The Syntax and Semantics of User-Defined Modifiers in Transportable Natural Language Processor

THE SYNTAX AND SEMANTICS OF USER-DEFINED MODIFIERS IN A TRANSPORTABLE NATURAL LANGUAGE PROCESSOR Bruce W. Ballard Dept. of Computer Science Duke University Durham, N.C. 27708 ABSTRACT The Layered Domain Class system (LDC) is an experimental natural language processor being developed at Duke University which reached the prototype stage in May of 1983. Its primary goals are (I) to provide English-language retrieval capabilities for structured but unnormaUzed data files created by the user, (2) to allow very complex semantics, in terms of the information directly available from the physical data file; and (3) to enable users to customize the system to operate with new types of data. In this paper we shall discuss (a) the types of modifiers LDC provides for; (b) how information about the syntax and semantics of modifmrs is obtained from users; and (c) how this information is used to process English inputs. I INTRODUCTION The Layered Domain Class system (LDC) is an experimental natural language processor being developed at Duke .University. In this paper we concentrate on the typ.~s of modifiers provided by LDC and the methods by which the system acquires information about the syntax and semantics of user- defined modifiers. A more complete description is available in [4,5], and further details on matters not discussed in this paper can be found in [1,2,6,8,9]. The LDC system is made up of two primary components. First, the Ic'nowledge aeTui.~i2ion component, whose job is to find out about the vocabulary and semantics of the language to be used for a new domain, then inquire about the composition of the underlying input file. Second, the User-Phase Processor, which enables a user to obtain statistical reductions on his or her data by typed English inputs. The top-level design of the User-Phase processor involves a linear sequence of modules for scavtvtir~g the input and looking up each token in the dictionary; pars/rig the scanned input to determine its syntactic structure; translatiort of the parsed input into an appropriate formal query; and finally query processing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . This research has been supported in part by the National Science Foundation, Grants MCS-81-16607 and IST-83-01994; in part by the National Library of Medicine, Grant LM-07003; and in part by the Air Force Office of Scientific Research, Grant 81-0221. The User-Phrase portion of LDC resembles familiar natural language database query systems such as INTELLECT, JETS. LADDER, LUNAR. PHLIQA, PLANES, REL, RENDEZVOUS, TQA, and USL (see [10-23]) while the overall LDC system is similar in its objectives to more recent systems such as ASK, CONSUL, IRUS, and TEAM (see [24-319. At the time of this writing, LDC has been completely customized for two fairly complex domains. from which examples are drawn in the remainder of the paper, and several simpler ones. The complex domains are a 2~al …

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