Abstract
The \( \sigma \)-irregularity index is a variant of the well-established Albertson irregularity index. For a graph \( G=(V,E) \) it is defined as \( \sigma(G)=\sum_{uv\in E}(d(u)-d(v))^2 \), where \( d(u) \) and \( d(v) \) denote the degrees of vertices \( u \) and \( v \), respectively. In this note, we characterize chemical trees of a given order with maximal \( \sigma \)-irregularity index.
