Trace Prediction and Recovery with Unlexicalized PCFGs and Slash Features Helmut Schmid author 2006-07 text Proceedings of the 21st International Conference on Computational Linguistics and 44th Annual Meeting of the Association for Computational Linguistics Nicoletta Calzolari editor Claire Cardie editor Pierre Isabelle editor Association for Computational Linguistics Sydney, Australia conference publication schmid-2006-trace 10.3115/1220175.1220198 https://aclanthology.org/P06-1023/ 2006-07 177 184