The story
Introduced by Hassler Whitney (1907–1989), American mathematician.
Etymology from Wiktionary, CC BY-SA 4.0.
Whitney's theorem
Today it means: A theorem stating that two connected graphs are isomorphic if and only if their line graphs are isomorphic, with a single exception: K₃, the complete graph on three vertices, and the complete bipartite graph K_(1,3), which are not isomorphic but both have K₃ as their line graph. Full definition →