I think most of us don't believe that two firms is enough to make it a perfect competition, that the regulator shouldn't worry about the third firm.

我想大多数人不相信两家公司,就足够产生完全竞争,不相信监控者不必调查第三家公司

耶鲁公开课 - 博弈论课程节选

And to make this more concrete, if a firm is competing against a competitor it can be pretty sure, that competitor is a pretty sophisticated game player and knows that the firm is itself.

再具体点说,如果一家公司在和它的竞争对手竞争,可以肯定其竞争对手一定很老练,这家公司当然也很老练啦

耶鲁公开课 - 博弈论课程节选