[Top] [All Lists]

Re: [ontolog-forum] Time representation

To: "[ontolog-forum] edbark@xxxxxxxx," <ontolog-forum@xxxxxxxxxxxxxxxx>, Pat Hayes <phayes@xxxxxxx>
From: Duane Nickull <dnickull@xxxxxxxxx>
Date: Tue, 22 Jan 2008 12:14:48 -0800
Message-id: <C3BB8EB8.B947%dnickull@xxxxxxxxx>
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
<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
<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)

"Speaking only for myself"
Senior Technical Evangelist - Adobe Systems, Inc.
Blog - http://technoracle.blogspot.com
Community Music - http://www.mix2r.com
My Band - http://www.myspace.com/22ndcentury
Adobe MAX 2008 - http://technoracle.blogspot.com/2007/08/adobe-max-2008.html
**********************************************************************    (016)

Message Archives: http://ontolog.cim3.net/forum/ontolog-forum/  
Subscribe/Config: http://ontolog.cim3.net/mailman/listinfo/ontolog-forum/  
Unsubscribe: mailto:ontolog-forum-leave@xxxxxxxxxxxxxxxx
Shared Files: http://ontolog.cim3.net/file/
Community Wiki: http://ontolog.cim3.net/wiki/ 
To Post: mailto:ontolog-forum@xxxxxxxxxxxxxxxx    (017)

<Prev in Thread] Current Thread [Next in Thread>