Pat, (01)
Your note of 12:15 is now in the same size as the note of 11:18. (02)
JFS>> An approach with explicit time represents time with a linear
>> coordinate system. (03)
PH> Why linear? There are branching-time ontologies, circular-time
> ontologies, etc.. And it need not be a coordinate system exactly:
> many temporal ontologies have no metric information in them at all. (04)
I agree. Sandewall's examples, which I cited, include those.
When I contrasted explicit time with temporal logics, I just
happened to be thinking of the default model. (05)
JFS>> But finite intervals with domain-dependent granularity
>> are more realistic. (06)
PH> But such intervals tend to have points at their ends, and meet
> at points. Its usually most useful to have both kinds of entity,
> or if you must restrict to one, use points and treat an interval
> as a pair of (end)points. (07)
You could also consider a grain to be specified by a probability
distribution of measurements whose median, mean, or mode is the
designated point. Or variations of fuzzy or rough methods. (08)
PH> And there are other options in more expressive notations,
> such as treating relations as predicates on time-intervals:
> (HasPart(x,y))(t) (09)
Yes, that's another example of the open-ended range of ontologies
that may be useful for various purposes. (010)
PH> Sure they [RDF and OWL] do [have the option of representing
> extra arguments for time]. One simply has to use the (now standard)
> trick of introducing 'facts' (not the best word) which have temporal
> properties and also are systematically related to the arguments and
> property of the predication. So the above becomes (there is fact of
> type HasPart with the haver role being x and the having role being y
> and the time-extent being t) (011)
I admit that one can indeed define such constructions. (012)
PH> In the N-triples notation for RDF this would look like this
>
> _:x rdf:type HasPart .
> _:x rdf:type PredicationFact .
> _:x ex:whole X .
> _:x ex:part Y .
> _:x ex:timeTrue T .
>
> Now, I will admit immediately that such a representation has its
> problems: but it does actually work, if used consistently; and it
> is systematic. In fact, if you think of the _:x here as being a
> proposition, it can be viewed as a restricted subset of IKL. (013)
But I still recall Guha's original argument for RDF as "simple".
And I cringe at the thought of what those N-triples would become
when expanded to the full XML form. (014)
John (015)
PS: Speaking of bloatware, have you seen the reports that Microsoft
is already testing a replacement for Vista with "key partners":
http://www.tgdaily.com/html_tmp/content-view-35641-118.html ? (016)
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