sentences:  Giuseppe Graviano recently gained an academic degree in mathematics and his brother Filippo in economics.According to the pentito Antonino Giuffrè the Graviano brothers were the intermediaries between Cosa Nostra and prime minister Silvio Berlusconi.Cosa Nostra decided to back Berlusconi's Forza Italia party from its foundation in 1993, in exchange for help in resolving the mafia's judicial problems.