The maximum possible toughness among graphs with \(n\) vertices and \(m\) edges is considered for \(m \geq \lceil n^2/4 \rceil\). We thus extend results known for \(m \geq n\lfloor n/3 \rfloor\). When \(n\) is even, all of the values are determined. When \(n\) is odd, some values are determined, and the difficulties are discussed, leaving open questions.
Citation
Lynne L.Doty, Kevin K.Ferland. Some Maximally Tough Circulants[J], Ars Combinatoria, Volume 087. 193-203. .