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Weaving the Threads

Making the Semantic Web a reliable, smoothly functioning tool will take several parallel developments. One involves the creation of robust computing tools capable of handling information in a way that mimics the intricacies of everyday human language. Web pages also will have to be encoded in a manner that makes (at least some of) their meaning explicit. Today, there are about 2.1 million Web pages encoded in Semantic Web formats, and companies such as IBM, Oracle, Adobe, and Northrop Grumman have begun to use the technology.

Currently the Semantic Web is decentralized, like the Web itself. A number of slight variations of it are being developed around the world and must be able to communicate with each other, so that a Semantic Web program created at the Institute could be linked to one at IBM.

Given the broad range of competencies involved in developing this tool, Rensselaer is bringing together a diverse group of researchers for the Tetherless World constellation. For example, Hendler has spent much of his career analyzing how the overall structure of the Semantic Web can work best. “I’m more of an engineer than a mathematician,” says Hendler, who joined Rensselaer from the University of Maryland. McGuinness, meanwhile, has focused more on artificial intelligence, studying the essentials of how computers can represent meaning and creating intelligent computer environments.

By changing the way data is encoded into Web pages and transmitted among them, we may soon develop highly reliable, efficient new ways of locating useful information. These tools would not replace the Internet search engines we use so often, but would add a new dimension to our ability to find things online.


The constellation plans to hire one more full-time professor for the 2008-09 academic year. Other faculty already working with the constellation include Sibel Adali, an associate professor of computer science studying the relationship between databases and the Semantic Web; Boleslaw Szymanski, director of the Center for Pervasive Computing and Networking; and Selmer Bringsjord, chair of the Department of Cognitive Science.

Both Hendler and McGuinness have made their reputations in the research community through their work on the Semantic Web. Many of Hendler’s articles, both in the popular press and in academic circles, have functioned as road maps for the computer science community. He is currently the editor of IEEE Intelligent Systems, one of the main journals in the field, and he is the first computer scientist to have been on the board of reviewing editors of Science, the largest scientific publication in America.

McGuinness’ work included co-authoring an influential Semantic Web standard known as the OWL Web Ontology Language, which has been recommended by the World Wide Web Consortium, the group Berners-Lee helped found to ensure that the Web maintains globally compatible formats so it remains a truly worldwide network. The pair collaborated on a widely cited 2000 article in IEEE Intelligent Systems, on applying these principles within the U.S. Defense Advanced Research Projects Agency (where Hendler once served as chief scientist of the Information Systems Office).

The hiring of Hendler and McGuinness has been recognized by researchers at other institutions as major “gets” for Rensselaer. “Jim Hendler is one of the most significant figures in getting the Semantic Web to where it is today,” says Jeff Heflin, a computer scientist at Lehigh University, who has collaborated with Hendler in the past. “I’m not sure where we would be right now without his work.” Similarly, McGuinness “has been crucial in the development of the description logic, and the Ontology Web Language we use,” says Heflin, who got to know McGuinness while she was co-directing Stanford University’s Knowledge Systems Lab, which she left to join Rensselaer.

Wei Zhao, dean of the School of Science and a computer scientist himself, says the team will have far-reaching impact both in its specific field and across the Institute. “We have a lot of potential here in this group, which the community can leverage and use to expand their own work,” he says.

Berners-Lee agrees. “The whole constellation should be a great success,” he says.

At the moment, further refining OWL will be an important task for the Semantic Web community. An ontology is a description of what exists in the world around us. In Web terms, that means a set of definitions pertaining to a particular subject area, plus a set of rules about how computers should read and handle the information in those documents. Health-care companies—one place where the Semantic Web is gaining traction—may develop their own ontologies, while financial services companies may do the same. But it’s clear to researchers that interoperable systems would benefit all fields of inquiry.

OWL provides a more powerful set of rules, and a more flexible structure, than had previously existed, although, as McGuinness notes, it is by its nature a work in progress. “You never really want to have a system only one person can maintain,” says McGuinness, who emphasizes that OWL, like particular ontologies, is a work in progress. “I build languages that allow people to create ontologies, and I want to build environments that allow those ontologies to evolve.”

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Rensselaer (ISSN 0898-1442) is published in Spring, Summer, Fall, and Winter by the Office of Strategic Communications and External Relations, Rensselaer Polytechnic Institute, Troy, NY 12180-3590. Opinions expressed in these pages do not necessarily reflect the views of the editors or the policies of the Institute. ©2008 Rensselaer Polytechnic Institute.