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Re: Semantics, Basic, OWL 2 and POWDER

From: Stasinos Konstantopoulos <konstant@iit.demokritos.gr>
Date: Wed, 14 May 2008 13:48:45 +0300
To: Public POWDER <public-powderwg@w3.org>
Message-ID: <20080514104845.GA15995@iit.demokritos.gr>

On Wed May 14 12:08:07 2008 Andrea Perego said:

>>> The proposal for the POWDER-BASIC schema requires just includeregexp, 
>>> i.e., it does not require any constraint on the IRI host. This means  
>>> that, if a POWDER-BASIC document is obtained from a POWDER one, the  
>>> constraint on the IRI host is kept, since it is in the original 
>>> POWDER document. However, if anyone writes directly his/her own 
>>> POWDER-BASIC document, we cannot be sure that the constraint on the 
>>> IRI host will be kept.
>>>
>>> So, we have two options:
>>>
>>> 1. Drop the constraint on the IRI host: in such a case, this won't be 
>>> required by POWDER, and POWDER-BASIC will be as proposed.
>>>
>>> 2. Keep the constraint: in such a case, the POWDER XML schema won't 
>>> be changed, but we have to put such constraint in the POWDER-BASIC 
>>> XML schema. I see here a possible option: the POWDER-BASIC XML schema 
>>> requires one and exactly one instance of <includehosts /> AND  
>>> <includeregexp /> in an <iriset />.
>>
>> The whole point of POWDER-BASIC is that it knows nothing about
>> <includehosts />, so (2) is not possible.
>>
>> (1) is possible, but unnecessary. We can keep the POWDER constraint, and
>> not worry about POWDER-BASIC (or, for that matter, POWDER-S) authors.
>>
>> Implementors of POWDER-BASIC extensions will have to specify their own
>> constraints, depending on their domain and target audience.
>>
>> So, I suggest:
>>
>> 3. Keep the constraint: in such a case, the POWDER XML schema won't be
>> changed. Futhermore, not all POWDER-BASE documents can be turned into
>> valid POWDER documents. This looks OK, there is no reason to guarantee
>> the convertibility in this direction.
>
> I was not proposing to keep the constraint on the IRI host with the  
> purpose of converting POWDER-BASIC into POWDER. The problem is, as I  
> said, that, if only includeregexp is required, I can write a  
> POWDER-BASIC document claiming that "all the resources hosted by any  
> host, and having a path starting with /foo, are blue." Should we allow 
> this?

POWDER-BASIC knows nothing about hosts and paths, it only knows how to
match IRIs against regexps. So, yes, POWDER-BASIC authors can write
overly generic regexps like "http://[^/]+/foo" or even ".*" if they
really want to.

Note, however, that POWDER-BASIC is not meant for POWDER authors but for
POWDER extension developers, who should know better than to define an
extension that allows this to happen. See how POWDER requires
includehosts, ISAN could, for example, require includeroots, and so on.

s
Received on Wednesday, 14 May 2008 10:49:39 GMT

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