The solutions to the unsolved problems are not in the back of the book. They are in the spaces between the problems. You are now an edge, not a vertex. Walk.
By Chapter 7 — Planar Graphs — the world had begun to rearrange itself permanently. Elena saw the subway map as a non-planar embedding in need of Kuratowski’s theorem. Her cat’s fur was a bipartite graph (white and black vertices, contact edges). Her own reflection in the mirror was a fixed point of an involution on the set of all possible hairstyles. Combinatorics And Graph Theory Harris Solutions Manual
But below it, in a different handwriting — small, red ink — someone had written: See solution on page 347. Then see yourself. The solutions to the unsolved problems are not
“Harris,” she said, and smiled.