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Subject: Re: WAC #2

Author: Klaus Friedel

Date: 02:16:49 05/02/04

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On May 02, 2004 at 05:09:15, Klaus Friedel wrote:

>On May 01, 2004 at 22:51:55, Robert Hyatt wrote:
>
>>On May 01, 2004 at 01:41:52, Klaus Friedel wrote:
>>
>>>On April 30, 2004 at 23:04:24, Andrew Wagner wrote:
>>>
>>>>Here's the position:
>>>>
>>>>[d] 8/7p/5k2/5p2/p1p2P2/Pr1pPK2/1P1R3P/8 b - -
>>>>
>>>>The move to find here is Rxb2. My question is...what ply does your program find
>>>>the solution on? To tactically work it out to see that you can force queening
>>>>requires something like 13 or 14 ply. This is an interesting knowledge vs.
>>>>search position...can you special-case this somehow to find it sooner? The
>>>>problem is, as an FM friend of mine pointed out, if the king were just a bit
>>>>closer, the sac is losing. E.g. In this position:
>>>>
>>>>[d] 8/7p/5k2/5p2/p1p2P2/Pr1p1K2/1P1R3P/8 b - - (white pawn missing on e3)
>>>>...the sac would be losing because the king is close enough to stop the pawns.
>>>>So my first inclination to somehow make the static eval see that the pawns were
>>>>worth being down a pawn seems to be bad. Any thoughts?
>>>
>>>Snitch finds it at ply 9
>>>
>>>I hava a special eval term "rook vs 2 connected pawns with king far away"
>>>to help in such positions.
>>>
>>>Snitch0.3.57  WB2 35 MB:
>>> 1   00:00  0,20   b3b2
>>> 1   00:00  1,78   b3b2 d2b2 f6g6
>>> 1   00:00  1,87   b3a3
>>> 2   00:00  1,72   b3a3 e3e4
>>> 2   00:00  1,78   b3b2 d2b2 f6g6
>>> 3   00:00  1,96   b3b2 d2b2 c4c3
>>> 4   00:00  1,66   b3b2 d2b2 c4c3 b2b7 f6g6
>>> 5   00:00  1,66   b3b2 d2b2 c4c3 b2b6 f6g7 b6b7 g7g6
>>> 5   00:00  1,78   f6f7 h2h3 b3b2 d2b2 c4c3
>>> 6   00:00  0,53   f6f7 e3e4 f7e6 f3e3 b3b7 e4e5 e6d5
>>> 6   00:00  1,15   b3b2 d2b2 c4c3 b2b6 f6g7 b6b7 g7g6 b7h7 g6h7
>>> 6   00:00  1,49   c4c3 b2c3 b3c3 e3e4 c3a3 f3e3
>>> 7   00:00  1,20   c4c3 b2c3 b3c3 e3e4 c3a3 e4e5 f6e6 f3e3
>>> 7   00:00  1,30   f6g6
>>> 8   00:01  0,51   f6g6 e3e4 b3b7 d2g2 g6f6 f3e3 f5e4 e3e4 b7e7 e4d4
>>> 8   00:01  0,67   b3b5 e3e4 f5e4 f3e4 b5b7 e4d4 b7c7 d4e4 c7e7 e4d5
>>> 8   00:01  0,80   b3b6 e3e4 f5e4 f3e4 b6e6 e4f3 h7h6 d2g2 e6e7 h2h4 f6f5
>>> 8   00:01  0,82   b3b7 e3e4 f5e4 f3e4 b7e7 e4d4 e7e2
>>> 9   00:01  0,95   b3b7 e3e4 f5e4 f3e4 b7e7 e4d4 e7e2 d2d1 e2c2 d1e1 c2e2
>>> 9   00:01  1,02   b3b2
>>> 9   00:02  1,86   b3b2 d2b2 c4c3 b2b6 f6e7 b6b7 e7d8 b7f7 c3c2 f7f5 c2c1q f5d5
>>>d8e7 d5d3 e7e6
>>>10   00:02  1,86   b3b2 d2b2 c4c3 b2b6 f6f7 b6b7 f7e6 b7b6 e6e7
>>>11   00:02  1,86   b3b2 d2b2 c4c3 b2b6 f6f7 b6b7
>>>12   00:04  2,06   b3b2
>>>12   00:08  3,00   b3b2 d2b2 c4c3 b2b6 f6e7 b6b7 e7e6
>>>13   00:14  3,20   b3b2
>>>13   00:19  3,74   b3b2 d2b2 c4c3 b2b6 f6e7 f3f2 c3c2 b6c6 e7d7 f2e1 d7c6 e1d2
>>>c6d5 h2h3 d5e4 h3h4 c2c1q d2c1 e4e3 c1b2 e3f4
>>>
>>>
>>>Regards,
>>>Klaus Friedel
>>
>>
>>See what happens if you move the white pawn on e3 to g3.  I once had a bug that
>>would _still_ think this sac (Rb2) was winning in that position when it
>>definitely is not...
>
>Evaluation still works as designed. Rb2 is not selected in this case.
>
>Position with pawn moved to g3
>

Sorry wrong position.
Hier is the right one. Rb2 avoided almost instantly.

[d] 8/7p/5k2/5p2/p1p2P2/Pr1p1KP1/1P1R3P/8 b - - 0 1

Snitch0.3.57  WB2 35 MB:
 1   00:00  0,20   b3b2
 1   00:00  1,73   b3b2 d2b2 f6g6
 1   00:00  1,81   b3a3
 2   00:00  1,73   b3b2 d2b2 f6g6
 3   00:00  1,91   b3b2 d2b2 c4c3
 3   00:00  1,93   b3a3
 3   00:00  1,92   b3a3 f3e3
 4   00:00 -3,34   b3a3 b2a3 f6e6 f3e3 e6d5
 4   00:00  1,60   b3b2 d2b2 c4c3 b2b7 f6g6
 5   00:00 -3,54   b3b2 d2b2 c4c3 b2b6 f6e7 f3e3
 5   00:00 -3,34   b3a3 b2a3 f6e6
 5   00:00  0,59   h7h5 f3e3 b3b8 e3d4 b8c8
 5   00:00  0,87   b3b5 f3e3 b5d5 d2f2 d5d8
 5   00:00  0,96   b3b6 f3e3 b6e6 e3d4 e6e4 d4c3 e4e2
 6   00:00  0,87   b3b6 f3e3 b6d6 d2d1 f6e6 d1e1 d3d2
 6   00:00  0,99   b3b7 f3e3 b7d7 h2h3 d7e7 e3d4 e7e2
 7   00:00  1,02   b3b7 f3e3 b7d7 d2d1 f6e6 d1c1 e6d5 c1e1
 7   00:00  1,19   f6e6
 7   00:00  1,18   f6e6 f3e3
 8   00:00  1,18   f6e6 f3e3 e6d5 h2h3 b3b6 g3g4 b6h6 g4f5 h6h3 e3f2 d5e4
 9   00:00  1,18   f6e6 f3e3 e6d5 h2h3 b3b6 g3g4
10   00:00  1,21   f6e6 f3e3 e6d5 h2h3 b3b6 g3g4 b6h6 g4f5 h6h3 e3f2 d5e4 f2g2
11   00:02  1,36   f6e6 f3e3 e6d5 h2h3 b3b6 d2f2 b6e6 e3f3 h7h5 f2d2 d5d4 f3g2
d4e4
12   00:02  1,36   f6e6 f3e3 e6d5 h2h3 b3b6 d2f2 b6e6
13   00:04  1,37   f6e6 f3e3 e6d5 h2h3 b3b6 d2g2 h7h5 h3h4 b6b7 g2d2 b7e7
14   00:06  1,38   f6e6 f3e3 e6d5 h2h3 b3b6 e3f3 h7h5 f3e3
15   00:16  1,56   f6e6 f3e3 e6d5 h2h3 b3b6 d2g2 b6e6 e3f3 d5d4 g2f2 h7h5 f3g2

Regards,
Klaus



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