Re: terminating 'imports' loops

From: Dan Connolly (
Date: 03/22/01

pat hayes wrote:
> I suggest adding the following sentence to the end of the paragraph
> in the ref manual.
> Comments? re-wordings?

I could live with that specification, but I wonder...
do you really want to use the same term for 'imports'
and its transitive closure?

While I've got your attention on this
subject... I think I first ran into it
as 'Assertion of another document'
in TimBL's semantic web toolbox.

In my attempts to formalize it, I've always done
so by way of something list ist from context logic; or
maybe it's something like the entails/gate thingy:

  (forall (?ont1 ?ont2 ?f)
          (and (sw:entails ?ont1 ?f)
	       (daml:imports ?ont2 ?ont1))
          (entails ?ont2 ?f)

where entails is built on some kind of says thingy:

  (forall (?doc ?f1 ?f2)
    (=> (and (sw:says ?doc ?f1)
             (wtr ^(=> ,?f1 ,?f2)) )
        (sw:entails ?doc ?f2) ) )

but of course this binds sw:entails very closely
with KIF wtr and such... which brings up
all those KIF annoyances about using variables
in the syntactic place where predicates go and
such... you're working on fixing that, aren't
you Pat? Any news?

I'm aware of a few other approaches that might
work, but they seem to use
higher order logic: McDermott's lambda

and the PCA stuff.

> Pat
> -----------------
> Imports
> Each daml:imports statement references another DAML+OIL ontology
> containing definitions that apply to the current DAML+OIL resource.
> Each reference
> consists of a URI specifying from where the ontology is to be
> imported from. See the example above. Imports statements are
> transitive, that is, if ontology A
> imports B, and B imports C, then A imports both B and C.  Importing
> an ontology into itself is considered a null action, so if ontology A
> imports B and B imports A, then they are
> considered to be equivalent.
> ---------------------------------------------------------------------
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Dan Connolly, W3C
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  (put return phone number in from/subject)

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