Tom Beckman wrote: (01)
> I am
> also puzzled by absence of mechanisms in all of these upper ontology systems
> to describe the importance of an attribute and to measure the certainty of a
> value. It would seem to me that any robust reasoning system would require
> representation of these features to have realistically high performance. (02)
Although there is a movement towards all kinds of fuzzified and
vague versions of ontology languages like OWL (PROWL, FOWL, ...),
this seems to us in our work on spatial reasoning systems to be
missing the point of ontology. Our *knowledge* is uncertain,
but our ontologies less so. Therefore we separate out layers
of representation: the ontological level has modules that
are straight first order logic, description logic, modal
logic and the like; the epistemological level is what our
reasoning systems see. These take the ontological layer
and make an 'image' of it, where links are weighted and
effected by a variety of evidential reasoning. For our future
work, we'd like epistemological configurations that appear
very certain to be put forward as tentative candidates for
importing into the ontological layer (losing their
vagueness), but we would not want yet to allow the ontology
to deal head-on with intrinsically (i.e., formally)
uncertain entities. Possibly a simplifation, but until
we have real cases of *ontological vagueness* forced
on us, it seems better to avoid confusing where the
uncertainty lies. We have some papers in the area of
cognitive vision where we take this approach, but
its early days. I'd be interested to hear from anyone
else who is taking similar approaches. (03)
John B. (04)
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