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pellierd / pddl4j

PDDL4J is an open source library under LGPL license whose purpose of PDDL4J is to facilitate the development of JAVA tools for Automated Planning based on PDDL language (Planning Domain Description Language).
https://lig-membres.imag.fr/pellier/
GNU Lesser General Public License v3.0
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HDDL - initial task network returns a list of null #92

Open o-fir opened 1 year ago

o-fir commented 1 year ago

Calling problem.getInitialTaskNetwork().getTasks()on Towers benchmark (IPC) returns a list with a null task.

Also, if original HTN was simply (task0 (shiftTower t1 t2 t3)) and I introduce an additional task (task1 (shiftTower t1 t2 t3)), getInitialTaskNetwork().getTasks() returns [null, null].

Domain file: `(define (domain towers)

(:requirements :negative-preconditions :hierarchy :typing :method-preconditions )

(:types RING - OBJ TOWER - OBJ)

(:predicates (on ?r - RING ?o - OBJ) (goal_on ?r - RING ?o - OBJ) (towerTop ?o - OBJ ?t - TOWER) (smallerThan ?r - RING ?o - OBJ)) (:task shiftTower :parameters (?t1 - TOWER ?t2 - TOWER ?t3 - TOWER)) (:task selectDirection :parameters (?r - RING ?t1 - TOWER ?t2 - TOWER ?t3 - TOWER)) (:task rotateTower :parameters (?t1 - TOWER ?T2 - TOWER ?t3 - TOWER)) (:task exchange :parameters (?t1 - TOWER ?t2 - TOWER ?t3 - TOWER)) (:task move_abstract :parameters (?t1 - TOWER ?t2 - TOWER))

(:method m-shiftTower ; shift tower from ?t1 to ?t3 using ?t2 :parameters (?r - RING ?t1 - TOWER ?t2 - TOWER ?t3 - TOWER) :task (shiftTower ?t1 ?t2 ?t3) :precondition (and (towerTop ?r ?t1)) :ordered-tasks (and (selectDirection ?r ?t1 ?t2 ?t3)))

(:method selectedDirection :parameters (?r - RING ?t1 - TOWER ?t2 - TOWER ?t3 - TOWER) :task (selectDirection ?r ?t1 ?t2 ?t3) :precondition (on ?r ?t1) :ordered-tasks (and (rotateTower ?t1 ?t3 ?t2)))

(:method m-selectDirection :parameters (?r - RING ?r1 - RING ?t1 - TOWER ?t2 - TOWER ?t3 - TOWER) :task (selectDirection ?r ?t1 ?t2 ?t3) :precondition (on ?r ?r1) :ordered-tasks (and (selectDirection ?r1 ?t1 ?t3 ?t2)))

(:method m-rotateTower :parameters (?t1 - TOWER ?t2 - TOWER ?t3 - TOWER) :task (rotateTower ?t1 ?t2 ?t3) :ordered-tasks (and (move_abstract ?t1 ?t2) (exchange ?t1 ?t2 ?t3)))

(:method exchangeClear :parameters (?t1 - TOWER ?t2 - TOWER ?t3 - TOWER) :task (exchange ?t1 ?t2 ?t3) :precondition (and (towerTop ?t1 ?t1) (towerTop ?t3 ?t3)) :ordered-subtasks (and) )

(:method exchangeLR :parameters (?r1 - RING ?o3 - OBJ ?t1 - TOWER ?t2 - TOWER ?t3 - TOWER) :task (exchange ?t1 ?t2 ?t3) :precondition (and (towerTop ?r1 ?t1) (towerTop ?o3 ?t3) (smallerThan ?r1 ?o3)) :ordered-tasks (and (move_abstract ?t1 ?t3) (rotateTower ?t2 ?t3 ?t1)))

(:method exchangeRL :parameters (?o1 - OBJ ?r3 - RING ?t1 - TOWER ?t2 - TOWER ?t3 - TOWER) :task (exchange ?t1 ?t2 ?t3) :precondition (and (towerTop ?o1 ?t1) (towerTop ?r3 ?t3) (smallerThan ?r3 ?o1)) :ordered-tasks (and (move_abstract ?t3 ?t1) (rotateTower ?t2 ?t3 ?t1)))

(:method newMethod21 :parameters (?r - RING ?o1 - OBJ ?t1 - TOWER ?o2 - OBJ ?t2 - TOWER) :task (move_abstract ?t1 ?t2) :ordered-subtasks (move ?r ?o1 ?t1 ?o2 ?t2))

(:action move :parameters (?r - RING ?o1 - OBJ ?t1 - TOWER ?o2 - OBJ ?t2 - TOWER) :precondition (and (towerTop ?r ?t1) (towerTop ?o2 ?t2) (on ?r ?o1) (smallerThan ?r ?o2)) :effect (and (not (on ?r ?o1)) (on ?r ?o2) (not (towerTop ?r ?t1)) (towerTop ?o1 ?t1) (not (towerTop ?o2 ?t2)) (towerTop ?r ?t2))) ) `

Problem file: `(define (problem tower_problem_1)

(:domain towers)

(:objects t1 t2 t3 - TOWER r1 - RING) (:htn :parameters () :ordered-tasks (and (task0 (shiftTower t1 t2 t3)) ) ) (:init (smallerThan r1 t1) (smallerThan r1 t2) (smallerThan r1 t3) (on r1 t1) (towerTop r1 t1) (towerTop t2 t2) (towerTop t3 t3) (goal_on r1 t3))

(:goal (and (on r1 t3) )) ) `

pellierd commented 1 year ago

This means that PDDL4J considers that there are no methods decomposing the tasks of the initial task network. Please check that the problem has a solution and let me know. I will investigate further.