The OWL-time ontology agrees. (01)
On 1/22/08 12:06 PM, "Ed Barkmeyer" <edbark@xxxxxxxx> wrote: (02)
> Pat wrote:
>
>> All true and important. Nevertheless, it is also important to
>> distinguish having points in ones ontology from claiming to be able to
>> locate points numerically with absolute precision. These are not the
>> same issue. One can embrace the former without claiming the latter.
>
> Absolutely. It is meaningful to talk about time points and time
> intervals in *an ontology*, where the presumption is that the users
> share the meanings of the individuals, however exact or fuzzy that may be. (03)
Instant(t) --> TemporalEntity(t) (04)
Interval(T) --> TemporalEntity(T) (05)
(A T)[TemporalEntity(T) --> [Instant(T) v Interval(T)]] (06)
Intervals are, intuitively, things with extent and
instants are, intuitively, point-like in that they have no interior
points. (In what follows, lower case t is used for instants, upper
case T for intervals and for temporal-entities unspecified as to
subtype. This is strictly for the reader's convenience, and has no
formal significance.) (07)
_begins_ and _ends_ are relations between instants and temporal
entities.
<axiom id="2.1-4">
begins(t,T) --> Instant(t) & TemporalThing(T)
</axiom> (08)
<axiom id="2.1-5">
ends(t,T) --> Instant(t) & TemporalThing(T)
</axiom> (09)
For convenience, we can say that the beginning and end of an instant is
itself. The converses of these rules are also true.
<axiom id="2.1-6">
Instant(t) <--> begins(t,t)
</axiom> (010)
<axiom id="2.1-7">
Instant(t) <--> ends(t,t)
</axiom> (011)
The beginnings and ends of temporal entities, if they exist, are
unique.
<axiom id="2.1-8">
TemporalEntity(T) & begins(t1,T) & begins(t2,T) --> t1=t2
</axiom> (012)
<axiom id="2.1-9">
TemporalEntity(T) & ends(t1,T) & ends(t2,T) --> t1=t2
</axiom> (013)
It does not talk about precision. IMO - precision is best described in a
mid level or domain specific ontology so it can be meaningful and suitable
for its purposes. (014)
Duane (015)
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