Extremal graphs of diameter at most 6 after deleting any vertex
Yoko Usami · Journal of Graph Theory · 1985
Abstract Suppose G is a graph of n vertices and diameter at most d having the property that, after deleting any vertex, the resulting subgraph has diameter at most 6. Then G contains at least max{n, (4n ‐ 8)/3} edges if 4 ≤ d ≤ 6.