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PDDL 1.2

Contributors: Adam Green,


PDDL 1.2 (Ghallab et al., 1998) formed the basis of the 1998 AIPS Competition. PDDL 1.2 is based largely on concepts set out for STRIPS, a sort of precursor languages which used a similar design pattern for describing problems through the use of predicates and actions.

Problems in PDDL are defined in two parts, a domain and a problem file. The following sections divide respectively, representing constituent parts of the domain and the problem.

Domain And Problem File


    (domain construction)
    (:extends building)
    (:requirements :strips :typing)
        site material - object
        bricks cables windows - material
    (:constants mainsite - site)

    ;(:domain-variables ) ;deprecated

        (walls-built ?s - site)
        (windows-fitted ?s - site)
        (foundations-set ?s - site)
        (cables-installed ?s - site)
        (site-built ?s - site)
        (on-site ?m - material ?s - site)
        (material-used ?m - material)

    (:timeless (foundations-set mainsite))

        ;    (?s - site) (walls-built ?s)))

    (:action BUILD-WALL
        :parameters (?s - site ?b - bricks)
        :precondition (and
            (on-site ?b ?s)
            (foundations-set ?s)
            (not (walls-built ?s))
            (not (material-used ?b))
        :effect (and
            (walls-built ?s)
            (material-used ?b)
        ; :expansion ;deprecated

        :vars (?s - site)
        :context (and
            (walls-built ?s)
            (windows-fitted ?s)
            (cables-installed ?s)
        :implies (site-built ?s)

    ;Actions omitted for brevity

Problem File

    (problem buildingahouse)
    (:domain construction)
    ;(:situation <situation_name>) ;deprecated
        s1 - site
        b - bricks
        w - windows
        c - cables
        (on-site b s1)
        (on-site c s1)
        (on-site w s1)
    (:goal (and
            (walls-built ?s1)
            (cables-installed ?s1)
            (windows-fitted ?s1)
  1. Ghallab, M., Knoblock, C., Wilkins, D., Barrett, A., Christianson, D., Friedman, M., Kwok, C., Golden, K., Penberthy, S., Smith, D., Sun, Y., & Weld, D. (1998). PDDL - The Planning Domain Definition Language.

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