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Re: PROV-ISSUE-85 (What-is-Entity): Definition of Entity is confusing, maybe over-complex [Conceptual Model]

From: Graham Klyne <GK@ninebynine.org>
Date: Mon, 05 Sep 2011 21:36:54 +0100
Message-ID: <4E6532E6.8000600@ninebynine.org>
To: Luc Moreau <L.Moreau@ecs.soton.ac.uk>
CC: public-prov-wg@w3.org

I think it's better, but:
(a) I still think the term "Entity" doesn't quite reflect what is being defined, and
(b) I still think the first sentence doesn't really tackle what an Entity 
[Assertion] actually *is* - your more oblique approach via "representation" 
leaves me, as a reader, guessing at what it is you really mean to convey.

I still think that starting out with something like:

"A (BOB) is an assertion about an identifiable characterized thing" (if you'll 
excuse the resurrection of "BOB" here) gets the key information in front of the 
reader in a way that is less easily overlooked.  Subsequent text can explain in 
more detail, as you do, the details of what this actually means.


On 05/09/2011 15:53, Luc Moreau wrote:
> Hi Graham, Jim, and Simon,
> Following the discussion this WE, Paolo and I have revised the definition of
> entity.
> Before editing the document, we would like to get your feedback.
> General assumption (to appear in section 4): in the real world, we find:
> - identifiable characterized things, their situation in the world
> - activities
> - events
> Cheers,
> Luc
> -----
> Revised section 5.1
> -------
> In PIDM, an entity construct is a representation of an identifiable
> characterized thing.
> An instance of an entity construct, expressed as entity(id, [ attr:
> val, ...]) in the Provenance Abstract Syntax Notation:
> - contains an identifier id, denoting a characterized thing
> - contains a set of attribute-value pairs [ attr: val, ...], representing
> this characterized thing's situation in the world.
> The assertion of an instance of an entity construct , entity(id, [ attr: val,
> ...]), states, from a given asserter's viewpoint, the existence of an
> identifiable characterized thing, whose situation in the world is represented by
> the attribute-value pairs, which remain unchanged during a characterization
> interval, i.e. a continuous interval between two events in the world (which may
> collapse into a single instant).
> Example: <same example>
> ... states the existence of a thing of type File and location /shared/crime.txt,
> and creator alice, denoted by identifier e0, during some characterization interval.
> Further properties:
> - If an asserter wishes to characterize a thing with same attribute-value pairs
> over several intervals, then they are required to assert multiple entity
> assertions, each with its own identifier.
> - There is no assumption that the set of attributes is complete and that the
> attributes are independent/orthogonal of each other.
> Cheers,
> Luc
> On 09/01/2011 05:32 PM, Provenance Working Group Issue Tracker wrote:
>> PROV-ISSUE-85 (What-is-Entity): Definition of Entity is confusing, maybe
>> over-complex [Conceptual Model]
>> http://www.w3.org/2011/prov/track/issues/85
>> Raised by: Graham Klyne
>> On product: Conceptual Model
>> See also: http://lists.w3.org/Archives/Public/public-prov-wg/2011Aug/0383.html
>> Section 5.1.
>> The definition of "Entity" seems to introduce un-needed complications. I don't
>> see anything here that fundamentally distinguishes an entity from anything
>> that can be named, i.e. a web resource.
>> I don't see what useful purpose is served by the insistence on "characterized
>> thing".
>> This section seems to spend more effort describing "entity assertion" is is
>> apparently a different concept, but not formally part of the model. There is
>> some sense that an entity must have associated entity assertions... but I
>> can't see why this is needed, and indeed it may be not possible to enforce
>> this idea in RDF's open world model.
>> There's been talk of Entities being part of the occurrent vs continuant
>> distinction, but I'm not seeing that explained.
>> Suggest: why not just have an entity as an identifiable thing, and build the
>> rest around that? What would break with this approach?
Received on Monday, 5 September 2011 20:37:52 UTC

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