PDDL Graphplan找不到计划

Question

我已经用PDDL写了一个域和一个测试问题，但很明显，graphplan实现找不到一个计划。域名如下：

(define (domain aperture)
    (:requirements :strips :typing :negative-preconditions)
    (:types
        cube
        hallway room - location
        )
    (:predicates
        (at ?l - location)
        (has ?c - cube)
        (connected ?l1 - location ?l2 - location)
        (in ?c - cube ?l - location)
        )
    (:action enter
        :parameters (?h - hallway ?r - room)
        :precondition (and (connected ?h ?r) (connected ?r ?h) (at ?h)
                        (not (at ?r)))
        :effect (and (at ?r) (not (at ?h)))
        )
    (:action exit
        :parameters (?r - room ?h - hallway)
        :precondition (and (connected ?r ?h) (connected ?h ?r) (at ?r)
                        (not (at ?h)))
        :effect (and (at ?h) (not (at ?r)))
        )
    (:action move
        :parameters (?h1 ?h2 - hallway)
        :precondition (and (connected ?h1 ?h2) (connected ?h2 ?h1) 
                           (at ?h1) (not (at ?h2)))
        :effect (and (at ?h2) (not (at ?h1)))
        )
    (:action pickup
        :parameters (?c - cube ?l - location)
        :precondition (and (at ?l) (not (has ?c)) (in ?c ?l))
        :effect (and (has ?c) (not (in ?c ?l)))
        )
    (:action drop
        :parameters (?c - cube ?l - location)
        :precondition (and (at ?l) (has ?c) (not (in ?c ?l)))
        :effect (and (not (has ?c)) (in ?c ?l))
        )
)

现在问题来了：

(define (problem pb1)
  (:domain aperture)
  (:requirements :strips :typing) 
  (:objects h1 - hallway
        h2 - hallway
        h3 - hallway
        r1 - room
        c1 - cube)
  (:init (at h1)
     (connected h1 h2)
     (connected h2 h1)
     (connected h2 h3)
     (connected h3 h2)
     (connected h2 r1)
     (connected r1 h2)
     (in c1 r1)
     )
  (:goal (and 
      (has c1)
      )
    )
)

对于这个特定的问题，解决方案的状态集应该是：

move(h1,h2)
enter(h2,r1)
pickup(c1,r1)

但是，正如我已经说过的，我正在使用的graphplan实现(graphplan)找不到任何计划。

Answer 1

我能够使用strips找到一个解决方案。然而，我不得不稍微调整一下你的域名。具体地说，我更改域操作"pickup“和"drop”，将参数类型"location“替换为"room”。通过此更改，我找到了以下解决方案：

1. move h1 h2
2. enter h2 r1
3. pickup c1 r1

也许这也是graphplan无法找到解决方案的原因？以下是修改后的域和问题pddl文件。

domain.pddl

(define (domain aperture)
    (:requirements :strips :typing :negative-preconditions)
    (:types
        cube
        hallway room - location
        )
    (:action enter
        :parameters (?h - hallway ?r - room)
        :precondition (and (connected ?h ?r) (connected ?r ?h) (at ?h)
                        (not (at ?r)))
        :effect (and (at ?r) (not (at ?h)))
        )
    (:action exit
        :parameters (?r - room ?h - hallway)
        :precondition (and (connected ?r ?h) (connected ?h ?r) (at ?r)
                        (not (at ?h)))
        :effect (and (at ?h) (not (at ?r)))
        )
    (:action move
        :parameters (?h1  - hallway ?h2 - hallway)
        :precondition (and (connected ?h1 ?h2) (connected ?h2 ?h1) 
                           (at ?h1) (not (at ?h2)))
        :effect (and (at ?h2) (not (at ?h1)))
        )
    (:action pickup
        :parameters (?c - cube ?l - room)
        :precondition (and (at ?l) (not (has ?c)) (in ?c ?l))
        :effect (and (has ?c) (not (in ?c ?l)))
        )
    (:action drop
        :parameters (?c - cube ?l - room)
        :precondition (and (at ?l) (has ?c) (not (in ?c ?l)))
        :effect (and (not (has ?c)) (in ?c ?l))
        )
)

problem.pddl

(define (problem pb1)
  (:domain aperture)
  (:objects h1 - hallway
        h2 - hallway
        h3 - hallway
        r1 - room
        c1 - cube)
  (:init (at h1)
     (connected h1 h2)
     (connected h2 h1)
     (connected h2 h3)
     (connected h3 h2)
     (connected h2 r1)
     (connected r1 h2)
     (in c1 r1)
     )
  (:goal (and 
      (has c1)
      )
    )
)