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Subject: Re: Position to ponder

Author: Robert Hyatt

Date: 13:07:20 02/13/02

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On February 13, 2002 at 15:13:29, pavel wrote:

>On February 13, 2002 at 15:07:36, Robert Hyatt wrote:
>
>>On February 13, 2002 at 15:01:25, pavel wrote:
>>
>>>Chess Tiger 14.0 - Shredder 6
>>>[D]8/8/3r4/6p1/4k1B1/2K2R2/8/8 w - - 0 1
>>>
>>>Analysis by Chess Tiger 14.0:
>>>
>>>69.Kc3-c4 Rd6-d2 70.Rf3-f8 Ke4-e3 71.Kc4-c5 Rd2-g2 72.Bg4-h5 g5-g4 73.Rf8-e8+
>>>Ke3-f2
>>>  +-  (2.34)   Depth: 9   00:00:00  154kN, tb=54
>>>69.Kc3-c4 Rd6-d2 70.Rf3-f8 Ke4-e3 71.Kc4-c5 Rd2-g2 72.Bg4-h5 g5-g4 73.Rf8-e8+
>>>Ke3-f2 74.Kc5-d5
>>>  +-  (2.34)   Depth: 10   00:00:00  337kN, tb=111
>>>69.Kc3-c4 Rd6-d1 70.Rf3-f8 Rd1-c1+ 71.Kc4-b5 Rc1-g1 72.Bg4-f5+ Ke4-d4 73.Rf8-g8
>>>g5-g4 74.Rg8-d8+ Kd4-e5 75.Rd8-f8
>>>  +-  (2.28)   Depth: 11   00:00:03  1045kN, tb=432
>>>69.Kc3-c4 Rd6-d1 70.Rf3-f8 Rd1-c1+ 71.Kc4-b3 Rc1-g1 72.Bg4-f5+ Ke4-d4 73.Kb3-c2
>>>g5-g4 74.Kc2-d2 g4-g3 75.Kd2-e2 Rg1-g2+ 76.Ke2-f1
>>>  +-  (2.18)   Depth: 12   00:00:09  3250kN, tb=1522
>>>69.Kc3-c4 Rd6-h6 70.Rf3-f7 Rh6-h4 71.Bg4-c8 g5-g4 72.Rf7-d7 Ke4-e3 73.Rd7-d3+
>>>Ke3-f2 74.Rd3-d4 Rh4-h3 75.Rd4-d2+ Kf2-f1 76.Rd2-d7
>>>  +-  (1.94)   Depth: 13   00:00:35  12081kN, tb=4966
>>>69.Rf3-g3 Ke4-f4 70.Rg3-g1 Rd6-a6 71.Kc3-d4 Ra6-a3 72.Bg4-e2 g5-g4 73.Rg1-f1+
>>>Kf4-g5 74.Be2-d3 g4-g3 75.Kd4-e3 g3-g2 76.Rf1-f5+ Kg5-g4
>>>  +-  (2.06)   Depth: 13   00:00:45  15209kN, tb=7564
>>>
>>>(Mahamood, MyTown 13.02.2002)
>>>
>>>
>>>Analysis by Shredder 6:
>>>
>>>69...Ke4-f4 70.Kc3-b4
>>>  ³  (-0.26)   Depth: 1/2   00:00:00
>>>69...Ke4-f4 70.Rg3-g2
>>>  ³  (-0.26)   Depth: 2/4   00:00:00
>>>69...Ke4-f4 70.Rg3-g1 Rd6-g6
>>>  ³  (-0.31)   Depth: 3/6   00:00:00
>>>69...Ke4-f4 70.Rg3-g1 Rd6-g6 71.Kc3-d3
>>>  =  (-0.14)   Depth: 4/8   00:00:00
>>>69...Ke4-f4 70.Rg3-g1 Rd6-d8 71.Bg4-e6 Rd8-d6 72.Kc3-c2
>>>  ³  (-0.26)   Depth: 5/10   00:00:00
>>>69...Ke4-f4 70.Rg3-g1 Rd6-d8 71.Bg4-e6 Rd8-e8 72.Be6-d7
>>>  =  (-0.12)   Depth: 6/12   00:00:00
>>>69...Ke4-f4 70.Rg3-g1 Rd6-a6 71.Kc3-d4 Ra6-a2 72.Kd4-d3 Ra2-a3+ 73.Kd3-e2
>>>  =  (-0.06)   Depth: 7/14   00:00:00  14kN, tb=292
>>>69...Ke4-f4 70.Rg3-g1 Rd6-a6 71.Bg4-e2 Ra6-c6+ 72.Kc3-d4 Rc6-d6+ 73.Kd4-c5
>>>Rd6-d2 74.Rg1-g2
>>>  =  (-0.05)   Depth: 8/16   00:00:00  30kN, tb=723
>>>69...Ke4-f4 70.Rg3-g1 Rd6-a6 71.Bg4-e2 Ra6-c6+ 72.Kc3-d2 Rc6-d6+ 73.Be2-d3 g5-g4
>>>74.Rg1xg4+ Kf4xg4
>>>  =  (-0.01)   Depth: 9/18   00:00:00  60kN, tb=1707
>>>69...Ke4-f4 70.Rg3-g1 Rd6-a6 71.Bg4-e2 Ra6-c6+ 72.Kc3-d2 Rc6-d6+ 73.Be2-d3 g5-g4
>>>74.Rg1xg4+ Kf4xg4
>>>  =  (-0.01)   Depth: 10/20   00:00:00  133kN, tb=4019
>>>69...Ke4-f4 70.Rg3-g1 Rd6-a6 71.Bg4-e2 Ra6-c6+ 72.Kc3-d2 Rc6-d6+ 73.Be2-d3 g5-g4
>>>74.Rg1xg4+ Kf4xg4
>>>  =  (-0.01)   Depth: 11/22   00:00:01  217kN, tb=6821
>>>69...Ke4-f4 70.Rg3-g1 Rd6-g6 71.Kc3-d4 Rg6-d6+ 72.Kd4-c5 Rd6-a6 73.Kc5-d5
>>>  =  (-0.01)   Depth: 12/24   00:00:01  423kN, tb=12440
>>>69...Ke4-f4 70.Rg3-g1 Rd6-g6 71.Kc3-d4 Rg6-d6+ 72.Kd4-c5 Rd6-a6 73.Bg4-d7 Ra6-g6
>>>74.Rg1-f1+ Kf4-g3 75.Bd7-f5 Kg3-g2 76.Rf1-d1
>>>  =  (0.00)   Depth: 13/25   00:00:02  642kN, tb=18694
>>>69...Ke4-f4 70.Rg3-g1 Rd6-g6 71.Kc3-d4 Rg6-d6+ 72.Kd4-c5 Rd6-a6 73.Bg4-d7 Ra6-g6
>>>74.Rg1-g4+ Kf4-e5
>>>  =  (0.00)   Depth: 14/26   00:00:04  1086kN, tb=29673
>>>69...Ke4-f4 70.Rg3-g1 Rd6-g6 71.Kc3-d4 Rg6-d6+ 72.Kd4-c5 Rd6-a6 73.Bg4-d7 Ra6-g6
>>>74.Rg1-g4+ Kf4-e5
>>>  =  (0.00)   Depth: 15/27   00:00:06  1567kN, tb=40819
>>>69...Ke4-f4 70.Rg3-g1 Rd6-g6 71.Kc3-d4 Rg6-d6+ 72.Kd4-c5 Rd6-a6 73.Bg4-d7 Ra6-g6
>>>74.Rg1-g4+ Kf4-e5
>>>  =  (0.00)   Depth: 16/28   00:00:09  2284kN, tb=56293
>>>
>>>(Mahamood, MyTown 13.02.2002)
>>>
>>>
>>>
>>>Why does chesstiger thinks it's better.
>>>A possible bug?
>>>
>>>pavs
>>
>>
>>It is missing a piece of knowledge that says "king, rook and bishop vs a
>>king and rook is a draw, so a king, rook and bishop vs a king, rook and
>>pawn can't possibly be won by the KRB side...
>>
>>IE:  here is crafty's static evaluation of this position with no
>>search at all:
>>
>>note: scores are for the white side
>>material evaluation.................   3.60
>>development.........................   0.00
>>pawn evaluation.....................  -0.24
>>passed pawn evaluation..............   0.16
>>passed pawn race evaluation.........   0.00
>>king safety evaluation..............   0.00
>>interactive piece evaluation........  -3.52
>>total evaluation....................   0.00
>>
>>
>>Or after a search:
>>
>>              time surplus   0.00  time limit 30.00 (3:30)
>>         nss  depth   time  score   variation (1)
>>                1     0.00   0.00   1. Bh5
>>                1->   0.00   0.00   1. Bh5+
>>                2     0.00   0.00   1. Bh5 Rd1
>>                2->   0.00   0.00   1. Bh5 Rd1
>>                3     0.00   0.00   1. Bh5 Rd1 2. Kb4
>>                3->   0.00   0.00   1. Bh5 Rd1 2. Kb4
>>                4     0.00   0.00   1. Bh5 Rd1 2. Kb4 Ra1
>>                4->   0.00   0.00   1. Bh5 Rd1 2. Kb4 Ra1
>>                5     0.00   0.00   1. Bh5 Rd1 2. Kb4 Ra1 3. Bg4
>>                5->   0.01   0.00   1. Bh5 Rd1 2. Kb4 Ra1 3. Bg4
>>                6     0.01   0.00   1. Bh5 Rd1 2. Kb4 Ra1 3. Bg4 Ke5
>>                6->   0.02   0.00   1. Bh5 Rd1 2. Kb4 Ra1 3. Bg4 Ke5
>>                7     0.04   0.00   1. Bh5 Rd1 2. Kb4 Ra1 3. Bg4 Ke5 4.
>>                                    Kc5
>>                7->   0.05   0.00   1. Bh5 Rd1 2. Kb4 Ra1 3. Bg4 Ke5 4.
>>                                    Kc5
>>
>>It is something the engine has to "know" as search won't be able to see
>>that eventually the pawn is lost, and then the resulting KRB vs KR is
>>_still_ a draw.
>
>
>Even without the knowledge, shouldn't TB kick in to help?
>note that the search might not be deep enough, also note that the game is
>currently running and CT is consistent with it's eval throughout the last 10+
>moves.
>
>pavs


Nope...  both sides recognize that KRB vs KR is a draw.  So the side with
the KRB will delay taking that pawn for as long as possible, to prevent the
score from dropping to zero.




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