translation.en: My uncle was a very prominent mathematician, and he told me, "Look, there's a problem which I could not solve 25 years ago, and which nobody can solve.
translation.zh: 我的叔叔是一位非常著名数学家，他告诉我， “你看，有一道难题， 我花了25年也没有解决， 别人也没有解决。