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Re: a new way of thinking about RDF and RDF Schema

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Mon, 22 Oct 2001 22:33:31 -0400
To: melnik@db.stanford.edu
Cc: bwm@hplb.hpl.hp.com, www-rdf-interest@w3.org, simeon@research.bell-labs.com
Message-Id: <20011022223331F.pfps@research.bell-labs.com>
From: Sergey Melnik <melnik@db.stanford.edu>
Subject: Re: a new way of thinking about RDF and RDF Schema
Date: Mon, 22 Oct 2001 18:52:11 -0700

> "Peter F. Patel-Schneider" wrote:
> > 
> > From: Sergey Melnik <melnik@db.stanford.edu>
> > Subject: Re: a new way of thinking about RDF and RDF Schema
> > Date: Mon, 22 Oct 2001 16:47:00 -0700
> > 
> > >
> > > The above suggestion does assign meaning to any well-formed XML
> > > document. As explained in "syntax.html", by default every XML tag
> > > encountered during processing is considered to be a property name.
> > >
> > > Sergey
> > 
> > How can you handle
> > 
> > <foo>
> >  7
> >  <bar>8</bar>
> >  <baz>
> >    <bay>9</bay>
> >  </baz>
> > </foo>
> > 
> > You can't make all the tags be property names unless you do some serious
> > surgery on the XML.  (It does appear that you are doing some surgery in
> > your fusion document, but I can't seem find out just what you are doing.  A
> > specification of what is going on would be very useful.)
> > 
> > peter
> 
> Peter,
> 
> http://www-db.stanford.edu/~melnik/rdf/syntax.html
> 
> contains a complete specification of a parsing algorithm. Think of
> "getUniqueURI()" as a function that creates a bNode (aka anonymous
> node). If two "property nodes" are nested, one of them is assumed to be
> the type of a bNode.

How can this be?  generateRDF is called on each elementnode and only looks
at the node and its attributes.  How can it do different things for the
middle elements in

	<foo1>
	  <foo2>
	    <foo3>
	     <foo4>
	       <foo5>
	         7
	       </foo5>
	     </foo4>
	    </foo3>
	  </foo2>
	</foo1>

It appears to me that generateRDF would do something like

           foo1    foo2      foo3    foo4      foo5
	.------->.------->.------->.------->.------->.7

which works, and is quite general, except that generateRDF doesn't handle 

	<foo1>
	  <foo2>
	    <foo3>
	     <foo4>
	       <foo5 rdf:instance="bar">
	         7
	       </foo5>
	     </foo4>
	    </foo3>
	  </foo2>
	</foo1>
	
           foo1    foo2      foo3    foo4  bar  ??
	.------->.------->.------->.------->.------->.??
					    |
					    |
					    |
					    v
					    . foo5

> http://www-db.stanford.edu/~melnik/rdf/fusion.html provides a graphical
> interpretation of a sample XML document. In fact, in this example a
> slighly different definition of "getObject()" is used that handles
> dangling PCDATA like "7" in your example above. 

So http://www-db.stanford.edu/~melnik/rdf/syntax.html does not handle
arbitrary XML then?  

The example in http://www-db.stanford.edu/~melnik/rdf/fusion.html appears
to use information not in the XML document.  At least it translates title
and abstract differently and they have what looks to me to be the same
context.

> The example uses ordinal
> properties to represent order. As of now, I'm not convinced that this is
> a good idea any more. How would you represent order in an RDF graph?

Pat's RDF graphs don't handle order.  However, it is possible to, and has been
done (but my reference is at work), add order to a graph that represents
RDF and XML information.  There are lots of ways to do this, one would be
to add a partial order over edges.

> Sergey

peter
Received on Monday, 22 October 2001 22:34:11 GMT

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