RE: [ubl-lcsc] Alan Stitzer Comments on DateTime

[Chin Chee-Kai <cheekai@softml.net>]

On Wed, 21 May 2003, Michael Adcock wrote:

>>The 'Particular Point of Date and/or Time' is (a.)
Ok, independent definition.  Let this be T.


>>The 'Duration' is (b.)
Ok, measures a time range, which may or may not repeat.
Let this be D.


>>The 'Period' is either a combination of (a.) + (b.), (a.) + (a.) or
>>(b.) + (a.)
>>The 'Periodicity/Recurrent'  is either:
>>- a series of (a.) within a (b.)
>>- a series of (Period) within a (b.)
>>- a series of (a.) within a (Period)
>>- a series of (b.) within a (Period)
>>which seems to imply we need to define only expressions for (a.) and
>>(b.).

Think I agree with Michael Adcock that (a) & (b) may not be
sufficient.  Fundamental Physics of waves (and others) defines
a "period" to be the minimum amount of time over which a
complete wavelength spans.  A wave necessarily repeats itself
over and over until the source terminates wave generation.
For instance, a person blowing flute in G# for 5 seconds
produces a wave of period P at time T for a duration D=5 seconds.

Borrowing that concept from Physics, then, Period necessarily
implies a recurrent activity.  The "recurrence" R attribute is
then a vector that defines a starting point T (e.g. when the 
flute starts to sound), and an ending point E (e.g. 5 seconds 
after start, or an absolute date-time reference), thus giving 
a duration of D = (E - T).

So basically, it would seem that T, D, P and R are all quite
independent variables.

Just to give another perspective, but I'll leave the
decision to the group



Best Regards,
Chin Chee-Kai
SoftML
Tel: +65-6820-2979
Fax: +65-6743-7875
Email: cheekai@SoftML.Net
http://SoftML.Net/




>>
>>To my mind Periodicity needs more than just a series of (a) or (b)
>>- it may be unbounded, i.e. with no start, end or duration specified
>>- it may be bounded, i.e. with a start or end or duration in
>>combination
>>Those are the 'bounds': then there are the 'occurrences'
>>- dates as such do not figure as occurrences: that's just a list of
>>dates
>>- 'events' e.g. day names, 1st week or e.g. 15th day of the month do
>>figure, and I think these are conceptually different to 'date'. One
>>might need an 'occurrence period', e.g. Tuesday-to-Thursday, 15th-18th.
>>- I think 'time' might appear connected with 'event', e.g. making
>>"10:00hrs every Tuesday", and that this might be a time period, e.g.
>>10:00-to-13:00 every Tuesday.
>>
>>Any more thoughts, everyone?
>>