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Subject: Re: Level of complexity

Author: martin fierz

Date: 01:27:01 01/08/04

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On January 07, 2004 at 22:55:36, Ed Trice wrote:

[[snip]

>Of interest is that my partner and I found some 7-piece checkers endings that
>are won for the side with 4 pieces that programs cannot win. We have a perfect
>play database that can announce the win in 253 plies and play it perfectly, but
>when we defend the losing side, we can draw it.

i don't know whether that is correct. IIRC your experiments were done with
wyllie (a weak program) and with an old version of kingsrow (which was
absolutely no good at winning these kind of positions - i know this because i
discussed this with the author of kingsrow, ed gilbert - of course, you couldn't
know this!).
after some discussion with ed gilbert, his program is now much better at
converting wins. you should try again against his latest version 1.14l; if that
can't win against the perfect play database then you have a point!

i noticed that there is a downloadable version of WCC gold plus now,
unfortunately for this purpose it only has a 6pc perfect play database. can you
give me a couple of hard 6-piece wins that i can try against cake?
in one of the games i played between cake 6-pc and WCC gold plus, cake got into
a winning 3-2 ending where WCC announced that it would lose in 75 ply, and cake
needed 79 ply to finally win (it twice played a move that left the
distance-to-win unchanged) - not bad; but of course it probably gets
exponentially harder with distance-to-win.

cheers
  martin



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