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

From: Luc Moreau <L.Moreau@ecs.soton.ac.uk>
Date: Tue, 06 Dec 2011 17:18:20 +0000
Message-ID: <EMEW3|7781f38f7688b780417f57026c90ce47nB5HIM08L.Moreau|ecs.soton.ac.uk|4EDE4E5C.3070208@ecs.soton.ac.uk>
To: Paul Groth <p.t.groth@vu.nl>
CC: Provenance Working Group WG <public-prov-wg@w3.org>
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 
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>
>

-- 
Professor Luc Moreau
Electronics and Computer Science   tel:   +44 23 8059 4487
University of Southampton          fax:   +44 23 8059 2865
Southampton SO17 1BJ               email: l.moreau@ecs.soton.ac.uk
United Kingdom                     http://www.ecs.soton.ac.uk/~lavm
Received on Tuesday, 6 December 2011 17:18:59 UTC

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