W3C home > Mailing lists > Public > w3c-rdfcore-wg@w3.org > October 2003

Re: RDF Review

From: pat hayes <phayes@ihmc.us>
Date: Thu, 2 Oct 2003 20:47:39 -0500
Message-Id: <p06001f05bba284fc0680@[]>
To: Ian Horrocks <horrocks@cs.man.ac.uk>
Cc: www-webont-wg@w3.org, Jeff Pan <panz@cs.man.ac.uk>

>Dear All,
>Jeff and I (mostly Jeff) have looked at the latest RDF MT, in
>particular the Datatypes section. We did not have time for an
>exhaustive review, but here are some comments:
>Regards, Ian

Further to my last message, here is a proposed text for the relevant 
part of section 7. This effectively defines 'datatype clash' more 
broadly to cover all the various cases, including the ill-formed 
literal cases.


If the datatypes in the datatype map D impose disjointness conditions 
on their value spaces, it is possible for an RDF graph to have no 
D-interpretation which satisfies it. For example, XML Schema defines 
the value spaces of xsd:string and xsd:decimal to be disjoint, so it 
is impossible to construct a XSD-interpretation satisfying the graph

<ex:a> <ex:b> "25"^^xsd:decimal .
<ex:b> rdfs:range xsd:string .

This situation could be characterized by saying that the graph is 
XSD-inconsistent, or more generally as a datatype clash. Note that it 
is possible to construct a satisfying rdfs-interpretation for this 
graph, but it would violate the XSD conditions, since the class 
extensions of I(xsd:decimal) and I(xsd:string) would have a nonempty 

Datatype clashes can arise in several other ways. For example, any 
assertion that something is in both of two disjoint dataype classes:

_:x rdf:type xsd:string .
_:x rdf:type xsd:decimal .

or that a property with an 'impossible' range has a value:

<ex:p> rdfs:range xsd:string .
<ex:p> rdfs:range xsd:decimal .
_:x <ex:p> _:y .

would constitute a datatype clash. A datatype clash may also arise 
from the use of a particular lexical form, for example:

<ex:a> <ex:p> "2.5"^^xsd:decimal .
<ex:p> rdfs:range xsd:integer .

or by the use of an ill-typed lexical form:

<ex:a> <ex:p> "abc"^^xsd:integer .
<ex:p> rdfs:range xsd:integer .

Datatype clashes are the only inconsistencies recognized by this 
model theory ; note however that datatype clashes involving XML 
literals can arise in RDF and RDFS.

IHMC	(850)434 8903 or (650)494 3973   home
40 South Alcaniz St.	(850)202 4416   office
Pensacola			(850)202 4440   fax
FL 32501			(850)291 0667    cell
phayes@ihmc.us       http://www.ihmc.us/users/phayes
Received on Thursday, 2 October 2003 21:47:42 UTC

This archive was generated by hypermail 2.4.0 : Friday, 17 January 2020 20:24:26 UTC