CONTEXT IN ARTIFICIAL INTELLIGENCE AN - Bilkent University人工智能的一个- Bilkent大学背景.docVIP

CONTEXT IN ARTIFICIAL INTELLIGENCE: A FLEETING OVERVIEW Varol Akman Department of Computer Engineering, Bilkent University Bilkent, Ankara 06533, Turkey .tr/~akman email: akman@.tr phone: +90 312 290-1537 fax: +90 312 266-4047 Introduction The notion of context arises in assorted areas of artificial intelligence (AI), including knowledge representation, natural language processing, intelligent information retrieval, etc. Although the term ‘context’ is frequently employed in descriptions, explanations, and analyses of computer programs in these areas, its meaning is frequently left to the reader’s understanding. In other words, it is used in an intuitive manner. In an influential paper, Clark and Carlson (1981) state that context has become a favourite word. They then complain that the denotation of the word has become murkier as its uses have been extended in many directions, making context some sort of ‘conceptual garbage can.’ An example of how contexts may help in AI is found in a study (McCarthy, 1984) of MYCIN -- a program for advising physicians on treating bacterial infections of the blood and meningitis (Shortliffe, 1976). When MYCIN is told that the patient has Cholerae Vibrio in his intestines, it would immediately recommend two weeks of tetracycline treatment and nothing else. While this would indeed do away with the bacteria, the patient would perish long before that due to diarrhoea. A contextual version of MYCIN, on the other hand, needs to add the context of a treatment and notice that any prescription must be made in the light of the fact that there is alarming dehydration. The main motivation in AI for studying formal contexts is to resolve the ‘problem of generality’ (McCarthy, 1987). McCarthy believes that AI programs suffer from a lack of generality. A seemingly minor addition (as in the MYCIN example) to the predetermined possibilities that a program is required to handle would often necessitate a partial redesign of the program. Explicitly r