Y Combinator President Sam Altman said China had been "an important missing piece of our puzzle. ": American start-up incubator Y Combinator is setting up shop in China, with a new unit to be led by former Baidu chief operating officer Qi Lu. Sam Altman, Y Combinator's president, said in a company announcement Wednesday that China had been "an important missing piece of our puzzle" when it came to sourcing new start-ups to take under its wing.