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Re: Models and their use

From: Simon Miles <simon.miles@kcl.ac.uk>
Date: Thu, 14 Jul 2011 11:26:05 +0100
Message-ID: <CAKc1nHeF9aB-7UfJ1YU_LdFG-FGX_kYhEq2V6HKKC8Y-PzVy3w@mail.gmail.com>
To: Provenance Working Group WG <public-prov-wg@w3.org>
Hi Paul,

> Thing = Bob or Entity State

Sorry to be difficult, but... BOB is currently defined in terms of
Entity State, so if they are both replacing Thing it's a circular
definition. Alternatively, they are two separate terms, one of which
replaces Thing, making three along with Entity.

> Finally I would suggest that the participates divide issues into two threads if possible (e.g. Model vs ivp)

I agree with the sentiment, but I think maybe the key issues
(specifying models in a helpful way, definition of entity, definition
of IVP) are all tangled up at the moment. If I can see a possible way
to split off a topic, I will try to do so.


> Thanks
> Paul
> On Jul 14, 2011, at 8:40 AM, Graham Klyne <GK@ninebynine.org> wrote:
>> Myers, Jim wrote:
>>> I'm having a hard time understanding how this discussion changes the model (or what version/interpretation of the model).
>> A trite response might be that, lacking a model, it changes nothing.
>> But I suspect that what is happening here is, lacking a common model at this
>> stage, that we each have our own model which we are using to interpret or think
>> about the terms we're trying to describe.
>>> Leaving out description, which I agree is separable, where do we stand with thing/IVP?
>> Well, I thought Simon's proposal [1] captured that part quite nicely.
>> (The term "entity" for was agreed at F2F1 [2] - I always thought that "thing"
>> was just another term for entity, but checking the log at [2] I see this is not
>> universally held - I never really tuned in to the distinction here.)
>> [1] http://www.w3.org/2011/prov/wiki/Talk:F2F1ConceptDefinitions#Entity_and_IVP_of
>> [2] http://www.w3.org/2011/prov/meeting/2011-07-06#Session_2__3a__Model_Task_Force
>>> Thing is being talked about as entity now (and was Bob for a while)?
>> I think "bob" was never entirely clear - and may well have been the subject of
>> multiple interpretations.  I for one am not comfortable with the notion of a
>> "state" that "bob"
>>> 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, 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?
>> There are several issues in this.  Let me try to pick apart:
>> "we don't need to distinguish between the idea of a provenance thing and the
>> entity definitions in other ontologies" - I'm not arguing this - I think a
>> distinction *is* needed.
>> (If you had used entity "description" instead of entity "definition" (implying
>> possible arbitrary metadata about an entity), then I'd be less clear cut, but at
>> some level I think this group does want to have some notion of provenance from
>> other descriptions.  My mental model has provenance as a subset of arbitrary
>> entity descriptions; I imagine a property like "hasProvenance", which may be a
>> subproperty of something like rdfs:seeAlso.  As for exactly what constitutes
>> provenance information, I think that is somewhat open.)
>> "the mapping of instances of the classes 'comet' and 'comet-near-star' to
>> provenance entities is not part of the model" - I'm having trouble with two
>> terms here: "mapping" and "entity".  I think we have adopted the term "entity"
>> (pro tem, at least) to be roughly "something about which we wish to express
>> provenance".  I don't know what you mean by "mapping instances" here, but I'm
>> guessing something like "relating".  In any case, I can't find an interpretation
>> of this that I'd agree with.
>> That is, I think the relationship between entities and provenance *is* part of
>> the model, just not part that is covered by Simon's definition.  Again, we seem
>> to be back to the problems of considering term definitons in isolation.
>>> 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".)
>> That's a question of epistemology.  In my mental model, we know that if it is
>> asserted.  We might even define a property for it ... which is what I saw
>> Simon's definition edging towards.
>>> What terms/description of 'representation' and 'stuff' is current?
>>> Do we still agree that there is something out there behind/beyond entities?
>> I understand the current term here is "entity" for anything about which we might
>> wish to express provenance.  Like a web _resource_, an _entity_ can be
>> identified by a URI (but is not required to be).  In my mental model, _entities_
>> may be related to each other by a notion like IVP, though I prefer to think of
>> that as "contextual constraint" which can be expressed in terms of
>> truth-of-assertions.
>>> Where does IVP stand?
>> See above for a personal take.
>>> 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?
>> I see IVP being hierarchical, but I do think that it is transitive:
>> Comet -> Halley's comet       -> Halley's comet near sun
>>       -> comet near sun
>>       -> Kahoutek             -> Kahoutek near sun
>> (where *all* of the things (sensu colloq.) mentioned above are _entities_)
>> So we have:
>> Halley's comet          _IVP_   comet
>> Kahoutek                _IVP_   comet
>> Comet near sun          _IVP_   comet
>> Halley's comet near sun _IVP_   Haley's comet
>> Halley's comet near sun _IVP_   comet near sun
>> Halley's comet near sun _IVP_   comet
>> Kahoutek near sun       _IVP_   Kahoutek
>> Kahoutek near sun       _IVP_   comet near sun
>> Kahoutek near sun       _IVP_   comet
>> But NOT other relations that would be needed if IVP were to be hierarchical.
>> I'm sorry of all this is a bit laboured, but I hope this helps to clarify my
>> understanding.
>> #g
>> --
>>>> -----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 Thursday, 14 July 2011 10:26:35 UTC

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