# Re: equivalent domain & range

From: Jerome Euzenat <Jerome.Euzenat@inrialpes.fr>
Date: Sun, 3 Mar 2002 18:16:11 +0100
Message-Id: <a05101400b8a6ec6370f4@[194.199.20.189]>

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

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.

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 GMT

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