From: Austin Tate (a.tate@ed.ac.uk)
Date: 03/07/03
How about the "primitives" Jerry...
Space Time
----- ----
location time-point
(interval) <- though I treat that as derived
The idea being that a neutral word like location which does not restrict
the meaning to be only one of a "point" or "area" or "volume" and leaves
nature of the "location" open can be useful to allow relationships to be
stated to give real meaning. It also then allows relationships to be given
to grid and coordinate systems in some way.
This is much like having a temporal ontology primitive like time point
which allows you to relate time points to one another and to metric time
descriptions on a calendar or timeline.
Jerry Hobbs wrote in reply:
>Good idea. In the time ontology I tried to axiomatize instants in a
>way that didn't force one to accept their existence. So Allen's approach
>in which everything is an interval is subsumed, and for him the axioms about
>the properties of instants are all vacuously true. I think I'd want to
>do a similar thing for locations -- be silent about whether points actually
>exist, but axiomatize what their properties would be if they did exist.
>
>I'd suggest that you send this bit to daml-spatial, to help get a discussion
>going.
Done via this message. James Allen and I discussed the issue of time
points and time intervals by the way while developing other ontologies such
as PIF and NIST PSL and he believe (I hope I am not misrepresenting him)
that time points can be seen as primitive and intervals as made up of two
time points. But his temporal calculus then uses these derived intervals
of course - which is fine.
Austin
--
Prof. Austin Tate, Artificial Intelligence Applications Institute, Informatics,
University of Edinburgh, Appleton Tower, Crichton Street, Edinburgh EH8 9LE, UK
Tel: +44 131 650 2732 Fax: +44 131 650 6513 E-mail: a.tate@ed.ac.uk
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