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Re: SKOS modeling

From: Thomas Francart <thomas.francart@sparna.fr>
Date: Fri, 11 Nov 2016 11:14:13 +0100
Message-ID: <CAPugn7V8z4D7BuKPjBg16dFJRW4cQsksJmJuFfr7Vce0ZrBB1Q@mail.gmail.com>
To: Alessandro Seganti <alessandro.seganti@gmail.com>
Cc: Reto Gmür <reto@gmuer.ch>, Semantic Web <semantic-web@w3.org>, Alessandro Seganti <a.seganti@cognitum.eu>

2016-11-10 9:19 GMT+01:00 Alessandro Seganti <alessandro.seganti@gmail.com>:

> 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?

You use it to browse the resources you have indexed/tagged. You can feed a
search engine with synonyms, translations, etc. to enable autocomplete,
search expansion, faceted search, etc.
You align it with other thesauri for better interoperability (OnaGUI is a
nice little tool to align thesauri :
You visualize/print it with SKOS Play (http://labs.sparna.fr/skos-play/).


> 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


*Thomas Francart* -* SPARNA*
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Received on Friday, 11 November 2016 10:15:07 UTC

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