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Re: PS-16: Regular Expression Comparison of Datatype Lexical Forms

From: Janne Saarela <janne.saarela@profium.com>
Date: Fri, 02 Apr 2004 15:55:47 +0300
Message-ID: <406D62D3.3070707@profium.com>
To: public-rdf-dawg@w3.org
Cc: Patrick Stickler <patrick.stickler@nokia.com>

>> Is this use case as generic as I think it is?
>>
>> For example, if the data type is XSD#dateTime and I was
>> looking for *2*, I would be matching both lexical forms
>>
>> 2002-12-13T12:03:23
>> 1999-03-14T12:45:13
>>
>> I am not sure this is a necessary use case.
>> I would agree regular expressions are useful for some
>> datatypes such as strings but not for all of them such as
>> dateTime.
> 
> 
> I don't see any need to "protect the users from themselves"
> by only permitting certain kinds of regular expression comparision.

No, I'm not saying certain kinds of regular expressions but
"regular expressions should be applicable for only certain data types
such as strings".

Let's say a triple store stores dates in a Oracle DATE specific
column. I don't think it is a useful use case to
look for substring *2* match in the lexical form of the stored
value. In fact, the search would be very inefficient.

Janne

> So long as we make it clear that trying to match a substring of
> a URI or lexical form is "stepping outside the bounds" of the
> RDF MT, then we should allow folks to do it.
> 
> After all, one could just as well argue that plain literal values
> are to be treated just as opaquely as typed literal lexical forms
> or URIs. They only have meaning as a whole, not per any substring
> of their form. Looking into a plain literal is "stepping outside
> the bounds" of the RDF MT just as much as looking inside a URI.
> 
> Patrick
> 
> 
>>
>> Janne
>>
>>> A client wishes to discover resources which for a given property
>>> have datatype values having lexical forms which match a particular
>>> regular expression, and obtain descriptions of those resources.
>>> The client is aware of a source of knowledge from
>>> which such resources might be discovered.
>>> Following the DAWG recommendation, the client formulates a
>>> query which describes one or more example templates which
>>> reflect the desired characteristics and submits the query
>>> to the knowledge source.
>>> The knowledge source returns a set of zero or more
>>> resource descriptions, each description describing a
>>> resource which matched an example template.
>>> -- 
>>> Patrick Stickler
>>> Nokia, Finland
>>> patrick.stickler@nokia.com
>>
>>
>>
>> -- 
>> Janne Saarela <janne.saarela at profium.com>
>> Profium, Lars Sonckin kaari 12, 02600 Espoo, Finland
>>
>>
> 
> -- 
> 
> Patrick Stickler
> Nokia, Finland
> patrick.stickler@nokia.com
> 
> 
> 


-- 
Janne Saarela <janne.saarela at profium.com>
Profium, Lars Sonckin kaari 12, 02600 Espoo, Finland
Tel. +358 (0)9 855 98 000 Fax. +358 (0)9 855 98 002
Mob. +358 (0)40 508 4767  Internet: http://www.profium.com
Received on Friday, 2 April 2004 07:58:05 GMT

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