Silicon Graphics Inc. said it agreed to acquire ParaGraph International, a Campbell-based company that makes 3-D Internet software for personal computers. Mountain View-based Silicon Graphics also said it is establishing a company called Cosmo Software to focus on the fast-emerging market for interactive 3-D Internet software, which runs on multiple computer systems. ParaGraph will be integrated into the new Cosmo unit, which will spearhead Silicon Graphics' Second Web initiative to bring more engaging multimedia content and applications to the World Wide Web. Financial terms of the acquisition were not disclosed. ParaGraph was founded in 1989 by world chess champion Garry Kasparov and others. Silicon shares rose 50 cents to close at $15.75 on the New York Stock Exchange.