Re: residuation for compositional search?

From: Michael Hanus <>
Date: Tue, 24 May 2011 21:57:26 +0200

Sebastian Fischer wrote:
> So this is an example where residuation helps to keep the program modular
> and the search space finite at the same time.

Thanks for the nice example.
Unfortunately, the relation between residuation and narrowing
is still not clear since there are also examples where
narrowing has a finite search space whereas the use of
residuation leads to an infinite seach space.

> P.S. There seems to be a bug in PAKCS. The definition
> partition l | concat (ensureSpine p) =:= l &
> all (not . null) p =:= True = p
> where p free
> fails to find a solution if the argument is non-empty. MCC succeeds.

This must be due to some tricky combination of backtracking
and coroutining behavior in Prolog, since I don't see an
immediate reason for it. Thanks for the bug report.

Best regards,

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Received on Di Mai 24 2011 - 21:59:10 CEST

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