The A graph is the graph on 6 vertices illustrated above. Unfortunately, at least one author (Farrugia 1999, p. 2) uses the term "A-graph" to refer to the 5-node bull graph.
The 6-vertex A-graph is implemented in the Wolfram Language as GraphData["AGraph"].
See also
Banner Graph, Bull Graph, E Graph, H Graph, Longhorn Graph, R Graph
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References
Brandstädt, A.; Le, V. B.; and Spinrad, J. P. Graph Classes: A Survey. Philadelphia, PA: SIAM, p. 18, 1987.Farrugia, A. "Self-Complementary Graphs and Generalisations: a Comprehensive Reference Manual." Aug. 1999. http://www.alastairfarrugia.net/sc-graph/sc-graph-survey.pdf.ISGCI: Information System on Graph Class Inclusions v2.0. "List of Small Graphs." http://www.graphclasses.org/smallgraphs.html.
Referenced on Wolfram|Alpha
Cite this as:
Weisstein, Eric W. "A Graph." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/AGraph.html