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Subject: Re: Tough passed pawn theme from ECM98

Author: Bernhard Bauer

Date: 23:49:54 02/23/00

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On February 22, 2000 at 16:14:20, Howard Exner wrote:

>This from Wood - KLein,  Brighton - 1938
>Are programs able to solve this?
>
>[D]8/6Bp/6p1/2k1p3/4PPP1/1pb4P/8/2K5 b - -
>
>
>
>
>Solution:
>
>1... b2+ 2. Kc2 exf4 3. Bxc3 f3 4. Be1 Kd4
>Note that the move 2. ... exf4! must be in the line in order to consider
>the position solved.

As I haven't seen any Crafty solution for this position up to now I will post
mine here.

               15->   1:12   0.28   1. ... Kd6 2. g5 Ba1 3. Kb1 Bd4 4.
                                    h4 Ke6 5. Bxe5 Bxe5 6. fxe5 Kxe5 7.
                                    Kb2 Kxe4 8. Kxb3 Kd3 9. Kb4
               16     3:01   0.28   1. ... Kd6 2. g5 Ba1 3. Kb1 Bd4 4.
                                    h4 Ke6 5. Bxe5 Bxe5 6. fxe5 Kxe5 7.
                                    Kb2 Kxe4 8. Kxb3 Kd3 9. Kb4 Ke3
               16->   3:46   0.28   1. ... Kd6 2. g5 Ba1 3. Kb1 Bd4 4.
                                    h4 Ke6 5. Bxe5 Bxe5 6. fxe5 Kxe5 7.
                                    Kb2 Kxe4 8. Kxb3 Kd3 9. Kb4 Ke3
               17    15:02   0.00   1. ... Kd6 2. Bf8+ Ke6 3. f5+ Kf6 4.
                                    Bc5 gxf5 5. gxf5 h5 6. Kb1 Kg7 7. Ba3
                                    Kf6 8. Bc5
               17->  20:48   0.00   1. ... Kd6 2. Bf8+ Ke6 3. f5+ Kf6 4.
                                    Bc5 gxf5 5. gxf5 h5 6. Kb1 Kg7 7. Ba3
                                    Kf6 8. Bc5
               18    26:22   0.00   1. ... Kd6 2. Bf8+ Ke6 3. f5+ Kf6 4.
                                    Bc5 gxf5 5. gxf5 h5 6. Kb1 Kg7 7. Ba3
                                    Kf6 8. Bc5
         (3)   18->  39:56   0.00   1. ... Kd6 2. Bf8+ Ke6 3. f5+ Kf6 4.
                                    Bc5 gxf5 5. gxf5 h5 6. Kb1 Kg7 7. Ba3
                                    Kf6 8. Bc5
         (2)   19    55:22   0.00   1. ... Kd6 2. Bf8+ Ke6 3. f5+ Kf6 4.
                                    Bc5 gxf5 5. gxf5 h5 6. Kb1 Kg7 7. Ba3
                                    Kf6 8. Bc5
               19    95:41   0.24   1. ... b2+ 2. Kc2 exf4 3. Bxc3 f3 4.
                                    Be1 Kd4 5. e5 Kxe5 6. h4 Ke4 7. h5
                                    Ke3 8. hxg6 hxg6 9. g5 f2 10. Bxf2+
                                    Kxf2 11. Kxb2 Ke3 12. Kc3 Ke4
         (4)   19->  98:58   0.24   1. ... b2+ 2. Kc2 exf4 3. Bxc3 f3 4.
                                    Be1 Kd4 5. e5 Kxe5 6. h4 Ke4 7. h5
                                    Ke3 8. hxg6 hxg6 9. g5 f2 10. Bxf2+
                                    Kxf2 11. Kxb2 Ke3 12. Kc3 Ke4
         (3)   20   110:00   0.34   1. ... b2+ 2. Kc2 exf4 3. Bxc3 f3 4.
                                    Be1 Kd4 5. e5 Kxe5 6. h4 Ke4 7. h5
                                    Ke3 8. hxg6 hxg6 9. Ba5 f2 10. Bb6+
                                    Ke2 11. Bxf2 Kxf2 12. Kxb2 Kf3 13.
                                    g5
         (4)   20-> 221:54   0.34   1. ... b2+ 2. Kc2 exf4 3. Bxc3 f3 4.
                                    Be1 Kd4 5. e5 Kxe5 6. h4 Ke4 7. h5
                                    Ke3 8. hxg6 hxg6 9. Ba5 f2 10. Bb6+
                                    Ke2 11. Bxf2 Kxf2 12. Kxb2 Kf3 13.
                                    g5
         (3)   21   288:19   0.34   1. ... b2+ 2. Kb1 exf4 3. Bxc3 f3 4.
                                    Be1 Kd4 5. e5 Kxe5 6. Bf2 Ke4 7. Bc5
                                    Kd3 8. h4 Ke2 9. h5 f2 10. Bxf2 Kxf2
                                    11. Kxb2 Kf3 12. hxg6 hxg6 13. g5
         (4)   21-> 635:35   0.34   1. ... b2+ 2. Kb1 exf4 3. Bxc3 f3 4.
                                    Be1 Kd4 5. e5 Kxe5 6. Bf2 Ke4 7. Bc5
                                    Kd3 8. h4 Ke2 9. h5 f2 10. Bxf2 Kxf2
                                    11. Kxb2 Kf3 12. hxg6 hxg6 13. g5
         (3)   22   705:38   0.34   1. ... b2+ 2. Kb1 exf4 3. Bxc3 f3 4.
                                    Be1 Kd4 5. e5 Kxe5 6. Bf2 Ke4 7. Bc5
                                    Kd3 8. g5 Ke2 9. Kxb2 f2 10. Bxf2 Kxf2
                                    11. Kc3 Kg2 12. Kd4 Kxh3 13. Ke5
              time=900:00  cpu=200%  mat=0  n=1627492646  fh=0%  nps=30138
              ext-> checks=-2069570188 recaps=56036988 pawns=145669847
1rep=78542220 thrt:2109056
              predicted=0  nodes=1627492646  evals=101718645
              endgame tablebase-> probes done=2889757  successful=1806362
              SMP->  split=13695  stop=2150  data=12/64  cpu=1800:13
elap=900:00

Black(1): b2+
              time used: 900:00
whisper ply=22; eval=+0.34; nps=30k; time=900:00; cpu=200%; egtb=1806362
whisper  1. ... b2+ 2. Kb1 exf4 3. Bxc3 f3 4. Be1 Kd4 5. e5 Kxe5 6. Bf2 Ke4 7.
Bc5 Kd3 8. g5 Ke2 9. Kxb2 f2 10. Bxf2 Kxf2 11. Kc3 Kg
2 12. Kd4 Kxh3 13. Ke5

So Crafty 17.8 running on a 2 proc PIII-450 system takes 95 min to find 1...b2.
And even after more than 10 h the score is very low.
I am under the impression that Crafty needs some work on this area.
It may help a little to lower the extension values, but not much.
Crafty currently has same tactical weekness especially for combiations which
require many moves.

Kind regards
Bernhard




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