Author: Richard Pijl
Date: 02:32:06 03/07/06
Go up one level in this thread
>>You'll need to know that two connected passers beat a rook when progressed to
>>3rd rank (or one to 4 and 2) and the defending king is too far away.
>>You will not find it in reasonable time without this 'knowledge' in your passed
>>pawn evaluation if you are doing any kind of pruning (including nullmove
>>pruning)
>This is not correct
>
>Movei find it in a few seconds without that knowledge and it certainly has
>pruning including null move pruning.
ok. I was assuming that Rxb2 would not survive pruning, pushing it away at least
a few more ply, and the checks on 6-7th rank would push it even 6 ply minus
extensions further. Of course, pawn push extensions would help as well (The
Baron doesn't have those anymore). Seems that my assumptions were not correct.
>This knowledge is not correct and based on this knowledge it may find Rxb2 also
>in the following diagram with the same PV.
>
>
>[D]8/7p/5k2/5p2/p1p2P2/Pr1p1K2/1P1R3P/8 b - -
The key here is that the white king can help stop the black pawns, in the
original position its own pawn block the white's king access to the black pawn.
You removed it in this position so the defending king is close enough. The Baron
recognizes this and doesn't play the sac:
ply time nodes score pv
2( 2)& 0:00.00 82 +2.04 h7-h6 Rd2-g2
2( 4)& 0:00.00 153 +2.09 Kf6-e6 h2-h4
2( 4)& 0:00.00 195 +2.11 Rb3-b6 Rd2-g2
2( 4)& 0:00.00 231 +2.19 Rb3-b7 Rd2-g2
2( 4)& 0:00.00 267 +2.22 Rb3-b8 Rd2-g2
2( 4). 0:00.00 300 +2.22 Rb3-b8 Rd2-g2
3( 4)& 0:00.00 416 +2.34 Rb3-b8 h2-h3 Rb8-g8
3( 4). 0:00.00 551 +2.34 Rb3-b8 h2-h3 Rb8-g8
4( 6)& 0:00.02 1355 +2.28 Rb3-b8 h2-h4 Rb8-d8 h4-h5
4( 6)+ 0:00.02 1875 +3.00 c4-c3 (b2xc3) (Rb3xc3)
4( 6)& 0:00.02 2062 +3.18 c4-c3 b2xc3 Rb3xc3 Rd2-a2 Rc3-c2
4( 6). 0:00.02 2379 +3.18 c4-c3 b2xc3 Rb3xc3 Rd2-a2 Rc3-c2
5( 7)& 0:00.02 3342 +3.13 c4-c3 b2xc3 Rb3xc3 Kf3-e3 Rc3xa3
Ke3-d4
5( 7). 0:00.02 4125 +3.13 c4-c3 b2xc3 Rb3xc3 Kf3-e3 Rc3xa3
Ke3-d4
6(10)& 0:00.03 7344 +3.04 c4-c3 b2xc3 Rb3xc3 Rd2-b2 Rc3xa3
Rb2-b6 Kf6-f7 Kf3-e3
6(10). 0:00.03 8824 +3.04 c4-c3 b2xc3 Rb3xc3 Rd2-b2 Rc3xa3
Rb2-b6 Kf6-f7 Kf3-e3
7(17)& 0:00.05 17120 +2.85 c4-c3 b2xc3 Rb3xc3 Rd2-b2 Rc3xa3
Rb2-b6 Kf6-f7 Rb6-b7 Kf7-g6 Kf3-e3
7(17). 0:00.08 24303 +2.85 c4-c3 b2xc3 Rb3xc3 Rd2-b2 Rc3xa3
Rb2-b6 Kf6-f7 Rb6-b7 Kf7-g6 Kf3-e3
8(15)+ 0:00.09 36415 +3.20 c4-c3 (b2xc3) (Rb3xc3) (Rd2-b2) (Rc3xa3)
(Rb2-b6) (Kf6-f7) (Rb6-b7) (Kf7-e6)
(Rb7xh7) (Ra3-b3)
8(19)& 0:00.13 47775 +3.26 c4-c3 b2xc3 Rb3xc3 Rd2-b2 Rc3xa3
Rb2-b6 Kf6-e7 Rb6-b7 Ke7-d6 Rb7xh7 Ra3-a2
8(19). 0:00.14 56430 +3.26 c4-c3 b2xc3 Rb3xc3 Rd2-b2 Rc3xa3
Rb2-b6 Kf6-e7 Rb6-b7 Ke7-d6 Rb7xh7 Ra3-a2
9(20)& 0:00.25 105174 +3.20 c4-c3 b2xc3 Rb3xc3 Rd2-a2 Rc3-c2
Ra2-a1 Rc2xh2 Kf3-e3 d3-d2 Ra1-d1 h7-h5
(Rd1xd2)
9(20). 0:00.31 128780 +3.20 c4-c3 b2xc3 Rb3xc3 Rd2-a2 Rc3-c2
Ra2-a1 Rc2xh2 Kf3-e3 d3-d2 Ra1-d1 h7-h5
(Rd1xd2)
10(17)& 0:00.48 208226 +3.20 c4-c3 b2xc3 Rb3xc3 Rd2-a2 Rc3-c2
Ra2-a1 Rc2xh2 Kf3-e3 d3-d2 Ra1-d1 h7-h5
Rd1xd2
10(17). 0:00.53 230088 +3.20 c4-c3 b2xc3 Rb3xc3 Rd2-a2 Rc3-c2
Ra2-a1 Rc2xh2 Kf3-e3 d3-d2 Ra1-d1 h7-h5
Rd1xd2
11(23)- 0:01.44 666278 +2.85 c4-c3 (b2xc3) (Rb3xc3) (Kf3-e3) (Rc3xa3)
(Rd2xd3) (Ra3xd3) (Ke3xd3) (a4-a3)
(Kd3-c3) (Kf6-e7)
(Kc3-b3)
11(23)& 0:01.53 711987 +2.87 c4-c3 b2xc3 Rb3xc3 Kf3-e3 Rc3xa3
Rd2xd3 Ra3-b3 Ke3-d4 Rb3xd3 Kd4xd3 Kf6-e7
Kd3-c3 h7-h6 (Kc3-b4)
11(23). 0:01.53 712002 +2.87 c4-c3 b2xc3 Rb3xc3 Kf3-e3 Rc3xa3
Rd2xd3 Ra3-b3 Ke3-d4 Rb3xd3 Kd4xd3 Kf6-e7
Kd3-c3 h7-h6 (Kc3-b4)
12(23)& 0:02.16 984002 +2.93 c4-c3 b2xc3 Rb3xc3 Kf3-e3 Rc3xa3
Rd2-b2 Kf6-e6 Rb2-b6 Ke6-d5 Rb6-h6 Kd5-c4
Rh6xh7 Ra3-c3 Rh7-a7 (a4-a3)
12(23). 0:02.44 1132721 +2.93 c4-c3 b2xc3 Rb3xc3 Kf3-e3 Rc3xa3
Rd2-b2 Kf6-e6 Rb2-b6 Ke6-d5 Rb6-h6 Kd5-c4
Rh6xh7 Ra3-c3 Rh7-a7 (a4-a3)
13(23)+ 0:04.72 2175124 +3.28 Kf6-e6 (Kf3-e3) (Ke6-d5)
13(23)& 0:08.34 3853828 +3.32 Kf6-e6 Kf3-f2 c4-c3 b2xc3 Rb3xc3
Kf2-e3 Rc3xa3 Rd2xd3 Ra3xd3 Ke3xd3 Ke6-d5
h2-h4 h7-h6 Kd3-c2 Kd5-c4
13(23). 0:08.63 3976328 +3.32 Kf6-e6 Kf3-f2 c4-c3 b2xc3 Rb3xc3
Kf2-e3 Rc3xa3 Rd2xd3 Ra3xd3 Ke3xd3 Ke6-d5
h2-h4 h7-h6 Kd3-c2 Kd5-c4
14(25)& 0:11.69 5343438 +3.49 Kf6-e6 Kf3-f2 Ke6-d5 Kf2-e3 h7-h6
h2-h3 Kd5-c5 h3-h4 h6-h5 Rd2-g2 d3-d2
Ke3xd2 Rb3xb2 Kd2-c3 Rb2-b3 Kc3-c2
(Rb3xa3)
14(25). 0:12.05 5498764 +3.49 Kf6-e6 Kf3-f2 Ke6-d5 Kf2-e3 h7-h6
h2-h3 Kd5-c5 h3-h4 h6-h5 Rd2-g2 d3-d2
Ke3xd2 Rb3xb2 Kd2-c3 Rb2-b3 Kc3-c2
(Rb3xa3)
15(26)+ 0:23.13 10360065 +3.84 Kf6-e6 (Kf3-f2) (Ke6-d6)
15(27)& 0:25.17 11272776 +3.81 Kf6-e6 Kf3-f2 Ke6-d6 h2-h3 Kd6-d5
Kf2-e3 h7-h6 h3-h4 h6-h5 Ke3-f3 Kd5-d4
Kf3-f2 c4-c3 b2xc3 Rb3xc3 Rd2-d1 Rc3xa3
If you look at the position you'll see that in the WAC#2 position it is harder
to recognize that the king is blocked out than to see that the king is too close
in this last position.
Richard.
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