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How Does it Work?

The approach of the OneAcross clue solver is similar to that of the meta-search engines on the web. We ask a number of sources the same question, and then combine these results to produce a unified answer.

Crossword Database
The main source of knowledge for our system comes from a large collection of previously seen crossword puzzles. These puzzles come from a variety of sources and span a number of years. Currently the database contains over 9000 puzzles, or around 750,000 clues.

Candidate Generation
The clue and length that you entered is passed to a handful of Expert Modules. Each expert module suggests possible answers to the clue, weighted by confidence. These expert modules can each do a different kind of search. For example, one might simply return all words in the dictionary of the correct length (ignoring the clue), while another might look for keywords in the clue that match previously seen clues.

Partial list of current Expert Modules:

  • Exact   Looks for word-for-word matches with previous clues.
  • Partial   Looks for words in common with previous clues.
  • Transformation   Looks for ways of changing your clue into a previous clue.
  • Word Path   Looks for a chain of associations from a word in your clue to word that fits your pattern.
  • Crossword Dictionary   Returns common crossword answers that fit the pattern.
  • Dictionary   Returns words that fit the pattern.
In our research system Proverb, we had 33 different expert modules, including expert modules for movies and fill-in-the-blank clues.

Reweighting
Once the system has these weighted lists of candidates, it must combine them into a single list for presentation. It first scales each expert module's list to account for its historic success. That is, if an expert module has been successful in the past, we might increase the weight of all its guesses. Finally, these lists are combined together, and sorted based on confidence.