|From:||Pat Hayes <phayes@xxxxxxx>|
|Date:||Mon, 21 Jan 2008 11:15:41 -0600|
On the CG forum, there was a question about representing time in
No, no. Its a subset of full FO logic, true, but its not any more hostile to temporal relationships than any other logic, and one can approach the matter systematically, and indeed in much the same ways it is handled in more expressive logics.
Why linear? There are branching-time ontologies, circular-time ontologies, etc.. And it need not be a coordinate system exactly: many temporal ontologies have no metric information in them at all.
That raises more questions, whose answers
are more realistic.
But such intervals tend to have points at their ends, and meet at points. Its usually most useful to have both kinds of entity, or if you must restrict to one, use points and treat an interval as a pair of (end)points.
And there are other options in more expressive notations, such as treating relations as predicates on time-intervals:
The first option adds more complexity to
Sure they do. One simply has to use the (now standard) trick of introducing 'facts' (not the best word) which have temporal properties and also are systematically related to the arguments and property of the predication. So the above becomes
(there is fact of type HasPart with the haver role being x and the having role being y and the time-extent being t)
In the N-triples notation for RDF this would look like this
_:x rdf:type HasPart .
_:x rdf:type PredicationFact .
_:x ex:whole X .
_:x ex:part Y .
_:x ex:timeTrue T .
Now, I will admit immediately that such a representation has its problems: but it does actually work, if used consistently; and it is systematic. In fact, if you think of the _:x here as being a proposition, it can be viewed as a restricted subset of IKL.
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