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Subject: Re: Draw by 2nd repetition?

Author: Will Singleton

Date: 12:36:02 03/31/99

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On March 31, 1999 at 13:06:17, Bruce Moreland wrote:

>On March 31, 1999 at 12:46:42, Jeremiah Penery wrote:
>>On March 31, 1999 at 12:08:49, James Robertson wrote:
>>>I have noticed from a post below that some people consider the position a draw
>>>if it has repeated twice in the search. What are the advantages and
>>>disadvantages of this? I am currently waiting until 3rd repetition; is this
>>From what I've seen, it's good to wait until the 3rd repetition.  Very often,
>>I've seen times when Crafty (which scores a draw at 2nd repetition) finds that
>>it can force the position to repeat (for the second time) and so scores it as a
>>draw, even when the opponent has any number of winning moves it can play before
>>the third repetition.  It often plays inferior moves thinking it can draw by
>>I'm not sure where it could be better to detect draws after the second
>>repetition - it seems it'd be just as easy, and more reliable, to detect them
>>only at the third rep.
>My program was playing a game against Greg Kennedy a long time ago, and the
>following situation occurred.
>The program was down two pawns and was completely lost.  But Kennedy made a
>mistake, and my program made a move that won a pawn.  At this point the best
>move from Kennedy's point of view was to undo the move he'd just done.  My
>program's move forced him off of something he was defending, and he had to go
>back to where he was, and now the program could simply take a pawn that was
>sitting there for free, vastly improve its chances for a draw.
>But that's not what it did.  The move it made to win the pawn was also
>retractable, so it chose to repeat the position, and scored this as 0.00.
>Of course, rather than repeating his mistake, Kennedy chose a better move and my
>program was down two pawns again.

I've seen similar situations.  My opponent makes a mistake, then I move, he then
moves the piece back where it was (unusual), and I now repeat instead of taking
advantage of the better situation.  This can occur only when I want the draw, of
course, and usually it's not harmful.  But it could be.

Is this worth fooling with?


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