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PDDL Cheatsheet
Francesco Ganci edited this page Jun 26, 2022
·
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- Closed World Assumption : any predicate not explicitly stated as true is false. This means that each predicate is false when "instanced" at the beginning of the program.
🔗 see planning.wiki, a awesome resource for learning what is needed to deal with PDDL.
(define (domain ???)
(:requirements :strips :adl :typing)
(:types
;; o1 o2 o3 - type/object
)
(:predicates
;; (predicate-name ... ?pi1 ?pi2 ?pi3 - type ...)
)
;; === ACTIONS === ;;
(:action ???action_name???
:parameters ( ???list_of_the_params??? )
:precondition (and
;; trivial checkings
;; other checkings
)
:effect (and
;; NEGATIVE EFFECTS -- make them false
;; (not (predicate ...))
;; AFFERMATIVE -- make them true
;; (predicate ...)
)
)
)(define (domain ???)
(:requirements :strips :adl :typing :time)
(:types
;; o1 o2 o3 - type/object
)
(:predicates
;; (predicate-name ... ?pi1 ?pi2 ?pi3 - type ...)
)
(:functions
;; (fluent-name ?p1 ?p2 ...)
;; even with typing
)
;; === ACTIONS === ;;
(:action ???action_name???
:parameters ( ???list_of_the_params??? )
:precondition (and
;; trivial checkings
;; other checkings
)
:effect (and
;; NEGATIVE EFFECTS -- make them false
;; (not (predicate ...))
;; AFFERMATIVE -- make them true
;; (predicate ...)
)
)
;; === PROCESSES === ;;
(:process ???process name???
:parameters (<params>)
:precondition (and
<predicates -- activation conditions>
)
:effect (and
<updates frame by frame (remember #t)>
)
)
;; === EVENTS === ;;
(:process ???process name???
:parameters (<params>)
:precondition (and
<predicates -- trigger conditions>
)
:effect (and
<predicates -- effect>
)
)
)🔗 see also planning.wiki requirements for classical PDDL
(:requirements :strips :adl :typing)🔗 see also planning.wiki requirements for PDDL2.1
;; the complete set
(:requirements strips :adl :typing :durative-actions :fluents :duration-inequalities)
;; the minimal set
(:requirements :durative-actions :fluents :duration-inequalities)🔗 see also planning.wiki PDDL+, in partiular the examples.
;; complete
(:requirements :strips :adl :typing :time)
;; minimal
(:requirements :time :typing)🔗 see also Object Types on planning.wiki
;; === DOMAIN FILE ===
;; types declaration
(:types
site material - object
bricks cables windows - material
)
;; using types in predicates (see also listing and other syntactic variants)
;; valid also with fluents
(material-used ?m - material)
;; using types in actions, processes and events
(:action MOVE-MATERIAL
:parameters (?s1 - site ?s2 - site ?m -material)
...
)
;; === PROBLEM FILE ===
;; using types in objects instances (with variants)
(:objects
s1 - site
b - bricks
w - windows
c - cables
)☝️ Closed World Assumption : any predicate not explicitly stated as true is false. This means that each predicate is false when "instanced" at the beginning of the program.
In domain file:
;; syntax
(:predicates
(<predicate_name> <argument_1> ... <argument_n>)
)
;; a simple example
(:objects
obj1 obj2
obj3 ob3a - object
obj4 - type-my
obj5
)
;; an example
(:predicates
(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)
);; and
(and (...) (...) (...))
;; or
(or (...) (...) (...))
;; not (your planner could not support it)
(not (...))(:functions
(<variable_name> <parameter_name> - <object_type>)
...
(<variable_name> <parameter_name> - <object_type>)
)
;; some example
(:functions
(distance ?wp1 - waypoint ?wp2 - waypoint)
)
(:functions
(battery-level ?r - rover)
);; MAIN SYNTAX with <f1> <f2> fluents
(<op> <f1> <f2>)
;; simple operations (in actions)
(+ <f1> <f2>)
(- <f1> <f2>)
(* <f1> <f2>)
(/ <f1> <f2>)
;; increase decrease (in actions)
(increase <f1> <f2>)
(decrease <f1> <f2>)
;; comparisons (in preconditions and goals)
(< <f1> <f2>)
(<= <f1> <f2>)
(> <f1> <f2>)
(>= <f1> <f2>)
(= <f1> <f2>)
;; continuous effects
;; use the symbol #t which is the frame time
;; for instance, (use them in actions)
(increase (fuel ?tank) #t)
(decrease (battery ?battery) (* 5 #t));; assignment (in actions, processes, events)
(assign <f1> <f2>)
;; init fluents (in (init ...) statement)
(= <f1> <f2>)In the domain file:
;; syntax
(:types
mytype1
mytype2
...
)
;; example
(:types
site material - object
bricks cables windows - material
);; in predicates, see the example
(:predicates
(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)
)
;; in action definitions, see the example
(: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
)
;; in fluents, see the example
(:functions
(battery-amount ?r - rover)
(sample-amount ?r - rover)
(recharge-rate ?r - rover)
(battery-capacity)
(sample-capacity)
(distance-travelled)
)
;; in objects, see the example
(:objects
s1 - site
b - bricks
w - windows
c - cables
);; === SYNTAX
(:action <action_name>
:parameters (<argument_1> ... <argument_n>)
:precondition (<logical_expression>)
:effect (<logical_expression>)
; :expansion
)
;; === classical PDDL example
(: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
)
;; === PDDL+ and PDDL2.1 example
;; action to serve the cookie to the client OOG
(:action serve-cookie-OOG
:parameters (?who - client ?w - waiter ?p - position)
:precondition (and
(waiter-OOG-mode ?w)
(waiter-gripper-carry ?w)
(cookie-to ?who)
(waiter-client ?w ?who)
(pos-is-table ?p)
(waiter-at ?w ?p)
(client-at-table ?who ?p)
)
:effect (and
(not(cookie-to ?who))
(not (waiter-gripper-carry ?w)) (waiter-gripper-empty ?w)
(not (waiter-client ?w ?who))
(client-served ?who)
(assign (client-drinking-progress ?who) 4)
)
)(:durative-action <action_name>
:parameters (<arguments>)
:duration (= ?duration <duration_number>)
:condition (logical_expression)
:effect (logical_expression)
)🔗 see also :condition from planning.wiki
;; === :duration statement === ;;
;; action duration (<f> for a fluent or an expression involving fluents)
:duration (= ?duration <f>)
;; for example (also a numeric literal works well)
:duration (= ?duration 10)
;; === :condition statement === ;;
;; START -- the condition must be true at the start of the
;; action in order for the action to be applied
(at start (at ?rover ?from-waypoint))
;; END -- the condition must be true at the end of the action
;; in order for the action to be applied
(at end (>= (battery-amount ?rover) 0))
;; OVER ALL -- the condition must be true throughout the action,
;; including at the start and end
(over all (can-move ?from-waypoint ?to-waypoint))
;; === :effect statement === ;;
;; the durative action can specify when to apply the effect
;; for example,
:effect
(and
(at start (not (at ?rover ?from-waypoint)))
(at start (decrease (battery-amount ?rover) 8))
(at end (at ?rover ?to-waypoint))
(at end (been-at ?rover ?to-waypoint)))🔗 see processes on planning.wiki
syntax identical to the one seen for the actions:
(:process FALLING
:parameters (?b - ball)
:precondition (and
(not (held ?b))
(< (velocity ?b) 100)
)
:effect (and
(increase (velocity ?b) (* #t 9.8))
(decrease (distance-to-floor ?b) (* #t (velocity ?b)))
)
)🔗 see Events on Planning.wiki
syntax identical to the one seen for the actions:
(:event HIT-GROUND
:parameters (?b - ball)
:precondition (and
(not (held ?b))
(<= (distance-to-floor ?b) 0)
(> (velocity ?b) 0)
)
:effect (
(assign (velocity ?b) (* -0.8 (velocity ?b)))
)
)☝️ delete (:metric ...) if you're not dealing with PDDL2.1
☝️ remember to replace ???
(define
(problem ???)
(:domain ???)
(:objects
;; simple: obj (subsumed type object)
;; simple with type: obj - type
;; list: o1 o2 o3
;; list with type: o1 o2 o3 - type
)
(:init
;; fluents: (= (battery-amount r1) 100)
;; predicates: (on-site building site1)
)
(:goal (and
;; fluents: (= (battery-amount r1) 100) or other comparisons
;; predicates: (on-site building site1)
))
;; metrics available: maximize, minimze
(:metric maximize
;; an expression involving fluents: +, -, *, /, one fluent fluent
)
)☝️ this is not a goal, but a optimization instead: the planner will do the best to keep the given quantity minimized or maximized depending on the metric.
☝️ only one statement (metric ...) for each problem file! If you want to optimize two fluents, you should create a measure involving both to minimize or maximize. Not possible to optimize both separately.
;; try to minimize something
(:metric minimize (<numeric_operation> ...))
;; try to maximize something
(:metric maximize (<numeric_operation> ...))(define
(domain construction)
(:extends building)
(:requirements :strips :typing)
(:types
site material - object
bricks cables windows - material
)
(:constants mainsite - site)
;(:domain-variables ) ;deprecated
(:predicates
(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))
;(:safety
;(forall
; (?s - site) (walls-built ?s)))
;deprecated
(: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
)
(:axiom
:vars (?s - site)
:context (and
(walls-built ?s)
(windows-fitted ?s)
(cables-installed ?s)
)
:implies (site-built ?s)
)
;Actions omitted for brevity
)(define
(problem buildingahouse)
(:domain construction)
;(:situation <situation_name>) ;deprecated
(:objects
s1 - site
b - bricks
w - windows
c - cables
)
(:init
(on-site b s1)
(on-site c s1)
(on-site w s1)
)
(:goal (and
(walls-built ?s1)
(cables-installed ?s1)
(windows-fitted ?s1)
)
)
)(define
(domain ballphysics)
(:requirements :time :typing)
(:types
ball - object
)
(:predicates
(held ?b - ball)
)
(:functions
(velocity ?b - ball)
(distance-to-floor ?b - ball)
)
(:process FALLING
:parameters (?b - ball)
:precondition (and
(not (held ?b))
(< (velocity ?b) 100)
)
:effect (and
(increase (velocity ?b) (* #t 9.8))
(decrease (distance-to-floor ?b) (* #t (velocity ?b)))
)
)
(:event HIT-GROUND
:parameters (?b - ball)
:precondition (and
(not (held ?b))
(<= (distance-to-floor ?b) 0)
(> (velocity ?b) 0)
)
:effect (
(assign (velocity ?b) (* -0.8 (velocity ?b)))
)
)
; Actions omitted
)same as PDDL2.1 ; what distinguishes PDDL+ from the other versions is the domain.
(define (domain rover-domain)
(:requirements :durative-actions :fluents :duration-inequalities)
(:types rover waypoint)
(:functions
(battery-amount ?r - rover)
(sample-amount ?r - rover)
(recharge-rate ?r - rover)
(battery-capacity)
(sample-capacity)
(distance-travelled)
)
(:predicates
... ; Predicates omitted
)
(:durative-action move
:parameters
(?r - rover
?fromwp - waypoint
?towp - waypoint)
:duration
(= ?duration 5)
:condition
(and
(at start (rover ?rover))
(at start (waypoint ?from-waypoint))
(at start (waypoint ?to-waypoint))
(over all (can-move ?from-waypoint ?to-waypoint))
(at start (at ?rover ?from-waypoint))
(at start (> (battery-amount ?rover) 8)))
:effect
(and
(at end (at ?rover ?to-waypoint))
(at end (been-at ?rover ?to-waypoint))
(at start (not (at ?rover ?from-waypoint)))
(at start (decrease (battery-amount ?rover) 8))
(at end (increase (distance-travelled) 5))
)
)
... ; Additional actions omitted
)(define
(problem rover1)
(:domain rover-domain)
(:objects
r1 r2 - rover
wp1 wp2 - waypoint
)
(:init
(= (battery-amount r1) 100)
(= (recharge-rate r1) 2.5)
...
)
(:goal (and
...
)
)
(:metric maximize (+
(battery-amount r1)
(battery-amount r2)
)
)
)