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Re: Models and their use

From: Simon Miles <simon.miles@kcl.ac.uk>
Date: Wed, 13 Jul 2011 16:55:06 +0100
Message-ID: <CAKc1nHemaYuX2FA2k1gbRuTZKAg=pq-tR0PU9fnDKKwyUP+v=g@mail.gmail.com>
To: Provenance Working Group WG <public-prov-wg@w3.org>
Jim,

> Leaving out description, which I agree is separable, where do we stand with thing/IVP?
> Thing is being talked about as entity now (and was Bob for a while)?

But this is exactly the problem - from the F2F discussions, there
ended up being three separate concepts: thing/BOB, stuff/entity, and
entity state. Thing was not being talked about as entity, but as the
"representation of entities with properties modelling aspects of
entity states".

> And the argument is that we don't need to distinguish between the idea of a provenance thing and the entity definitions in other ontologies

That is a possible consequence of the disentanglement of concepts.

> , or perhaps better - the mapping of instances of the classes 'comet' and 'comet-near-star' to provenance entities is not part of the model, but is an implementation detail?

Not sure about this... what is the relevant difference between an
instance and an entity?

> How do we know that "Halley's Comet" and "Halley's comet near the sun" are related and not 'representations' of different 'stuff'? ("Kahoutek-near-the-sun" Is not an IVP of/not related to "Halley's comet".) What terms/description of 'representation' and 'stuff' is current? Do we still agree that there is something out there behind/beyond entities?

I don't see what "behind/beyond entities" means, and I don't remember
agreeing with it :-). If you mean that "Halley's Comet" is
behind/beyond "Halley's comet near the sun", then I agree there is a
relation to be captured, and I thought IVP of did that.

On the other hand, if we keep "representation" as part of
thing/entity's definition, then "Halley's comet near the sun" is not a
thing/entity, only the "representation of Halley's comet near the
sun". This complexity shouldn't arise coz the model should be about
the world and its usage about the representation.

> Where does IVP stand? What I'm picking up for the most part is that IVP can't be hierarchical in general, which I think has faded as we tried to talk about properties of one entity having to be immutable in an IVP of it. Technically, I'm not sure we ever said that there couldn't be properties going in the reverse direction (allowing A IVP of B and B IVP of A), and my original arguments were that invariance was relative to the processes being discussed which also implies IVP relationships could go in both directions depending on the processes you wanted to talk about. Is the current discussion just reaffirming that we're not talking about hierarchies of invariance, or is there more to the discussion about how the IVP relationship has to change?

As far as I can see, this is a separate point from the discussion on
this thread. I don't think either the current definitions or my
suggested alternatives preclude properties in the reverse direction.

With regard to invariance relative to processes, I agree that my
proposal does not capture that, though I don't think the original
definitions did either. The intuition implied at the start of this
thread was that there are many things which assertions could be
relative to and that this was collectively the "perspective" of the
assertion. I suggested that we simply state that any assertion using a
(our) model is by necessity from some perspective, and not make it
part of any one definition. This allows for the simplicity of
definitions urged by Graham. Is that inadequate?

Thanks,
Simon


>  Thanks,
>  Jim
>
>
>
>
>> -----Original Message-----
>> From: public-prov-wg-request@w3.org [mailto:public-prov-wg-
>> request@w3.org] On Behalf Of Simon Miles
>> Sent: Wednesday, July 13, 2011 8:36 AM
>> To: Provenance Working Group WG
>> Subject: Re: Models and their use
>>
>> Jim, Graham,
>>
>> Reading through your comments, I'm pretty much in agreement with them.
>> The discrepancy between my view and Jim's is, I think, just a matter of what
>> we assume is being defined at the moment (i.e. by entity/thing).
>>
>> As in Graham's last mail, I am assuming that we are first defining any
>> (contextualised) entity ((1) in Graham's classification).
>>
>> I fully agree with you that assertion/observation/description (2) is also an
>> important and distinct concept. However, I see it as secondary to the idea of
>> entity in the model and, as Graham says, a description is itself a kind of
>> entity. This may be comparable to agents or process executions, i.e. agents,
>> executions and descriptions are all particularly important (for provenance)
>> subclasses of entity.
>>
>> And I think this difference in our views about what was being defined by
>> "thing" nicely illustrates the original point I was trying to make about the
>> conflation in the definition :-)
>>
>> Thanks,
>> Simon
>>
>> On 13 July 2011 11:01, Graham Klyne <GK@ninebynine.org> wrote:
>> > Jim,
>> >
>> > I've been thinking about your comments, and have come to a view that
>> > there are two things going on here, which are not being clearly
>> distinguished:
>> >
>> > 1. an entity constrained to some context
>> >
>> > 2. observations or descriptions of an entity
>> >
>> > which when combined can model observations/descriptions of an entity
>> > constrained to some context.  I have been focusing on (1), with the
>> > expectation that (2) would be dealt with separately in the model,
>> > where provenance is a kind of description.  If I understand correctly,
>> > you are particularly concerned to distinguish between entity and
>> > description.  It seems to me that "bob" has been adopted variously to fulfil
>> both these distinctions.
>> >
>> > ...
>> >
>> > Example: suppose we're interested in Halley's comet, and in particular
>> > in the periods when it is close to the sun or visible from earth.  So
>> > we have two
>> > concepts:  Halley's comet and Halleys comet when close to Earth.  To
>> > my mind, these are both *entities* (sensu F2F1).  Any description that
>> > is true of Halley's comet generally should also be true of it when
>> > close to Earth, but there are many other assertions are true the
>> > constrained Halley's comet that are probably not true at all times
>> > (e.g. the appearance of a tail due to expulsion of gas and dust caused by
>> solar heating).
>> >
>> > The page http://en.wikipedia.org/wiki/Halley's_Comet is a
>> > *description* of Halley's comet.  Being a Wikipedia page, it probably
>> > changes over time.  So we may wish to discuss it as it exists in a
>> > particular period of time.  Today, for example, it contains a list of
>> > 95 references indicating sources of information used in the page.
>> > Thus we may expect this page to be a description of Halley's comet for
>> > its entire lifetime, but needs to be constrained to make statements
>> > about the number of references it contains.  In this respect, the page is
>> both an "entity" and a "description" of an entity.
>> >
>> > The page at http://en.wikipedia.org/wiki/Halley's_Comet also has a
>> > brief description of a Cuneiform-inscribed clay tablet which is both
>> > an entity in its own right, with its own description and provenance,
>> > *and* a record of observation of Halley's comet.  I don't think we can
>> > easily disjoin the class of descriptions from the class of entities.
>> >
>> > Thus, I perceive that the notion of constraint so that some aspects of
>> > a constrained entity are invariant needs to be dealt with separately
>> > from the notion of description, which often (but not always, I think)
>> > applies to a constrained form of some entity.
>> >
>> > Does this make any sense?
>> >
>> > #g
>> > --
>> >
>> >
>> > Jim McCusker wrote:
>> >> My issue is more with Simon's desire to conflate things with the
>> >> descriptions of those things. We need to be able to say "x, as
>> >> described by y", which is a separate issue from relating "x1" as an
>> >> invariant view of "x2".
>> >>
>> >> "x as described by y" can be done in semweb using a URI for X and the
>> >> URI for a named graph or graph literal for y, assuming that there are
>> >> assertions in y about x. Another alternative is that y can be
>> >> discussed as an information artifact, as in the Information Artifact
>> >> Ontology (http://code.google.com/p/information-artifact-ontology).
>> >> Since x changes over time, we need something that nails down what was
>> >> actually "seen", or at least, claimed when the agent identified x in
>> >> its context.
>> >>
>> >> A BOB is the y in the above paragraph, and I think that the fact that
>> >> it's something that's describing an x, it must have the extra
>> >> qualification in place in its name.
>> >>
>> >> Jim
>> >>
>> >> On Tue, Jul 12, 2011 at 3:27 PM, Graham Klyne <GK@ninebynine.org>
>> wrote:
>> >>> [Off-list]
>> >>>
>> >>> Jim,
>> >>>
>> >>> I had some small reservations about Simon's definition, but I felt
>> >>> that it was such a big improvement over what we currently have that
>> >>> I didn't want to muddy the waters just yet by adding qualifications
>> >>> to my support :)
>> >>>
>> >>> (Specifically, I would remove "and something more is invariant about
>> >>> B" from the efinition of invariant view, so that anything can be an
>> >>> invariant view of itself (or not excluded from so being) - which I
>> >>> think is one of the concerns you raised.)
>> >>>
>> >>> Apart from that, I think there is an aspect of an invariant view
>> >>> that is in some sense fundamentally subsumptive -- there is a
>> >>> distinct sense that A and B are generally the same, except that one may
>> be more constrained.
>> >>>
>> >>> But, more importantly, I think we need to be looking to say less, not
>> more.
>> >>> I feel that Simon's definition captures close to what we need to say
>> >>> without adding too much more.
>> >>>
>> >>> In this, I'm arguing for the minimum useful semantics - it's easier
>> >>> to add (or layer) constraints later than to remove them from an
>> >>> established defintion.  By providing a little as we can for people
>> >>> to disagree with, I think we maximize the potential for take-up of the
>> WG outputs.
>> >>>
>> >>> #g
>> >>> --
>> >>>
>> >>>
>> >>> Jim McCusker wrote:
>> >>>> On Tue, Jul 12, 2011 at 12:02 PM, Graham Klyne <GK@ninebynine.org>
>> wrote:
>> >>>>> Simon Miles wrote:
>> >>>>>> To understand the consequences of the above points, I suggest
>> >>>>>> alternative definitions at the link below:
>> >>>>>>
>> >>>>>>
>> >>>>>>
>> http://www.w3.org/2011/prov/wiki/Talk:F2F1ConceptDefinitions#Enti
>> >>>>>> ty_and_IVP_of
>> >>>>> +1
>> >>>>>
>> >>>>> I think this is a big improvement over what we have.
>> >>>> I like the Entity definition, but I'm not sure how we then go about
>> >>>> qualifying assertions about Entities. We need a way of making those
>> >>>> assertions (which is what BOBs were for) and a way of relating
>> >>>> Entities that are the same, even if they aren't mathematically the
>> >>>> same (different state, different aspect, etc.). IVP of as it's
>> >>>> defined there is not quite enough, since it only allows for
>> >>>> relations between entities that have subsumptive (a is IVP of b,
>> >>>> therefore a has all the states of b plus some).
>> >>>>
>> >>>> Jim
>> >>>> --
>> >>>> Jim McCusker
>> >>>> Programmer Analyst
>> >>>> Krauthammer Lab, Pathology Informatics Yale School of Medicine
>> >>>> james.mccusker@yale.edu | (203) 785-6330
>> >>>> http://krauthammerlab.med.yale.edu
>> >>>>
>> >>>> PhD Student
>> >>>> Tetherless World Constellation
>> >>>> Rensselaer Polytechnic Institute
>> >>>> mccusj@cs.rpi.edu
>> >>>> http://tw.rpi.edu
>> >>>>
>> >>>
>> >>>
>> >>
>> >>
>> >>
>> >
>> >
>> >
>> __________________________________________________________
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>> __________________________________________________________
>> ____________
>> >
>>
>>
>>
>> --
>> Dr Simon Miles
>> Lecturer, Department of Informatics
>> Kings College London, WC2R 2LS, UK
>> +44 (0)20 7848 1166
>
>
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-- 
Dr Simon Miles
Lecturer, Department of Informatics
Kings College London, WC2R 2LS, UK
+44 (0)20 7848 1166
Received on Wednesday, 13 July 2011 15:55:37 GMT

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