Dear John, (01)
> 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. (02)
There is an ISO standard for the representation of time, ISO 8601.
I commend its use, rather than coming up with something else. (03)
Regards (04)
Matthew West
Reference Data Architecture and Standards Manager
Shell International Petroleum Company Limited
Registered in England and Wales
Registered number: 621148
Registered office: Shell Centre, London SE1 7NA, United Kingdom (05)
Tel: +44 20 7934 4490 Mobile: +44 7796 336538
Email: matthew.west@xxxxxxxxx
http://www.shell.com
http://www.matthew-west.org.uk/ (06)
> -----Original Message-----
> From: ontolog-forum-bounces@xxxxxxxxxxxxxxxx
> [mailto:ontolog-forum-bounces@xxxxxxxxxxxxxxxx]On Behalf Of
> John F. Sowa
> Sent: 21 January 2008 14:38
> To: [ontolog-forum]
> Subject: Re: [ontolog-forum] Time representation
>
>
> Paola,
>
> > what is the accepted syntax for pTim
> > can pTim be a timestamp? is there a prescribed format
> > for time/date in ikl
>
> 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.)
>
> 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:
>
> [Date: "21 January 2008"] -- granularity of 1 day
>
> [Time: "21 January 2008, 14:03"] -- granularity, 1 minute
>
> [Time: "21 January 2008, 14:03:16.217"] -- granularity, 1 ms
>
> 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.
>
> 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.
>
> John
>
>
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> (07)
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