W3C home > Mailing lists > Public > w3c-rdfcore-wg@w3.org > July 2001

Re: #rdfms-uri-substructure

From: Aaron Swartz <me@aaronsw.com>
Date: Fri, 20 Jul 2001 13:41:15 -0500
Message-Id: <200107201844.f6KIifF01532@theinfo.org>
Cc: RDFCore WG <w3c-rdfcore-wg@w3.org>
To: Sergey Melnik <melnik@db.stanford.edu>
On Friday, July 20, 2001, at 01:41  PM, Sergey Melnik wrote:

>         Property names must be associated with a schema. This can be
>         done by qualifying the element names with a namespace prefix
>         to unambiguously connect the property definition with the
>         corresponding RDF schema or by declaring a default namespace
>         as specified in [NAMESPACES]. [...]
>
>         Namespaces are simply a way to tie a specific use of a word in
>         context to the dictionary (schema) where the intended
>         definition is to be found. In RDF, each predicate used in a
>         statement must be identified with exactly one namespace, or
>         schema.
>
> Aha! Namespaces (at least those of properties) *must* identify
> schemas. These schemas *must* (or *should*?) contain the definitions
> of the corresponding vocabulary elements.

I think this is a bug in the spec. The spec is clearly trying to 
provide an introductory description of RDF topics. Note the use 
of language like "Namespaces are simply a way to..." rather than 
"RDF uses namespaces to..." or "Namespaces must..."

> - Michael Sintek who was working on a new version of Protege last year,
>   expressed serious concerns that namespaces of resources could not
>   be identified in RDF API at that time. In fact, in a schema editor it
> is of
>   paramount importance to be able to create a schema in a given
>   namespace, translate all resources into a new namespace when a
>   subsequent version of the schema is defined, display namespaces,
>   identify them properly in parsed RDF content, save, etc.

There are many ways for Protege to find out the name of the 
schema -- I don't think this use case is a strong enough reason 
to change the model.

> - Jonathan Borden points out that XML Schema datatypes cannot 
> be used if
>   concatenation is deployed:
>
>         http://www.w3.org/2000/03/rdf-tracking/#rdfms-qname-uri-mapping

This is not true -- XML Schema datatypes have URIs and can be 
dealt with just  like anything else with a URI. IMO, Jonathan is 
somewhat confused on this point.

> There are several procedural issues that arise from M&S. The spec
> states that the namespaces of all resources that are properties can be
> used for retrieving the definitions of the properties. Must these
> namespaces be URLs or would URIs also do?

As I said, I think this is a bug and any kind of URI reference 
may be used.

What's the use case that makes it worth our while to change the spec?
--
       "Aaron Swartz"      |              The Semantic Web
  <mailto:me@aaronsw.com>  |  <http://logicerror.com/semanticWeb-long>
<http://www.aaronsw.com/> |        i'm working to make it happen
Received on Friday, 20 July 2001 14:41:19 EDT

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