STRIPS: "STanford Research Institute Problem Solver"

The Stanford Research Institute Problem Solver (STRIPS) is a classical problem solving system which develops a list of actions which will reach a goal state from an initial state given a list of possible actions. STRIPS was developed for Shakey

It is an automated planning technique that works by executing a domain and problem to find a goal. With STRIPS, you first describe the world. You do this by providing objects, actions, preconditions, and effects. These are all the types of things you can do in the game world.

Once the world is described, you then provide a problem set. A problem consists of an initial state and a goal condition. STRIPS can then search (often using A*) all possible states, starting from the initial one, executing various actions, until it reaches the goal.

STRIPS Terms:

States: A list of knowns without variables or functions; in other words, they are limited to literals. Unlisted states are assumed to be false. May be:
- propositions e.g. "Big ^ Tall"
- first-order e.g. "At(Billy, Desk)"
Goal: The final desired state.
Actions: In three parts,
1. Name and parameter list
2. Preconditions: The states which must be true before the action can be used. Variables are allowed.
3. Effects: A list of function-free literals. Variables are allowed if they appear in the actions parameter list.

Example:

Action: PushBox(x, y)
Precond: BoxAt(x)
Effect: BoxAt(y), ¬ BoxAt(x)

Note: ¬ indicates that the state is deleted.