RE: JESS: [EXTERNAL] Dynamic rule matching in the LHS

Not sure what "dynamic" means in this context. But you can use the "foral=
l" conditional element to implement this rule. You could read the LHS her=
e as "For all values of ?name in bag-of-items, there's a corresponding it=
em fact."

(defrule check-bag-valid
    (forall
        (bag-of-items (names $?    ?name   $?))
        (item (name ?name)))
    =3D>
    (printout t "The bag is valid" crlf))

NOTE: Like many complex Jess rules, this one won't fire unless before add=
ing your facts you've executed the "(reset)" command to asset (initial-fa=
ct).


-----Original Message-----
From: [email protected] [mailto:[email protected]] On=
 Behalf Of Aurelien Mazurie
Sent: Friday, July 26, 2013 4:56 PM
To: jess-users
Subject: JESS: [EXTERNAL] Dynamic rule matching in the LHS

Dear Jess users,
I am wondering how to write a rule that would dynamically match multiple =
facts based on their names.

Let say I have two types of facts; one representing the information that =
an item (with a given name) exists, and the other one representing a list=
 of items (e.g., as a list of names in a multislot). It could be somethin=
g like
this:

  (deftemplate item (slot name))
  (deftemplate bag-of-items (multislot names))

  (assert (item (name A))
  (assert (bag-of-items (names A B))

What I am trying to write is a rule that would, for any bag-of-items fact=
, fire if all the items listed in the multislot 'name' are item facts tha=
t have been asserted.

I am wondering if there is an easy way to do that, or if I'll need to hac=
k my way through it with loops and tests in the LHS of my rule.

Any suggestion?
Best,
Aur=C3=A9lien



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ule-matching-in-the-LHS-tp4654176.html
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