Effects of Activities

Extension Name: effects.def

Primitive Lexicon: None

Defined Lexicon:

Relations:

(effects_equiv ?a ?s1 ?s2)
(context_free ?a)
(null ?a)

Theories Required by this Extension: disc_state.th, occtree.th, psl_core.th

Definitional Extensions Required by this Extension: none

Grammar: effects.bnf

Definitions

Definition 1 Two occurrences of an atomic activity are effects equivalent iff the same states hold after the occurrences.

(forall (?a ?s1 ?s2) (iff (effects_equiv ?a ?s1 ?s2)
(and    (occurrence_of ?s1 ?a)
        (occurrence_of ?s2 ?a)
        (forall (?f)
                (iff	(holds ?f ?s1)
			(holds ?f ?s2))))))

Definition 2 An activity is context-free iff any fluent changed by one occurrence of the activity is changed by all occurrences of the activity.

(forall (?a) (iff (context_free ?a)
(forall (?s1 ?s2)
	(if	  (and	(occurrence_of ?s1 ?a)
			(occurrence_of ?s2 ?a))
		  (effects_equiv ?a ?s1 ?s2)))))

Definition 3 An activity is null iff it does not have any effects, that is, none of its occurrences either achieves or falsfies any fluent.

(forall (?a) (iff (null ?a)
(forall (?s)
        (if	  (occurrence_of ?s ?a)
		  (forall (?f)
			(iff    (holds ?f ?s)
                                (prior ?f ?s)))))))