The HarborthGraph() command constructs the Harborth graph.

The Harborth graph is a 4-regular graph with 52 vertices and 104 edges, named after H. Harborth. It is the smallest known 4-regular matchstick graph.

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

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

$H≔\mathrm{HarborthGraph}\left(\right)$

$H≔\mathrm{Graph\; 1:\; an\; undirected\; graph\; with\; 52\; vertices\; and\; 104\; edge(s)}$

$\mathrm{IsPlanar}\left(H\right)$

$\mathrm{true}$

$\mathrm{IsRegular}\left(H\right)$

$\mathrm{true}$

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

$3$

$\mathrm{DrawPlanar}\left(H\right)$

"Matchstick graph", Wikipedia. http://en.wikipedia.org/wiki/Matchstick_graph

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

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