Tower of Hanoi Domain for the Metric-FF Planner

hanoi-domain.pddl

(define (domain hanoi-domain)
(:types disk peg - object)
(:predicates (smaller ?x - disk ?y - object ) 
             (on ?x - disk ?y - object) 
             (clear ?x - object ))
(:functions (cost))
(:action Move
:parameters (?d - disk ?c - object ?n - object)
:precondition (and 
    (smaller ?d ?n)
    (not (= ?n ?c))
    (not (= ?n ?d))
    (not (= ?c ?d))
    (on ?d ?c)
    (clear ?d)
    (clear ?n))
:effect (and 
    (clear ?c)
    (on ?d ?n)
    (not (on ?d ?c))
    (not (clear ?n))
    (increase (cost) 1)))
)