Existing search engines -- with Google at the top -- have many remarkable capabilities; but what is not among them is deduction capability -- the capability to synthesize an answer to a query from bodies of information which reside in various parts of the knowledge base.
In recent years, impressive progress has been made in enhancing performance of search engines through the use of methods based on bivalent logic and bivalent-logic-based probability theory. But can such methods be used to add nontrivial deduction capability to search engines, that is, to upgrade search engines to question-answering systems? A view which is articulated in this note is that the answer is "No." The problem is rooted in the nature of world knowledge, the kind of knowledge that humans acquire through experience and education. It is widely recognized that world knowledge plays an essential role in assessment of relevance, summarization, search and deduction. But a basic issue which is not addressed is that much of world knowledge is perception-based, e.g., "it is hard to find parking in Paris," "most professors are not rich," and " it is unlikely to rain in midsummer in San Francisco." The problem is that (a) perception-based information is intrinsically fuzzy; and (b) bivalent logic is intrinsically unsuited to deal with fuzziness and partial truth.
To come to grips with the fuzziness of world knowledge, new tools are needed. The principal new tool--a tool which is briefly described in their note -- is Precisiated Natural Language (PNL). PNL is based on fuzzy logic and has the capability to deal with partiality of certainty, partiality of possibility and partiality of truth. These are the capabilities that are needed to be able to draw on world knowledge for assessment of relevance, and for summarization, search and deduction.
Lotfi A. Zadeh is a Professor in the Graduate School at the University of California, Berkeley, and serves as Director of the Berkeley Initiative in Soft Computing (BISC).
Since 1965, when he published his first paper on fuzzy sets Lotfi Zadeh has been involved in development of fuzzy logic and its applications. His recent work has been focused on Computing with Words, Precisiated Natural Language and the Computational Theory of Perceptions. He has received numerous awards, including twenty-two honorary doctorates.
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