I think Osvaldo Pinali Doederlein wrote:
>
> Hi,
>
> I'm a bit new to Jess, but I already have lots of stuff working (thanks to
> this thing being so easy!) and it's so much stuff that I am already needing
> help on performance and design... :)
>
> 1. I have a very big graph of Java objects that I'm converting to JESS
> facts. But my approach is killing all my collections and using back
> references in the pointed things. For example if I have a class A with a
> list of instances of B, in my facts I will have this:
>
> (A (code 777) (...other slots...))
> (B (code 778) (owner 777) (...other slots...))
> (B (code 779) (owner 777) (...other slots...))
>
> I think this is a good idea, but I could try to use the multislots too,
> but would that be slower?
Matching on multislots is definitely slower.
>
> 2. Is it a good idea to have those unique ID codes to do references between
> things (I'm using deftemplates for all stuff). My objects are a complex
> graph and there's no way I can generate the facts using references for the
> fact-IDs in a single pass; I would need to do some postprocessing in the
> fact database in order to have that but it's an option. Basically, I need
> to have tons of pointers btw facts and I have forward references, cycles,
> every damn thing.
>
This is a classic complaint about the CLIPS fact model. Have you
looked, by the way, at using defclasses and Beans instead of
deftemplates? That's a better technique for object-like things.
> 3. I instinctively transformed my model in several ways while doing the
> templates -- inlining the fields of small aggregate objects in their owners,
> placing unique IDs everywhere, denormalizing structure, commenting out
> unused slots, creating new templates to encode N-N relationships... except
> for the template inheritance, isn't that surprisingly similar to good old
> relational databases? :-) This is not actually a question, just tell me if
> I'm doing a very unholy and bad thing, as I'm totally fresh to CLIPS.
>
It's very similar to RDBMSs. In fact, there was (and is) a lot of
overlap between the people who developed this sort of ES technology
and who developed heavy-duty relational database technology. Many
folks (David Miranker is a a good example) continue to blur the distinction.
> 4. Now a really novice question. How can I prevent things from being
> detected lots of times. I see that I can retract facts, but I don't want to
> retract any fact because I'm using them to detect several things. For
> example I have this simple rule:
>
> (defrule siblings "Finds sibling classes in the inheritance tree"
> (Generalization (parent ?parent-code) (child ?child-code-1))
> (Generalization (parent ?parent-code) (child ?child-code-2))
> (test (neq ?child-code-1 ?child-code-2))
> (Class (code ?child-code-1) (name ?child-name-1))
> (Class (code ?child-code-2) (name ?child-name-2))
> =>
> (printout t "Found siblings: " ?child-name-1 ", " ?child-name-2 crlf)
> )
>
> This code works, but it will detect twice all my sibling classes, e.g. if I
> have A and B derived from the same base class, I'll get "Found siblings: A,
> B" and also "Found siblings: B, A". I fully understand why this happens,
> but not how to prevent it :)
The most common solution is to put a note onto the fact-list
(defrule siblings "Finds sibling classes in the inheritance tree"
(Generalization (parent ?parent-code) (child ?child-code-1))
(Generalization (parent ?parent-code) (child ?child-code-2))
(test (neq ?child-code-1 ?child-code-2))
(not (done ?child-code-2 ?child-code-1))
(Class (code ?child-code-1) (name ?child-name-1))
(Class (code ?child-code-2) (name ?child-name-2))
=>
(printout t "Found siblings: " ?child-name-1 ", " ?child-name-1 crlf)
(assert (done ?child-code-2 ?child-code-1))
)
>
> Thanks a lot!! :)
>
> ----------------------------------------------------------------
> *** The Free, Open and Pure Java Shell *** Current: Alpha6
> http://www.geocities.com/ResearchTriangle/Node/2005/java_shell.htm
> http://student.vub.ac.be/~opinalid/java_shell.htm
> ----------------------------------------------------------------
> Osvaldo Pinali Doederlein [EMAIL PROTECTED]
> MSc student, Developer, Java & CORBA evangelist, Rainmaker, etc.
>
>
>
>
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>
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Distributed Systems Research Phone: (925) 294-2154
Sandia National Labs FAX: (925) 294-2234
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