The bull graph is a simple graph on 5 nodes and 5 edges whose name derives from its resemblance to a schematic illustration of a bull
or ram (whose face is the triangle and horns are the graph's two bridges).
It could perhaps equally well be called the "for all-graph"
or "A-graph," and unfortunately sometimes is (e.g., Farrugia 1999, p. 2),
even though that term is usually applied to a particular 6-node graph.
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