Game Development Reference
2. What conditions could cause a node to move from the closed list back onto
the open list in A*? This can happen when the heuristic is inadmissible and
there are branching paths that can rejoin. This never happens if the
algorithm is written with the usual optimization to ignore all nodes on the
3. When is a machine-learning system easier to implement than a directly
programmed system? Machine learning is superior when it is easier to teach
the machine than it is to directly program the machine.
4. What is the major advantage of behavior trees over FSMs? They control
complexity better, allowing faster iteration cycles in development.
5. Why does the search run backward in a GOAP system and forward in an
HTN system? In GOAP the number of actions that are close to the goal is
typically smaller than the number of actions that are close to the agent. A
is faster when it has fewer branches to explore. HTN task libraries are
designed to present goal states to the agents, making a forward search faster.