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Re: PROV-ISSUE-29 (mutual-iVP-of): can two bobs be mutually "IVP of" each other [Conceptual Model]

From: Luc Moreau <L.Moreau@ecs.soton.ac.uk>
Date: Mon, 02 Apr 2012 10:32:22 +0100
Message-ID: <EMEW3|e52c8df9335b3f76b1fd7ae51362b36do31AWQ08L.Moreau|ecs.soton.ac.uk|4F797226.1000001@ecs.soton.ac.uk>
To: public-prov-wg@w3.org
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 GMT

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