=uvE[d(u)2+d(v)2]αSO_{\alpha}(G)=\sum_{uv\in E} \left[d(u)^2+d(v)^2\right]^\alpha where SO(G)=SO0.5(G)SO(G)=SO_{0.5}(G) is the recently invented Sombor index. In this paper, we show that in the class of connected graphs with a fixed degree sequence (for which the minimum degree being equal to one), there exists a special extremal BFSBFS-graph with minimum general Sombor index for 0<α<10<\alpha<1 (resp. maximum general Sombor index for either α>1\alpha>1 or α<0\alpha<0). Moreover, for any given tree, unicyclic, and bicyclic degree sequences with minimum degree 1, there exists a unique extremal BFSBFS-graph with minimum general Sombor index for 0<α<10<\alpha<1 and maximum general Sombor index for either α>1\alpha>1 or α<0\alpha<0.

Keywords

Cite

@article{arxiv.2211.02911,
  title  = {Note on Sombor index of connected graphs with given degree sequence},
  author = {Peichao Wei and Muhuo Liu},
  journal= {arXiv preprint arXiv:2211.02911},
  year   = {2022}
}