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Báo cáo khoa học: "Features and Values"

The paper discusses the linguistic aspects of a new general purpose facility for computing with features. The program was developed in connection with the course I taught at the University of Texas in the fall of 1983. It is a generalized and expanded version of a system that Stuart Shieber originally designed for the PATR-II project at SRI in the spring of 1983 with later modifications by Fernando Pereira and me. Like its predecessors, the new Texas version of the "DG {directed graph}" package is primarily intended for representing morphological and syntactic information but it may turn out to. | Features and Values Lauri Karttunen University of Texas at Austin Artificial Intelligence Center SRI International and Center for the Study of Language and Information Stanford University Abstract The paper discusses the linguistic aspects of a new general purpose facility for computing with features. The program was developed in connection with the course I taught at the University of Texas in the fall of 1983. It is a generalized and expanded version of a system that Stuart Shieber originally designed for the PATR-II project at SRI in the spring of 1983 with later modifications by Fernando Pereira and me. Like its predecessors the new Texas version of the DG directed graph package is primarily intended for representing morphological and syntactic information but it may turn out to be very useful for semantic representations too. 1. Introduction Most schools of linguistics use some type of feature notation in their phonological morphological syntactic and semantic descriptions. Although the objects that appear in rules and conditions may have atomic names such as k NP Subject and the like such high-level terms typically stand for collections of features. Features in this sense of the word are usually thought of as attribute-value pairs person 1st number sg although singleton features are also admitted in some theories. The values of phonological and morphological features are traditionally atomic e.g. 1st 2nd 3rd they are often binary -. Most current theories also allow features that have complex values. A complex value is a collection of features for example In graphs of this sort values are reached by traversing paths of attribute names. We use angle brackets to mark expressions that designate paths. With that convention the above graph can also be represented as a set of equations Agreement number sg agreement person - 3rd Such equations also provide a convenient way to express conditions on features. This idea lies at the heart of UG LFG and the PATR-II .