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[protege-owl] Pellet gives strange, wrong error with Booleans

Stephen Larson slarson at ucsd.edu
Thu Aug 30 11:19:22 PDT 2007


Bijan,

   Sorry for not using the appropriate channels before.  I have included
other lists on this because I think that it is important to clear this up.

   I'm sending you the simplest example of this problem that I can find.  It
doesn't seem to happen with a single simple case of the presence of a
boolean.  The behavior appears to be more complex than that.  But it is the
case that the problem exists, I've sent you an example ontology that
exhibits it, and it can be reversed by commenting out the booleans.  It is
reproducible if you use the tools that I have described.

   I understand if you are frustrated with the DIG interface.  But, it seems
like you are implying that Pellet doesn't really support the interface.

   I'm just a naive user here with limited resources.  I'd like to use
Pellet to check out my ontology in Protege 3.3.1 without having to acquire a
'toolchain' in order to do it.  The pellet website says it supports DIG:
http://pellet.owldl.com/faq/protege/.  But it seems like maybe it doesn't
really.  So it seems like the DIG interface is really just a distraction and
shouldn't be included in code intended for naive end-users.  Maybe some
agreement between the Pellet and the Protege people to stop supporting the
DIG interface would be the best route to avoid naive users like me from
falling into these kinds of traps, getting misleading error statements and
thus being unable to fix their ontologies so that Pellet can reason with
them.  I think that would be best for the community.

--Stephen

On 8/30/07, Bijan Parsia <bparsia at cs.man.ac.uk> wrote:
>
> First, there is a Pellet support mailing list:
>         <http://lists.owldl.com/mailman/listinfo/pellet-users/>
>
> I really prefer these sorts of question to be directed there or to
> public-owl-dev at w3.org, that way more people benefit and more people
> can pitch in.
>
> Second, DIG is just unreliable, esp. with datatypes. I tried your
> ontology in Protege4alpha (afaict, you are using Protege 3.x, which
> really makes the report "latest Protege" meaningless). It works with
> both FaCT++ and Pellet in Protege4. It works in OWLSight.
>
> (You do well to try several different avenues to avoid getting stuck
> in these sorts of tool effects. These days, there are plenty of ways
> to gather data about what part of the toolchain is causing trouble.)
>
> So, as I cannot reproduce your problem, I don't see what it is ;) A
> tiny fragment that exactly exhibited the problem would be very
> helpful, esp. when you have the sort of evil property names such as:
>         sao1239937685
>
> Take home lesson: DIG should be avoided, esp. with datatypes.
>
> Cheers,
> Bijan.
>


------------

Hi Bijan, Alan,

   I think I just figured out a problem that has plagued me for several
months with individuals.  When we have created individuals in the past, we
have gotten the error message shown in the screenshot.  However, we have
never been able to find an int that is labelled with false.  This has caused
us to discard instances in the past in order to get rid of the problem.

   Well today, I went on the assumption that the problem is actually with
the booleans themselves.

 <sao:sao1863785805 rdf:datatype="http://www.w3.org/2001/XMLSchema#boolean "
        >false</sao:sao1863785805>

   I've attached an ontology that has booleans in it with false as the
value.  When I run it through Pellet using the DIG interface in the latest
Protege, it returns the error in the screen shot.  However, when I got rid
of all the statements with booleans in it, there is no problem, and the
ontology checks out just fine.

   Is this a problem with case sensitive 'false' values or something?  At
the minimum, I feel that the error message needs to be corrected.  Could you
advise me how booleans are supposed to be used?

Thanks,
   Stephen
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