[Pellet-users] (no subject)

[Massimo Paolucci]

Dear all,

I am running Pellet 1.5 RC1, the latest release and I encountered a  
couple of strange behavious that I cannot quite explain (which is to  
say that I suspect that there is a bug somewhere).

I load a bunch of ontologies (UsersKB attached and imported files), I  
do the needed classifications, and then I query the KB to extract the  
types of an instance.  I then load a new ontology (MVV.owl) and I run  
exactly the same query.  The first query goes fine and returns a  
result in 2 secs, The second query takes 65 secs and when I try to  
extract the results from the ResultSet iterator, the statement  
results.hasNext() hangs for ever.   The code that I use is in  
Drop_Incremental_query.java, the hanging line is 117.

My first question is of course why it is hanging, which is my main  
concern at this point.
My second question is why by adding only a few nominals which do not  
affect the classification I get a degrade of performance of such a  
dimension: from 2 secs to 65 secs during query time (see log in  
"Pellet test 2").

The third question is that I tried to modify the way the models are  
constructed by using

	model =  ModelFactory.createOntologyModel 
( PelletReasonerFactory.THE_SPEC );

and the rest of the code is pretty much the same.  But I get a much  
worse performance (the classification takes between 280 and 438 secs)  
but the query answering is almost instantaneous and the bug reported  
above does not happen.

Unfortunately I have no time to analyze the code any further digging  
into Jena or Pellet's code, but I am wondering whether I am doing  
something wrong.

Best Regards,

--- Massimo

 ---------------------------------------------------
Massimo Paolucci
Senior Researcher
DoCoMo Communications Laboratories Europe GmbH
Landsberger Strasse 308-312, 80687 Munich

Phone:  +49-89-56824-238
Fax:    +49-89-56824-301
Mobile: +49-163-34860553

mailto:paolucci at docomolab-euro.com
http://www.docomolab-euro.com

Managing Directors (Geschaeftsfuehrer):
Dr. Toru Otsu, Dr. Narumi Umeda, Kazushige Yoshida
Amtsgericht Muenchen, HRB 132967
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