Actions

Action definitions and goal descriptions have the same syntax as in PDDL2.1.

$\langle$ action-def$\rangle$		::=		( :action $\langle$ action symbol$\rangle$
				[:parameters ( $\langle$ typed list (variable)$\rangle$ )]
				$\langle$ action-def body$\rangle$ )
$\langle$ action symbol$\rangle$		::=		$\langle$ name$\rangle$
$\langle$ action-def body$\rangle$		::=		[:precondition $\langle$ GD$\rangle$]
				[:effect $\langle$ effect$\rangle$]
$\langle$ GD$\rangle$		::=		$\langle$ atomic formula (term)$\rangle$  |  ( and $\langle$ GD$\rangle$* )
		|		:equality ( = $\langle$ term$\rangle$ $\langle$ term$\rangle$ )
		|		:equality ( not ( = $\langle$ term$\rangle$ $\langle$ term$\rangle$ ) )
		|		:negative-preconditions ( not $\langle$ atomic formula (term)$\rangle$ )
		|		:disjunctive-preconditions ( not $\langle$ GD$\rangle$ )
		|		:disjunctive-preconditions ( or $\langle$ GD$\rangle$* )
		|		:disjunctive-preconditions ( imply $\langle$ GD$\rangle$ $\langle$ GD$\rangle$ )
		|		:existential-preconditions ( exists ( $\langle$ typed list (variable)$\rangle$ )
				$\langle$ GD$\rangle$ )
		|		:universal-preconditions ( forall ( $\langle$ typed list (variable)$\rangle$ )
				$\langle$ GD$\rangle$ )
		|		:fluents $\langle$ f-comp$\rangle$
$\langle$ atomic formula (x)$\rangle$		::=		( $\langle$ predicate$\rangle$ $\langle$ x$\rangle$* )  |  $\langle$ predicate$\rangle$
$\langle$ term$\rangle$		::=		$\langle$ name$\rangle$  |  $\langle$ variable$\rangle$
$\langle$ f-comp$\rangle$		::=		( $\langle$ binary-comp$\rangle$ $\langle$ f-exp$\rangle$ $\langle$ f-exp$\rangle$ )
$\langle$ binary-comp$\rangle$		::=		<  |  <=  |  =  |  >=  |  >
$\langle$ f-exp$\rangle$		::=		$\langle$ number$\rangle$  |  $\langle$ f-head (term)$\rangle$
		|		( $\langle$ binary-op$\rangle$ $\langle$ f-exp$\rangle$ $\langle$ f-exp$\rangle$ )  |  ( - $\langle$ f-exp$\rangle$ )
$\langle$ f-head (x)$\rangle$		::=		( $\langle$ function symbol$\rangle$ $\langle$ x$\rangle$* )  |  $\langle$ function symbol$\rangle$
$\langle$ binary-op$\rangle$		::=		+  |  -  |  *  |  /

A $\langle$ number$\rangle$ is a sequence of numeric characters, possibly with a single decimal point (“.”) at any position in the sequence. Negative numbers are written as (- $\langle$ number$\rangle$ ).

The syntax for effects has been extended to allow for probabilistic effects, which can be arbitrarily interleaved with conditional effects and universal quantification.

$\langle$ effect$\rangle$		::=		$\langle$ p-effect$\rangle$  |  ( and $\langle$ effect$\rangle$* )
		|		:conditional-effects ( forall ( $\langle$ typed list (variable)$\rangle$ ) $\langle$ effect$\rangle$ )
		|		:conditional-effects ( when $\langle$ GD$\rangle$ $\langle$ effect$\rangle$ )
		|		:probabilistic-effects ( probabilistic $\langle$ prob-effect$\rangle$ + )
$\langle$ p-effect$\rangle$		::=		$\langle$ atomic formula (term)$\rangle$  |  ( not $\langle$ atomic formula (term)$\rangle$ )
		|		:fluents ( $\langle$ assign-op$\rangle$ $\langle$ f-head (term)$\rangle$ $\langle$ f-exp$\rangle$ )
		|		:rewards ( $\langle$ additive-op$\rangle$ $\langle$ reward fluent$\rangle$ $\langle$ f-exp$\rangle$ )
$\langle$ prob-effect$\rangle$		::=		$\langle$ probability$\rangle$ $\langle$ effect$\rangle$
$\langle$ assign-op$\rangle$		::=		assign  |  scale-up  |  scale-down  |  $\langle$ additive-op$\rangle$
$\langle$ additive-op$\rangle$		::=		increase  |  decrease
$\langle$ reward fluent$\rangle$		::=		( reward )  |  reward

A $\langle$ probability$\rangle$ is a $\langle$ number$\rangle$ with a value in the interval [0, 1].