Apple Inc., AAPL 0.23 % stepping up its involvement in one of Silicon Valley's hottest arenas, is acquiring machine-learning specialist Turi Inc. Financial terms couldn't immediately be determined. GeekWire, which reported the acquisition Friday, said Apple is paying around 200 million. An Apple spokesman issued the company's standard statement in connection with such transactions: "Apple buys smaller technology companies from time to time, and we generally do not discuss our purpose or plans." Turi's chief executive is Carlos Guestrin, who holds the title of Amazon professor of machine learning at the University of Washington--a position endowed by Amazon.com He is also an associate professor of computer science and engineering.