Since the birth of artificial intelligence (AI), games and puzzles have received much attention. The game that has captured most of the attention of computer scientists is chess. The founding fathers of AI such as McCarthy, Simon (Simon and Schaeffer 1992), Samuel, Shannon (Shannon 1950), Turing, and Von Neumann have all been involved in automatic chess playing. After decades of unsuccessful attempts (Mittman and Newborn 1980, Munakata 1996), the IBM machine Deep Blue achieved the astonishing result of defeating world champion Gary Kasparov in May 1997 (Campbell, Hoane, and Hsu 2002). Games play the role of a laboratory where machines can safely be tested by a direct competition with humans.

A crossword-solving computer program yesterday triumphed in a competition against humans. Two versions of the program, called WebCrow, finished first and second in a competition that gave bilingual entrants 90 minutes to work on five different crosswords in Italian and English. The competition took place in Riva del Garda, Italy, as part of the European Conference on Artificial Intelligence. WebCrow took on 25 human competitors, mostly conference attendees, while more than 50 crossword enthusiasts and AI researchers competed online. Among the five crosswords were two American-style ones from that day's editions of the New York Times and Washington Post.

Crosswords are very popular and represent a useful domain of investigation for modern artificial intelligence. In contrast to solving other celebrated games (such as chess), cracking crosswords requires a paradigm shift towards the ability to handle tasks for which humans require extensive semantic knowledge. In competitions at the European Conference on Artificial Intelligence (ECAI) in 2006 and other conferences this web-based approach enabled WebCrow to outperform its human challengers. Just as chess was once called "the Drosophila of artificial intelligence," we believe that crossword systems can be useful Drosophila of web-based agents.

Crosswords are very popular and represent a useful domain of investigation for modern artificial intelligence. In contrast to solving other celebrated games (such as chess), cracking crosswords requires a paradigm shift towards the ability to handle tasks for which humans require extensive semantic knowledge. This article introduces WebCrow, an automatic crossword solver in which the needed knowledge is mined from the web: clues are solved primarily by accessing the web through search engines and applying natural language processing techniques. In competitions at the European Conference on Artificial Intelligence (ECAI) in 2006 and other conferences this web-based approach enabled WebCrow to outperform its human challengers. Just as chess was once called “the Drosophila of artificial intelligence,” we believe that crossword systems can be useful Drosophila of web-based agents.