It was never really used in practice because it didn't actually give you good results in practice. Because you don't have perfect estimates. But what we came up with, is a way to dramatically improve the performance without giving up any theoretical guarantees. With this thing called Reach Subgame Solving. So, here's an example of how this works. This is going to get a little tricky, so if you have any questions in the next few slides please let me know. So, let's say that we have this slightly larger game now.