It could have been a law firm; it could have been working in the study group on a homework assignment.

可能是一家律师事务所,也可能是一起做作业的学习小组

耶鲁公开课 - 博弈论课程节选

So one example would be a firm that they both earn, sorry, they both own, and another example would be two of you working as a study group on my homework assignment.

也就是说这两家公司互相赚钱,我说错了,是交叉控股,另外一个例子是两名同学,为了做作业组成了一个学习小组

耶鲁公开课 - 博弈论课程节选