Trees have no cycles but must be connected.
Tourn'ments are cliques with their edges directed.
Hamilton circuits, Eulerian paths,
These are a few of my favorite graphs.
Matchings and bicliques and blossoms and bases,
Kempe chains, hypercubes, forests, and faces,
AKS networks that split into halves,
These are a few of my favorite graphs.
Short paths of co-authors leading to Erdos,
Large neural networks that translate from Kurdish,
Finite projective planes - they make me laugh.
These are a few of my favorite graphs.
Chorus: Propositions, corollaries,
Problems that are starred,
I simply remember my favorite graphs
And then they don't seem so hard.
If there's no K_5 or K_{3,3} minor,
Old Kuratowski says it'll be 'plinor'.
Four's enough colors if there are no gaffes!
These are a few of my favorite graphs.
Quadrangles, thrackles, and triangulations,
Minor-closed families and sparsifications,
Voronoi diagrams found on giraffes,
These are a few of my favorite graphs.
Chorus: Propositions, corollaries,
When they're just too deep,
I simply remember my favorite graphs
And then I go right to sleep.
Composed by Jeff Erickson