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Re: [ontolog-forum] Time representation

To: "[ontolog-forum]" <ontolog-forum@xxxxxxxxxxxxxxxx>
From: "John F. Sowa" <sowa@xxxxxxxxxxx>
Date: Mon, 21 Jan 2008 09:37:56 -0500
Message-id: <4794AE44.1010505@xxxxxxxxxxx>
Paola,    (01)

 > what is the accepted syntax for pTim
 > can pTim be a timestamp?  is there a prescribed format
 > for time/date in ikl    (02)

The dyadic relation PTim (point in time) is not an official
part of either conceptual graphs or IKL.  It is part of an
ontology for time, which I commonly use with CGs.  (And yes,
I would be happy to send or point to the ontology, if I had
it written down in a convenient form.  Right now, it is
scattered in a very inconvenient form.)    (03)

As I use it, the first argument of PTim is some physical event
or situation, and the second argument is some time specification.
Since I assume that time "points" can never be observed or
specified as true points, there is always an implicit granularity.
Therefore, the second argument could be any of the following,
each of which has a default granularity determined by the least
significant digit of the specification:    (04)

    [Date: "21 January 2008"] -- granularity of 1 day    (05)

    [Time: "21 January 2008, 14:03"] -- granularity, 1 minute    (06)

    [Time: "21 January 2008, 14:03:16.217"] -- granularity, 1 ms    (07)

As pure logics, CGs, CL, and IKL have no ontology or prescribed
format for time, space, or anything else.  Any string enclosed
in double quotes is interpreted as a name in those languages.
Therefore, "21 January 2008, 14:03:16.217" would be the name
of some entity of type Time.  The assumptions about granularity
are not official parts of CGs or any of the other languages.    (08)

But any project that used any of those languages would have to
adopt some standard representation for times and dates, and
the ontology would also have to include axioms that stated any
default assumptions about granularity.    (09)

John    (010)

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