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Re: PROV-ISSUE-35: Section 4: How one would know that two BOBs are characterizations of the same entity? [Conceptual Model]

From: Khalid Belhajjame <Khalid.Belhajjame@cs.man.ac.uk>
Date: Mon, 25 Jul 2011 18:03:36 +0100
Message-ID: <4E2DA1E8.7090306@cs.man.ac.uk>
To: Paolo Missier <Paolo.Missier@ncl.ac.uk>
CC: public-prov-wg@w3.org

Hi Paolo,

On 25/07/2011 13:27, Paolo Missier wrote:
> Khalid, Jim
> the issue that lurks behind this discussion is, once again, that of 
> identity in the space of characterized entities (C-entities). The 
> draft doc avoids talking about identity and instead mentions 
> /identifiers/ which belong in the model. These identifiers have more 
> of a technical than a semantic meaning, i.e., they exist so one can 
> refer to, and link across, different Bobs in the model.
> With this, see if I can summarize that we have:
> - Khalid suggests to introduce sameEntityAs as an equivalence relation 
> in the C-entities space, and then admit axiomatic assertions of the form
> (1)  sameEntity(b1,b2)
> where b1, b2 are (identifiers of) two Bobs in the model.
> - Jim suggests that it should be possible to assert, also axiomatically:
> (2)  "Bob b1 refers to entity A",   "Bob b2 refers to entity A"
> The main difference is that assertions (2) require us to mention A, 
> which lives in C-Entity space, and so far we have not made any 
> provision to do so. (1) has not such requirement.

That is exactly why I thought of (1) instead of (2), this way we don't 
have to include a new term to the vocabulary.

Thanks, khalid

> If you use the Royal Society example 
> http://dvcs.w3.org/hg/prov/raw-file/default/model/ProvenanceModel.html#IVP-of 
> for reference, this means:
> - using (2) I need to be able to say "Royal Society" somewhere in the 
> language
> - using (1) I don't, but then I never really know what the BOBs refer to.
> To me it boils down to whether we ever need to mention "Royal Society" 
> or we are happy to say "b1, b2 refer to the same C-entity 
> which-shall-not-be-named".
> Notes:
> - if we have (2), then (1) follows.
> - (1) is sufficient to reason about IVP-of relations, i.e. using 
> entity resolution algorithms (which, as Jim points out, are outside 
> the PIL language).
> -Paolo
> On 7/21/11 9:11 PM, Jim McCusker wrote:
>> In the simple case, if a BOB refers to Entity A (for instance, as a
>> URI), and another BOB also refers to Entity A, then the BOBs refer to
>> the same Entity.
>> The complex case, where we try to resolve the entities by examining
>> the BOBs closely, I think is outside of the PIL, and can be determined
>> by applications using whatever algorithms they think are important.
>> Jim
>> On Thu, Jul 21, 2011 at 3:39 PM, Khalid Belhajjame
>> <Khalid.Belhajjame@cs.man.ac.uk>  wrote:
>>> On 21/07/2011 20:20, Luc Moreau wrote:
>>> Hi Khalid,
>>> Can you expand on this? What would it help us to achieve?
>>> At F2F1, some mentioned "turtle all way down" to refer to the idea 
>>> that we
>>> are not trying
>>> to make a distinction between an entity and its state (as we used to 
>>> say
>>> then).
>>> This would translate into the fact that we only have characterized 
>>> entities
>>> ...
>>>    and are not trying to distinguish an entity from a characterized 
>>> entity.
>>> Can you explain what benefits you see in distinguishing entity from
>>> characterized entity?
>>> So, does it mean in the example, you would say that e1 is same 
>>> entity as e2?
>>> Potentially, this could be captured by (the very rough) definition of
>>> version.
>>> Yes, possibly, I actually first thought that "isRevisionOf" can be 
>>> used, but
>>> I think it poses stronger condition that what is needed by 
>>> "sameEntity".
>>> Regarding your question about the benefits. I think, having 
>>> "sameEntity()"
>>> can be used in the definition of IVPof:
>>> Specifically, in page 10, it is stated that:
>>> "An assertion "B is an IVP of A" holds over the temporal 
>>> intersection of A
>>> and B, only if:
>>> if a mapping can be established from an attribute X of B to an 
>>> attribute Y
>>> of A, then the values of A and B must be consistent with that mapping
>>> B has some attribute that A does not have"
>>> I think, if "sameEntity" exists then it can be used as a third 
>>> condition, to
>>> make sure that A and B refers to the same entity, otherwise one 
>>> cannot be an
>>> IVPof the other.
>>> Also, given a BOB bi, a user  may be interested in tracing the 
>>> history of
>>> all the BOBs that were used to derive b1 and that refer to the same 
>>> entity.
>>> In other words, the query here is give me the history of the entity 
>>> that bi
>>> refers to.
>>> khalid
>>> Luc
>>> On 21/07/2011 20:06, Provenance Working Group Issue Tracker wrote:
>>> PROV-ISSUE-35: Section 4: How one would know that two BOBs are
>>> characterizations of the same entity? [Conceptual Model]
>>> http://www.w3.org/2011/prov/track/issues/35
>>> Raised by: Khalid Belhajjame
>>> On product: Conceptual Model
>>> Do we need a mean to specify that two BOB are characterizations of 
>>> the same
>>> entity?
>>> In the initial draft, I think that the editors intentionally avoided
>>> defining the term "entity" as part of the vocabulary. I don't suggest
>>> defining that term, but having a means by which one would know that 
>>> two Bobs
>>> are characterizations, possibly different, of the same entity, e.g., 
>>> using
>>> an assertion like "sameEntity(bob1, bob2)".
>>> I think this will be useful, amongst other things, in the definition of
>>> IVPof.
>>> Khalid
Received on Monday, 25 July 2011 17:04:07 UTC

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