Jennifer Zaino
SemanticWeb.com Contributor

Cycorp Inc., the developer of the Cyc Knowledge Server, a multi-contextual knowledge base and inference engine, has released a new version of the open source OpenCyc. The latest version now makes available as a download the entire OpenCyc ontology as an OWL file, as well as making all the OpenCyc content available as URIs.

Users can use the OpenCyc terms to represent web content. The company is putting forward these terms and a set of the relationships among them to serve as a shared vocabulary and knowledge-set to create meaningful information exchange among applications. With a shared vocabulary, Web applications can automatically reason about, and integrate, the content of Web sites and Web services, the company says.

The commercial product from which the open source OpenCyc draws is, to put it simply, an encyclopedia of knowledge about the world put in a form that machines can reason from. That system, whose development was begun nearly 25 years ago, was designed to address the problem with the brittleness of expert systems, in that such systems only know what they need to know to do the job. For example, an expert system in the medical field can provide a diagnosis of a disease for a person, but it doesn’t understand what a person or disease actually is.

“It’s what we know about the world that we don’t have to write — that water is wet, or is a liquid, and what is a liquid,” says Larry Lefkowitz, executive director for customer solutions. “You need that information in a way that machines can reason, and you want machines to reason.”

So, if you know that liquids flow freely and that water flows freely, the machine should reason that water is a liquid. “It’s a collection of millions of facts about the world. But from that million it can conclude many other things,” he says.

The commercial version sports hundreds of thousands of concepts — for example, that a bird is an animal with feathers, and beaks, and flies — and tens of thousands of ways of relating these concepts. The system distinguishes between concepts and the words that refer to them — for instance, the concept of dog is that it is a pet, and a mammal, no matter what word you call it by, whereas the concept for the English word “dog” includes that the word is a noun, and that you can count nouns, and so on. The OpenCyc version has all the concepts, and Cycorp has released a portion of its knowledge about the relationships among concepts. There’s enough there for people to draw from if they want to write their own concepts or relationships, Lefkowitz says.

The company expects to make available in short order web services — for example, a free version of a document tagging service. Commercial web services are expected to follow, which users can take advantage of without having to license the overall knowledge base.

With some 200,000 concepts, people can get very precise in how they tag content and its relationship o other information, he says. And now there’s easy access to the concepts via URIs, which makes it easier to write applications — that could be especially useful for small bloggers and information aggregators and publishers who want to more seamlessly leverage the power of the semantic web.

“We’re trying to provide a skeleton or spine or backbone that people can choose to hook up to that is broader than a couple of the high level ontologies trying to serve the same purpose,” says Lefkowitz. “But they don’t have the depth or representational power.”

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