An evaluation function takes a search tree state as an argument and returns a
numerical measure of its "goodness".
Two types:
- Evaluates the strength of a state (as in chess playing programs)
- The higher the evaluation the better
- Good for adversarial search
- Estimates the number of actions required to get to the goal
- The lower the evaluation the better
- Good for individual problem solving
The latter type of evaluation function is also called a
heuristic.