[doap-interest] On the cardinality of properties

[Jorge Santos]

Damian Steer <pldms at mac.com> writes:

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> On 26 Jan 2005, at 23:11, Jorge Santos wrote:
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>> Hello, I have reviewed the IBM developerWorks articles and the mailing
>> list and I couldn't find an answer to this so here it is: wouldn't it
>> be a good idea to give a cardinality property
>> (http://www.w3.org/TR/2004/REC-owl-guide-20040210/#simpleCardinality)
>> to some of the properties defined in the DOAP schema to make some
>> fields compulsory.
>
> Strictly speaking cardinality restrictions say things like 'property X
> has a value' not 'property X must have a value'. So it doesn't really
> say what (I think) you want. As a result you don't see it used in RDF
> schemas.
>

What I want to express is: resources which are instances of
such-and-such class have at least one of such-and-such properties.  I
understand that RDF Schemas are merely descriptive if that is what you
meant.

> However although OWL restrictions don't do the same job as
> restrictions in XML schema I think this is a good idea. The RSS 1.1
> proposal [1] does what you suggest. I've also be using OWL for
> validation-ish tasks in a project I'm working on currently, and I've
> even put in a paper covering this topic for XTech. Basically it's
> useful documentation in the schema, and one might even (gently)
> suggest that those properties should have values if they're missing in
> documents.
>

And refering specifically to the DOAP schema, shouldn't the
cardinality of some properties be specified?

Jorge