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Re: Some thoughts about the revised provenance Model document

From: Luc Moreau <L.Moreau@ecs.soton.ac.uk>
Date: Fri, 30 Sep 2011 09:19:14 +0100
Message-ID: <EMEW3|60949a271436356dc7cf3d837ee86050n8Y9JH08L.Moreau|ecs.soton.ac.uk|4E857B82.1020601@ecs.soton.ac.uk>
To: public-prov-wg@w3.org
Hi Graham,

I agree with what Paul and Jim are saying.

Looking back at OPM: artifacts didn't have such a notion of attributes. 
It's because
they are snapshots of state, where nothing is supposed to change. On the 
other
hand, in PROV, we allow for changes still to happen, but we can only 
really talk about
the provenance of entities for which some aspects have been frozen.

So the provenance of an entity only describes the origin of the entity,  
for these attributes.
Without attributes, we wouldn't know which entity facet the provenance 
relates to.

Cheers,
Luc

On 09/30/2011 08:33 AM, Paul Groth wrote:
> Hi Graham,
>
> I think the purpose of characteristic attributes is to define what 
> your describing the provenance of.
>
> So when I hand you provenance information for example for a web page, 
> you'll know that I'm describing the provenance of x attributes of the 
> web page and not everything there.
> Paul
>
>
> Graham Klyne wrote:
>> Jim,
>>
>> If I understand you correctly, the significance of attributes is for 
>> discovery
>> of of related resources.
>>
>> My understanding is that the primary purpose of provenance is to 
>> establish a
>> basis for trust, a reason to believe (or not) some information that 
>> is presented
>> about some subject.  It's not clear to me what need there is to use 
>> attributes
>> for resource discovery to achieve this end.  (But I may well be missing
>> something here.)
>>
>> So, on this basis, there may be perfectly good reasons to have defined
>> attributes and values for discovery purposes, I'm not seeing why they 
>> are needed
>> to achieve the goals of *provenance* information.
>>
>> (But it's getting late here, and maybe I'm missing some key point in 
>> your message.)
>>
>> In summary: I think your concerns are reasonable, but what makes them 
>> in scope
>> specifically for *provenance* information?
>>
>> #g
>> -- 
>>
>> On 29/09/2011 18:44, Myers, Jim wrote:
>>> Graham,
>>>
>>> How would we use provenance to find, for example, how Luc got to 
>>> Boston? It's clear if we have fixed attributes for name and location 
>>> such that we could query for an entity with name Luc that has an 
>>> ivpOf relationship with an entity in Boston and then look at the 
>>> provenance from there. How would it work without fixed attributes in 
>>> the prov model? I'm guessing that you're thinking that we can find 
>>> those attributes outside the language somewhere (e.g. non-prov RDF 
>>> statements) but what are the minimal requirements there and what 
>>> language/models exist that meet them? Can we only model provenance 
>>> of things for which ontologies have been developed? Presumably it 
>>> has to be possible to associate descriptive metadata with the 
>>> entities through some path (what relationship(s)?)? And it has to be 
>>> clear which metadata is fixed? You mention being able to infer 
>>> across ivpOf relationships - is there one set of inference rules for 
>>> all possible descriptive metadata? Or do we need to be able
>
>> to distinguish further between types of metadata?
>>> -->   As you can probably guess from the questions above, I'm 
>>> concerned that kicking fixed attributes out will end up being more 
>>> complex and place a higher burden on users than keeping them in, but 
>>> I may be misunderstanding how such an alternative would work. Part 
>>> of that concern is that I think I hear that modeling experts in this 
>>> group can handle defining classes for different types of entities 
>>> that would allow discovery by attribute, but I'm concerned that 
>>> being able to do this becomes a requirement for using provenance 
>>> (versus asserting entities defined solely by attributes(entity, 
>>> name=Luc)  or perhaps in a mixed mode (e.g. an entity representing 
>>> Luc that 'hasBaseType' foaf:person and one representing him in 
>>> Boston that also hasBaseType foaf:person and location=Boston as a 
>>> fixed attribute.) Again - perhaps I'm misunderstanding how discovery 
>>> based on descriptive information could be done if we don't have 
>>> fixed characterizing attributes in the prov standard....
>>>
>>>    Jim
>>>
>>>> 3. Do we need to model "Characterizing attributes"?
>>>>
>>>> The notions of "characterizing attributes" have developed to derive 
>>>> the
>>>> relationship between different entities that are views of some common
>>>> thing in the world.  I am not convinced that we need to model these
>>>> attributes, and I'm not sure the way they are modelled can 
>>>> necessarily apply
>>>> in all situations that applications might wish to represent.
>>>>
>>>> At heart:  when it comes to exchanging provenance information, why 
>>>> do we
>>>> *need* to know exactly what makes one entity a constrained view of
>>>> another?  What breaks (at the level of exchanging provenance 
>>>> information) if
>>>> we have no access to such information?  How are applications that 
>>>> exchange
>>>> provenance information about entities for which they don't actually 
>>>> know
>>>> about these attributes to know about their correspondences with 
>>>> real-world
>>>> things?
>>>>
>>>> I think the role of attributes here is mainly to *explain* some 
>>>> aspects of the
>>>> provenance model, but they do not need to be part of the model.
>>>>
>>>> To my mind, a simpler approach would be to allow for assertion of 
>>>> an IVPof
>>>> type of relationship between entities, from which some useful 
>>>> inferences
>>>> about any attributes present might flow, but I don't see the need 
>>>> for the
>>>> attributes to be in any sense defining of the entities.
>>>>
>>>> <aside>
>>>> My suggested definition of IVPof might be something like this:
>>>>
>>>>      A IVPof B  iff  forall p : (Entity ->   Bool) . p(B) =>   p(A)
>>>>
>>>> where A, B are Entities, and the values of p are predicates on 
>>>> Entities.
>>>> </aside>
>>>>
>>>> ...
>>>>
>>>> #g
>>>>
>>>
>>>
>>
>

-- 
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 Friday, 30 September 2011 08:19:57 GMT

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