W3C home > Mailing lists > Public > public-rdf-comments@w3.org > October 2013

RDF Semantics - datatypes and "identifies" vs "denotes" - ISSUE-145

From: David Booth <david@dbooth.org>
Date: Mon, 28 Oct 2013 21:55:31 -0400
Message-ID: <526F1593.6080907@dbooth.org>
To: Pat Hayes <phayes@ihmc.us>, public-rdf-comments <public-rdf-comments@w3.org>
Hi Pat,

I'm trying to understand the rationale for defining the notion of 
"identifies" as being distinct from "denotes".  As I mentioned before, 
at first reading this appeared to me to be a contrived distinction that 
was created to avoid having a URI denote more than one thing.  But you 
argued that it was needed for the datatype semantics to work out, so I 
wanted to understand that.

http://www.w3.org/TR/2013/WD-rdf11-mt-20130723/#literals-and-datatypes

Section 7 says: "We assume that a recognized IRI identifies a unique 
datatype wherever it occurs, and the semantics requires that it refers 
to this identified datatype."  Therefore, for a recognized IRI, the 
"identifies" mapping is the same as the "denotes" mapping.  So at least 
for recognized IRIs, there appears to be no need to distinguish between 
"identifies" and "denotes".  Is the distinction then needed for 
non-recognized IRIs?  But I don't think I saw any semantic conditions or 
entailment rules for non-recognized IRIs.  Are there some that I missed? 
  I'm not seeing how the datatype semantics requires a distinction 
between "identifies" and "denotes".  Can you explain?  Please feel free 
to shift your reply to www-archive@w3.org instead of posting to this list.

Also, a few small editorial issues/typos:

1. Two typos in this sentence: "RDF processors which are not able to 
determine which datatype is identifier by an IRI cannot recognize that 
IRI, and should treat any literals type with that IRI as unknown names."
s/identifier/identified/
s/type/typed/

2. "Such literals SHOULD be treated like IRIs and assumed to denote" 
should be "Such literals SHOULD be treated like IRIs and SHOULD be 
assumed to denote"?

3. "A literal with datatype d denotes the value obtained by applying 
this mapping to the character string sss: L2V(d)(sss)." should be "A 
literal composed of character string sss with datatype d denotes the 
value obtained by applying this mapping to sss: L2V(d)(sss)."?

Thanks,
David
Received on Tuesday, 29 October 2013 01:56:02 UTC

This archive was generated by hypermail 2.3.1 : Tuesday, 6 January 2015 20:29:58 UTC