Node Locking

In a poker game tree, each decision point is called a "node," and "node locking" is a process where the solver fixes or locks certain decisions or actions at specific nodes while computing strategies. It means that the solver assumes a particular decision or action at a certain node and then calculates the optimal strategies for the remaining parts of the game tree based on that assumption.

By fixing decisions at specific nodes, players or analysts can gain insights into how different choices or actions affect the outcome of the game and the recommended strategies.

For example, many players do not check-raise flop bets as often as they should after they defend in the big blind. We can lock the "node" of their flop decision to call instead of raise, and then see the appropriate response. In this example, our bluffing frequency should go up.