restricting to subclasses

[Ed Shaya]

Here is a small problem with OWL Restrictions.  When the restriction on 
a property is SomeValuesOf, you can not easily narrow down this 
restriction in subsequent descendents.  So say you have object A and 
measurement class M.
A hasMeasurement M.
and you want to have Aa (a subclass of A) have measurement Mm (A 
subclass of M) but not the entire M class.  You can not use 
AllValuesFrom because then A can not have any other hasMeasurement. So 
you try SomeValuesFrom
Aa hasMeasurement some Mm.
Unfortunately this does not restrict the M here to be only Mm.  It just 
ensures that there is at least one Mm, there could still be a Mn.
This gets worse for deeper levels:
Aaa hasMeasurement some Mmm.
This just ensures that Aaa has subclass of Mm, Mmm, but Aaa also 
inherits from Aa and therefore must have at least one Mm and still could 
have an Mn.

Now, I would have expected that using subproperties would be the way 
out.  One might expect that if I had a subproperty of hasMeasurement 
call hasMm then one could provide the statement
Aa hasMm Mm.
And only Mm would go at the end of Aa hasMm.  Unfortunately, Aa still 
inherits the hasMeasurement and one does not accomplish the goal of
preventing Aa hasMeasurement Mn.

I can think of a way to get what I am after but it is ugly.  It uses 
AllValuesFrom:
Aa hasMeasurement only (Measurement and not M) and Mm
This removes all M from the allowable Measurements and then adds Mm.
Of course, a real case will be more complicated because there may be 
other types of Measurements which need to be narrowed down. One could
also create a class AaMeasurement with subclasses Mm, M1, M2m and M3, 
some of which are subclasses specifically for Aa and some not.  And then 
just state
Aa hasMeasurement only AaMeasurement.


Can anyone think of a better way?
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