Underview

The morphology, syntactic, and tree databases together comprise the English grammar. A lexical item that is not in the databases receives a default tree selection and features for its part of speech and morphology. In designing the grammar, a decision was made early on to err on the side of acceptance whenever there are conflicting opinions as to whether or not a construction is grammatical. In this sense, the XTAG English grammar is intended to function primarily as an acceptor rather than a generator of English sentences. The range of syntactic phenomena that can be handled is large and includes auxiliaries (including inversion), copula, raising and small clause constructions, topicalization, relative clauses, infinitives, gerunds, passives, adjuncts, it-clefts, wh-clefts, PRO constructions, noun-noun modifications, extraposition, determiner sequences, genitives, negation, noun-verb contractions, clausal adjuncts and imperatives.