According to the Internet company's corporate Web site, Ask Jeeves is a company that allows Web surfers to conduct a search using "your native English, the language you use when conversing," making the Internet accessible for those not familiar with Web jargon.

Ask Jeeves, which licenses its technology to the Altavista search engine, was the first company to implement a question-answering service of this kind.

It maintains that its systems are independently developed.

"What they describe in their patents is fundamentally different from what we do," said company spokesperson Heather Staples. "We didn't buy any technology from someone and then create this system. Everything was developed at Ask Jeeves."

Both Katz and Winston are prominent researchers in the fields of artificial intelligence and natural language. Winston is the Ford Professor of Artificial Intelligence and Computer Science at MIT, and Katz is a principal research scientist at MIT's Artificial Intelligence Laboratory.

The professors are not the first to accuse Ask Jeeves of patent infringement. Last July, in a suit that is still pending, Mountain View's IPLearn LLC, a company that uses natural language queries, filed a similar patent infringement suit in Oakland, Calif. Ask Jeeves denied the accusation.

Financial wire services picked up the story Friday, and Ask Jeeves stock fell almost seven and a half dollars that day, closing at $118.50.