Re: equivalent domain & range

Hi,

In his message (equivalent domain & range) of 26/02/2002,
Michael Denny wrote:
>Is there a way in DAML+OIL to simply specify that the domain and the range
>of a superslot are equivalent, so that when a subslot is applied to a class,
>its range is implicitly restricted to this same class?  (I guess this would
>be a form of property overloading.)  Thanks for the help.

This requires second order because what you want to express is that:

superslot: * -> *
	(* being a type variable in the ML fashion -- and this needs 
type unification for being propagated the way you want to the 
subslots).

The equivalent in FOL (LaTeX variant) would be:
$\forall subslot\leq superslot, \exists c; \forall i, j, 
subslot(i,i')\implies c(i) \wedge c(i')$
This quantifies both on slots and classes.

So, I do not think that there is even a way to (non simply) specify 
it in DAML+OIL. This would require constraints on _class variables_.
The only doable thing is exhaustive expression of the constraints.

Note that, in OOProgramming too, property overloading is generaly 
explicitely expressed (i.e., you have to overload and you cannot 
express what you asked for in the first place).

-- 
  Jérôme Euzenat                  __
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Received on Monday, 4 March 2002 03:32:27 UTC