A method of grammar rule induction comprises obtaining a monolingual set of phrases from a bilingual corpus of translation pairs. For each of the monolingual phrases in turn, initialising, with inactive edges formed from headwords identified in the phrase, the agenda of a dependency grammar chart parser arranged to form packed edges in the chart. Running the chart parser and adding to the agenda, for each inactive edge removed from the agenda, one or more active edges created as if all possible grammar rules existed. When the agenda is empty, ascertaining the alternations of each edge in the packed edge corresponding to the complete phrase, and finding their respective highest frequencies. For the set of phrases, summing, for each alternation, its respective highest frequencies, and ranking the sums. Then, selecting alternations in rank order to form the required set of grammar rules until the required set has become sufficient such that for each monolingual phrase there exists at least one analysis corresponding to the required set of grammar rules.
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