Re: SKOS modeling

Hi Folsom

On Wed, 9 Nov 2016, at 18:19, Folsom, Steven wrote:
> I’d be curious to know what objections exist, if any, for using dog
> species Classes as the subject of the book in the case below. E.g.
>
> book1 :about :DalmationsClass .
No objection against this statement. But would it allow to conclude that
book1 is about :DogsClass? I don't think so.

But the following statement should probably not be true as books can be
about things other than classes.

:about rdfs:range owl:Class.

By contrast, given the liberal definition of skos:Concet the following
is probably true

:about rdfs:range skos:Concept.

So :DalmationsClass  would be both an owl:Class and a skos:Concept.
Which is fine.

Cheers,
Reto

>
>
>
>
> *From: *Reto Gmür <reto@gmuer.ch> *Date: *Wednesday, November 9, 2016
> at 12:00 PM *To: *"semantic-web@w3.org" <semantic-web@w3.org>
> *Subject: *Re: SKOS modeling *Resent-From: *<semantic-web@w3.org> *Resent-
> Date: *Wednesday, November 9, 2016 at 12:00 PM
>
>
> 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
>
>
>

--
  Reto Gmür
  reto@gmuer.ch