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Title:
Extremal Unicyclic Graphs for the Euler Sombor Index
Authors:
Alexandru-Petre Tache, Rozica-Maria Tache, Iulius Stroe
Volume
94
Issue
2
Year
2025
Pages
561-578
Abstract

The Euler Sombor index of a graph G is a recently introduced topological index, defined as \[ EU(G)~=~\sum_{uv\in{E(G)}}\sqrt{d(u)^2+d(v)^2+d(u)d(v)}, \] where \( d(u) \), \( d(v) \) are the degrees of the vertices \( u \), respectively \( v \) of \( G \). The purpose of this paper is to determine the first, second and third minimal and maximal unicyclic graphs of order \( n \) with respect to the Euler Sombor index for all \( n \geq 5 \).