STRIPS: A New Approach to the Application of Theorem Proving to Problem Solving — AiGameDev.com
The use of two different search algorithms: the first for doing the planning itself which figures out what should be done next on a high-level, and the second for working out what is currently true in the world and if the goals have been satisfied. For example, one algorithm would be responsible for working out the series of operators for assassinating a target, and another search algorithm would work out if the goal has been achieved by looking at the facts in the world model.