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Re: log:notIncludes (conclusion?)

From: Sandro Hawke <sandro@w3.org>
Date: Sat, 27 Aug 2005 14:51:42 -0400
To: Michael Kifer <kifer@cs.sunysb.edu>
Cc: public-rule-workshop-discuss@w3.org
Message-Id: <20050827185146.451A44EEBF@homer.w3.org>

> I think the key is that semantics(+URL,-Formula) predicate and the fact
> that you are leaving out of the picture the actual formulas that are
> sitting at URL. The formula that you are getting using semantics/2 is (as I
> understand) a list of terms that reify logical statements.
> So, you have
> formulas sitting at URL  (*)
> the built-in semantics(URL,Formula)
> and then you have something like
>     Formula notIncludes somelist
> So, adding a new formula to the set (*) can change the list Formula
> and invalidate a previously true statement of the form
> Formula notIncludes somelist.

Yes.  I think we're understanding each other very well, now.

> This is nonmonotonic.

I'm not sure I know the right words for this, but that stuff sitting
at that URL is considered immutable within one inference run.  cwm
makes no attempt to read it more than once; any change in it would go
along with an overall change in the state of the world.  A
long-running N3-based agent would have to start everything over each
delta-t (or cleverly act like it did).  Each time something observable
about the universe changes, we're talking about a new set of models
and interpretations.

Going back to the definition of monotonicity you and DanC were using
[1], the stuff sitting at that URL isn't part of A or B.  Nothing is
entailed by that stuff at the URL.  To be slightly silly, adding a
formula to it is no more relevant to the notion of monotonicity than
is adding characters to the end of some constant symbol in an FOL

Now, am I sounding confused again or like this is a sensible design
(even if not the one you might chose)....?     

      -- sandro

[1] http://lists.w3.org/Archives/Public/public-rule-workshop-discuss/2005Aug/0072
Received on Saturday, 27 August 2005 18:51:49 UTC

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