On Tue, 25 Jun 2002, Adrian Ettlinger wrote:
> Shlomi says (in reply to Bill Raymond):
>
> <<I don't understand you exactly. Do you mean something that one of the
> subsequent positions needed to solve the state was already entered by the
> scan and so won't be checked?>>
> Shlomi, you're so polite. My inclination is to suggest that Bill has
> his head where the sun don't shine.
>
> Maybe what he really means is that in a given solver design, an
> intermediate position might be "intractable" in one case but not in another.
> I. e., the time it takes the solver to reach a verdict might be much longer
> in one case and not in the other. What I cannot conceive is that a correct
> and definitive verdict would be different in the two cases.
>
That's not what I mean. I mean the following:
The solution to the problem is S1 leading to S2 leading to S3 leading to
S4. (not directly) Now the scan starts from S1, goes to S3 and from it
reaches S2. Since S3 is in the DFS stack it cannot be visited, so S2 is
reported as unsolvable.
Regards,
Shlomi Fish
> Early on in my acquaintance with Bill, we had problems in our mutual
> understanding of the distinction between "impossible" and "intractable".
> It's two different things for a solver to say "I guarantee you that there is
> no solution for this particular position" versus "I can't find a solution in
> the time or space you have allotted to me."
>
With Freecell Solver the terms are a bit more fuzzy because of the
meta-moves and the possibility that a scan will only have a subset of
the possible moves.
Regards,
Shlomi Fish
> Best regards, -----------------Adrian
>
>
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----------------------------------------------------------------------
Shlomi Fish shlomif_at_vipe.technion.ac.il
Home Page:
http://t2.technion.ac.il/~shlomif/
Home E-mail: shlomif_at_iglu.org.il
He who re-invents the wheel, understands much better how a wheel works.
Received on Tue Jun 25 2002 - 07:17:01 IDT