PuzzledDelightful graph theory
Peter M. Winkler · Communications of the ACM · 2008
Welcome to the new puzzle column. Each column will present three puzzles. The first two will have known (and usually elegant) solutions that will appear in the next issue of Communications. The third will be an open problem; good luck with that one. Readers are encouraged to submit prospective puzzles for future columns to [email protected]. We start with three delightful graph-theoretic puzzles. Here we go.