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Re: [ontolog-forum] Role of definitions (Remember the poor human)

To: paola.dimaio@xxxxxxxxx
Cc: "[ontolog-forum]" <ontolog-forum@xxxxxxxxxxxxxxxx>
From: Pat Hayes <phayes@xxxxxxx>
Date: Thu, 15 Feb 2007 15:40:29 -0600
Message-id: <p06230917c1fa7fbd476c@[10.100.0.26]>
>*mild digression from discourse*
>
>Water is a good example of natural reality, so real yet so versatile
>yet so elusive    (01)

Indeed. I made an attempt at this a while back 
(Ontology of liquids, 1985). I found I had to 
distinguish between a 'piece of liquid' (roughly 
a particular set of molecules) and a 'liquid 
object' which is defined essentially by its 
spatial boundaries. Like a river, for example, 
which is the same liquid object but a different 
piece of liquid every moment. (I was living in 
Geneva at the time, so my example was Lac Leman, 
which has the Rhone flowing in one end and out 
other, and in spring changes color completely in 
two days or so, so evidently is a very different 
piece of liquid.) The fact the geographic volumes 
of water apparently are individuated in the 
second way, spatially, may account for why it 
seems natural to refer to a river even when it 
has no water in it, like a Wadi or wash.    (02)

>Maybe, a river is always a river if thats what you call that kind of
>thing,(define)  but it has different states.(river can be rivololet,
>or stream, eventually even steam - probably the reverse is true).
>
>The states depend on different conditions of the air.atmosphere,
>temperature.earth, and the natural cycles.
>
>Then again, if we want to define river and all its
>properties/transformations/states, we should really not forget to take
>a step back. River is water, water is Ho2,. So the river is just a
>state of some gas combination.    (03)

You have to distinguish chemical composition from 
massing together in a body from physical mixing, 
they are all kinds of combination.    (04)

>
>Model that?
>
>Depends, if it's the ontology for a mapping system, then it's a
>particular state that we
>are interested in modelling, although any representation is likely to
>be an approximation
>of what ther river in any given time/space coordinate    (05)

Indeed. Again, we have developed a semantics for 
maps which makes this very clear, because if you 
'back-project' eg a river line on the map to the 
terrain using the inverse of the projection 
function, it is often very much wider than the 
actual river. So you have to say that the 
semantics of the map is not that the line shows 
the actual position of the river, but that it 
*constrains* the actual position (ie the real 
position is 'inside' the back-projection). And 
then for example a road shown going to a town on 
the map could actually miss that town (there is 
enough 'room' for this to be possible) , unless 
we add a special map-interpretation convention 
which says that some kinds of coincidence on the 
map really do mean coincidence in the world.    (06)

>If the ontology is to map geophysical resources from the region, then
>maybe the representation can be more granular -
>
>depending what one is interested in modelling obviously, waht
>definition and representation
>one choses, however, we should keepin mind that 
>nothing is in a permanent state,
>and the state of everything is correlated by its dependencies, and
>dependencies are bound by some cycles.and laws, even they appear
>chaotic at times, I guess
>
>Model that in the ontology.    (07)

Hmm, that sounds like a philosophical position in 
metaphysics. Im not sure if we should try to 
model those in ontologies.    (08)

Pat    (09)

>
>just thinking lound    (010)

Great, we should all do more of it.    (011)

>
>*digression ends*
>
>
>Paola DM
>
>
>
>
>On 2/15/07, Kathryn Blackmond Laskey <klaskey@xxxxxxx> wrote:
>>  >...
>>  >As a matter of fact, a river IS always a river:
>>  >this is a necessary truth.
>>
>>  Except when it's a stream, or a brook, or a rivulet.
>>
>>  There is flowing water (well, today it may be frozen; last week, it
>>  was flowing) that passes under a bridge I drive over on the way from
>>  my home to GMU.  Whether that something is a river or a stream or a
>>  creek, is open to endless debate.  I agree that it is what it is, but
>>  is it always a river?  Always not a river?  I don't think that
>>  question has a definite answer.
>>
>>  Kathy
>  >
>>
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>
>
>--
>
>************************************
>Paola Di Maio
>Senior Lecturer
>School of IT, MFU.ac.th
>*************************************
>
>"For as long as space and time endures
>may I too abide to dispel misery and ignorance"
>
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>    (012)


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