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When people find out that I write crosswords for a living, they often ask, "Can't you just write crosswords using a computer program now?" After I finish crying—some people really know how to hurt a guy—I respond that, yes, computers play a role in crossword design these days. There are three parts to constructing a crossword: coming up with a theme, filling in the grid, and writing the clues. Until artificial intelligence makes some serious leaps, humans will do the heavy lifting when it comes to theme creation and clue writing. But the second part, filling grids with words, is quite computer-friendly. It's here that machines have revolutionized the construction of crossword puzzles.

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Early efforts in computer-aided crossword design spat out marginal little grids filled with obscure words. But in the late 1980s, Boston computer programmer Eric Albert had an insight while tangling with this problem: A computer could generate high-quality crossword puzzles if each entry in its word database were ranked on, say, a scale from one to 10. An excellent puzzle word like JUKEBOX (gotta love all those high-scoring Scrabble letters) might be worth a nine or 10, while a hacky obscurity like UNAU (a type of sloth that has appeared in crosswords more times than it's been spotted in real life) would be a one or a two. By ranking the words, the junk would be left out and just the good stuff would go in.

This is how computer-aided crossword design still works today. The database operator has to place theme entries and black squares logically in the grid; this placement is done intuitively, based on what the human thinks the computer can handle. After the computer fills in the blanks, the human operator will likely do some further tweaking, such as marking off a corner of the grid he doesn't like so the computer can take another shot at it.