Generating action sequences
To solve the route-finding problem from Arad to Bucharest, for example, we start off with just the initial state, Arad.
The first step is to test if this is a goal state.
This is done by applying the operators GENERATING to the current state, thereby generating a new set of states.
The process is called expanding the state.
In this case, we get three new states, "in Sibiu," "in Timisoara," and "in Zerind," because there is a direct one-step route from Arad to these three cities.