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Ron, I also agree, but 'truth in advertising' forces me to point out that 'spatio-temporal region' is not much of a restriction. Essentially, if you extend ISO 19107 through subtyping GM_Object, you get viable domain spaces for coverages. For example, in ISO 19141: Moving Features, we've extended geometry to involve a 3D object moving through 3D space during time. If you count carefully, you can get 4, 7, or 10 dimensions. The 4 is geographic space x time, the 7 is geographic space x object coordinates x time. For a moving truck, you know the time, the spot on the highway your truck's 'reference point' has reached, and the spot on the truck, which is a 3D offset from the reference point. This collapses to 4D, but if you do it you lose the 'spot on the truck' information, and fuzzy up the object trajectory. You can then blissfully add 3 more D's for each set of motion derivative you want to track. So, geo-space x time x truck-space x velocities-at-point-on-truck gives you 10D If you express the motion derivatives as coverages, you get a 7D domain, and a 3D range. BTW: Poincare's conjecture is trivial in 1, 2, 4, 5,... dimensions, but unsolved in 3. Sometimes you just need to an extra dimension or two to move around in. Regards, John
-----Original Message----- On Behalf Of Ron Lake Sent: Friday, May 13, 2005 12:20 PM HI, I agree with Simon's description - but it would not be difficult to generalize the current coverage concept to allow the domain to be other than a spatial-temporal region. Ron
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