I believe the following should work, but I haven't tried it all
out. For this to work, all your defclasses need the "class"
slot. The one you show below does. To ensure that a defclass has this
slot, define a defclass
(defclass object java.lang.Object)
and then define all your subsequent defclasses to extend this one:
(defclass button java.awt.Button extends object)
OK, anyway, the trick is to use
(have (possession-type (class (call Class forName "package.pencil"))))
where you've got "(have (possession ?pencil <of type pencil>))"
below. Then the need-have fact should have the posession-type slot
filled in with the appropriate class object, which you can use to
synthesize the "pencil" object and "have" fact.
> An additional question: is it possible to let need-have only be
> asserted when (want-to-write) - a non-backward-chaining fact - is
> asserted?
This is how it works already.
I think Sander Faas wrote:
[Charset iso-8859-1 unsupported, filtering to ASCII...]
> Hello,
>
> My agent has a knowledgebase in which every fact is a definstance fact. The
> reason for this is that I use the Jade ontology support which specifies all
> concepts, predicates and actions in the agent's world. This ontology support
> maps all elements (concepts, predicates etc.) on Java classes.
>
> For example the predicate (have :POSSESSION (pencil) :OWNER (human :NAME
> Jaap)) results in the following fact:
>
> (MAIN::have(class <External-Address:java.lang.Class>) (owner
> <External-Address:storyagents.storyworldontology.Human>) (possession
> <External-Address:storyagents.storyworldontology.Pencil>) (OBJECT
> <External-Address:storyagents.storyworldontology.Have>)
>
> Suppose I have a rule that says: if I want to write and I have a pencil,
> then I will write. This could be done in the following manner:
>
> (defrule write
> (want-to-write)
> (have (possession ?p))
> (pencil (OBJECT ?p))
> =>
> (printout t "I am writing" crlf)
> )
>
> However, I want to use backtracking and do something like:
> (do-backward-chaining have)
> (defrule write
> (want-to-write)
> (have (possession ?p <of type pencil>))
> =>
> (printout t "I am writing" crlf)
> )
>
> Is such a thing possible? The problem with the first method is that if I use
> backward chaining all I get is an empty need-have fact (all slots nil).
>
> Bye,
> Sander
>
>
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Ernest Friedman-Hill
Distributed Systems Research Phone: (925) 294-2154
Sandia National Labs FAX: (925) 294-2234
Org. 8920, MS 9012 [EMAIL PROTECTED]
PO Box 969 http://herzberg.ca.sandia.gov
Livermore, CA 94550
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