- From: Luc Moreau <L.Moreau@ecs.soton.ac.uk>
- Date: Mon, 02 Apr 2012 10:32:22 +0100
- To: public-prov-wg@w3.org
- Message-ID: <EMEW3|e52c8df9335b3f76b1fd7ae51362b36do31AWQ08L.Moreau|ecs.soton.ac.uk|4F797226>
Hi James, To be specific, I am not trying to start yet another debate on this, I am looking for guidance on how to complete/edit: http://dvcs.w3.org/hg/prov/raw-file/default/model/prov-dm-constraints.html#component4 Concrete suggestions welcome. Thanks, Luc On 04/02/2012 10:27 AM, Luc Moreau wrote: > Hi James, > > I am not trying to defend one point of view or the other, but I seek > some guidance > about what to write in part II, which should be released by end of the > day. > > /Taking my editor's hat off: *my* view is that we should not specify > any of these properties > in our documents, and we should see what the community does with the > relations. > / > Editor's hat on, further comments below: > > > On 04/02/2012 09:58 AM, James Cheney wrote: >> Hi Luc, >> >> The point of having each Entity mapped to a (unique) Thing in the >> semantics is to avoid this kind of confusion. >> >> I did it this way precisely because of examples like this, and >> because of I thought there was a rough consensus that specialization >> > ... that specialization ...?? is transitive you mean? > > >> If you think the formal semantics as is mismatches the data >> model/constraints and should not do this, please raise an issue on it >> and we can discuss it. > > I have no view about it. The english definition does not disallow for > my interpretation. So, something > needs to be changed somewhere. > > My reading of Jim and Stian's messages is that transitivity does not > hold, but apologies if I have misread. > >> >> Considering your (brief) example (I think I am restating Stian's >> response in more formal terms): >> >> So there are two things: >> >> thing1 = woman in red >> thing2 = man in black >> >> I'll assume their lifetimes both include t1,t2. From t0 to t1, >> thing1 is in the chair, then thing1 leaves and thing2 gets in the >> chair at t2. >> >> If you have one "entity" >> >> ent0 = person on chair at times [t1,t2] >> >> then there can't be a single thing that the entity maps to, i.e., >> it's not allowed in the semantics. > > is it the consensus? > how do we modify the english definition to reflect this? >> >> You need two entities >> >> ent1 = person on chair at time t1 >> ent2 = person on chair at time t2 >> >> Note that officially, we are not required to give ent1 and ent2 >> different attributes (or any attributes at all), but if we intend >> them to denote different things >> >> Incidentally, the example you gave has nothing at all to do with >> specialization: specialization is a relation on entities, not things, >> and the two entities ent1 and ent2 are not specializations of each >> other, nor is ent1 or ent2 a specialization of ent0 (or vice versa). >> Ent0 is not even a sensible entity anyway. So, in my view your >> example is not a use case for allowing entities to refer to multiple >> things. > > I am not sure which example you refer to. > But surely, thing1 and thing2 can also be regarded as entities! > >> >> I see absolutely no point to or motivation for allowing an entity to >> refer to more than (or less than) one thing. >> > So, still trying to understand, if it's the case, what is the point of > talking about things? > Shouldn't the English definition of these concepts be expressed > without the term 'thing'? > > Luc > > >> --James >> >> On Apr 1, 2012, at 8:20 PM, Luc Moreau wrote: >> >>> >>> >>> >>> On 1 Apr 2012, at 12:12, "Paul Groth" <p.t.groth@vu.nl >>> <mailto:p.t.groth@vu.nl>> wrote: >>> >>>> My answers: >>>> >>>> 1. An entity refers to one thing that thing may or may not be >>>> identified >>> >>> >>> At a given point in time, possibly, but is it the case when time >>> changes? >>> >>> Can't recall the exact detail, but the 'customer on the third chair' >>> may be the >>> woman in red at t1 and the man in black at t2. Can't it? >>> >>> >>> Luc >>> >>> >>>> >>>> 2. Specialization thus is defined in terms of 1 >>>> >>>> Paul - not a specialization/alternator guru >>>> >>>> On Apr 1, 2012, at 9:46, Luc Moreau <l.moreau@ecs.soton.ac.uk >>>> <mailto:l.moreau@ecs.soton.ac.uk>> wrote: >>>> >>>>> Hi all specializationOf/alternateOf gurus, >>>>> >>>>> The current definition of alternateOf does not allow us to decide >>>>> whether James's or my interpretation >>>>> is right. The question is essentially: does an entity refer to >>>>> one and only one thing or not. >>>>> >>>>> So, >>>>> >>>>> 1. What is intended? >>>>> 2. How do we clarify definitions? >>>>> >>>>> Cheers, >>>>> Luc >>>>> >>>>> >>>>> On 31/03/2012 15:46, James Cheney wrote: >>>>>> On 30/03/12 10:01, Luc Moreau wrote: >>>>>>> >>>>>>> Dear all, >>>>>>> >>>>>>> I am getting conflicting messages on this topic! >>>>>>> >>>>>>> James has listed some properties derived from the semantics >>>>>>> http://lists.w3.org/Archives/Public/public-prov-wg/2012Mar/0470.html >>>>>>> But not all of them seem to be aligned with what we are reading >>>>>>> on this thread. >>>>>>> >>>>>>> So, I started drafting a section in prov-dm part II listing the >>>>>>> properties of these relations [1]. >>>>>>> >>>>>>> I am proposing to justify each property either by reasoning >>>>>>> based on its definition, >>>>>>> or by a counter-example. >>>>>>> >>>>>>> *Your suggestions are needed to help us complete this section. * >>>>>>> >>>>>>> James, unless my reasoning is incorrect, I do not have >>>>>>> transitivity for specializationOf. >>>>>> >>>>>> Hi Luc, >>>>>> >>>>>> Your reasoning (quoting from [1]) is: >>>>>> >>>>>>> Specialization is /not transitive/. Indeed if >>>>>>> specializationOf(e1,e2) holds, then there is some common thing, >>>>>>> say e1-2 they both refer to. Likewise, if >>>>>>> specializationOf(e2,e3) holds, then there is some common thing, >>>>>>> say e2-3 they both refer to. It does not follow there is a >>>>>>> common thing both e1 and e3 refer to. >>>>>> >>>>>> In the WD3 formal semantics [2], I modeled >>>>>> entities-referring-to-things as a function thingOf : Entity -> >>>>>> Thing. >>>>>> >>>>>> Thus, if thingOf(e1) = e1-2 = thingOf(e2) and thingOf(e2) = e2-3 >>>>>> = thingOf(e3) then (by transitivity of equality) e1-2 = e2-3 and >>>>>> all three entities refer to the same thing, e1-2. >>>>>> >>>>>> Of course, it is an assumption I made that an entity "refers to" >>>>>> exactly one thing. If we want to allow entities to refer to >>>>>> multiple things, then the reasoning I give above fails, and >>>>>> specializationOf is not necessarily transitive. >>>>>> >>>>>> --James >>>>>> >>>>>> [1] >>>>>> http://dvcs.w3.org/hg/prov/raw-file/default/model/prov-dm-constraints.html#component4 >>>>>> [2] http://www.w3.org/2011/prov/wiki/FormalSemanticsWD3 >>>>>> >>>>>> >>>>>> The University of Edinburgh is a charitable body, registered in >>>>>> Scotland, with registration number SC005336. >>>>>> >> >> >> The University of Edinburgh is a charitable body, registered in >> Scotland, with registration number SC005336. >> > > -- > 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 Kingdomhttp://www.ecs.soton.ac.uk/~lavm > -- 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 Monday, 2 April 2012 09:32:59 UTC