FWIW, this matches another aspect of the Date Time Vocabulary. All so-called
'time points', like July and Tuesday and "day-of-month 1" and 4 o'clock, are
classes of time intervals, which makes them predicates in CLIF. This allows
one to talk about every Tuesday, and every Tuesday that occurs in the first
week of a month, and so on. A date like 'July 14' is a designation for a 'day
of year', composed of a designation for a month, and a designation for a 'day
of month'. One can interpret it as: a time interval that is-a "day of month
14" and that is-part-of a time interval that is-a July. (01)
(In DTV, a 'time point' is an element of a 'time scale', which is typically
defined by a 'calendar'. So 'month-of-days' is a time scale, consisting of 31
'day-of-month' time points, each of which is a class of time intervals.) (02)
-Ed (03)
> -----Original Message-----
> From: ontolog-forum-bounces@xxxxxxxxxxxxxxxx [mailto:ontolog-forum-
> bounces@xxxxxxxxxxxxxxxx] On Behalf Of Pat Hayes
> Sent: Wednesday, June 18, 2014 11:26 AM
> To: David Whitten
> Cc: [ontolog-forum]
> Subject: Re: [ontolog-forum] Requesting Opinions on the Benefits of
> Predicates as Nodes
>
>
> On Jun 17, 2014, at 9:08 AM, David Whitten <whitten@xxxxxxxxxx> wrote:
>
> > I would like to point out that using July as a time is problematic,
>
> I entirely agree, but didn't want to complicate my response by going into to
> many issues at the same, er, time.
>
> > as I believe that:
> >
> > (cl:comment 'C employs P during time interval T'
> > (employs C P July)
> > )
> >
> > would say that July is a time interval.
> > To my way of thinking, July is the name of the (infinite) set of all
> > time intervals that can be classified as overlapping with the month of
> > July in any year.
>
> A class of time intervals, in other words. Makes sense. There are other
> approaches, of course, but for sure, one needs to have a carefully thought
> through ontology of times and intervals and dates, and stick to it carefully.
> Just using words like "July" and hoping for the best, is not going to work.
>
> >
> > Thus, the statement (employs IBM Fred July) says that IBM employs Fred
> > during the month of July in every possible year. (perhaps Fred is a
> > seasonal worker)
> >
> > This is a different statement by far than saying IBM employs Fred for
> > a particular month of July in a particular year.
> > I expect also that the 3-D vs 4-D time view would argue that it is
> > actually a time-slice of Fred that is employed rather than the Fred
> > that exists at all times.
>
> I have come to think that the blood spilled over this 3d/4d contrast is not
> worth the cost. We all agree that things like persons last through time while
> retaining their identity: I am the same person now as I was ten years ago.
> Exactly how you reconcile this with the other obvious fact that things change
> with time, is really only a matter of notation. If you prefer to write the
>time
> parameter as attached to relations or predicates, and think of properties
> changing with time, then that is one way to do it (often called 3-D); if you
> prefer to attach the time parameter to object names and think of this as
> time-slices of things, that is another (4-D). But it is straightforward to
> translate between these, and with an expressive enough logic (such as ISO
> common logic) even to state their equivalence using axioms. As long as we all
> keep our philosophers on a short leash and stop them snarling at one
> another, we should have no trouble.
>
> Pat Hayes
>
> >
> > David Whitten
> > 713-870-3834
> >
> >
> >
> >
> > On Tue, Jun 17, 2014 at 7:51 AM, Tara Athan <taraathan@xxxxxxxxx>
> wrote:
> > On 6/17/14 1:03 AM, Pat Hayes wrote:
> > >> Using the IKL "that" operator and a "during" relationship and the
> concept "July" (a 'calendar month'):
> > > Whoa. No, this is NOT the right way to do it. In fact, this is
>meaningless.
> According to the IKL semantics, (that (employs C P)) denotes a fixed
> proposition which is true or false. There is no room for any time-dependent
> variability in its truth value, or for making it depend on some other
> parameter.
> > >
> > It may not be the *best* way to do it, but I don't agree that it's
> > wrong or meaningless. Using the proposition (that (employs C P)) as an
> > argument in a relation is not obstructed by its denotation of a fixed
> > proposition which is true or false (in any given interpretation).
> >
> > Starting off without quantifiers:
> >
> > (cl:comment 'C employs P'
> > (employs C P) )
> >
> > (cl:comment 'It holds during time interval T that C employs P'
> > (during (that (employs C P)) T )
> >
> > Nothing wrong with that - the truth values of these sentences are
> > independent of each other.
> >
> > Now bring on the quantifiers to relate the two
> >
> > (forall C P
> > (if
> > (cl:comment 'C employs P'
> > (employs C P) )
> > (exists T
> > (cl:comment 'It holds during some time interval T that C employs P'
> > (during (that (employs C P)) T )
> > ) ) )
> >
> > Some users may find this clearer than the polymorphic representation.
> > Why not let them use it?
> > It is still possible to have the polymorphic representation behind the
> > scenes for reasoning purposes.
> > (forall C P T
> > (iff
> > (cl:comment 'It holds during time interval T that C employs P''
> > (during (that (employs C P)) T ) (cl:comment 'C employs P
> > during time interval T'
> > (employs C P T)
> > ) )
> >
> > Also, using the "that" operator for temporal context is a gateway to
> > using it for other contexts/modalities.
> > I find the symmetry appealing:
> > (cl:comment 'It holds before time interval T that C employs P'
> > (before (that (employs C P)) T)
> > (cl:comment 'It holds after time interval T that C employs P'
> > (after (that (employs C P)) T )
> > (cl:comment 'It is possible that C employs P'
> > (possible (that (employs C P)) )
> > (cl:comment 'It is forbidden that C employs P'
> > (forbidden (that (employs C P)) )
> > (cl:comment 'Jane believes that C employs P'
> > (believes Jane (that (employs C P)) ) (cl:comment 'Omar knows that
> > C employs P'
> > (knows Omar (that (employs C P)) ) (cl:comment 'Maria asserts that
> > C employs P'
> > (asserts Maria (that (employs C P)) ) ...
> >
> > Tara
> >
> >
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