The Schläfli graph is a strongly regular graph on 27 nodes which is the graph complement
of the generalized quadrangle . It is the unique strongly
regular graph with parameters
(Godsil and Royle 2001, p. 259). It is illustrated
above in two embeddings, the first one corresponding to an order-9 generalized LCF notation.
The Schläfli graph is implemented in the Wolfram Language as GraphData["SchlaefliGraph"].
It is distance-regular with intersection array .
It is also distance-transitive.
It is an integral graph with graph spectrum .