Mildly Non-Projective Dependency Structures Marco Kuhlmann author Joakim Nivre author 2006-07 text Proceedings of the COLING/ACL 2006 Main Conference Poster Sessions Association for Computational Linguistics Sydney, Australia conference publication kuhlmann-nivre-2006-mildly https://aclanthology.org/P06-2066/ 2006-07 507 514