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Re: ISSUE-54: Do we need (descriptions of) property functions in SD? Is this in scope for us?

From: Gregory Williams <greg@evilfunhouse.com>
Date: Tue, 2 Mar 2010 16:07:43 -0500
Cc: SPARQL Working Group WG <public-rdf-dawg@w3.org>
Message-Id: <4B836E55-14D4-4F6D-9065-F7D3883B846F@evilfunhouse.com>
To: Andy Seaborne <andy.seaborne@talis.com>, Paul Gearon <gearon@ieee.org>, Steve Harris <steve.harris@garlik.com>
On Feb 22, 2010, at 5:34 AM, Andy Seaborne wrote:

> On 16/02/2010 4:52 PM, Paul Gearon wrote:
>> I believe that we want this.
>> 
>> The scope of what property functions are capable of is essentially
>> unrestricted, so I don't think it's possible to really describe what
>> these functions do. However, it should be possible to obtain a list of
>> properties that fall into this category. As a user I would find that
>> useful in two ways:
>> 
>> 1. I'd know that using this property in a query, or getting it back in
>> a result involves entailed data, and not just extensional data.
>> 2. If I happen to recognize a property from the list, I will know that
>> a particular feature will be available to me.
>> 
>> Regards,
>> Paul Gearon
> 
> I agree.  Property functions are just vocabulary but they also represent a feature that a system provides and an app writer might be aware of. c.f. a custom filter function.  Regarding them as a vocaulary of one property seems rather heavy weight.
> 
> It is hard to define what one is but most of the interesting part is what the specific one does, again, like a custom filter function. We have the opportunity to provide the vocabulary hook to talk about them; it's a feature several systems provide; and the current work on SD gives us a chance to have the same property across descriptions.

Paul, Andy, Steve,

I'd like to try to push the property function issue forward and see if we can't reach some sort of consensus. Andy and Paul seem to see this as an easy thing to include that would have pragmatic benefits while Steve is worried about not being able to define what a property function is and not being able to defend it as in-scope. Have I got that basically right? Is there any sort of compromise to reach here?

thanks,
.greg
Received on Tuesday, 2 March 2010 21:08:13 GMT

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