Computer Science Department
School of Computer Science, Carnegie Mellon University


Learning to Extract Symbolic Knowledge from the World Wide Web

Mark Craven, Dan DiPasquo, Dayne Freitag, Andrew McCallum,
Tom Mitchell, Kamal Nigam, Sean Slattery

September 1998


The World Wide Web is a vast source of information accessible to computers, but understandable only to humans. The goal of the research described here is to automatically create a computer understandable knowledge base whose content mirrors that of the World Wide Web. Such a knowledge base would enable much more effective retrieval of Web information, and promote new uses of the Web to support knowledge-based inference and problem solving. Our approach is to develop a trainable information extraction system that takes two inputs. The first is an ontology that defines the classes (e.g., Company, Person, Employee, Product) and relations (e.g., Employed.By, Produced.By) of interest when creating the knowledge base. The second is a set of training data consisting of labeled regions of hypertext that represent instances of these classes and relations. Given these inputs, the system learns to extract information from other pages and hyperlinks on the Web. This paper describes our general approach, several machine learning algorithms for this task, and promising initial results with a prototype system that has created a knowledge base describing university people, courses, and research projects.

51 pages

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