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Re: [dxwg] Use of dct:type with both Class and Concept

From: Karen Coyle <kcoyle@kcoyle.net>
Date: Fri, 17 Aug 2018 11:35:34 -0700
To: public-dxwg-wg@w3.org
Message-ID: <d0f41afc-4662-ec0c-72d2-26c06d414b0a@kcoyle.net>

On 8/17/18 1:28 AM, Rob Atkinson via GitHub wrote:
> Really interested in the take of others here - there are a couple of
> ways of looking at this - but I have never been able to find a cogent
> argument why we shouldnt assume that a rdfs:Class is actually a type of
> skos:Concept - classes are nothing more that concepts that define sets
> of instances.
> It seems to be explicitly supported in OWL 2 as "punning"
> [https://www.w3.org/2007/OWL/wiki/Punning]

"3.5.1. SKOS Concepts, OWL Classes and OWL Properties

Other than the assertion that skos:Concept is an instance of owl:Class,
this specification does not make any additional statement about the
formal relationship between the class of SKOS concepts and the class of
OWL classes. The decision not to make any such statement has been made
to allow applications the freedom to explore different design patterns
for working with SKOS in combination with OWL."



> It seems a perfectly natural Use Case to me to model skos:Concepts as
> types in systems, then generate rdfs: and owl Class models only if and
> when we need to model additional behaviours.
> skos:Concept is relevant for "soft-typing" and rdfs:Class for
> hard-typing - and the equivalence is actucally a useful thing.
> Is OWL-Full really a problem? I think not for several reasons:
> 1) I dont see evidence that OWL-DL (or any other flavour) inferencing is
> happening at run-time across distributed systems - all "semantic web"
> implementations I have see cache any models they want to use.
> 2) There is currently no way of telling a client, not specification,
> constraining referenced models to be any particular profile of OWL - so
> no assumptions can be made anyway
> 3) With negotiation-by-profile the same concept can be served with a
> graph that conforms to SKOS, RDFS, OWL-DL, OWL-Full, SHACL and any other
> specific profile needed by a client.
> IMHO there is a need to provide a specific example of the problem and
> why its a problem, and how to handle the use cases of soft-typing.
> My feel here, although I can prove it, is that negotiation by profile
> and OWL 2 punning are two sides of the same coin - implementation and
> theory,  and essentially we can get out of the bind by the URI
> dereferencing architecture - OWL-DL reasoners can ask for the metaclass
> representation they want.
> Default behaviour for OWL - i.e. if a client asks for OWL perhaps an
> OWL-DL representation SHOULD be returned.  I dont know if the profile
> guidance or content negotiation scope will allow us to go into this
> platform specific detail - or where and who in W3 cares about the
> general architecture of distributed OWL models?

Karen Coyle
kcoyle@kcoyle.net http://kcoyle.net
m: 1-510-435-8234 (Signal)
skype: kcoylenet/+1-510-984-3600
Received on Friday, 17 August 2018 18:35:59 UTC

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