To:  "[ontologforum] " <ontologforum@xxxxxxxxxxxxxxxx> 

Cc:  SWforum <semanticweb@xxxxxx> 
From:  Kathryn Blackmond Laskey <klaskey@xxxxxxx> 
Date:  Wed, 01 Aug 2007 12:26:40 0400 
Messageid:  <p06110405c2d65f54795e@[129.174.89.24]> 
Chris,
Your remark hearkens back to our discussion of what an ontology
is really about.
Model theoretic semantics says there is a domain D, which is a
set, and the objects, attributes and relationships defined in the
ontology refer to elements of, functions defined on, and subsets of
this set D.
Many people feel this is way too abstract. "But my
ontology of horse racing is about horses!!! And jockeys
and racetracks and betting odds! It emphatically is not about
sets!"
We have had many heated discussions in this forum about whether
sentences in a biology textbook are about cells in the world or about
cells in a biological model of cells. Jon suggested maybe they
are about both. That they can be about both is why engineering works!
It's why you can get up in the morning expecting your car to start,
the traffic lights to work, and the bridge not to collapse.
Engineers build a computer model of the bridge because there is a
great deal less loss of life and a much greater return on the dollar
from building computer simulations of cars driving across the bridge
and testing out various designs before setting the cement mixers and
beam layers to work. We have learned in the school of hard
knocks that it is not a good idea to try out a bridge design by
building it and seeing whether it collapses under the load we put on
it.
The equations the engineer programs into the simulation are about
the bridge model. The engineer uses this fact to debug her
simulation and to test out various bridge designs by changing aspects
of the computer model. Because the equations are about the model, she
can be confident that changes in parameters of the model will result
in changes to the simulation output that accurately reflect her
intentions. The equations are also about the actual
bridge that is going to be built. Well, to be precise, the
equations for the discarded designs are about bridges she is
considering building, and the ones in the final design are about the
bridge she plans to build, but they will probably be modified somewhat
by the time concrete is poured. In any case, because the
equations are about both the bridge model and the bridge, she
can be confident (if it's a good model) that predictions she makes on
the basis of the simulation (such as how much load the bridge can
bear) will be true of the actual bridge when it is built. Thus,
the fact that the assertions are true both of the bridge model
and the real bridge is the reason that engineers can design bridges
that can carry the traffic they are designed to carry. Our lives
depend on this vital characteristic of models.
Some of the very same equations could, under different
circumstances, be used to model airplanes or electrical circuits or
pollution in the Chesapeake Bay. That is the beauty of
mathematics. There are common mathematical structures that are
generally useful across a wide variety of problem domains. It is
also the bane of students who are interested in nursing or robotics or
baseball, but have to sit through a generic mathematics course that
either uses almost no examples or requires them to do problems about
applications about which they don't care a hoot. This gives rise
to frequent turf wars between the math department, which is sure the
psychology department or the nursing school is incapable of teaching
math the way it ought to be taught, and the nursing school or
psychology department, which complains that the mathematicians lose
the students by teaching abstractions divorced from applications that
would hold the students' interest. Probably, both are right 
that's part of the price we pay for massproducing education.
But that's a different soapbox.
Kathy
At 10:31 AM 0500 8/1/07, Christopher Menzel wrote:
> The scopes and subject matters of Ontology and Logic shouldn't be > defined by _________________________________________________________________ Message Archives: http://ontolog.cim3.net/forum/ontologforum/ Subscribe/Config: http://ontolog.cim3.net/mailman/listinfo/ontologforum/ Unsubscribe: mailto:ontologforumleave@xxxxxxxxxxxxxxxx Shared Files: http://ontolog.cim3.net/file/ Community Wiki: http://ontolog.cim3.net/wiki/ To Post: mailto:ontologforum@xxxxxxxxxxxxxxxx (01) 
<Prev in Thread]  Current Thread  [Next in Thread> 


Previous by Date:  Re: [ontologforum] Current Semantic Web Layer Cake, Christopher Menzel 

Next by Date:  Re: [ontologforum] Current Semantic Web Layer Cake, Christopher Menzel 
Previous by Thread:  Re: [ontologforum] Current Semantic Web Layer Cake, Christopher Menzel 
Next by Thread:  Re: [ontologforum] Current Semantic Web Layer Cake, Christopher Menzel 
Indexes:  [Date] [Thread] [Top] [All Lists] 