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Subject: Re: Crafty and draw by repetition ?!

Author: Robert Hyatt

Date: 14:46:46 04/21/00

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On April 21, 2000 at 16:32:21, pete wrote:

>Game : Crafty17.10 (winboard)- Junior6 on 2 computers ( rest really irrelevant
>); crafty played with the "official" book.bin .
>
>1.e4 e5 2.Nf3 Nc6 3.Bb5 a6 4.Ba4 Nf6 5.0-0 Be7 6.Re1 b5 7.Bb3 d6 8.c3 0-0 9.h3
>Bb7 10.d4 Re8 11.Ng5 Rf8 12.Nf3 Re8 13.Ng5 Rf8 14.Nf3
>
>Here crafty claimed draw by repetition !?

This looks reasonable to me.  After white moves Nf3, the position is the same
as it was after moves 10 and 12.  Nf3 is the third repetition of that position.


>
>Part of crafty-logfile :
>
>Black(13): time 462484
>time remaining:  77:04 (crafty).
>Black(13): otim 447395
>time remaining:  74:33 (opponent).
>Black(13): e8f8
>predicted move made.
>              time=5:41  cpu=99%  mat=0  n=67749325  fh=90%  nps=198567
>              ext-> checks=777869 recaps=260250 pawns=28570 1rep=59721 thrt:1500
>              predicted=14  nodes=67749325  evals=22514617
>              endgame tablebase-> probes done=0  successful=0
>              time used:   1:38
>White(14): Nf3
>              time used:   4:03
>game is a draw by repetition.
>1/2-1/2 {Drawn by 3-fold repetition}
>
>       +---+---+---+---+---+---+---+---+
>    8  | *R|   |   | *Q|   | *R| *K|   |
>       +---+---+---+---+---+---+---+---+
>    7  |   | *B| *P|   | *B| *P| *P| *P|
>       +---+---+---+---+---+---+---+---+
>    6  | *P|   | *N| *P|   | *N|   |   |
>       +---+---+---+---+---+---+---+---+
>    5  |   | *P|   |   | *P|   |   |   |
>       +---+---+---+---+---+---+---+---+
>    4  |   |   |   | P | P |   |   |   |
>       +---+---+---+---+---+---+---+---+
>    3  |   | B | P |   |   | N |   | P |
>       +---+---+---+---+---+---+---+---+
>    2  | P | P |   |   |   | P | P |   |
>       +---+---+---+---+---+---+---+---+
>    1  | R | N | B | Q | R |   | K |   |
>       +---+---+---+---+---+---+---+---+
>         a   b   c   d   e   f   g   h
>
>              puzzling over a move to ponder.
>              clearing hash tables
>         nss  depth   time  score   variation (1)
>                6->   0.83   0.00   14. ... Re8
>                7     0.83   0.00   14. ... Re8
>Black(14): Re8 [pondering]
>              clearing hash tables
>              time limit 2:42 (16:15)
>         nss  depth   time  score   variation (1)
>Black(14): result 1/2-1/2 {Drawn by 3-fold repetition}
>Black(14): force
>Black(14): quit
>LearnBook() executed
>execution complete.
>
>This seems to be a bug to me . As far as I understand the rule the 1st one who
>could claim draw here is black when he plans Re8 which is btw not forced at all


See above....  I think it repeats the position seen after white's move 10 and
12, making it the third repetition.




>.
>
>Minor issue is that I have seen this special opening line in a few computer
>programs opening books now and I remember a few that won't avoid the draw by
>simply choosing something else .
>
>happy easter.
>
>pete

Crafty won't play the draw as a book line, but it thinks it is the right thing
to do after a long search...




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