Re: [DL-Learner discussion] DL Learner Java 1.7 Bug & Side Effect Question

[Lorenz B. <spo...@st...>]

Hi,

can you provide us the ontology such that we can reproduce the strange 
appearance of rdfs:Resource? Unfortunately, NodeSet as well as Node 
objects use HashSets internally, thus a non-determinsm might occur in 
the OWLAPIReasoner. I guess we'll have to wrap it into TreeSets.

Thanks for the bug report.

Regards,
Lorenz
On 05/03/2013 12:49 AM, Donnie Rivera wrote:
>
> To Whom It May Concern:
>
> My name is Donnie Rivera, and I work at Intelligent Software 
> Solutions. I've taken over Chris Shellenbarger's project over the last 
> year which I've completed several changes to the software. One of the 
> changes included moving from Java 1.6 to Java 1.7 which was the cause 
> for the DL Learner bug to appear. Our software still utilizes DL 
> Learner for what we call the "Hypothesis Refinement" process. During 
> this process DL Learner used to find specific types. Unfortunately 
> with all the changes, DL Learner stopped learning these concepts.
>
> After looking into the problem, I've discovered a bug within DL 
> Learner, but also wanted to get input from the side effect for the 
> current working around.
>
> The issue starts with an assumption made within the OWLAPIReasoner. 
> The getSuperClassesImp() assumes that an ordered 
> NodeSet<OWLClass> will be return from the PelletReasoner. This is true 
> with Java 1.6, but not Java 1.7.  That assumption is what leads to the 
> bug within DL Learner's ClassHierarchy. thinOutSubsumptionHierarchy() 
> process.
>
> During the cloneAndRestrict() restrict process, DL Learner's 
> OWLAPIReasoner. getFirstClasses() grabs the first node from the 
> NodeSet<OWLClass> that was returned from the PelletReasoner. This is 
> the cause of the problem because classes are getting mapped to both 
> owl:Thing and rdfs:Resource in Java 1.7 whereas in Java .1.6 they were 
> only getting mapped to owl:Thing. Then during the 
> thinOutSubsumptionHierarchy() process, the upward mapping gets horked 
> which is why DL Learner stopped learning specific types.
>
> This is easily worked around by setting the 
> improveSubsumptionHierarchy attribute to false, but what are the side 
> effects from doing so?
>
> Regards,
>
> Donnie Rivera
>
> Software Engineer
>
> Intelligent Software Solutions (ISS)
>
> Work:  (719) 457-0228
>
> Moblie: (719) 242-8522
>
> Email: don...@is... <mailto:don...@is...>
>
>
>
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