Knowledge Structures in UC, the UNIX Consultant

Knowledge Structures in UC, the UNIX* Consultantt David N. Chin Division of Computer Science Department of EECS University of California, Berkeley Berkeley, CA. 94720 ABSTRACT The knowledge structures implemented in UC, the UNLX Consultant are sufficient for UC to reply to a large range of user queries in the domain of the UNIX operating sys- tem. This paper describes how these knowledge struc- tures are used in the natural language tasks of parsing, reference, planning, goal detection, and generation, and ~ow they are organized to enable efficient access even with the large database of an expert system. The struc- turing of knowledge to provide direct answers to common queries and the high usability and efficiency of knowledge structures allow UC to hold an interactive conversation with a user. 1. Introduction UC is a natural language program that converses in English with users in the domain of the UNIX operating system. UC provides information on usage of system utilities, UNIX terminology, and plans for accomplishing specific tasks in the UNIX environment, all upon direct query by the user. In order to accomplish these tasks, UC must perforce have a considerable knowledge base, a large part of which is particular to the UNIX domain. The specific representations used in this knowledge base are essential to the successful operation of UC. Not only are the knowledge structures used in parsing, inference, planning, goal detection, and generation, but also the for- mat of representation must permit the high efficiency in access and processing of the knowledge that is required in an interactive system like UC. This paper describes the details of this representation scheme and how it manages to satisfy these goals of usability and efficiency. Other aspects of the UC system are described in Arens (1982}, Faletti (1982}, Jacobs (1983}, Rau {1983), and Wilensky and Arens (1980a and b). An overview of the UC system can be found in Wilensky (1982). • UNIX is Lradem,trk of Bell Labor~.tone$ t This research wu sponsored ia part by the O~¢e of NavLl Re~etrcb under coBtrLct N00014-80-C-0732 ~ad the NLt,oa=d Scieace Foaadztiou =ader grant MCSTg-06543. 2. Speeifleations for the Representation The first step in the design of knowledge structures involves determining what forms of knowledge will be needed. In this case, the domain of conversation for a UNIX consultant is specific enough that it reduces the range of knowledge structures necessary for the task. Some insight into the kinds of knowledge structures that are needed can be gleaned from looking at the variety of questions which users actually ask. Since UC is aimed at the naive user of UNIX, a majority of the queries UC receives are of the following forms (taken from actual UC sessions}: User: How can [ change the write protection on my termi- nal? UC: To turn on write permission on your terminal, type 'mesg y'. To turn off write permission on your terminal, type 'mesg n'. User: What is a search path? UC: A search path in UNIX is a list …

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