Re: SKOS modeling

Thank you very much for the answer, I think that now I better understand
the theory behind it.

Still I am wondering: once you have a thesaurus written in SKOS in place,
what do you do with it? You use it for tagging? As all relations are
written as annotations, you cannot reason on it using any OWL profile so
the only way to get all the broader concepts is to make SPARQL queries.
What if you want to get the broader concept of a broader concept? You
translate the SKOS ontology to an OWL ontology?

I think that my point here is that while SKOS seems easier to use because
all relations are not "hard", it seems to me of less practical use of an
RDF/OWL ontology but again I am not a SKOS expert so I probably just don't
understand it :)


Alessandro



2016-11-09 18:00 GMT+01:00 Reto Gmür <reto@gmuer.ch>:

> Hi Alessandro
>
>
> On Wed, 9 Nov 2016, at 15:36, Alessandro Seganti wrote:
>
> Hi everyone,
> after some years working with semantic technologies, I am still not 100%
> sure I understand what SKOS is used for.
>
> To my understanding, SKOS should be used to model relations between
> entities that are not certain so instead of modeling it as "is a" we say
> that it is "broader than" or things like this.
>
> No, it's not about certainty. A SKOS concept may be an owl:Class in which
> case a super-class would probably be a broader concept.
>
>
> If this is true, then I don't understand why I see many people building
> taxonomy trees using SKOS relations. Is there some confusion around or
> maybe I am missing something?
>
> There are certainly many cases where you could use either SKOS or OWL or
> use them together. The main difference is that OWL classes can have and
> typically have instances while SKOS concepts cannot be instantiated (unless
> they are also classes).
>
>
> Also could you give me an example where it is better to use SKOS than to
> use "is a" relationships?
>
>
> If your data describes different individual dogs you might have various
> classes for the different breeds of dogs, there probably are some sub-class
> relations between those classes. Each individual dog is an instance of one
> or several of those classes. If however your data is about dog books, these
> books are obviously not an instance of a particular breed of dog but may
> have a breed of dog as subject. In this case you would better model the
> different dog breeds as skos:Concepts rather than as owl:Classes.
>
> So to summarize:
> - if you want to categorize some resources use classes so that the
> resources can have meaningful types
> - if you want to describe your thesaurus or want something a bit more
> formalized than tags to annotate your items (to say "this has to do with")
> use SKOS
>
> Hope this helps.
>
> Reto
>
>
>