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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 09:53:34 -0500
Message-id: <4794B1EE.5060007@xxxxxxxxxxx>
Dear Matthew,    (01)

JFS>> This list of options illustrates why it is so difficult to
 >> handle time in RDF and OWL:  they have no way of representing
 >> contexts, extra arguments for time, or modal and temporal
 >> operators.  For a specific problem, some ad hoc solution may
 >> be possible, but there is no systematic representation.    (02)

MW> These difficulties do not apply to 4-dimensionalism, because
 > periods in time are 4D spatio-temporal extents, and you can
 > simply say that a process, or a state was part of that period.
 > This can be handled by either OWL or CL.    (03)

The major difficulties are not in representing a single time
or date and associating it with something else that has been
identified.  The problem is to develop a systematic representation
that relates times to evolving processes in a way that can support
systematic methods for reasoning about them.  See that summary of
2304 types of processes by Eric Sandewall:    (04)

    http://www.jfsowa.com/ontology/process.htm    (05)

I agree that a 4D representation has a lot of advantages for many
purposes, but a 3+1 D form also has advantages for certain kinds
of problems.    (06)

In his book (from which I took that list), Sandewall goes into
great detail about methods for using logic for those kinds of
reasoning, and he's using a much richer logic than OWL and RDF.    (07)

John    (08)

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