Getting Around

This technical report presents the English XTAG grammar as implemented by the XTAG Research Group at the University of Pennsylvania. The technical report is organized into four parts, plus a set of appendices. Part 1 contains general information about the XTAG system and some of the underlying mechanisms that help shape the grammar. Chapter 2 contains an introduction to the formalism behind the grammar and parser, while Chapter 3 contains information about the entire XTAG system. Linguists interested solely in the grammar of the XTAG system may safely skip Chapters 2 and 3. Chapter 4 contains information on some of the linguistic principles that underlie the XTAG grammar, including the distinction between complements and adjuncts, and how case is handled. The actual description of the grammar begins with Part 2, and is contained in the following three parts. Parts 2 and 3 contains information on the verb classes and the types of trees allowed within the verb classes, respectively, while Part 4 contains information on trees not included in the verb classes (e.g. NP's, PP's, various modifiers, etc). Chapter 5 of Part 2 contains a table that attempts to provide an overview of the verb classes and tree types by providing a graphical indication of which tree types are allowed in which verb classes. This has been cross-indexed to tree figures shown in the tech report. Chapter 6 contains an overview of all of the verb classes in the XTAG grammar. The rest of Part 2 contains more details on several of the more interesting verb classes, including ergatives, sentential subjects, sentential complements, small classes, ditransitives, and it-clefts. Part 3 contains information on some of the tree types that are available within the verb classes. These tree types correspond to what would be transformations in a movement based approach. Not all of these types of trees are contained in all of the verb classes. The table (previously mentioned) in Part 2 contains a list of the tree types and indicates which verb classes each occurs in. Part 4 focuses on the non-verb class trees in the grammar. NP's and determiners are presented in Chapter 19, while the various modifier trees are presented in Chapter 20. Auxiliary verbs, which are classed separate from the verb classes, are presented in Chapter 21, while certain types of conjunction are shown in Chapter 22. The XTAG treatment of comparatives is presented in Chapter 23, and our treatment of punctuation is discussed in Chapter 24. Throughout the technical report, mention is occasionally made of changes or analyses that we hope to incorporate in the future. Appendix A details a list of these and other future work. The appendices also contain information on some of the nitty gritty details of the XTAG grammar, including a system of metarules which can be used for grammar development and maintenance in Appendix C, a system for the organization of the grammar in terms of an inheritance hierarchy is in Appendix D, the tree naming conventions used in XTAG are explained in detail in Appendix E, and a comprehensive list of the features