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Re: [SKOS] SKOS ontology sanity-check?

From: Antoine Isaac <aisaac@few.vu.nl>
Date: Mon, 09 Mar 2009 22:39:37 +0100
Message-ID: <49B58C99.8050208@few.vu.nl>
To: Alistair Miles <alistair.miles@zoo.ox.ac.uk>
CC: SWD WG <public-swd-wg@w3.org>
Hello,

I have now finished checking the XL RDF file [1]!

As for my review of the SKOS RDF file [2], there are really not many important mistakes/comments (most important comments are put between stars).

I however decided to ask quite a lot of questions, even if on minor points, in case these could help improving the overal quality of the work. But as for the SKOS file [3], I'd say that the quality is already extremely high :-)

Cheers,

Antoine

[1] http://www.w3.org/2006/07/SWD/SKOS/reference/20081001/skos-xl.rdf
[2] http://lists.w3.org/Archives/Public/public-swd-wg/2009Mar/0012.html
[3] http://www.w3.org/2006/07/SWD/SKOS/reference/20081001/skos.rdf


=============== general comments

*Dublin core namespace:*
As for the SKOS vocabulary, the new DC namespace (http://purl.org/dc/terms/) is introduced as namespace in the ontology, but only the legacy one (http://purl.org/dc/elements/1.1/) is used. I would suggest to move to the new one. 

Labeling:
If a decision is made to change the labels of the SKOS file, we should check the labels of XL as well.

skos-xl, skosxl or xl?
In the XL file comments, the "xl:" namespace abbreviation is used. In the reference the vocabulary is coined as "XL", but the namespace is abbrevated as "skosxl:". And the namespace itself is "http://www.w3.org/2008/05/skos-xl". Is there a way to enforce some more coherence? Personally I'd prefer using consistently the "skos-xl" brand, to keep to the actual namespace.

*Importing standard SKOS in XL?*
Actually the SKOS reference also defines the axioms that apply to XL constructs refering to "SKOS+XL" data model. This is perfectly fine, but potentially harmful terminologically, related to the previous comment.
In fact, considering that XL is an extension for SKOS, couldn't we just OWL-import the SKOS ontology in the XL RDF file? That could streamline all our story. Also this could give more specific spec for the (OWL) reasoners that want to use both SKOS and XL at the same time.

Formal semantics:
As for my SKOS file review, I would suggest to already give a try at representing the axioms S55, S56 ans S57 in OWL2, to include them in our spec as soon as OWL2 is moved to a more advanced status. 

Issue date
For all vocabulary elements, and contrary to what happen for the SKOS file itself, in XL all resources have a
<dct:issued>2008-12-04</dct:issued>
Is there a specific reason for this? And why 2008-12-04, which is not not the date the Reference was published? I would suggest to just remove these triples.

=============== comments on specific parts of the ontology 

labelRelation:
<rdfs:comment xml:lang="en">xl:labelRelation is not intended to be used directly, but rather as the basis for a design pattern which can be refined for more specific labeling scenarios.</rdfs:comment>
could be a skos:scopeNote

prefLabel, altLabel, hiddenLabel:
I suggest to make these properties disjoint, to mirror what is done for the simple SKOS labelling properties.
I know that in general the dumbing down of the XL labels will reveal cases when a label is assigned by different means to a concept. But there might be (hopefully very marginal) cases where instances of xl:Label with different lexicalForms may be asserted (or inferred) to be the same. In such cases the inconsistency would not be detected.


================================

> On Sat, Feb 07, 2009 at 03:17:00PM +0100, Antoine Isaac wrote:
>> Hi,
>>
>> Note that the second comment raised by Magnus in [1] raises the issue of the sanity-checking the SKOS ontology at [2].
>>
>> I have the feeling that even though this document is crucial for the Recommendation, we (*as a group*) have not scrutinized it as thoroughly as we did for the Reference.
>>
>> Is this feeling right? If yes, I'd propose we take action on this, by having one or two persons browse and validate it.
>> I don't know how this should formally handled with. But I'd be happy to volunteer to make a small review, if need be.
> 
> Yes, it would be great to get some more eyes on the formal schemas for
> SKOS [2] and XL [3].
> 
> I did run some scripts over them to check for consistency with the
> SKOS Reference, but my scripts are fairly simple so cannot check for
> everything.
> 
> FWIW I did...
> 
> [4] --[5]-> [6] (extract formal prose sentences from reference)
> [6] --[7]-> [8] (generate python version of skos as triples)
> [6] --[9]-> [10] (generate python version of xl as triples)
> [2]+[8] --[11]-> [12] (check python skos against rdf skos)
> [3]+[10] --[13]-> [14] (check python xl against rdf xl)
> 
> Cheers,
> 
> Al
> 
> [1] http://lists.w3.org/Archives/Public/public-esw-thes/2009Feb/0014.html 
> [2] http://www.w3.org/2006/07/SWD/SKOS/reference/20081001/skos.rdf
> [3] http://www.w3.org/2006/07/SWD/SKOS/reference/20081001/skos-xl.rdf
> [4] http://www.w3.org/2006/07/SWD/SKOS/reference/20081001/
> [5] http://www.w3.org/2006/07/SWD/SKOS/reference/utils/extract-statements.xsl
> [6] http://www.w3.org/2006/07/SWD/SKOS/reference/20081001/skos.txt
> [7] http://www.w3.org/2006/07/SWD/SKOS/reference/20081001/GeneratePythonSkos.py
> [8] http://www.w3.org/2006/07/SWD/SKOS/reference/20081001/skos.py
> [9] http://www.w3.org/2006/07/SWD/SKOS/reference/20081001/GeneratePythonSkosXl.py
> [10] http://www.w3.org/2006/07/SWD/SKOS/reference/20081001/skosxl.py
> [11] http://www.w3.org/2006/07/SWD/SKOS/reference/20081001/CheckSchema.py
> [12] http://www.w3.org/2006/07/SWD/SKOS/reference/20081001/check-schema-report.txt
> [13] http://www.w3.org/2006/07/SWD/SKOS/reference/20081001/CheckSchemaXl.py
> [14] http://www.w3.org/2006/07/SWD/SKOS/reference/20081001/check-schema-report-xl.txt
> 
Received on Monday, 9 March 2009 21:40:12 GMT

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