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

My answers:

1. An entity refers to one thing that thing may or may not be identified

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
>> 
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