Given the following classes and rules
(def-kb-class number-object ()
((value :initarg :value)))
(def-kb-class have-some-large-numbers ()
())
(defrule notice-a-large-number :forward
(logical (number-object ? value ?value)
(test (> ?value 100)))
-->
(assert (have-some-large-numbers ?)))
then a
have-some-large-numbers
object will be created when a number larger than 100 exists:
(setq n1 (make-instance 'number-object :value 10))
(infer)
(any '?x '(have-some-large-numbers ?x)) ==> false
(setf (slot-value n1 'value) 200) ; this is large
(infer)
(any '?x '(have-some-large-numbers ?x)) ==> true
In addition, when the large number becomes smaller, the
have-some-large-numbers
object will be erased again:
(setf (slot-value n1 'value) 55)
(infer)
(any '?x '(have-some-large-numbers ?x)) ==> false
because a logical dependency was tracked between the preconditions
(number-object ? value ?value)
(test (> ?value 100)
and the
have-some-large-numbers
object.