STRIPS

STRIPS (Stanford Research Institute Problem Solver) is a classical automated planning formalism that represents world states as conjunctions of propositions and defines actions via precondition, add-list, and delete-list operators. It introduced the core abstraction underlying modern planning languages such as PDDL and remains foundational to symbolic AI planning.

Semantic Classification

Content

Definition

STRIPS (Stanford Research Institute Problem Solver) is a classical automated planning language and algorithm developed in the 1970s. It represents states as conjunctions of propositions (facts), actions as operators with preconditions and effects, and uses means-ends analysis to construct plans by backward chaining from goals to achievable states.

STRIPS Representation

State:

• Set of ground atomic formulas

• Closed-world assumption

• Example: {On(A,B), On(B,Table), Clear(A)}

  Operators (Actions):

• Name and parameters

• Preconditions: must be true to execute

• Add list: facts made true

• Delete list: facts made false

  Classic Example: Blocks World

  Action: Move(block, from, to)
  Preconditions:
  - On(block, from)
  - Clear(block)
  - Clear(to)
  Add effects:
  - On(block, to)
  - Clear(from)
  Delete effects:
  - On(block, from)
  - Clear(to)
  

  STRIPS Algorithm

  1. Start with initial state and goal
  2. Find unsatisfied goal condition
  3. Find operator that achieves it
  4. Recursively plan for operator’s preconditions
  5. Execute operator
  6. Repeat until all goals satisfied

  Limitations

• Propositional representation only

• No time or resources

• Deterministic actions

• Complete observability

• Static world during planning

  Historical Significance

• Foundation for modern planning

• Influenced PDDL standard

• Basis for many planning competitions

• Led to hierarchical and temporal extensions

  Successors

• ADL (richer representation)

• PDDL (standardized language)

• HTN (hierarchical planning)

Provenance