First-order bgic: Definition of Plan Result in terms of iesut: )is the result of xcuting p in s Making plans:A better way ..Making plans: A better way Represent plans as action sequences [a1, a2, . . . , an] PlanResult(p, s) is the result of executing p in s Then the query Ask(KB, ∃ p Holding(Gold,PlanResult(p, S0))) has the solution {p/[Forward, Grab]} Definition of PlanResult in terms of Result: ∀ s PlanResult([ ], s) = s ∀ a, p, s PlanResult([a|p], s) = PlanResult(p, Result(a, s)) Planning systems are special-purpose reasoners designed to do this type of inference more efficiently than a general-purpose reasoner Chapter 8 31 Summary First-order logic: – objects and relations are semantic primitives – syntax: constants, functions, predicates, equality, quantifiers Increased expressive power: sufficient to define wumpus world Situation calculus: – conventions for describing actions and change in FOL – can formulate planning as inference on a situation calculus KB Chapter 8 32