Extremal Degree Irregularity Bounds for Albertson and Sigma Indices in Trees and Bipartite Graphs (2507.14568v1)

Abstract: In this paper, study of extreme values of bounds in topological indices plays an important role in determining the impact of these indices on trees and bipartite graphs. For any integers $\alpha, p$ where $1\leq p\leq \alpha\leq \Delta-3$, the upper bound of the minimum value of Albertson index $\operatorname{irr}{\min}$ satisfy: [ \operatorname{irr}{\min}\geqslant \Delta^2(\Delta-1)\frac{2^{\alpha}}{(\Delta-p)^2}. ] Studies the maximum and minimum values of the Albertson index in bipartite graphs based on the sizes of their bipartition sets. Leveraging a known corollary, explicit formulas and bounds are derived that characterize the irregularity measure under various vertex size conditions. Upper bounds for both the Albertson and Sigma indices are established using graph parameters such as degrees and edge counts. Theoretical results are supported by examples and inequalities involving degree sequences, enhancing understanding of extremal irregularity behavior in bipartite graphs.