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## Re: [ontolog-forum] Time representation

 To: "[ontolog-forum] " Pat Hayes Tue, 22 Jan 2008 11:19:29 -0600
 ```At 4:47 PM +0000 1/22/08, Ian Bailey wrote: >Hi Pat, > >In a 4D Ontology, what you refer to as a point in time is actually an extent >with one dimension (time) tending towards zero and the other three tending >towards infinity.    (01) Hi. I'm familiar with the 4-d approach, and like it: but the 4-d vs. continuant debate is a tarpit of endless debate which we can avoid while sticking closely to the topic of time.    (02) When discussing 4-d, time is indeed a dimension, so the intervals/points discussion is about the structure of that particular coordinate.    (03) >More usually, one is interested in a "point in time" over >a finite 3D extent though (ignoring relativistic considerations, which in >most earth-bound situations we can    (04) Yes, lets please ignore relativity. Never mind earth-bound: the Voyager probe got all the way to the Kuiper belt using Newtonian physics.    (05) >). We can talk about 4:00 UST all over the >world. That is not a point, it's an extent in four dimensions.    (06) 4:00 all over the world is a 3-d extent in 4 dimensions, forming the temporal boundary of a 4-d entity which we might call 3:00-to-4:00 all over the world. However, 4pm is indeed a point on the time axis, the projection of 4:00 all over the world onto that axis.    (07) >I'm sure Chris Partridge or Matthew West can explain this more precisely >than me, so apologies if my terminology is not quite correct. > >>From a purely pragmatic point of view (I'm what Chris describes as a >"hairy-arsed engineer"), 4D works and works very well - we've been working >with for years in ISO15926, and we chose the same approach for the IDEAS >Ontology (www.ideasgroup.org) 'cos it works. I've seen far too many bodged >and inconsistent attempts to manage time in data models and ontologies over >the years. The 4D approach gives you a pattern for representing change over >time that works in all cases and works consistently.    (08) I agree wholeheartedly. One of the worst decisions in recent ontology engineering has been the rejection of the 4-d approach in the medical ontology standards such as BOF and DOLCE. Putting these into a 4-d framework eliminates the useless and confusing need to duplicate content in two 'styles', once for continuants (things) and the other for occurrents (events).    (09) Pat    (010) > >Cheers >-- >Ian Bailey >www.modelfutures.com >T: +44 207 193 4605 >M: +44 7768 892362 >Skype > >Model Futures Limited is a company registered in England and Wales with >company number 05248454 >Registered Company Address: 1 Nelson Street, Southend-On-Sea, Essex, SS1 1EG >VAT Number: 848 7357 75 > > >But those start and end times ARE points. Really, >you can't get away from it: if you have >intervals, you have the points at their ends. >They might not be points in the mathematical real >line, but they are points in the following senses: > >1. they are indivisible (unless you change your interval topology) >2. they are the places where intervals meet one another >3. they are uniquely determined by your intervals >4. they determine the time ordering on the intervals > >And this is independent of whether or not you have continuous or dense time. > >Pat > > >>All this for me is independent of whether time is ultimately granular >>or continuous. Ultimately this only means at what point we can not longer >>tell whether one event happened before another. >> >> >>Regards >> >>Matthew West >>Reference Data Architecture and Standards Manager >>Shell International Petroleum Company Limited >>Registered in England and Wales >>Registered number: 621148 >>Registered office: Shell Centre, London SE1 7NA, United Kingdom >> >>Tel: +44 20 7934 4490 Mobile: +44 7796 336538 >>Email: matthew.west@xxxxxxxxx >>http://www.shell.com >>http://www.matthew-west.org.uk/ >> >> >>> -----Original Message----- >>> From: ontolog-forum-bounces@xxxxxxxxxxxxxxxx >>> [mailto:ontolog-forum-bounces@xxxxxxxxxxxxxxxx]On Behalf Of >>> John F. Sowa >>> Sent: 21 January 2008 17:48 >>> 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 >> > > >-- >--------------------------------------------------------------------- >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 > > >_________________________________________________________________ >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 >    (011) -- --------------------------------------------------------------------- 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    (012) _________________________________________________________________ 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    (013) ```
 Current Thread Re: [ontolog-forum] Time representation, (continued) Re: [ontolog-forum] Time representation, paola . dimaio Re: [ontolog-forum] Time representation, matthew.west 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, Pat Hayes Re: [ontolog-forum] Time representation, matthew.west Re: [ontolog-forum] Time representation, Pat Hayes Re: [ontolog-forum] Time representation, Ian Bailey Re: [ontolog-forum] Time representation, Pat Hayes <= Re: [ontolog-forum] Time representation, John F. Sowa Re: [ontolog-forum] Time representation, Pat Hayes Re: [ontolog-forum] Time representation, Duane Nickull Re: [ontolog-forum] Time representation, Pat Hayes Re: [ontolog-forum] Time representation, Randall R Schulz Re: [ontolog-forum] Time representation, Barker, Sean (UK) Re: [ontolog-forum] Time representation, Pat Hayes Re: [ontolog-forum] Time representation, Barker, Sean (UK) Re: [ontolog-forum] Time representation, Pat Hayes Re: [ontolog-forum] Time representation, Barker, Sean (UK)