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

• From: Luc Moreau <L.Moreau@ecs.soton.ac.uk>
• Date: Mon, 26 Sep 2011 09:56:38 +0100
```Hi Stephen,

I don't understand this idea of "defining a new entity" (your point (1)).
Where is this coming from?

Given that entity expressions are asserted by asserters, and therefore,
their specific attributes
selected by asserters, why would we have an entity with attribute-value
pairs formed by
the union of those of A and B?  While I can see we can do it
mathematically, why would such
an entity expression make sense from a practical view point (when A and
different perspectives over the same thing).

Looking back at the definition we had reached by the time of F2F [1], I
don't see this entity being
mentioned.

Cheers,
Luc

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

On 09/25/2011 10:03 PM, Cresswell, Stephen wrote:
>
> Jim Myers wrote:
> > I'm not sure what of 29 and 57 then survive as unresolved concerns -
> perhaps whether transitivity can be defined?
>
> I have two concerns (or perhaps the same concern approached from two
> directions).
>
> (1)
> I think that the assertion wasComplementOf(B,A) implicitly defines a
> new entity.
> The new entity has a time interval which is the temporal intersection
> of those of A and B.
> The new entity has a set of attribute-value pairs which is the union
> of those of A and B.
>
> However, if I want to make this new entity explicit, I can't.  The
> vocabulary I need to use to state its relationship to A and B is missing.
>
>
> (2)
> One use for the original IVPof was (I thought) to relate together
> long-term entities (e.g. Luc-over-his-lifetime) with shorter-term
> entities describing states (e.g. Luc-in-Boston).  Now it seems that
> the strongest assertion that I can make about the relationship of
> these two entities is:
>
>
> ... but this just asserts that Luc's visit to Boston *overlapped* with
> his lifetime, which is weaker than what I wanted to assert.
>
> If I also want to describe a visit to MIT that Luc made while in
> Boston, I could also assert
>
>   wasComplementOf( Luc-at-MIT, Luc-in-Boston )
>
> Since the assertions are quite vague, we can't infer that
> Luc-over-his-lifetime contained Luc-at-MIT, and we can't even infer
> that they overlapped.
> I think it would be useful to be able to make some stronger assertions
> that allow transitivity to be used here.  At some point during its
> evolution, IVPof was close to being that helpful transitive relation,
> but now its gone.  I think we still need it.
>
> Stephen Cresswell
>
> -----Original Message-----
> From: Myers, Jim [mailto:MYERSJ4@rpi.edu]
> Sent: Fri 23/09/2011 18:21
> To: Cresswell, Stephen; Paolo Missier; public-prov-wg@w3.org
> Subject: RE: PROV-ISSUE-29 (mutual-iVP-of): can two bobs be mutually
> "IVP  of"  each other  [Conceptual Model]
>
> When I read the current document, I see complementOF is defined as
> one-way - you can assert it in both directions, but the text talks
> about a case where B is a complementOf A but not the reverse. Can the
> editors confirm that's the intent? If so, perhaps we can move to
> refining text to avoid the perception that symmetry is required (i.e.
> talk about the asymmetric case first...). I'm not sure what of 29 and
> 57 then survive as unresolved concerns - perhaps whether transitivity
> can be defined?
>
> Cheers,
>  Jim
>
> > -----Original Message-----
> > From: public-prov-wg-request@w3.org [mailto:public-prov-wg-
> > request@w3.org] On Behalf Of Cresswell, Stephen
> > Sent: Friday, September 23, 2011 10:15 AM
> > To: Paolo Missier; public-prov-wg@w3.org
> > Subject: RE: PROV-ISSUE-29 (mutual-iVP-of): can two bobs be mutually
> "IVP
> > of" each other [Conceptual Model]
> >
> >
> > Hi Paolo,
> >
> > Yes, I agree that the current wasComplementOf can be symmetrical, and I
> > have no objection to closing issue 29.
> >
> > I do still think that a concept of IVPof that is antisymmetric and
> transitive, so
> > that "B IVPof A" means something like "B and A describe the same stuff,
> > and B's interval is within A's interval" is a simpler and stronger
> concept.  It
> > can co-exist with wasComplementOf, and it can be used to define (a
> > symmetric form of) wasComplementOf (which admittedly doesn't match
> > the current definition).
> > i.e.
> >   (B wasComplementOf A) <=> exists C.(C IVPof A & C IVPof B)
> >
> > Since wasComplementOf is a relation that only holds over the temporal
> > intersection A and B anyway, then saying it with this IVPof at least
> makes
> > you introduce an entity C that models the relevant interval.
> >
> > However, I think that's basically what Graham said and it is a
> different issue
> > - PROV-ISSUE-57.
> >
> > Stephen Cresswell
> >
> > Tel:  +44 (0) 01603 69 6926
> >
> > Web:  www.tso.co.uk
> >
> >
> >
> >
> > -----Original Message-----
> > From: public-prov-wg-request@w3.org
> > [mailto:public-prov-wg-request@w3.org] On Behalf Of Paolo Missier
> > Sent: 23 September 2011 12:06
> > To: public-prov-wg@w3.org
> > Subject: Re: PROV-ISSUE-29 (mutual-iVP-of): can two bobs be mutually
> "IVP
> > of" each other [Conceptual Model]
> >
> > Hi,
> >
> > as we are going through older issues, this one seems to have been
> > superseded by the current version of the model. We propose to close it
> > pending review (that means, Stephen can you please call in with your
> > current view on this, thank you).
> >
> > Specifically:  IVP-of has been replaced by ComplementOf, which *does*
> > allow for symmetry.
> >
> > -Paolo
> >
> >
> > On 7/11/11 12:22 PM, Provenance Working Group Issue Tracker wrote:
> > > PROV-ISSUE-29 (mutual-iVP-of): can two bobs be mutually "IVP of" each
> > other  [Conceptual Model]
> > >
> > > http://www.w3.org/2011/prov/track/issues/29
> > >
> > > Raised by: Stephen Cresswell
> > > On product: Conceptual Model
> > >
> > >
> > > 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"
> > >
> > > Stephen
> > >
> > >
> > >
> > >
> >
> >
> > --
> > -----------  ~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
> >
> >
> >
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--
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 Kingdom                     http://www.ecs.soton.ac.uk/~lavm
```

Received on Monday, 26 September 2011 08:57:11 UTC