The BrouwerHaemersGraph command creates the Brouwer-Haemers graph.

The Brouwer-Haemers graph is a strongly regular graph with 81 vertices and 810 edges.

$\mathrm{with}\left(\mathrm{GraphTheory}\right)\:$

$\mathrm{with}\left(\mathrm{SpecialGraphs}\right)\:$

$\mathrm{BH}≔\mathrm{BrouwerHaemersGraph}\left(\right)$

$\mathrm{BH}≔\mathrm{Graph\; 1:\; an\; undirected\; graph\; with\; 81\; vertices\; and\; 810\; edge(s)}$

$\mathrm{IsStronglyRegular}\left(\mathrm{BH}\,'\mathrm{parameters}'\right)$

$\mathrm{true},\left[20\,1\,6\right]$

$\mathrm{ChromaticNumber}\left(\mathrm{BH}\right)$

$7$

"Brouwer-Haemers graph", Wikipedia. http://en.wikipedia.org/wiki/Brouwer-Haemers_graph

The GraphTheory[SpecialGraphs][BrouwerHaemersGraph] command was introduced in Maple 2020.

For more information on Maple 2020 changes, see Updates in Maple 2020.