50 GAMES WORLD^ OF PUZZLES^ | may 2019
In each of these puzzles, the grid starts out filled with letters; your goal is to clear all of the
letters from the grid. A “move” consists of crossing out a pair of identical letters, provided
that the rectangle they share doesn’t contain any letters that haven’t been crossed out yet.
In these puzzles, there’s more than one way to clear the grid, meaning that a variety of
strategies can be used.
In the example at right, the pair of B’s can be crossed out first, followed by the pair of A’s.
With both of these pairs gone, the pair of C’s can now be crossed out. Note that the pair of
A’s could just as well have been crossed out first, before the B’s. ANSWERS, PAGE 77&ǝǔ3ǦǦ BY STEVEN MEYERS
The above puzzles were generated by the Android app for BoxOff, which was released in 2016. The algorithm that creates
the app’s puzzles was designed by Greg Schmidt. (The app is free to download. Search for “BoxOff,” not “Box Off.”) There is
also a separate free-to-download iOS app for BoxOff that was released in 2014, programmed by Michael Gilbert.
Cameron Browne and Frederic Maire have written an article about some of BoxOff’s mathematical properties, called “Monte
Carlo Analysis of a Puzzle Game.” Anyone interested in discussing BoxOff with me can reach me via email at swmeyers@
fuse.net.D
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EXAMPLE