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Re: Semantic Tags (was several threads)

From: Stian Soiland-Reyes <soiland-reyes@cs.manchester.ac.uk>
Date: Tue, 5 Feb 2013 13:44:51 +0000
Message-ID: <CAPRnXtkY_fX=v3oJ0H5LQKSVuTVoy9VjwFdKG9kyjmRk+x5WCA@mail.gmail.com>
To: Robert Sanderson <azaroth42@gmail.com>
Cc: Paolo Ciccarese <paolo.ciccarese@gmail.com>, Antoine Isaac <aisaac@few.vu.nl>, public-openannotation@w3.org
On Mon, Feb 4, 2013 at 6:04 PM, Robert Sanderson <azaroth42@gmail.com> wrote:
>>> 3.  (Rob) Use oa:SemanticTag class, with foaf:page.  This is the same
>>> as 2. but with a looser predicate that isn't functional.
>> The last one is compact, does not interfere with other constructs, gives a
>> little structure without too much commitment, is more declarative.
>> And I like how it reads for cases in which the URI is actually a page or
>> HTML document
>> ex:semtag a oa:SemanticTag ;
>>   foaf:page <http://omim.org/entry/104760> .
> I think so too.

Is the idea that there is a semantic concept, here minted as
ex:semtag, which happens to have a foaf:page at
<http://omim.org/entry/104760> ?  Or is a foaf:page considered
somewhat 'identifying' for an oa:SemanticTag? (Would it make sense to
have two distinct SemanticTag's with the same foaf:page?)

>From the text now at
http://www.openannotation.org/spec/future/core.html#Tagging (which
reads good, except figure Semantic Tag needs updating for class) is
that the foaf:page thing is a workaround for semantically tagging with
concepts which don't have a proper URI yet. Presumably you could still
use foaf:page for the 'normal' semantic tag as well without changing
much, ie.

  oa:hasBody <http://dbpedia.org/resource/Paris> .

<http://dbpedia.org/resource/Paris> a oa:SemanticTag ;
    foaf:page <http://dbpedia.org/page/Paris> ;

(and someone clever could relate this annotation with others which are
annotating the page)

I think the solution now in the HTML is workable. It is a bit
confusing because there are three different options, but thinking
about it now I think the foaf:page indirection is the most appropriate
for Paolo's use-case rather than hijacking the page URI and declare it
as some kind of semantic concept.

Perhaps the examples should be a bit clearer about where the actual
semantic tag URI can be found rather than using the generic <body1>

<anno1> a oa:Annotation ;
    oa:motivatedBy oa:tagging ;
    oa:hasBody <http://example.com/vocab/term1> ;
    oa:hasTarget <target1> ;

  <http://example.com/vocab/term1> a oa:SemanticTag .
  <target1> a dctypes:Image .

(As almost always the terms would come from a different namespace)

> For example, would clients be confused if they saw an Annotation that
> targeted a resource, say the dbpedia URI for Paris, and the RDF
> claimed that Paris was of class oa:SemanticTag ?  I think this
> actually *helps*, as the client would know not to dereference the URI
> looking for a document.  But perhaps we could have a better name for
> the class?

what we are talking about now sounds like a perfect fit for
skos:Concept - perhaps we should make oa:SemanticTag also subclass
skos:Concept (or use skos:Concept alone - but that might raise similar
in-from-the-outside concerns like my cnt:chars concerns, although here
it should be OK).

Forcing skos:Concept might have bigger impact than oa:SemanticTag
alone. I've checked with Sean in our office (one of the skos-reference
editors) who don't think so. (See below). Perhaps Antoine can fill in,
who wrote the skos-primer? :)

[12:17:35] Sean Bechhofer: The definition of skos:Concept is very open.
[12:17:39] Sean Bechhofer: [[SKOS leaves ample room for interpreting
the notion of concept, and many arti- facts from information science
and other fields fall in scope. As the SKOS Reference puts it [14], “a
SKOS concept can be viewed as an idea or notion; a unit of thought.
However, what constitutes a unit of thought is subjective, and this
definition is meant to be suggestive, rather than restrictive.”]]

>From http://www.w3.org/TR/skos-primer/

> SKOS has been designed to provide a low-cost migration path for porting existing organization systems to the Semantic Web. SKOS also provides a lightweight, intuitive conceptual modeling language for developing and sharing new KOSs. It can be used on its own, or in combination with more-formal languages such as the Web Ontology Language (OWL) [OWL]. SKOS can also be seen as a bridging technology, providing the missing link between the rigorous logical formalism of ontology languages such as OWL and the chaotic, informal and weakly-structured world of Web-based collaboration tools, as exemplified by social tagging applications.
> The aim of SKOS is not to replace original conceptual vocabularies in their initial context of use, but to allow them to be ported to a shared space, based on a simplified model, enabling wider re-use and better interoperability.

SKOS is quite permissive:


> Other than the assertion that skos:Concept is an instance of owl:Class, this specification does not make any additional statement about the formal relationship between the class of SKOS concepts and the class of OWL classes. The decision not to make any such statement has been made to allow applications the freedom to explore different design patterns for working with SKOS in combination with OWL.

For instance it allows both these mixes:

<MyConcept1> rdf:type skos:Concept , owl:Class .
<MyConcept2> rdf:type skos:Concept , owl:ObjectProperty .

(This depends on OWL 2 punning, and would not be valid in OWL 1)

Stian Soiland-Reyes, myGrid team
School of Computer Science
The University of Manchester
Received on Tuesday, 5 February 2013 13:45:40 UTC

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