-------- Original Message --------
Subject: early information on W3C RDF WG RDF 1.1 entailment
implementation reporting
Date: Fri, 1 Nov 2013 18:44:30 +0000
From: Patel-Schneider, Peter <[email protected]>
To: Undisclosed recipients <[email protected]>
Greetings (and apologies for the mass mailing):
The W3C RDF Working Group is planning on shortly going to Candidate
Recommendation stage for the RDF 1.1 Semantics document. The
Candidate Recommendation stage is when the working group formally asks
for implementation experience. For the RDF 1.1 Semantics document the
relevant implementations are those that perform entailment on RDF
graphs.
This is a bit of a heads-up to groups that are believed to have
implementations of entailment on RDF graphs, and an early request to
participate in the implementation experience process. An official
announcment and more details on the precise process will be forthcoming
soon.
The testing process has not yet been completely finalized, although the
process will involve generating something called an EARL report. The
only real requirement for testing is a system that can determine some
kind of RDF 1.1 entailment for some set of recognized datatypes (maybe
the empty set).
If you are interested in participating in the process, especially in
helping to determine which tests will be used, please respond to this
message. Early results, in any form, on the tests themselves would be
particularly useful.
The current proposed draft of the RDF 1.1 Semantics document is available at
https://dvcs.w3.org/hg/rdf/raw-file/default/rdf-mt/index.html
An informative description of the entailment-visible changes in RDF
1.1 is given below.
The main page for the testing is http://www.w3.org/2013/rdf-mt-tests/
The testing is described at
https://dvcs.w3.org/hg/rdf/file/tip/rdf-mt/tests/README
There is a set of tests for entailment, modified from the tests
performed in 2004. These tests are listed in
https://dvcs.w3.org/hg/rdf/file/tip/rdf-mt/tests/manifest.ttl
There is also another set of proposed tests,
concentrating on changes and extensions and difficult cases.
These proposed tests are listed in
https://dvcs.w3.org/hg/rdf/file/tip/rdf-mt/tests/manifest-az.ttl
Peter F. Patel-Schneider
Entailment-visible changes in 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. Datatype
entailment formally refers to a set of 'recognized' datatypes,
replacing the old datatype maps, but this does not have any effect on
implementation.
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 literals 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 it requires
special treatment. Implementations that have a special internal data
structure for plain literals might not need to appreciably change.
The zero Unicode character is not a valid element in xsd:string
values, but was allowed in plain literals, so there is a minor change
here.
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 rdf:HTML has at-risk aspects concerning
DOM4 normalization.) rdf:PlainLiteral is a newish optional datatype;
implementation experience and illustrative tests are requested.
RDF 1.1 includes RDF Datasets. However, the semantics of RDF Datasets
in RDF 1.1 is minimal and entailment per se is only defined on RDF
graphs so there are no changes here.
