RE: New Intro to RDF

I have not studied the paper, but glanced over it and it is always useful to get a 
new perspective.

One question I have come across lately is comparison of rdf vs opml, as the 
latter is purported in my understanding to having a similar function

I am not sure i this is a contentious issue, but if there is any practical 
similarity/distinction it could be useful to have it in there

i ll investigate the matter when I have a moment, but if someone has some 
knowledge please share
thanks

Paola Di Maio

> 
> 
> 
> Hi,
> 
> Thanks for this. I think it is particularly useful to distinguish RDF
> from its XML serialization. 
> 
> I have a couple of comments, but I am not a regular contributor to this
> list, so this is a personal view - please excuse me if I am out of
> place.
> 
> Under the section "What is RDF" you say "RDF is nothing more than a
> general method to decompose information into pieces". I think that this
> cuts straight to the heart of two views of RDF.
> 
> On the one hand, RDF is commonly used and treated as a database of
> information held in "triples". RDF has stimulated a lot of research into
> databases built on triple stores, and for some applications these offer
> significant advantages over conventional relational databases. I think
> the research is very valid and interesting. I also think that this view
> is the most likely to bring immediate benefits to a "Semantic Web". 
> 
> On the other hand, actually RDF IS more than this. It has a formal logic
> which allows you to deduce, for example, that 
> 
> 	<a foo b> implies <foo rdf:type rdf:Property>
> 
> This is pretty feeble on its own, but as you point out towards the end
> of the article, RDFS introduces a wider vocabulary with a richer
> semantics. The point is that the RDF semantics allow you to add extra
> triples that were **not in the original data**. This is part of the
> distinction between a database and an ontology, and I think this
> distinction is worth some extra clarification. 
> 
> 
> 
> Secondly, I would like to make a comment about the use of URLs as unique
> identifiers. This idea is central to RDF and is always included in a
> discussion of its benefits, but this has been an area of some
> controversy, and I think counter arguments deserve a mention. Some
> counter arguments are
> 
> 1. Names only have to be unique IN CONTEXT. For example, I can write a
> program using variable x without any danger of interfering with your
> program, also containing variable x. And in natural language, the phrase
> "I am going to try to catch the plane" has a different meaning in the
> context of an airport and the context of a woodwork shop, but there is
> no difficulty in using the same word for two different things because
> the meaning is clear from the context. 
> 
> 2. Using URLS does not guarantee uniqueness. Many people may choose to
> use the same URL to mean different things. 
> 
> 3. By avoiding the problem of using the same word for different things,
> you multiply the problem of using different words for the same thing,
> and this problem is probably more difficult to resolve. 
> 
> 4. Using URLs makes many people believe that the URL is an address of
> some useful information, and this is not the case. They are just names.
> The URLS can be completely fictitious. More dangerously, the content of
> a URL can change over time. 
> 
> 5. URLS make RDF difficult for humans to read and understand. The
> problem is compounded by that fact that prefixes can be used in some
> places but not in others. 
> 
> In other words, URLS are not a silver bullet, and I think the advantages
> should not be overstated. 
> 
> Tim Glover
> 
> 
> 
> 
> -----Original Message-----
> From: semantic-web-request@w3.org [mailto:semantic-web-request@w3.org]
> On Behalf Of Joshua Tauberer
> Sent: 03 October 2005 23:22
> To: 'SWIG'
> Subject: New Intro to RDF
> 
> 
> Hi,
> 
> As probably everyone on the list knows, there's a lot of negative 
> opinions of RDF out there, and it seems like some of this stems from a 
> confusion of RDF the XML format and RDF the general method for 
> expressing knowledge.  But, I haven't come across a deep explanation of 
> what RDF-the-method is that we can point people to so they know there's 
> more to RDF than the serialization format.
> 
> I know such a document may very well exist, but I figured I would take a
> 
> stab at writing one myself.  (If it has no value for anyone else, at 
> least I gained a deeper understand of RDF by writing it :-).  What I 
> wrote is posted at:
> 
> http://taubz.for.net/code/semweb/whatisrdf/
> 
> The goal was to introduce RDF from the beginning, show why it's useful 
> for modeling knowledge in a distributed way, and to give a basic 
> presentation of RDFS and OWL.
> 
> It's long for an introduction as I tried to be as explicit as possible 
> about what defines RDF (at least in my understanding of RDF).  A shorter
> 
> to-the-point version could be synthesized from this.
> 
> Comments welcome, especially if you think it was worth the time writing.
> :)
> 
> -- 
> - Joshua Tauberer
> 
> http://taubz.for.net
> 
> ** Nothing Unreal Exists **
> 
> 
> 
> 
> 



--

Received on Tuesday, 4 October 2005 11:17:28 UTC