The extremal graphs of order trees and their topological indices

Rui Song, Qiongxiang Huang, Peng Wang

Recently, D. Vuki$\check{c}$evi$\acute{c}$ and J. Sedlar in \cite{Vuki} introduced an order "$⪯$" on ${\mathcal{T}}_n$, the set of trees on $n$ vertices, such that the topologi…