UTILITY THEORY

Stuart Russell and Peter Norvig provide an excellent definition for utility theory in their book Artificial Intelligence: A Modern Approach: “Utility theory says that every state has a degree of usefulness, or utility, to an agent and that the agent will prefer states with higher utility.”

With this definition, you can see that every possible state has a utility value assigned to it, which is calculated every time a decision needs to be made and is based on how much happier the agent will be in the new state compared to its current state. Calculating the utility value is done by taking the current world state and seeing what the anticipated world state is after performing some action. The delta in happiness between those two states is the utility of that action. The action with the highest utility is then chosen.