# Re: Regarding the definition of IVP OF

From: Paolo Missier <Paolo.Missier@ncl.ac.uk>
Date: Mon, 11 Jul 2011 15:53:21 +0100
Message-ID: <4E1B0E61.2080402@ncl.ac.uk>

Hi,

still trying to come to grips with IVP. I must have left the room at the wrong time for my other meeting on day 2 :-)

on def [1]:

Let A and B be two entity states. An assertion "B is an IVP of A" indicates that, for its asserter, A and B represent the same
entity in the world, and the entity states modelled by A and B are consistent. "B is an IVP of A" is valid ony if, for its asserter,
the following holds:

* the properties they share must have corresponding values
* some mutable properties of A correspond to some immutable properties of B

B has invariant properties that have no correspondent for A

can someone please clarify (true/false):
1. "consistent" is the same as "the properties they share must have corresponding values"  ("corresponding" has been defined
elsewhere, so it's fine)
2. "mutable" is the same as "invariant"

my guess is true/true.
if so, isn't the last statement enough to conclude that IVP is anti-symmetric? (it can still be transitive, but no cycles are
allowed as in one of Luc's earlier examples in this thread)
/however/, in Jim's counter-example (the file/document duality), may I suggest that "for the asserter" is the key here, i.e., we may
have two asserters who hold "symmetric" views of the same entity, and that's fine.  Just a relativistic thought.

[1]  http://www.w3.org/2011/prov/wiki/F2F1ConceptDefinitions#IVP_of

thanks... -Paolo

On 7/11/11 8:34 AM, Luc Moreau wrote:
> Hi Khalid
>
> On page [1], we replaced "if" by "only if".  So the condition is necessary, and not sufficient.
> In other words, "IVP of" must be asserted, and cannot be inferred. I think it has always
> been the intent.
>
> Luc
>
> [1] http://www.w3.org/2011/prov/wiki/F2F1ConceptDefinitions
>
> On 07/08/2011 04:01 PM, Khalid Belhajjame wrote:
>>
>> 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
>>
>
> --
> 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

--
-----------  ~oo~  --------------
Paolo Missier - Paolo.Missier@newcastle.ac.uk, pmissier@acm.org
School of Computing Science, Newcastle University,  UK
http://www.cs.ncl.ac.uk/people/Paolo.Missier
Received on Monday, 11 July 2011 14:53:48 UTC

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