Degree-diameter problem $N(6,4)$
The largest possible number of vertices in a graph of maximum degree $6$ and diameter $4$.
Lower bound:
$390$
Upper bound:
Unknown
Updates
-
2001-05-25
Lower bound: $380$
Exoo, G. (2001). A family of graphs and the degree/diameter problem. Journal of Graph Theory, 37(2), 118-124. -
2008
Lower bound: $390$
Loz, E., & Sirán, J. (2008). New record graphs in the degree-diameter problem. Australasian Journal of Combinatorics, 41, 63.
[via Table of the largest known graphs of a given diameter and maximal degree - Wikipedia]