LC comments SWD Working Group

Dear OWL WG,

The Semantic Web Deployment (SWD) Working Group has reviewed the
OWL2 Last Call documents. We apologise that these comments are
provided to you after the deadline. We hope you will still be
able to consider them.

NOTE: Our comments are given from the perspective of the work of
SWD on SKOS [1], as SKOS is based on RDF/OWL.


1. The SWD WG notes that some of the extensions provided by OWL2
appear to be useful for SKOS. For example, property disjointness
can be used in specifying the semantics for SKOS mapping
relations. Although currently not needed in the SKOS semantics,
we can foresee use cases for new property characteristics such
as (ir)reflexivity and asymmetry, e.g. for specifying 
application-specific specializations of SKOS semantic relations. 
For alignment between SKOS and OWL DL the possibility to define 
axioms about annotation properties is perceived as useful.


2. The SWD WG is disappointed about the way the OWL2 material is
presented, in particular the lack of using either an RDF/XML or
an RDF triple representation of OWL2. Even the " New Features
and Rationale" document [2] refrains from using such syntax.
This makes the OWL2 documents inaccessible for the typical SKOS
user. We request that the OWL WG remedies this situation.


3. The SWD WG notes that most OWL2 documents give the impression
that OWL2 is just an extension of OWL1 DL, and not of OWL1 Full.
For example, the introduction of  OWL2 Direct Semantics document
states [3]:

    [[
      Since OWL 2 is an extension of OWL DL
    ]]

Only one document clearly makes the OWL2 DL and OWL2 Full
distinction [4]. In our experience  OWL Full is the dominant OWL
usage pattern for SKOS. We therefore request that the OWL2
document are edited in such a way that whenever the term "OWL2"
is used, it is used to refer to the OWL2 language as a whole
(OWL2 DL and OWL2 Full). If OWL2 DL is meant, it should be
explicitly marked as such. We also request that the nature and
role of OWL2 Full are clearly stated in other central OWL
documents, not just in [4].

4. The SWD Working Group would like the OWL Working Group to 
clarify in the documents that RDF/XML remains to be the 
normative exchange syntax for OWL and that the other syntaxes 
fulfil a role similar to the N-Triples syntax for RDF.

We hope these comments are of use to you.

Best,
Guus Schreiber
on behalf of the Semantic Web Deployment Working Group

[1] http://www.w3.org/TR/skos-reference/
[2] http://www.w3.org/TR/2008/WD-owl2-new-features-20081202/
[3]
http://www.w3.org/TR/2008/WD-owl2-semantics-20081202/#Introduction
[5] http://www.w3.org/TR/2008/WD-owl2-rdf-based-semantics-20081202/