The Goldner-Harary graph is an 11-vertex polyhedral nonhamiltonian graph (Goldner and Harary 1975a, Bernhart and Kainen 1979, de
Wet et al. 2018), illustrated above. Eleven is the smallest possible vertex
count of such a graph, and there exist 74 such graphs,
including the Herschel graph.
The Goldner-Harary graph has 11 vertices and 27 edges. It is exceptional for being the unique smallest
nonhamiltonian graph with only triangular
faces, meaning it is the only 11-vertex nonhamiltonian
polyhedral graph with this property. It is also
the unique 11-vertex nonhamiltonian polyhedral graph
having the maximum possible 27 edges, as well as being
a k-tree with .
The Goldner-Harary graph is shown above in a number of straight-line graph drawings.
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