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Subject: Re: Tablebase exits?

Author: James T. Walker

Date: 11:38:11 05/31/99

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On May 31, 1999 at 12:20:12, Dave Gomboc wrote:

>On May 31, 1999 at 08:51:38, James T. Walker wrote:
>
>>Hello David,
>>In the above code is the case where there are several "Last moves" in the EGTB
>>that are say "Mate in 13" covered?  You seem to say you have it covered where
>>the other moves are higher mates like "Mate in 14" but what keeps the program
>>from jumping from one mate in 13 to another mate in 13 since it's not worse?
>>Jim Walker
>
>It has to be better.
>
>When you've already found a "mate in n", your next position must be a "mate in
>n-1".  Otherwise, the first position wasn't actually a mate in n.
>
>BTW, I didn't examine the code.
>
>Dave

Hello Dave,
Please understand, I'm not a programmer so my questions may sound silly.  The
question I'm trying to clear up is when the program finds a mate in 13 but the
mate in 12 is only found by having the next tabelbase (which is missing).  Now
you have to force yourself to go to a score of say +9.3 instead of mate in 12
because the tabelbase is missing.  He seemed to be saying there was only two
possiblities, 1.  when the tablebase is available and 2 when only other moves
were mate in 14 (In my example).  This seemed to ignore the possibility of
having multiple mate in 13 positions in the tablebase.  So my question was about
how do you avoid the other mate in 13 positions since they are not worse than
the one you are in but only equal.  I ask this because I saw a program play
several moves at the mate in 13 level before dropping out of the tablebase.  I'm
not sure what caused it to finally drop out except maybe it was in danger of 3
times rep which would make dropping out preferable to staying at mate in 13 and
taking the draw.  I'm just trying to figure out if I missed something in the
explanation.
Jim Walker



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