The vast majority of states is not reachable, so you can roll out the full tree from the starting state and it's going to be very small. Even the super-naive ap

The vast majority of states is not reachable, so you can roll out the full tree from the starting state and it's going to be very small. Even the super-naive approach of unrolling the full state space is only 6^7 which is a big waste because connections are very sparse but even that's not big, it just wouldn't scale to larger problems.