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In this paper, we present an algorithm for extracting keywords representing the asserted main point in a document, without relying on external devices such as natural language processing tools or a document corpus. Our algorithm KeyGraph is based on the seg-mentation of a graph, representing the co-occurrence between terms in a document, into clusters. Each(More)
The small world topology is known widespread in biological, social and man-made systems. This paper shows that the small world structure also exists in documents, such as papers. A document is represented by a network; the nodes represent terms, and the edges represent the co-occurrence of terms. This network is shown to have the characteristics of being(More)
—Experts of chance discovery have recognized a new class of problems where the previous methods fail to visualize a latent structure behind observation. There are invisible events that play an important role in the dynamics of visible events. An invisible leader in a communication network is a typical example. Such an event is named a dark event. A novel(More)
Hypothetical reasoning (abduction) is an important knowledge processing framework because of its theoretical basis and its usefulness for solving practical problems including diagnosis, design, etc. In many cases, the most probable hypotheses-set for diagnosis or the least expensive one for design is desirable. Cost-based abduction, where a numerical weight(More)