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## Re: [ontolog-forum] Time representation

 To: "[ontolog-forum]" "John F. Sowa" Mon, 21 Jan 2008 13:43:35 -0500 <4794E7D7.8080907@xxxxxxxxxxx>
 ```Pat,    (01) Your note of 12:15 is now in the same size as the note of 11:18.    (02) JFS>> An approach with explicit time represents time with a linear >> coordinate system.    (03) PH> 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.    (04) I agree. Sandewall's examples, which I cited, include those. When I contrasted explicit time with temporal logics, I just happened to be thinking of the default model.    (05) JFS>> But finite intervals with domain-dependent granularity >> are more realistic.    (06) PH> 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.    (07) You could also consider a grain to be specified by a probability distribution of measurements whose median, mean, or mode is the designated point. Or variations of fuzzy or rough methods.    (08) PH> And there are other options in more expressive notations, > such as treating relations as predicates on time-intervals: > (HasPart(x,y))(t)    (09) Yes, that's another example of the open-ended range of ontologies that may be useful for various purposes.    (010) PH> Sure they [RDF and OWL] do [have the option of representing > extra arguments for time]. 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)    (011) I admit that one can indeed define such constructions.    (012) PH> 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.    (013) But I still recall Guha's original argument for RDF as "simple". And I cringe at the thought of what those N-triples would become when expanded to the full XML form.    (014) John    (015) PS: Speaking of bloatware, have you seen the reports that Microsoft is already testing a replacement for Vista with "key partners": http://www.tgdaily.com/html_tmp/content-view-35641-118.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) ```
 Current Thread Re: [ontolog-forum] Time representation, (continued) Re: [ontolog-forum] Time representation, Wacek Kusnierczyk Re: [ontolog-forum] Time representation, John F. Sowa Re: [ontolog-forum] Time representation, Pat Hayes Re: [ontolog-forum] Time representation, John F. Sowa Re: [ontolog-forum] Time representation, matthew.west Re: [ontolog-forum] Time representation, matthew.west Re: [ontolog-forum] Time representation, John F. Sowa Re: [ontolog-forum] Time representation, Jerry Hobbs Re: [ontolog-forum] Time representation, John F. Sowa Re: [ontolog-forum] Time representation, Pat Hayes Re: [ontolog-forum] Time representation, John F. Sowa <= Re: [ontolog-forum] Time representation, Duane Nickull Re: [ontolog-forum] Time representation, Alan Ruttenberg