The Maximal Total Irregularity of Unicyclic Graphs

Lihua You1, Jieshan Yang1, Zhifu You2
1School of Mathematical Sciences, South China Normal University, Guangzhou, 510631, P.R. China
2Detartment of Computer Science, Guangdong Polytechnic Normal University, Guangzhou, 510665, P.R. China

Abstract

In \([1]\), Hosam Abdo and Darko Dimitrov introduced the total irregularity of a graph. For a graph \(G\), it is defined as
\[\text{irr}_t(G) =\frac{1}{2} \sum_{{u,v} \in V(G)} |d_G(u) – d_G(v)|,\]
where \(d_G(u)\) denotes the vertex degree of a vertex \(u \in V(G)\). In this paper, we introduce two transformations to study the total irregularity of unicyclic graphs and determine the graph with the maximal total irregularity among all unicyclic graphs with \(n\) vertices.