Transforming a Constituency Treebank into a Dependency Treebank

We present a heuristic technique for converting a constituency treebank into a dependency treebank. In particular, we comment on our experience in converting the Spanish treebank Cast3LB. We extract a context-free grammar from the treebank, automatically identify the head in each rule, and use this information for constructing the dependency tree. Our heuristics have 99% precision and 80% recall in identifying the head in the rules, which gives 92% accuracy in identifying dependencies between words.