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

From: Timothy Lebo <lebot@rpi.edu>
Date: Mon, 2 Apr 2012 08:33:32 -0400
Cc: Luc Moreau <L.Moreau@ecs.soton.ac.uk>, Paul Groth <p.t.groth@vu.nl>, "public-prov-wg@w3.org" <public-prov-wg@w3.org>
Message-Id: <E45299BE-E357-4ACD-9CA8-CA6CF2D928E9@rpi.edu>
To: James Cheney <jcheney@inf.ed.ac.uk>

On Apr 2, 2012, at 4:58 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 see absolutely no point to or motivation for allowing an entity to refer to more than (or less than) one thing.  

+10

-TIm


> 
> --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> 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> 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.
Received on Monday, 2 April 2012 12:34:12 GMT

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