Imperfect information games are the more general case where this is a problem. So, what do we do? Well, it turns out that we don't actually have to know the strategy for the entire game as a whole. I mentioned that this sell action leads to a subgame, where both players might take actions. But you don't have to worry about that, the only that really matters for determining the optimal strategy in this play subgame, is the expected value of Player one choosing sell. So, what we can do is try to estimate what that value is to Player one,