JiscMail Logo
Email discussion lists for the UK Education and Research communities

Help for DC-ARCHITECTURE Archives


DC-ARCHITECTURE Archives

DC-ARCHITECTURE Archives


DC-ARCHITECTURE@JISCMAIL.AC.UK


View:

Message:

[

First

|

Previous

|

Next

|

Last

]

By Topic:

[

First

|

Previous

|

Next

|

Last

]

By Author:

[

First

|

Previous

|

Next

|

Last

]

Font:

Proportional Font

LISTSERV Archives

LISTSERV Archives

DC-ARCHITECTURE Home

DC-ARCHITECTURE Home

DC-ARCHITECTURE  June 2002

DC-ARCHITECTURE June 2002

Options

Subscribe or Unsubscribe

Subscribe or Unsubscribe

Log In

Log In

Get Password

Get Password

Subject:

Re: rdfs:isDefinedBy (Was Re: Representing DCMI semantics as RDF schemas versus Web pages)

From:

Patrick Stickler <[log in to unmask]>

Reply-To:

This list, which supersedes dc-datamodel, dc-schema, and dc-implementors, i" <[log in to unmask]>

Date:

Wed, 5 Jun 2002 10:40:11 +0300

Content-Type:

text/plain

Parts/Attachments:

Parts/Attachments

text/plain (169 lines)

On 2002-06-04 16:52, "ext Thomas Baker" <[log in to unmask]> wrote:

> On Fri May 31, Patrick wrote:
>> We need a way to relate a term to resources which define it. And
>> we should use rdfs:isDefinedBy (or a subproperty of it) to do this,
>> but that resource is not a namespace. It might be an RDF schema.
>> It might be an HTML instance with prose for humans. It might be
>> text. Whatever.
>
> This is why rdfs:ns would work alot better for me.

But I feel that rdfs:ns misses a very critical point -- namely
that *namespaces* per their function in XML simply do not exist
in RDF. They have no formal representation or semantics in RDF.
And furthermore, if a given URI which denotes an RDF schema that
defines some set of terms happens to do double duty and also
be used as a namespace URI, it is not the *namespace* that is
defining the terms, it is the resource denoted by the URI that
also is used as a namespace prefix.

A *namespace* is nothing but *punctuation*. That's it. It describes
nothing.

If folks decide to allow a namespace URI to denote some "namespace
document", well, they're free to do so, but the view that there
is a 1:1:1 relationship between a term, a namespace, and the
complete definition of that term defined by some resource
sharing identity with the namespace is (forgive me) naive and
short sighted.

A given term may be used by multiple functional vocabularies,
where each vocabulary has its own identity seperate from any
URI intesection with the term, and a term may be defined by
any number of separate schemas.

Managing complex families of ontologies with multiple versions
and internationalization and locale variations requires a far
more modular organization than the simplistic approach of
one term, one namespace, one schema.

> If rdfs:isDefinedBy is being used (in effect) like rdfs:ns,

Perhaps by some, but not by all, and the present definition
of the semantics of rdfs:isDefinedBy does not constrain it
to such a narrow usage.

> it seems we might sometimes still need a pointer from an
> individual term declaration to a canonical source document
> (in this case, in "prose") in the form of something like the
> differently defined rdfs:isDefinedBy Patrick wants?

Exactly. We need only one property, rdfs:isDefinedBy which
relates a term to a defining resource, and since we have the
URI of that resource, we can describe that defining resource
however we like.

We can say what it's MIME encoding is, what role it plays
(a'la RDDL), where it might be accessible (if the URI is
not a URL), what it's XML PUBLIC identifier is, etc. etc.

Then, an application can choose which defining resources it
can or wants to reference.

> In Roland's schema at
> http://www.mathematik.uni-osnabrueck.de/projects/dcqual/qual21.3.1/Schema/A/dc
> terms
> the arcs
>
> |  <dc:source
> |
> rdf:resource="http://www.dublincore.org/documents/2000/07/11/dcmes-qualifiers/
> "/>
> |  <dc:source rdf:resource="http://www.dublincore.org/usage/decisions/"/>
>
> point to a single source (prose) file for the entire RDF
> schema, as a whole.  However, I should think that as the
> number of terms and related namespaces increases, such a
> document-oriented pointer -- from one RDF schema document
> to one prose document -- would become increasingly less
> useful for locating the "source" resources that define any
> particular term.
>
> Already in
> http://www.gmd.de/People/Thomas.Baker/usage/terms/dc/ the
> terms defined come from two namespaces -- as a document,
> it replaces both http://dublincore.org/documents/dces/ and
> http://dublincore.org/documents/dcmes-qualifiers/.  And it
> is not difficult to imagine the more extreme cases Patrick
> (I believe) has in mind, where a schema uses terms from
> more than two namespaces.

Exactly. This is the difference between a vocabulary and
a namespace. It is the functional vocabularies that are of
interest, not the trivial punctuation that might make
serialization of commonly managed terms more convenient.

We care about the DC vocabulary, which includes terms
from more than one namespace, and those terms are defined
in various ways, in various encodings, for various purposes.

Namespaces simply do not fit into the organizational equation.
They are just a convenience for the XML serialization. That's
all. Any correlation to a namespace URI and a vocabulary is
an illusion -- or a personal preference by someone who controls
all the defining content (which more and more is the exception,
not the rule).

Folks really need to stop equating namespace with vocabulary.
Despite historical coincidences, they are not the same.

> In the RDF schema of DCMI terms, then, might it not
> be helpful to have a pointer to the precise source of
> a definition in the canonical prose document, such as
> http://www.gmd.de/People/Thomas.Baker/usage/terms/dc/#title-003
> (historically, the latest version of a term from
> the http://purl.org/dc/elements/1.1/ namespace) or
> http://www.gmd.de/People/Thomas.Baker/usage/terms/dc/#medium-002
> (a term from the http://purl.org/dc/terms/ namespace)?
>
> Such precision might not be necessary in an informational RDF
> schema defining "just the current" elements in English for
> use in general-purpose RDF applications, as Roland is doing.
> But would such a pointer not be more important in an RDF schema
> of the elements defined in Japanese?  How else would one point
> from a term declaration in Japanese back to the historically
> exact English wording upon which the translation was based?

I agree this is very important knowledge about resources, for which
dc:source seems well suited. Though this is knowledge about
the defining resource of a term, not necessarily about the term
itself.

> Would we not, then, need to ensure that
> each successive historical version of a term
> declaration has a unique identifier, such as
> http://dublincore.org/usage/terms/dc/#medium-002 or even
> http://purl.org/dc/terms/medium-002?

This is an interesting question from the viewpoint of
knowledge management. Do we want to reify all statements,
and then define their source and historical relations?

Of course, if we did so, we wouldn't need rdfs:isDefinedBy,
since we could easily obtain such information automatically
from the provenance captured in the reified statements.

I think it's probably sufficient to manage at a coarser
level of resolution, namely the schema, and then just
relate the terms to the schemas and define the historical
relationship between the schemas.

Each schema would have some functional significance, which
justifies its individual management, which may or may
not equate to the entire functional vocabulary, or perhaps
to a clear sub-component of that vocabulary. But in any
case, namespaces should be a minor or non-existent factor
in deciding where such partitioning occurs.

Cheers,

Patrick


--

Patrick Stickler              Phone: +358 50 483 9453
Senior Research Scientist     Fax:   +358 7180 35409
Nokia Research Center         Email: [log in to unmask]

Top of Message | Previous Page | Permalink

JiscMail Tools


RSS Feeds and Sharing


Advanced Options


Archives

February 2024
January 2024
October 2023
September 2023
August 2023
July 2023
June 2023
May 2023
April 2023
March 2023
February 2023
January 2023
December 2022
November 2022
September 2022
August 2022
June 2022
May 2022
April 2022
March 2022
February 2022
January 2022
November 2021
October 2021
September 2021
August 2021
July 2021
May 2021
April 2021
March 2021
February 2021
January 2021
December 2020
November 2020
September 2020
August 2020
July 2020
June 2020
April 2020
March 2020
February 2020
January 2020
December 2019
November 2019
September 2019
August 2019
July 2019
June 2019
May 2019
April 2019
March 2019
February 2019
January 2019
December 2018
November 2018
October 2018
September 2018
August 2018
July 2018
June 2018
May 2018
April 2018
March 2018
February 2018
January 2018
December 2017
November 2017
September 2017
August 2017
July 2017
June 2017
May 2017
April 2017
March 2017
February 2017
January 2017
December 2016
November 2016
October 2016
September 2016
August 2016
July 2016
June 2016
May 2016
April 2016
March 2016
February 2016
January 2016
December 2015
November 2015
October 2015
September 2015
August 2015
July 2015
June 2015
May 2015
April 2015
March 2015
February 2015
January 2015
December 2014
November 2014
October 2014
September 2014
August 2014
July 2014
June 2014
May 2014
April 2014
March 2014
February 2014
January 2014
November 2013
October 2013
September 2013
August 2013
July 2013
June 2013
May 2013
April 2013
March 2013
February 2013
January 2013
December 2012
November 2012
October 2012
September 2012
August 2012
July 2012
June 2012
May 2012
April 2012
March 2012
February 2012
January 2012
December 2011
November 2011
October 2011
September 2011
August 2011
July 2011
June 2011
May 2011
April 2011
March 2011
February 2011
January 2011
December 2010
November 2010
October 2010
September 2010
August 2010
July 2010
June 2010
May 2010
April 2010
March 2010
February 2010
January 2010
December 2009
November 2009
October 2009
September 2009
August 2009
July 2009
June 2009
May 2009
April 2009
March 2009
February 2009
January 2009
November 2008
October 2008
September 2008
August 2008
July 2008
June 2008
May 2008
April 2008
February 2008
January 2008
December 2007
November 2007
October 2007
September 2007
August 2007
July 2007
May 2007
April 2007
March 2007
February 2007
January 2007
December 2006
November 2006
October 2006
September 2006
August 2006
July 2006
June 2006
May 2006
April 2006
March 2006
February 2006
January 2006
December 2005
November 2005
September 2005
August 2005
July 2005
June 2005
April 2005
March 2005
February 2005
January 2005
December 2004
November 2004
October 2004
September 2004
August 2004
July 2004
June 2004
May 2004
March 2004
February 2004
January 2004
November 2003
October 2003
September 2003
August 2003
June 2003
May 2003
April 2003
March 2003
January 2003
December 2002
November 2002
October 2002
September 2002
August 2002
July 2002
June 2002
May 2002
April 2002
March 2002
February 2002
January 2002
December 2001
November 2001
October 2001
September 2001
August 2001
July 2001
June 2001
May 2001
April 2001
March 2001
February 2001
December 2000
November 2000
October 2000


JiscMail is a Jisc service.

View our service policies at https://www.jiscmail.ac.uk/policyandsecurity/ and Jisc's privacy policy at https://www.jisc.ac.uk/website/privacy-notice

For help and support help@jisc.ac.uk

Secured by F-Secure Anti-Virus CataList Email List Search Powered by the LISTSERV Email List Manager