Acquisition of Conceptual Data Models from Natural Language Descriptions

Acquisition of Conceptual Data Models from Natural Language Descriptions William J.Black, Department of Computation, UMIST, PO Box 88, Sackville Street, Manchester, M60 1QD, UK Abstract Acquiring information systems specifications from natural language description is presented as a problem class that requires a different treatment of semantics when compared with other applied NL systems such as database and operating system interfaces. Within this problem class, the specific task of obtaining explicit conceptual data models from natural language text or dialogue is being investigated. The knowledge brought to bear on this task is classified into syntactic, semantic and systems analysis knowledge. Investigations with a simple syntactic parse and with a semantic analysis using McCorcl's Slot Grammar are reported, and the structure of the systems analysis knowledge is considered. 1 Introduction This section introduces the application of computer-based tools for information systems requirements analysis, design. and implementation, and outlines a motivation for endowing such tools with natural language interfaces. It concludes with the structure of the remainder of the paper. Information systems development suffers from two widely acknowledged problems: • an applications backlog, whereby demand for applications exceeds resources available for its satisfaction. • a requirements analysis problem. This is often manifested as a maintenance problem, whereby resources that could be put into reducing the applications backlog are instead devoted to correcting faults in delivered systems. Most such faults are traceable to erroneous specifications, resulting from a failure to establish user requirements correctly. The industry has provided solutions to each of these problems: The problem of productivity has been addressed by the provision of more powerful higher-level languages known as 'application generators' or 'fourth generation languages ' (4GLs), in which the same functionality can be achieved in a tenth or less of the instructions needed in a conventional procedural computer language. A general feature of such software tools is that they do away with the need for much procedural programming by employing declarative notations in which requirements can be expressed in sufficient detail for the software to provide procedures to meet them. (Naturally, the sophistication of these declarative notations varies according to the breadth of their application coverage.) The requirements analysis problem has been addressed since the mid nineteen-seventies by a range of prescriptive development methods providing working procedures and graphical representation languages, in place of traditional approaches which rely heavily on natural language narrative to specify prooessing requirements. A typical representation or conceptual modelling language is described in section 2. A problem with both the high-level application generators and the development methods is that they have been established independently by a variety of manufacturers, software houses, consultants and academics, resulting in a multitude of competing products and methods, with no standard accepted by the industry. Suppliers and users therefore face considerable training and consultancy costs due to staff mobility. A more recent trend is to combine the two approaches to produce a more powerful software tool environment or analyst's workbench which enables the analyst to edit diagrams that formally represent the requirements, …

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