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

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


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