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## Re: [ontolog-forum] Time representation

 To: "[ontolog-forum] " Pat Hayes Tue, 22 Jan 2008 23:12:11 -0600
 ```At 11:31 PM -0500 1/22/08, Patrick Cassidy wrote: >Just a question about one point (so to speak): > >> >> Re PTim: I realize that calling an interval a point is problematical. >> But in anything that has to do with the physical world, there is no >> way to specify a true point. Perhaps a better term would be "grain >> in time", abbreviated "Grit". >> > >Has anyone observed any problems of *logical consistency* in classifying a >point on a line as being identical to a closed interval of zero length, with >beginning and end points identical?    (01) I presume you mean, interval on the real line. None: this is quite consistent. This model (actually several versions of it) is discussed in the 'time catalog'. But it does produce some complications. For example, consider a ball tossed into the air. At one point in its trajectory, its vertical velocity is zero. If this is a closed interval [b,b], then the intervals of positive and negative vertical velocity must be open (or semi-open) intervals (a,b) and (b,c). Now, these intervals have the same endpoint, so they apparently meet (in the sense used by Allen's interval algebra). Yet there is an interval *between* them, so they apparently cannot meet. So this model seems to be incompatible with the Allen algebra, which is a major problem. The ontology called the 'vector continuum' there takes this idea and develops it axiomatically rather than presuming the real line, and gives a temporal ontology which I think is quite neat. But it has some apparent oddities, eg it allows negative intervals (which turn out to be quite useful.) And it isn't possible (AFAIK) to interpret it in the real line.    (02) > Or are the 'point' and 'interval' >classifications merely two different views of the same thing?    (03) Really, there is no simple answer to this question. Try reading some of the options described in the catalog. I think the various intuitions are reasonably well explained there.    (04) PatH    (05) > >PatC  > >Patrick Cassidy >MICRA, Inc. >908-561-3416 >cell: 908-565-4053 >cassidy@xxxxxxxxx > >> -----Original Message----- >> From: ontolog-forum-bounces@xxxxxxxxxxxxxxxx [mailto:ontolog-forum- >> bounces@xxxxxxxxxxxxxxxx] On Behalf Of John F. Sowa >> Sent: Monday, January 21, 2008 12:48 PM >> To: [ontolog-forum] >> Subject: Re: [ontolog-forum] Time representation >> >> Pat, >> >> The position I most strongly advocate is not a specific ontology, >> but a framework of conventions for organizing a multiplicity >> of special cases (not necessarily consistent with one another), >> making the implicit relationships explicit, and providing tools >> and guidelines for mixing and matching. The lattice of theories >> is an example. Robert Kent's IFF is a much more ambitious example. >> >> I would recommend a fairly simple framework for starters, since >> there's a danger of freezing half-baked ideas before they're fully >> baked. (RDF, for example, was hardly out of the oven before >> Tim Bray tried, unsuccessfully, to pull it back in.) >> >> > Do you have any granularity axioms? That is one of the hardest >> > ontological problems, in my experience. >> >> There are so many hard problems, it's hard to say which are harder. >> But the idea of taking the least significant digit as the criterion >> for implicit granularity is fairly common for experimental data >> (unless some explicit margin of error is stated). >> >> Re PTim: I realize that calling an interval a point is problematical. >> But in anything that has to do with the physical world, there is no >> way to specify a true point. Perhaps a better term would be "grain >> in time", abbreviated "Grit". >> >> John >> >> PS re HTML email formats: Your note of 11:18 was in a readable font >> for Thunderbird, but your note of 11:37 appeared in a tiny, tiny font. >> I had to increase the font size by two steps to make it the same as >> the previous note. But then the fonts for all other notes were too >> big, and I had to decrease the default by two steps. > > >> At least each of your notes was entirely in one font size. I've >> received some email in which each paragraph was in a progressively >> smaller font. That's why I hate HTML email. >> >> >> _________________________________________________________________ >> 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 >> > > >_________________________________________________________________ >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 >    (06) -- --------------------------------------------------------------------- IHMC (850)434 8903 or (650)494 3973 home 40 South Alcaniz St. (850)202 4416 office Pensacola (850)202 4440 fax FL 32502 (850)291 0667 cell phayesAT-SIGNihmc.us http://www.ihmc.us/users/phayes    (07) _________________________________________________________________ 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    (08) ```
 Current Thread Re: [ontolog-forum] Time representation, (continued) Re: [ontolog-forum] Time representation, Christopher Spottiswoode Re: [ontolog-forum] Time representation .. and "context", Ed Barkmeyer Re: [ontolog-forum] Time representation .. and "context", Michael K. Bergman Re: [ontolog-forum] Time representation .. and "context", Christopher Spottiswoode Re: [ontolog-forum] Time representation, Pat Hayes Message not availableRe: [ontolog-forum] Time representation, creed Re: [ontolog-forum] Time representation, Pat Hayes Re: [ontolog-forum] Time representation, Ed Barkmeyer Re: [ontolog-forum] Time representation, Sharma, Ravi Re: [ontolog-forum] Time representation, Patrick Cassidy Re: [ontolog-forum] Time representation, Pat Hayes <= Re: [ontolog-forum] Time representation, Patrick Cassidy Re: [ontolog-forum] Time representation, Sharma, Ravi Re: [ontolog-forum] Time representation, Patrick Cassidy Re: [ontolog-forum] Time representation, Pat Hayes Re: [ontolog-forum] Time representation, Pat Hayes Re: [ontolog-forum] Time representation, Pat Hayes Message not availableRe: [ontolog-forum] Time representation, Pat Hayes Re: [ontolog-forum] Time representation, Chris Partridge Re: [ontolog-forum] Time representation, paola . dimaio Re: [ontolog-forum] Time representation, matthew.west