TACITUS: A Message Understanding System Jerry R Hobbs author Douglas Appelt author John Bear author Mark Stickel author Mabry Tyson author 1989 text Speech and Natural Language: Proceedings of a Workshop Held at Cape Cod, Massachusetts, October 15-18, 1989 conference publication hobbs-etal-1989-tacitus https://aclanthology.org/H89-2075/ 1989