Re: PROV-ISSUE-60: comments on bob [Conceptual Model]

Hi Graham,
This issue was closed, pending review.
Are you satisfied with the changes? Can we
close it? Alternatively, you can reopen it,
or create a more specific issue.
Thanks,
Luc

PS See note on this issue's page



On 29/07/11 10:06, Provenance Working Group Issue Tracker wrote:
> PROV-ISSUE-60: comments on bob [Conceptual Model]
>
> http://www.w3.org/2011/prov/track/issues/60
>
> Raised by: Graham Klyne
> On product: Conceptual Model
>
>
> "A BOB represents an identifiable characterized entity."
>
> What does it mean to be "characterized" here?  What does this tell us?
> What does it mean to not be "characterized"?  If this refers to the
> attribute-based assertions mentioned earlier, does this mean that if
> there are no such assertions, an entity cannot be a "BOB"?
>
> [[ A BOB assertion is about a characterized entity, whose situation in
> the world is variant. A BOB assertion is made at a particular point
> and is invariant, in the sense that all the attributes are assigned a
> value as part of that assertion.  ]]
>
> This section is, according to its heading, about "BOB".  But this is
> defining a different concept, so shouldn't this be in a separate
> section?
>
> It seems to me that what we're talking about here is a "provenance
> assertion". I think it would be clearer to just describe that, e.g.
> [[ A provenance assertion is about an entity, whose situation in the
> world is generally assumed to be variable.  ]]
>
> I either don't understand or don't agree with the second part of that
> description.  The notion of assigning values as party of an assertion
> seems wrong to me (I think the notion of constraining attributes is
> the job of the IVP-of relation).  I would expect something like:
>
> [[ A provenance assertion is made at a particular point and is
> invariant, in the sense that the attributes it mentions do not change
> for the entity concerned.  ]]
>
> [[ A BOB assertion must describe a characterized entity over a
> continuous time interval in the world (which may collapse into a
> single instant). Characterizing an entity over multiple time intervals
> requires multiple BOB assertions, each with its own identifier. Some
> attributes may retain their values across multiple assertions.  ]]
> This constraint seems rather unnecessary, and maybe
> counter-productive.
>
> Suppose we want to describe the collective observations of a
> particular telescope when pointed at a particular region of the sky.
> This might actually consist of a (possibly unknown) number of disjoint
> time-segments caused by the rotation of the earth and other factors. I
> can't see any clear benefit in being forced to treat these
> observation-sets as distinct entities.
>
> [[ There is no assumption that the set of attributes is complete and
> that the attributes are independent/orthogonal of each other.  ]] I
> don't see this adding any useful information here.  Remove?
>
>
>
>