W3C home > Mailing lists > Public > www-rdf-logic@w3.org > April 2001

Dirt simple RDF was: Re: A plea for peace.

From: Jonathan Borden <jborden@mediaone.net>
Date: Thu, 5 Apr 2001 17:57:40 -0400
Message-ID: <03ad01c0be1b$71706680$0a2e249b@nemc.org>
To: <pfps@research.bell-labs.com>
Cc: <phayes@ai.uwf.edu>, <www-rdf-logic@w3.org>
Peter F. Patel-Schneider wrote:
>
> OK, so you are claiming that transitivity, type inference, subtyping, and
> domain and range are not RDF.  That still leaves open-world, infinite
> domains, identity, URIs, reification, containers (especially alternative),
> distributive referents, and URI patterns.

Obviously the model/mapping to SQL is simplified, and I'm not disagreeing on
the desirability to work from something different than RDF M&S 1.0. I'm
happy to remove reification (and replace it with a URI syntax for triples
for example) as well as with containers. For example one might express a
so-called anonymous node given a unique property as:

the:[predicate][object]

and a triple as:

triple:[predicate][subject][object]

and perhaps triple:[predicate][][object] can be shorthand for the former

(this is a purely syntactic convention for quoting an RDF statement as a URI
using an invented scheme "triple:")

I think containers can be redone in a more useful fashion. Perhaps simply
expressed as the results of queries.

URI patterns? are you refering to the rdf:aboutEachPrefix attribute? I'm
happy to remove anything I don't use. Indeed, let's see how absolutely
simple we can make this and expand from there.

>
> > For RDF alone:
> >
> > DEFINE TABLE triples AS
> >     predicate : URI
> >     subject : URI
> >     object : URI
> >
> > -- note that RDF literals can be encoded as "an example":
data:text/plain,an
> > example so that all objects can be represented as URIs, literals using
the
> > "data:" scheme.
> >
> > -- a URI is a string having the syntax described in RFC 2396 (the EBNF
isn't
> > quite perfect but close enough)
> >
> > Let's start with this alone, and add concepts only as absolutely needed.
> >
> > -Jonathan
>
> The mapping above handles none of the above, not even URIs --- not all
> strings are valid URIs, which you indicate above, but the RDB schema
doesn't
> capture that; and string ordering is not a valid operation.
>

Groan. The syntax of a valid URI is described in RFC 2396 ... will you
accept ENBF as a valid syntactic constraint? I suppose that one _could_
write a stored procedure to check the URI syntax as a constraint. If not, I
might have to express the URI as a syntactic grove, for example in an
expanded XML syntax (see http://www.openhealth.org/XSet/URI.xml and
http://www.openhealth.org/XSet for a similar description of XML). One then
can express this XML'ized version of a URI in a set of tables representing
an XML DOM (e.g. DBDOM http://www.dbdom.org/) ...

in any case we can apply isValidURI(string) as a constraint.
we can also define isTypeOf(subjectURI,objectURI) as:

exists * from triples where (predicate = 'rdf:type' and subject=@subject and
object=@object) (admittedly rdfs:subClassOf _is_ useful but for the
moment...)

Why is string ordering needed (for the moment)?

-Jonathan
Received on Thursday, 5 April 2001 18:13:10 GMT

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