W3C home > Mailing lists > Public > www-rdf-comments@w3.org > April to June 2002

Re: need to determine what RDF is

From: patrick hayes <phayes@ai.uwf.edu>
Date: Thu, 30 May 2002 11:10:15 -0500
Message-Id: <p0511172ab91bfd4e11d5@[]>
To: Dan Connolly <connolly@w3.org>
Cc: danbri@w3.org, bwm@hplb.hpl.hp.com, www-rdf-comments@w3.org, em@w3.org, w3c-semweb-cg@w3.org, pfps@research.bell-labs.com

>On Thu, 2002-05-30 at 10:26, Peter F. Patel-Schneider wrote:
>>  I'm only interested in relationships between RDF graphs.  Which such
>>  relationships are RDF relationships? 
>>  My view is that the only such relationships are RDF entailment and RDFS
>>  entailment.  Any agent that computes any other relationship between RDF
>>  graphs is not doing RDF.
>Why is RDFS special? It's just the first of many RDF vocabularies,

Its more than just an RDF vocabulary because it has some extra 
semantic conditions. For example, if RDFS is considered purely as an 
RDF vocabulary, then rdfs:subClassOf is not required to be 
transitive; in fact, there is no way to express transitivity of a 
property in RDF. Considered as RDFS, however, it is required to be 
transitive. The distinction is made exact in the MT document by 
distinguishing between RDF-entailment and RDFS-entailment. In 
general, if a particular vocabulary has some extra semantic 
conditions attached to it, then there will be a new notion of 
entailment (I used the generic term 'vocabulary entailment' for this 
idea in the MT document: 
http://www.w3.org/TR/rdf-mt/#NameSpaceEntailment ). Most RDF 
vocabularies, eg dublin core, RSS, have no extra semantics attached 
to them. DAML+OIL certainly does, of course, but then I wouldn't even 
call that an RDF vocabulary in any ordinary sense (yet).

RDFS is also special because its specified in the RDF specs, I guess.


>I could understand a definition that said 'anybody doing more than
>RDF simple entailments isn't doing RDF', but I don't understand
>a definition of RDF that includes RDFS but not dublin core,
>>   (Well, actually, I suppose that an agent could be
>>  determining whether two RDF graphs RDF entail each other, which is
>>  different from RDF entailment, but I think that you should be able to get
>>  my drift.)
>>  peter
>Dan Connolly, W3C http://www.w3.org/People/Connolly/

IHMC					(850)434 8903   home
40 South Alcaniz St.			(850)202 4416   office
Pensacola,  FL 32501			(850)202 4440   fax
Received on Thursday, 30 May 2002 12:10:11 UTC

This archive was generated by hypermail 2.3.1 : Tuesday, 6 January 2015 21:15:18 UTC