Re: message to RDF entailment implementors

* Pat Hayes <phayes@ihmc.us> [2013-10-31 10:50-0500]
> Reads nicely. I wonder if the immediate-inconsistency of illtyped literals should be spelled out in a bit more detail, and the notion of recognized datatype be expanded slightly. Minor wording changes along those lines suggested here.

Is there any advice to be offered to folks who don't understand the implications of an inconsistency? I can imagine different classes of readers wondering if this change applies to them:

  SPARQL users who are unaware that they are just using graph entailment: SPARQL says that querying for {<s> <p> ?o FILTER (datatype(?o) = xsd:integer} over { <s> <p> "ab"^^xsd:integer } will get you {(?o->"ab"^^xsd:integer)}

  Same users who are using an engine doing RDF/S or DL entailment asking questions which don't require that triple with the malformed object.

  Same again, but who are touching the wretched triple (sameAs? cardinality? i dunno).

  Users of OWL API, etc.


> On Oct 30, 2013, at 3:11 PM, Peter Patel-Schneider <pfpschneider@gmail.com> wrote:
> 
> > One thing that I think would be nice to send out to implementers of RDF entailment systems is something saying what has changed.   Here is a draft of the information.  Comments are welcome.
> > 
> > peter
> > 
> > 
> >   Entailment-visible changes for RDF 1.1 (informative)
> > 
> > Most of the changes between RDF and RDF 1.1 do not have any effect on
> > implementations of entailment, but there are a few minor changes.
> > 
> > The sequence in which the versions of entailment are defined has changed.
> > Datatype entailment is now defined on top of simple entailment, and then
> > RDF and RDFS entailment are defined on top of datatype entailment. Datatype entailment refers to a set of 'recognized' datatypes.  RDF
> > entailment has two required datatypes xsd:string and rdf:langString which must be recognized, but
> > this doesn't appreciably add to RDF entailment as these two datatypes
> > replace plain literals. 
> > 
> > Literals formerly described as plain are now divided into xsd:string literals for plain literals
> > without language tags and rdf:langString literals for plain literals with
> > language tags. Thus, all literals have a type and there is no need for an implementation to have
> > separate data structures for plain literals and datatyped literals,
> > although rdf:langString is a special datatype as it has a language tag in
> > addition to a lexical form and thus requires special treatment.  The zero
> > Unicode character is not allowed in xsd:string, but was allowed in plain
> > literals, so there is a minor change here.  Implementations that have a
> > special internal data structure for plain literals might not need to
> > otherwise change.
> > 
> > One change that does affect entailment is that graphs containing invalid literals (e.g.,
> > "a"^^xsd:integer) are immediately inconsistent for recognized datatypes, even in sub-RDFS entailment regimes. 
> > 
> > There is a list of XML Schema datatypes that are deemed suitable for use
> > within RDF.  They are all optional except for xsd:string.
> > 
> > The rdf:XMLLiteral datatype is now optional.  rdf:HTML is a new optional
> > datatype; implementation experience and illustrative tests are requested.(Note also that this has at-risk aspects concerning DOM4 normalization.) 
> > rdf:PlainLiteral is a newish optional datatype; implementation experience
> > and illustrative tests are requested.
> > 
> 
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> 
> 
> 
> 

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Received on Friday, 1 November 2013 09:48:41 UTC