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RE: Regarding the definition of IVP OF

From: Cresswell, Stephen <stephen.cresswell@tso.co.uk>
Date: Fri, 8 Jul 2011 16:18:19 +0100
Message-ID: <F22D0BFCDD4DDC44B92C4E24D751CB930D9643@W3EXC017023.theso.co.uk>
To: "Khalid Belhajjame" <Khalid.Belhajjame@cs.man.ac.uk>, <public-prov-wg@w3.org>

I have another issue with the current definition of "IPV of".

As it currently stands, I believe that it does not exclude the possibility that two bobs may be mutually "IVP of" each other -
i.e. you could have bobs A, B such that (B IVPof A) & (A IVPof B), and this is surely not intended.

This could arise if, for bobs A, B :
- A and B both represent the same entity
- A and B share some immutable properties, and they have corresponding values.
- B has some immutable properties which correspond to mutable properties of A
- A has some immutable properties which correspond to mutable properties of B

Possibly the asserter-defined test (included in "IPV of" definition) that real world states modelled by A and B are "consistent" may disallow
"IPV of" in this situation.  However, unless that is guaranteed, I think that the definition of "B IPV of A" (if it is still to have a definition) should additionally require that: 
"A has no immutable properties which correspond to mutable properties of B"


-----Original Message-----
From: public-prov-wg-request@w3.org on behalf of Khalid Belhajjame
Sent: Fri 08/07/2011 16:01
To: public-prov-wg@w3.org
Subject: Regarding the definition of IVP OF

During the F2F meeting, there was a discussion in the second day 
regarding "IVP of". The definition that was suggested during the F2F can 
be found in [1]. In my opinion, the definition of "IVP of" should be 
simplified. Specifically, I would prefer a definition that states that 
"IVP of" is an asserted relationship between two entity states. I list 
in what follows the reasons:

(i) In the definition of "IVP of" [1], the conditions on the properties 
of the two entity states A and B (i.e., that the properties the entity 
states share must have corresponding values, and that some mutable 
properties of A correspond to some immutable properties of B), are not 
enough in order to infer that B is an IVP of A. This is because there is 
a third condition that is not included, because it is hard to formally 
specify, viz. A and B are consistent.

(ii) A consequence of (i), is that we will not be able to automatically 
infer that an entity state B is an IVP of another entity state B. All we 
can safely do, is identify cases in which an entity state B cannot be an 
IVP of another entity state of A.

(iii) Even if we find a means for formally specifying that two entity 
states A and B are consistent, e.g., using assertions, it will be 
difficult to use the definition of IVP of to make inference. This is 
because the definition of IVP of requires correspondences between the 
properties of two entity states to be specified. These correspondences 
can be complex many-to-many mappings that may turn out to be hard to 
encode using existing semantic web technologies.

Thanks, khalid

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Received on Friday, 8 July 2011 15:23:36 UTC

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