Domino Groups

[donkirkby]

Daniel Ashlock created an interesting puzzle on his Occupy Math blog where you have to assemble a set of dominoes so that all the numbers are in pairs. I think it might be possible to create a small number of puzzles with the standard double-six dominoes. To create more puzzles, I think I could generalize it from pairs of numbers to larger groups. It would probably reduce the search space if all the groups in a problem were the same shape. Particularly with the smaller groups, the layouts probably won't be rectangular. (It might work to exclude some numbers and make even smaller layouts.)