If the forum is going to begin discussing how to express time and the
semantics of time, I would seriously suggest the group look at the various
ISO standards and related IETF standards that dal with expressing time. If
you are interested in expressing time intervals etc, I would suggest you
look at the OGC Observations and Measurements standard. (01)
Any questions, please let me know. (02)
Regards (03)
Carl Reed
OGC (04)
> Dear John,
>
> I'm glad you brought it up, because it was on my mind too:
>
>> Re PTim: I realize that calling an interval a point is problematical.
>> But in anything that has to do with the physical world, there is no
>> way to specify a true point. Perhaps a better term would be "grain
>> in time", abbreviated "Grit".
>
> I think one of the constant challenges of ontology is to differentiate
> between common practice ways of representing things, e.g.
>
>> There are so many hard problems, it's hard to say which are harder.
>> But the idea of taking the least significant digit as the criterion
>> for implicit granularity is fairly common for experimental data
>> (unless some explicit margin of error is stated).
>
> And what they really are, i.e. in this case an interval or period. Now
> there is, in my mind, nothing wrong with naming an interval 14th Jan
> 2008, but it needs to be understood that it has a start time of midnight
> at the start of the day, and an end time of midnight at the end of the
> day, and that it is not in any sense a point in time.
>
> All this for me is independent of whether time is ultimately granular
> or continuous. Ultimately this only means at what point we can not longer
> tell whether one event happened before another.
>
>
> Regards
>
> 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
>
> Tel: +44 20 7934 4490 Mobile: +44 7796 336538
> Email: matthew.west@xxxxxxxxx
> http://www.shell.com
> http://www.matthew-west.org.uk/
>
>
>> -----Original Message-----
>> From: ontolog-forum-bounces@xxxxxxxxxxxxxxxx
>> [mailto:ontolog-forum-bounces@xxxxxxxxxxxxxxxx]On Behalf Of
>> John F. Sowa
>> Sent: 21 January 2008 17:48
>> To: [ontolog-forum]
>> Subject: Re: [ontolog-forum] Time representation
>>
>>
>> Pat,
>>
>> The position I most strongly advocate is not a specific ontology,
>> but a framework of conventions for organizing a multiplicity
>> of special cases (not necessarily consistent with one another),
>> making the implicit relationships explicit, and providing tools
>> and guidelines for mixing and matching. The lattice of theories
>> is an example. Robert Kent's IFF is a much more ambitious example.
>>
>> I would recommend a fairly simple framework for starters, since
>> there's a danger of freezing half-baked ideas before they're fully
>> baked. (RDF, for example, was hardly out of the oven before
>> Tim Bray tried, unsuccessfully, to pull it back in.)
>>
>> > Do you have any granularity axioms? That is one of the hardest
>> > ontological problems, in my experience.
>>
>> There are so many hard problems, it's hard to say which are harder.
>> But the idea of taking the least significant digit as the criterion
>> for implicit granularity is fairly common for experimental data
>> (unless some explicit margin of error is stated).
>>
>> Re PTim: I realize that calling an interval a point is problematical.
>> But in anything that has to do with the physical world, there is no
>> way to specify a true point. Perhaps a better term would be "grain
>> in time", abbreviated "Grit".
>>
>> John
>>
>> PS re HTML email formats: Your note of 11:18 was in a readable font
>> for Thunderbird, but your note of 11:37 appeared in a tiny, tiny font.
>> I had to increase the font size by two steps to make it the same as
>> the previous note. But then the fonts for all other notes were too
>> big, and I had to decrease the default by two steps.
>>
>> At least each of your notes was entirely in one font size. I've
>> received some email in which each paragraph was in a progressively
>> smaller font. That's why I hate HTML email.
>>
>>
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