Re: concrete extension

From: Jeff Heflin (
Date: 01/23/01

"Peter F. Patel-Schneider" wrote:
> Hi:
> There are differences between the abstract and concrete relationships that
> show up in the syntactic definition.  For example, toClass has a range of
> Class, which is different from the range of toDataType.  This indicates
> that we would lose something if we used toClass for both abstract and
> concrete properties.
> peter

Looking at daml+oil+concrete.daml, toDataType doesn't have a range
specified, which I think in RDF means anything (including a Class) could
be a valid object for the property, but that's not really the issue...

The issue is: are these range constraints artificial (i.e., created just
so we can differentiate the properties) or are the properties
fundamentally different? I argue that they aren't fundamentally
different because they both have identical semantics per

x in IC(?R) iff IR(?P)({x}) <= IC(?C)

If the only difference in meaning is that one applies to the concrete
domain and the other to the abstract, why confuse the user with
different syntactical constructs?


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