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Re: [dxwg] Change domain or create superclass of dcat:Distribution

From: Simon Cox via GitHub <sysbot+gh@w3.org>
Date: Tue, 04 Sep 2018 23:57:57 +0000
To: public-dxwg-wg@w3.org
Message-ID: <issue_comment.created-418555005-1536105476-sysbot+gh@w3.org>
Thanks @kcoyle . 

I suggest not fretting too much about UML. This is not a UML model. The diagram is merely a rendering of the OWL model using UML-style notation. The UML-style notation has been found to be expressive and familiar enough that it is scattered through many (most?) W3C Recommendations that describe ontologies. However, you do raise important concerns about not getting sucked into the OO paradigm. 

Whenever I'm stressed about RDFS/OWL modeling I remind myself that a _set based_ analysis is the correct approach. Venn diagrams would send that message better, but it is hard to show lists of class attributes. 

>From a set-theoretic point of view the 'abstract' class `dcat:Resource` exists - it is the union of `dcat:Dataset`, `dcat:DataService` plus any other catalogable things that people want to use DCAT for. I think we are all OK with that? There is no notion of 'abstract class' in RDFS or OWL - the best in this context would probably be an anonymous union class, but by giving it a name we provide an extensibility point for other kinds of catalog. 

What we are now thinking about is whether there is a corresponding class of `dcat:Representation` which has any members that are not `dcat:Distribution`. To resolve this question we should ask whether the Resource corresponding to every notional Representation is a `dcat:Dataset`. If yes, then every Representation is a `dcat:Distribution` and we don't need a new class. @rob-metalinkage confirmed that he created this issue because

> I dont think a **profile** is either a Dataset or a Service - so its a direct subclass of Resource, hence the need to have the equivalent of a Distribution

So maybe we should focus on that question first, and deal with whether that requires an (abstract?) class for Representation subsequently. 

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Received on Tuesday, 4 September 2018 23:57:58 UTC

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