Probability is 0 of their choosing Right is the same as saying they choose Left, so that my payoff from Up against that is given by the top box up there, I get 5.

如果对手选右的概率是0,其实就是说他们会选左,因此此情况下我选上的收益,从上面的矩阵看,我的收益是5

耶鲁公开课 - 博弈论课程节选