- From: Khalid Belhajjame <Khalid.Belhajjame@cs.man.ac.uk>
- Date: Mon, 25 Jul 2011 18:03:36 +0100
- 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