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Tutorial 5: The STRIPS algorithm

This version supports visualization of the STRIPS planner. Future versions of this applet will also demonstrate regression and partial order planners.

The STRIPS planner achieves a list of goals by choosing one unachieved goal at a time. If this goal is true in the world, then the algorithm proceeds to the next goal. If the goal is not true, then an action is chosen that will make the goal true. The preconditions of the action then become subgoals that must be achieved before the action is added to the plan. The algorithm continues until all goals have been achieved. However, the planner may not always be successful. It may never terminate or, if protecting subgoals, it may halt because there are no actions that won't undo subgoals. In some cases, changing the order in which subgoals are tackled may allow a solution to be found when the algorithm would otherwise fail.