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Re: PROV-ISSUE-145 (Tlebo): qualified identifiers may not work well with named graphs [Data Model]

From: Timothy Lebo <lebot@rpi.edu>
Date: Tue, 22 Nov 2011 10:41:56 -0500
Cc: Luc Moreau <L.Moreau@ecs.soton.ac.uk>, public-prov-wg@w3.org
Message-Id: <B50ED2AA-1855-41C0-9021-3FC8CC8C1728@rpi.edu>
To: Graham Klyne <GK@ninebynine.org>

On Nov 13, 2011, at 6:50 AM, Graham Klyne wrote:

> On 10/11/2011 17:13, Luc Moreau wrote:
>> Hi Graham,
>> 
>> When you say 'documents', do you mean accounts?
> 
> No.  I was talking generically about "documents" with a formal semantic interpretation, and more specifically I meant resources containing provenance information.
> 
> Reflecting on this, and qualifying the comment: it applies to using RDF without named graphs.  If named graphs are used then whether or not it applies will depend on the formal semantics of named graphs.
> 
> Generally, though, I think it is not a good idea to allow different accounts to use the same URI for different entities.


This violates the paramount design principle of the web.

http://example.org/id/entity/2 in http://example.org/id/account/2>
MUST be the same as 

http://example.org/id/entity/2 in http://example.org/id/account/1>

in http://dvcs.w3.org/hg/prov/file/7ef37443dc30/ontology/components/Account/different-accounts-can-include-the-same-entity.ttl

Anything I say about one, I am saying about the other.


>  While accounts may contain statemenbts that are specific to the account, they should also provide for inferences about things (specifically, Entities) that hold outside the context of an account; e.g. entity1 derivedfrom entity2, if true, should be true independently of any account considered.


And a provenance consumer could always choose to omit anything that is said in an Account.

-Tim


> 
> #g
> --
> 
> We are not saying
>> that two different accounts have to be combined. On the contrary,
>> they exist, but we may have to establish relations between the 'provenance records'
>> we made in these accounts. (wasComplementOf is an example of this)
>> 
>> Luc
>> 
>> On 11/10/2011 03:45 PM, Graham Klyne wrote:
>>> On 07/11/2011 08:57, Luc Moreau wrote:
>>>> Hence, two different entities could be asserted by two different asserters in
>>>> different accounts,
>>>> and both may have chosen the same URI to identify them.
>>> 
>>> That would be contradictory at the level of RDF.
>>> 
>>> I think any attempt to combine documents with such usage would render the
>>> result formally meaningless (or at least fail to formally convey the intended
>>> meaning).
>>> 
>>> #g
>>> --
>>> 
>>> 
>>>> If we want to avoid this, then it must be a requirement that new URIs are minted
>>>> for all
>>>> entities. But I thought the WG wanted to move away for that, since it prevents
>>>> lightweight assertions
>>>> of provenance.
>>>> 
>>>> So, the minting burden, i think, is put at the level of accounts.
>>>> BTW, prov-dm is currently not suggesting that, since it says that account
>>>> identifiers are also scoped,
>>>> but I think this is not good.
>>>> 
>>>> Luc
>>>> 
>>>> On 11/06/2011 11:49 PM, Tim Lebo wrote:
>>>>> Hi, Luc!
>>>>> 
>>>>> Sent from my iPhone
>>>>> 
>>>>> On Nov 6, 2011, at 17:44, Luc Moreau<L.Moreau@ecs.soton.ac.uk> wrote:
>>>>> 
>>>>>> Hi Tim,
>>>>>> 
>>>>>> We need to explore this in detail.
>>>>>> To me, it is crucial to be able to assert that entity e1 in account acc1 is
>>>>>> complementOf entity e2 in acc2.
>>>>> Absolutely.
>>>>> 
>>>>>> How do you propose doing this?
>>>>> Would the one triple
>>>>> 
>>>>> :e1 prov:wasComplementOf :e2 .
>>>>> 
>>>>> work? This would stand independent of what account the entities are in --
>>>>> which gets to the point I was making that the asserter needs to make distinct
>>>>> URIs and not depend on some account-based scoping mechanism to establish its
>>>>> identity.
>>>>> 
>>>>> Perhaps I am misinterpreting DM again from a "too RDF" perspective like the
>>>>> literal versus URI discussions earlier today.
>>>>> 
>>>>> Best,
>>>>> Tim
>>>>> 
>>>>>> 
>>>>>> 
>>>>>> Professor Luc Moreau
>>>>>> Electronics and Computer Science
>>>>>> University of Southampton
>>>>>> Southampton SO17 1BJ
>>>>>> United Kingdom
>>>>>> 
>>>>>> On 6 Nov 2011, at 21:24, "Timothy Lebo"<lebot@rpi.edu> wrote:
>>>>>> 
>>>>>>> By "appropriately scoped", I mean "predefined, consciously selected; URIs".
>>>>>>> 
>>>>>>> the note "refer to an identifier in the scope of a given account" sounds
>>>>>>> like we are going to permit lazy naming that can be computed in the future,
>>>>>>> which current named graph implementations do not support.
>>>>>>> 
>>>>>>> -Tim
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>> On Nov 6, 2011, at 2:32 AM, Luc Moreau wrote:
>>>>>>> 
>>>>>>>> Hi Tim,
>>>>>>>> 
>>>>>>>> What do you mean by appropriately scoped?
>>>>>>>> 
>>>>>>>> Luc
>>>>>>>> 
>>>>>>>> 
>>>>>>>> 
>>>>>>>> I propose that we require the asserters to define appropriately-scoped URIs
>>>>>>>> for their identifiers. Letting them be lazy up front will cause headaches
>>>>>>>> when actually trying to use it.
>>>>>>>> 
>>>>>>>> 
>>>>>>>> 
>>>>>>>> 
>>>>>>>> 
>>>> 
>>> 
>> 
> 
> 


Received on Tuesday, 22 November 2011 15:43:05 UTC

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