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Re: message to RDF entailment implementors

From: Pat Hayes <phayes@ihmc.us>
Date: Thu, 31 Oct 2013 10:50:23 -0500
Cc: RDF WG <public-rdf-wg@w3.org>
Message-Id: <8532EEFC-C94B-4DA2-8A2A-2677D282E2B3@ihmc.us>
To: Peter Patel-Schneider <pfpschneider@gmail.com>
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.

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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Received on Thursday, 31 October 2013 15:50:51 UTC

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