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

From: Cresswell, Stephen <stephen.cresswell@tso.co.uk>
Date: Thu, 29 Sep 2011 15:16:01 +0100
Message-ID: <F22D0BFCDD4DDC44B92C4E24D751CB938D7B88@W3EXC017023.theso.co.uk>
To: <public-prov-wg@w3.org>
 

Hi Jim,

 

Thanks for your comments.  Sorry for the delay in responding - please
see responses inline below.

 

Stephen Cresswell

 

________________________________

From: Myers, Jim [mailto:MYERSJ4@rpi.edu] 
Sent: 26 September 2011 16:35
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]

 

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.

---- Why not C with attributes location and membership that is a
complement of A and B?

If we have the assertions: wasComplementOf(B,A), wasComplement(C,A),
wasComplement(C,B), we still haven't expressed that the time interval of
C is within those of both A and B.  Because we couldn't express that, we
couldn't infer C's attributes, although of course we can assert them.


(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:

  wasComplementOf( Luc-in-Boston, Luc-over-his-lifetime )

... but this just asserts that Luc's visit to Boston *overlapped* with
his lifetime, which is weaker than what I wanted to assert.

--what's missing? I take this as meaning there was a Luc-in-Boston
entity that is an alternate characterization of Luc that is only valid
during his trip to Boston, not that these entities just coexist in time.
Do you want something more than that or do you think that interpretation
is not captured in the definition of complementOf?

I want to express that Luc-in-Boston was entirely within
Luc-over-his-lifetime, and therefore everything invariant in
Luc-over-his-lifetime is also invariant for the whole duration of
Luc-in-Boston.  Also, I want to make the transitive inference of the
same relationship between Luc-at-MIT and Luc-over-his-lifetime.


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.

 

--- What's missing from the complementOf definition (that was in
ivpOf?)? Doesn't your assumption above that there's a new entity that is
the intersection of two complementary entities force transitivity during
the intersection interval?

I don't see how to express that using wasComplementOf.  


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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Received on Thursday, 29 September 2011 14:16:30 GMT

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