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Re: PROV-ISSUE-183 (prov-dm-identifiers): identifiers in prov-dm [prov-dm]

From: Paul Groth <p.t.groth@vu.nl>
Date: Tue, 06 Dec 2011 18:35:59 +0100
Message-ID: <4EDE527F.7050508@vu.nl>
To: Luc Moreau <L.Moreau@ecs.soton.ac.uk>
CC: Provenance Working Group WG <public-prov-wg@w3.org>
Hi Luc,

Hmm, I think I remember this now..... so everything can be an entity 
record as soon as you type it as such.

For example if I have a webpage:

http://www.example.com/webpage

It becomes an entity record, as soon as I do:

entity(http://www.example.com/webpage, [])

Is that a correct interpretation?

Paul




Luc Moreau wrote:
> Hi Paul,
>
> So, OK, we could mint identifiers for entity record
>
>             entity(<a minted identifier here>, [ex:param="a", ex:port="foo"])
>
> (Which by the way is what OPM does.)
>
> How do you refer to the entity now? We don't know what this record is about.
>
> Luc
>
> On 12/06/2011 05:11 PM, Paul Groth wrote:
>> So I always thought that you could mint identifiers for entity records
>> but you didn't have to and we supported that.
>>
>> But maybe that's my head inserting text where it shouldn't have been....
>>
>> Paul
>>
>> Luc Moreau wrote:
>>> ... the conclusion issue ;-)
>>>
>>> No, we have no formal decision on this.
>>>
>>> We wrote this in the prov-dm document a long time ago (before fpwd), and
>>> we have
>>> been refining it over time.
>>>
>>> I think it's an inevitable consequence of two key decisions:
>>> - distinguishing entities (in the world) from entity records (in the
>>> provenance)
>>> - not mandating the minting of new URIs for entity records
>>>        (no formal decision on this, but I think we have support for
>>> it, since
>>>         we want to minimize the effort to generate provenance)
>>>
>>> Luc
>>>
>>>
>>> On 12/06/2011 04:56 PM, Paul Groth wrote:
>>>> Hi Luc,
>>>>
>>>> Do you have a pointer to wear we reached the consensus about the dual
>>>> role of identifiers?
>>>>
>>>> Thanks,
>>>> Paul
>>>>
>>>> Provenance Working Group Issue Tracker wrote:
>>>>> PROV-ISSUE-183 (prov-dm-identifiers): identifiers in prov-dm
>>>>> [prov-dm]
>>>>>
>>>>> http://www.w3.org/2011/prov/track/issues/183
>>>>>
>>>>> Raised by: Luc Moreau On product: prov-dm
>>>>>
>>>>>
>>>>> Hi,
>>>>>
>>>>> It think that it is now time to have a proper debate about
>>>>> identifiers in prov-dm since comments are regularly expressed about
>>>>> them. I have raised this issue about this topic so that we can track
>>>>> the conversation properly. Our hope is to reach consensus on this
>>>>> topic by the time of the third working draft.
>>>>>
>>>>> First, in the fpwd, there was a mention of "qualified identifier"
>>>>> (appearing in a note see [1]).  We have removed this term from the
>>>>> second working draft.
>>>>>
>>>>> Second, the complementarity record now explicitly allows for linking
>>>>> entity records across accounts. Its syntax allows for two accounts to
>>>>> be named.
>>>>>
>>>>> Third, identifiers for entities in prov-dm have a dual role [3]. An
>>>>> entity has got an id (typically given by an application). An entity
>>>>> record --- i.e. what we say about an entity in a provenance record
>>>>> --- also has an id. There is a consensus that we shouldn't mint
>>>>> identifiers for provenance records. Hence, the identifier of the
>>>>> entity record is defined to be the same as the identifier of the
>>>>> entity.
>>>>>
>>>>> The consequence of this is that two entity records in different
>>>>> accounts may have the same identifier: they may say different things
>>>>> about the same entity.  For example, the document ex:doc was
>>>>> generated by latex in account1, while in account 2, ex:doc is
>>>>> described to be the result of a survey of a field by different
>>>>> authors.
>>>>>
>>>>> This explains why we needed the complementarity record to name the
>>>>> accounts as well. This assumes that account names need to be named
>>>>> uniquely (see [4]).
>>>>>
>>>>> So, entity records identifiers are scoped to accounts.  Note, I said
>>>>> entity *records*, not entities. Hence, we are not breaking the
>>>>> semantic web approach: an entity is a resource and is denoted by a
>>>>> URI, and this remains true in all accounts. (I guess that from a
>>>>> semantic web perspective we are not looking at a provenance record as
>>>>> resource, since we don't have a global URI to name it.) Finally, we
>>>>> allow for accounts to be nested hierarchically; this fits nicely with
>>>>> abstraction in provenance records. Again, see [4].
>>>>>
>>>>> Can you express your views about this approach, as currently defined
>>>>> in the second draft of prov-dm?
>>>>>
>>>>> Thanks, Luc
>>>>>
>>>>> [1]
>>>>> http://www.w3.org/TR/2011/WD-prov-dm-20111018/#expression-identifier
>>>>> [2]
>>>>> http://dvcs.w3.org/hg/prov/raw-file/default/model/ProvenanceModel.html#record-complement-of
>>>>>
>>>>>
>>>>>
>>>>>
>>>> [3]
>>>> http://dvcs.w3.org/hg/prov/raw-file/default/model/ProvenanceModel.html#record-Entity
>>>>
>>>>
>>>>> [4]
>>>>> http://dvcs.w3.org/hg/prov/raw-file/default/model/ProvenanceModel.html#record-Account
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>

-- 
Dr. Paul Groth (p.t.groth@vu.nl)
http://www.few.vu.nl/~pgroth/
Assistant Professor
Knowledge Representation & Reasoning Group
Artificial Intelligence Section
Department of Computer Science
VU University Amsterdam
Received on Tuesday, 6 December 2011 17:36:42 UTC

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