HONG KONG (AP) — ChemChina's offer to buy Swiss pesticide giant Syngenta is the latest in a string of deals that has turned the company into a Chinese chemical colossus with an increasingly international profile. ChemChina bought Italy's Pirelli Tyre S.p.A. last year in a deal that gave it control of the world's fifth-biggest tire maker as well as access to the Formula One racing circuit, for which Pirelli is the official supplier. Ren, 58, has been dubbed the "undisputed king" of mergers and acquisitions in China's chemical industry by the country's state-owned media. Ren earned a master's degree in economics from Lanzhou University in northwestern Gansu province, according to ChemChina's website and reports in state media.