the idea is instead that we're just going to estimate what the expected value is for the opponent's Subgames, for the opponent's actions for different Subgames, and use that information to determine the optimal strategy for the Subgame that we're in. Now, this works if your expected values are perfect, but if they're not perfect you're obviously not going to compute an exact Nash equilibrium. So, it turns out that there's room for improvement here. By the way, this idea has been around for awhile. It's was first introduced in 2014.