Hare and Hare conjectured the 2-packing number of an \(m \times n\) grid graph to be \(\left\lceil \frac{mn}{5} \right\rceil\) for \(m, n \geq 9\). This is verified by finding the 2-packing number for grid graphs of all sizes.
Citation
David C.Fisher. The \(2\)-Packing Number of Complete Grid Graphs[J], Ars Combinatoria, Volume 036. 261-270. .