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Subject: Re: Programming Issue: When & how should the engine claim a draw or res

Author: Robert Hyatt

Date: 10:57:19 11/30/03

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On November 30, 2003 at 13:22:20, Dieter Buerssner wrote:

>On November 30, 2003 at 12:49:21, Robert Hyatt wrote:
>
>>On November 30, 2003 at 11:43:45, Bob Durrett wrote:
>>>How do the open-source engines, like Crafty, deal with this issue?
>>
>>_correctly_.
>>
>>:)
>
>Are you sure?
>
>Crafty 17.14 with the critical position set up:
>
>Black(37): go
>              time surplus   1:12  time limit 31.29 (3:07)
>         nss  depth   time  score   variation (1)
>               14->   0.17   0.00   37. ... Kh7
>               15     0.17   0.00   37. ... Kh7
>               15->   0.41   0.00   37. ... Kh7
>               16     0.41   0.00   37. ... Kh7
>               16->   0.74   0.00   37. ... Kh7
>               17     0.74   0.00   37. ... Kh7
>               17->   1.39   0.00   37. ... Kh7
>               18     1.39   0.00   37. ... Kh7
>               18->   2.75   0.00   37. ... Kh7
>               19     2.75   0.00   37. ... Kh7
>               19->   5.68   0.00   37. ... Kh7
>               20     5.68   0.00   37. ... Kh7
>               20->  11.87   0.00   37. ... Kh7
>               21    11.87   0.00   37. ... Kh7
>               21->  30.95   0.00   37. ... Kh7
>               22    30.95   0.00   37. ... Kh7
>              time=1:02  cpu=99%  mat=1  n=67680116  fh=90%  nps=1077022
>              ext-> checks=5044426 recaps=120656 pawns=243230 1rep=318232 thrt:4
>5078
>              predicted=0  nodes=67680116  evals=13317768
>              endgame tablebase-> probes done=4154  successful=460
>              hashing-> trans/ref=33%  pawn=99%  used=99%
>
>Black(37): Kh7
>              time used:   1:02
>game is a draw by repetition.
>
>Note, we first see the move, and then the info: "game drawn", which can easily
>be interpreted as not correct.

No it can't.  Because to play a game of chess, you are required to _move_ the
pieces, and _press_ the clock.  That is why humans have "blind rules" for a
player that can't see.  And the rules explain this very clearly.  If the
draw is a repetition before the move is played,
>
>Now the same in xboard mode. It may also show a small bug in Crafty. I had set
>up the position after white's 33rd move by fen and forced the moves in the
>actual game, just before the critical move. Crafty ignored the movenumber of the
>FEN, so I set mn to 37.
>
>White(38): undo
>ERROR!  move  is illegal
>NOTICE: 55 moves to next time control
>
>So I set back the mn, then:
>
>White(6): mn 6
>move number set to 6
>White(6): undo
>NOTICE: 56 moves to next time control
>Black(5): mn 37
>move number set to 37
>Black(37): xboard
>
>tellics set 1 Crafty v17.14
>kibitz Hello from Crafty v17.14!
>go
>move g8h7
>1/2-1/2 {Drawn by 3-fold repetition}
>
>Again, first the move (which would be shown on the GUI board). Then claiming the
>result. Arguably also not correct, and even bad timing could come in. Assume,
>xboard just sent the move to ICC. Opponent moves immediatly (say before ICC sees
>the draw claim, due to some lag) and with his move, he will not allow another
>repetition.
>
>There is no good solution in general for WB/XB. For a manually operated game,
>perhaps something like
>
>telluser I write Kh7 on my score sheet now, and claim a draw by this. Please
>call the TD, stop the clocks, don't do the move on the board ...
>
>would be sufficient.
>
>I think, GCP is quite right, when he says that probably no engine does this
>correctly.

Only if you use the context of playing chess.  Since no computer has "hands"
they certainly have a problem...


>
>Regards,
>Dieter



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