Planning

Logical Representation

• Proposition: A symbolic fact that can either be true or false
• Predicate: A parameterizable proposition
• Object: A symbolic parameter for a predicate
• State: A collection of propositions or instantiated predicates
  • Closed-world assumption: Any predicate not included in a state is false
• Action: An action contains parameters, preconditions and postconditions
  • Parameter: A free variable. Each precondition and postcondition predicate must select its own parameters from those of the action
  • Precondition: A predicate that must be true (or false) in a given State for the Action to be possible
  • Postcondition (or Effect): A predicate that is added to (or removed from) the State after the Action occurs
• Domain: A set of Predicates and Actions that employ them
• Problem: A Domain, a set of objects, an initial State, and a conjunction of Predicates representing a Goal
• An example domain: The Blocks World
  • A simple blocks world problem
• Towers of Hanoi?