Maintaining the Forest and Burning out the Underbrush in XTAG Christine Doran author Beth Hockey author Philip Hopely author Joseph Rosenzweig author Anoop Sarkar author B Srinivas author Fei Xia author 1997 text Computational Environments for Grammar Development and Linguistic Engineering conference publication doran-etal-1997-maintaining https://aclanthology.org/W97-1505/ 1997