[NLP2RDF] NIF: mandatory properties and types

[Martín Rezk]

> Indeed, the current version is underspecified regarding this respect. We
> could say, that each instance of str:Context has a reflexive connection via
> referenceContext to itself. This would make sense probably.
> Actually, this would solve the problem between the distinction between
> Context and StringInContext. As we could model the Context as a subClassOf
> String, i.e. the subclass, that has a reflexive reference to itself ..

It sounds complicated. Imho, I think that a cleaner solution would be
to move down some classes from the SSO to the String Ontology and
redefine the domain and range of  referenceContext.

> Do you know how to express this in OWL? Maybe

My background is on DL more than in OWL, so... when it comes to the
OWL syntax, I need to check the manual :)

Btw... reading the OWL manual I found this

NOTE: In OWL Full, object properties and datatype properties are not
disjoint. Because data values can be treated as individuals, datatype
properties are effectively subclasses of object properties. In OWL
Full owl:ObjectProperty is equivalent to rdf:Property In practice,
this mainly has consequences for the use of
owl:InverseFunctionalProperty. See also the
http://www.w3.org/TR/owl-ref/

>> Regarding the answer from the Pellet forum,  you told me that you will
>> not add axioms to prevent the wrong usage of OWL.
>> However, I think it would be interesting to give an optional simple
>> set of axioms that can be used to check the correctness of the
>> ontology.
>> Some of them could be
>>
>> 1) referenceContext is functional and mandatory.
>
> There is already an owl:hasKey axiom. This  provide something similar to
> functionality and is more light-weight :
> HasKey StringInContext ( referenceContext ) ( beginIndex , endIndex  ))

What are beginIndex and, endIndex there? By using those two dont you
loose the stability you gained using the Context Hash based URI?


> The best way to really solve this is to make some examples and then give
> different T-Boxes  and see the consequences. I am almost sure that there
> will not be *one* string ontology, but rather different sets of axioms for
> certain use cases. If you have a large text collection, you just might want
> to have RDFS inference over the hierarchy. Consistency might be (1)
> expensive to calculate (2) annoying. When I implemented it the first time, I
> had one tool, that made a tiny encoding mistake, but  there were too many
> functional properties involved. It was really annoying, because sometimes
> you just might want to continue and ignore it. Subclassof inference would
> have worked out fine regardless of this functional/encoding mistake.

Ok, I dont know how the ontologies will look like, so let's see that first.

> There is no class called str:Nothing. The OWL Doc documentation at
> http://nlp2rdf.lod2.eu/schema/doc/string/index.htmlis misleading. We will
> try to replace it soon. The class you see is owl:Nothing and it should not

Ok,

Best,

Martin Rezk.-



>
>>
>> Best wishes,
>>
>> Martin Rezk.-
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>
>
> --
> Dipl. Inf. Sebastian Hellmann
> Department of Computer Science, University of Leipzig
> Projects: http://nlp2rdf.org , http://dbpedia.org
> Homepage: http://bis.informatik.uni-leipzig.de/SebastianHellmann
> Research Group: http://aksw.org
>