用PDDL语言实现农夫过河问题的规划

好的，农夫过河问题可以用PDDL语言进行规划，以下是一个简单的PDDL实现：

(define (problem farmer-crossing)
  (:domain farmer-crossing)
  (:objects farmer - person
            wolf - animal
            goat - animal
            cabbage - vegetable
            left - location
            right - location)
  (:init
    (at farmer left)
    (at wolf left)
    (at goat left)
    (at cabbage left)
    (opposite left right))
  (:goal
    (and
      (at farmer right)
      (at wolf right)
      (at goat right)
      (at cabbage right)))
  (:action cross-farmer
    :parameters ()
    :precondition (at farmer here)
    :effect (and
              (at farmer there)
              (not (at farmer here))))
  (:action cross-wolf
    :parameters ()
    :precondition (and
                    (at farmer here)
                    (at wolf here))
    :effect (and
              (at wolf there)
              (not (at wolf here))))
  (:action cross-goat
    :parameters ()
    :precondition (and
                    (at farmer here)
                    (at goat here))
    :effect (and
              (at goat there)
              (not (at goat here))))
  (:action cross-cabbage
    :parameters ()
    :precondition (and
                    (at farmer here)
                    (at cabbage here))
    :effect (and
              (at cabbage there)
              (not (at cabbage here))))
  (:action return-farmer
    :parameters ()
    :precondition (at farmer there)
    :effect (and
              (at farmer here)
              (not (at farmer there))))
  (:action return-wolf
    :parameters ()
    :precondition (and
                    (at farmer there)
                    (at wolf there))
    :effect (and
              (at wolf here)
              (not (at wolf there))))
  (:action return-goat
    :parameters ()
    :precondition (and
                    (at farmer there)
                    (at goat there))
    :effect (and
              (at goat here)
              (not (at goat there))))
  (:action return-cabbage
    :parameters ()
    :precondition (and
                    (at farmer there)
                    (at cabbage there))
    :effect (and
              (at cabbage here)
              (not (at cabbage there))))
  (:predicate opposite
    :parameters (?x ?y)
    :precondition ()
    :effect (or
              (and (eq ?x left) (eq ?y right))
              (and (eq ?x right) (eq ?y left)))))

在这个例子中，我们定义了“farmer-crossing”领域，并定义了对象、初始状态和目标状态。我们还定义了动作，如“cross-farmer”、“cross-wolf”等，以及这些动作的前提条件和效果。最后，我们定义了谓词“opposite”，表示两个位置之间的关系。

通过这个PDDL实现，我们可以使用规划器来解决农夫过河问题。