Three Ways to Solve Domino Grids

Abstract

When my son brought home a paper from school with a 7μ 8 grid of numbers on it, I was immediately interested. The goal: cover the puzzle with all the dominoes from the “bone pile,” making sure that each number of the puzzle is covered by the same number on a domino. Many similar puzzles can be found online and in puzzle collections: see [1, 2, 3, 4, 5] for several online resources, which are the source of some of the examples considered here.