tricky endgame

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jdart
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tricky endgame

Post by jdart »

This is one of the trickier 6-piece endgames:

[d] 8/8/6K1/8/r1k5/7P/5PP1/8 w - -

f4 here draws - other moves lose. Rybka 3 does really well on this - see output below - but many other engines find it difficult.

Fen: 8/8/6K1/8/r1k5/7P/5PP1/8 w - - 0 1
Bm: f4

no 2 0 -185 256 g4
no 3 20 -175 540 g4
no 4 20 -188 907 g4
no 5 20 -195 1509 g4 Kd3
yes 5 30 -168 2273 f4
yes 5 30 -154 2718 f4 Kd5
yes 6 30 -162 3776 f4 Kd5 f5
yes 7 50 -142 4925 f4
yes 7 60 -136 5718 f4 Kd5 f5 Ra6+ Kg5
yes 8 110 -147 8846 f4 Kd5 f5 Ra6+ Kg5 Ke5 g4 Ra8
yes 9 200 -147 17943 f4 Kd5 f5 Ra6+ Kg5 Ke5 g4 Rf6
no 10 500 -153 44652 h4 Kd3 g3 Ra6+ Kg5 Ke2 h5 Kxf2
no 11 860 -135 75731 h4 Kd5 g3 Ke6 f3 Ra8 g4 Rg8+ Kh7 Rf8 h5
Rxf3 Kg6 Rf6+ Kg7 Rf7+ Kg6 Rf4 g5
no 12 1170 -135 96444 h4 Kd5 g3 Ke6 f3 Ra8 g4 Rg8+ Kh7 Rf8 h5
Rxf3 Kg6 Rf6+ Kg7 Rf7+ Kg6 Rf4 g5
no 13 1560 -148 124458 g3 Ra6+ Kg5 Ra5+ Kg6 Ra2 f4
no 14 1940 -147 149393 g3 Ra6+ Kg5 Ra5+ Kg6 Ra2 g4
no 15 4240 -135 318017 g3 Kd5 h4 Ke6
no 16 8910 -115 604914 h4
no 16 9310 -135 633470 h4 Kd5 g3 Ke6
yes 17 20470 -115 1535012 f4 Kd5 f5
yes 17 20600 -136 1546196 f4 Kd5 f5
yes 18 27810 -116 1978645 f4
yes 18 33670 -136 2418869 f4 Kd5 f5 Ra3 Kf6 Ra6+ Kg7
yes 19 38440 -116 2772110 f4
yes 19 45240 -96 3199966 f4
yes 19 60130 -56 4308679 f4
yes 19 75780 -30 5508877 f4 Kd5 f5 Ra3 Kf6 Ra6+ Kg7
yes 20 77770 -30 5655694 f4 Kd5 f5 Ra3 Kf6 Ra6+ Kg7
yes 21 84520 -30 6131478 f4 Kd5 f5 Ra3 Kf6 Ra6+ Kg7
yes 22 93300 -30 6700343 f4 Kd5 f5 Ra3 Kf6 Ra6+ Kg7 Ke5 g4 Rc6 Kf7
Rb6 Kg7 Rd6 Kf7
yes 23 104390 -30 7395631 f4 Kd5 f5 Ra3 Kf6 Ra6+ Kg7
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michiguel
Posts: 6401
Joined: Thu Mar 09, 2006 8:30 pm
Location: Chicago, Illinois, USA

Re: tricky endgame

Post by michiguel »

jdart wrote:This is one of the trickier 6-piece endgames:

[d] 8/8/6K1/8/r1k5/7P/5PP1/8 w - -

f4 here draws - other moves lose. Rybka 3 does really well on this - see output below - but many other engines find it difficult.

Fen: 8/8/6K1/8/r1k5/7P/5PP1/8 w - - 0 1
Bm: f4

no 2 0 -185 256 g4
no 3 20 -175 540 g4
no 4 20 -188 907 g4
no 5 20 -195 1509 g4 Kd3
yes 5 30 -168 2273 f4
yes 5 30 -154 2718 f4 Kd5
yes 6 30 -162 3776 f4 Kd5 f5
yes 7 50 -142 4925 f4
yes 7 60 -136 5718 f4 Kd5 f5 Ra6+ Kg5
yes 8 110 -147 8846 f4 Kd5 f5 Ra6+ Kg5 Ke5 g4 Ra8
yes 9 200 -147 17943 f4 Kd5 f5 Ra6+ Kg5 Ke5 g4 Rf6
no 10 500 -153 44652 h4 Kd3 g3 Ra6+ Kg5 Ke2 h5 Kxf2
no 11 860 -135 75731 h4 Kd5 g3 Ke6 f3 Ra8 g4 Rg8+ Kh7 Rf8 h5
Rxf3 Kg6 Rf6+ Kg7 Rf7+ Kg6 Rf4 g5
no 12 1170 -135 96444 h4 Kd5 g3 Ke6 f3 Ra8 g4 Rg8+ Kh7 Rf8 h5
Rxf3 Kg6 Rf6+ Kg7 Rf7+ Kg6 Rf4 g5
no 13 1560 -148 124458 g3 Ra6+ Kg5 Ra5+ Kg6 Ra2 f4
no 14 1940 -147 149393 g3 Ra6+ Kg5 Ra5+ Kg6 Ra2 g4
no 15 4240 -135 318017 g3 Kd5 h4 Ke6
no 16 8910 -115 604914 h4
no 16 9310 -135 633470 h4 Kd5 g3 Ke6
yes 17 20470 -115 1535012 f4 Kd5 f5
yes 17 20600 -136 1546196 f4 Kd5 f5
yes 18 27810 -116 1978645 f4
yes 18 33670 -136 2418869 f4 Kd5 f5 Ra3 Kf6 Ra6+ Kg7
yes 19 38440 -116 2772110 f4
yes 19 45240 -96 3199966 f4
yes 19 60130 -56 4308679 f4
yes 19 75780 -30 5508877 f4 Kd5 f5 Ra3 Kf6 Ra6+ Kg7
yes 20 77770 -30 5655694 f4 Kd5 f5 Ra3 Kf6 Ra6+ Kg7
yes 21 84520 -30 6131478 f4 Kd5 f5 Ra3 Kf6 Ra6+ Kg7
yes 22 93300 -30 6700343 f4 Kd5 f5 Ra3 Kf6 Ra6+ Kg7 Ke5 g4 Rc6 Kf7
Rb6 Kg7 Rd6 Kf7
yes 23 104390 -30 7395631 f4 Kd5 f5 Ra3 Kf6 Ra6+ Kg7
Even with EGTBs is difficult?

Gaviota with GTBs sticks to f4. I will let it run more but I doubt it will reach to a 0.00 score.

Miguel

Code: Select all

         8   1       0.0    -0.65  1.f4 Ra6+ 2.Kg5
        50   2       0.0    -1.04  1.f4 Ra2
       499   3       0.0    -1.00  1.f4 Ra6+ 2.Kg5 Ra2
      2914   4       0.0    -0.73  1.f4 Ra3 2.Kh5 Kd4
      4045   5       0.0      :-(  1.f4
     33805   5       0.1    -1.17  1.f4 Ra3 2.g4 Rxh3 3.f5 Rh2
     35930   5       0.1    -1.15  1.g4 Ra6+ 2.Kg7 Ra3 3.h4 Rf3 4.g5 Rxf2
    109192   6       0.3    -1.10  1.g4 Ra6+ 2.Kh5 Rf6 3.g5 Rf5 4.h4 Kd4
                                   5.Kg4 Rxf2
    167791   6       0.4      :-)  1.f4
    168413   6       0.4    -0.74  1.f4 Ra3 2.g4 Rxh3 3.f5 Rg3 4.g5 Rg2
    170940   6:      0.4    -0.74  1.f4 Ra3 2.g4 Rxh3 3.f5 Rg3 4.g5 Rg2
    408144   7       0.9    -0.50  1.f4 Kd5 2.f5 Ra3 3.g4 Rxh3 4.g5
    448588   7:      1.2    -0.50  1.f4 Kd5 2.f5 Ra3 3.g4 Rxh3 4.g5
    928877   8       2.0    -0.43  1.f4 Kc5 2.f5 Ra3 3.g4 Rxh3 4.g5 Rh2
                                   5.f6 Rg2
   1372118   8:      3.1    -0.43  1.f4 Kc5 2.f5 Ra3 3.g4 Rxh3 4.g5 Rh2
                                   5.f6 Rg2
   4972549   9       8.9    -0.39  1.f4 Ra6+ 2.Kg5 Ra8 3.g3 Kd4 4.Kg4 Rg8+
                                   5.Kf3 Rc8 6.f5 Ke5 7.g4 Rc3+ 8.Kg2
   6359916   9:     11.8    -0.39  1.f4 Ra6+ 2.Kg5 Ra8 3.g3 Kd4 4.Kg4 Rg8+
                                   5.Kf3 Rc8 6.f5 Ke5 7.g4 Rc3+ 8.Kg2
  15402455  10      20.7    -0.20  1.f4 Ra6+ 2.Kg5 Ra8 3.f5 Kd5 4.g4 Ke5
                                   5.Kg6 Kf4 6.f6 Kg3 7.g5 Kxh3
  17619846  10:     23.4    -0.20  1.f4 Ra6+ 2.Kg5 Ra8 3.f5 Kd5 4.g4 Ke5
                                   5.Kg6 Kf4 6.f6 Kg3 7.g5 Kxh3
 187799747  11     138.8    -0.38  1.f4 Ra6+ 2.Kg5 Kd4 3.h4 Ra5+ 4.Kg4 Ke3
                                   5.h5 Kf2 6.h6 Kxg2 7.h7 Ra8
 630909231  11:    424.9    -0.38  1.f4 Ra6+ 2.Kg5 Kd4 3.h4 Ra5+ 4.Kg4 Ke3
                                   5.h5 Kf2 6.h6 Kxg2 7.h7 Ra8
 926670236  12     616.5    -0.74  1.f4 Kd5 2.f5 Ra6+ 3.Kf7 Ke5 4.g4 Rf6+
                                   5.Kg8 Rh6 6.Kg7 Rc6 7.Kf7 Kf4 8.Ke7 Rc3
                                   9.f6 Rxh3
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michiguel
Posts: 6401
Joined: Thu Mar 09, 2006 8:30 pm
Location: Chicago, Illinois, USA

Re: tricky endgame

Post by michiguel »

michiguel wrote:
jdart wrote:This is one of the trickier 6-piece endgames:

[d] 8/8/6K1/8/r1k5/7P/5PP1/8 w - -

f4 here draws - other moves lose. Rybka 3 does really well on this - see output below - but many other engines find it difficult.

Fen: 8/8/6K1/8/r1k5/7P/5PP1/8 w - - 0 1
Bm: f4

no 2 0 -185 256 g4
no 3 20 -175 540 g4
no 4 20 -188 907 g4
no 5 20 -195 1509 g4 Kd3
yes 5 30 -168 2273 f4
yes 5 30 -154 2718 f4 Kd5
yes 6 30 -162 3776 f4 Kd5 f5
yes 7 50 -142 4925 f4
yes 7 60 -136 5718 f4 Kd5 f5 Ra6+ Kg5
yes 8 110 -147 8846 f4 Kd5 f5 Ra6+ Kg5 Ke5 g4 Ra8
yes 9 200 -147 17943 f4 Kd5 f5 Ra6+ Kg5 Ke5 g4 Rf6
no 10 500 -153 44652 h4 Kd3 g3 Ra6+ Kg5 Ke2 h5 Kxf2
no 11 860 -135 75731 h4 Kd5 g3 Ke6 f3 Ra8 g4 Rg8+ Kh7 Rf8 h5
Rxf3 Kg6 Rf6+ Kg7 Rf7+ Kg6 Rf4 g5
no 12 1170 -135 96444 h4 Kd5 g3 Ke6 f3 Ra8 g4 Rg8+ Kh7 Rf8 h5
Rxf3 Kg6 Rf6+ Kg7 Rf7+ Kg6 Rf4 g5
no 13 1560 -148 124458 g3 Ra6+ Kg5 Ra5+ Kg6 Ra2 f4
no 14 1940 -147 149393 g3 Ra6+ Kg5 Ra5+ Kg6 Ra2 g4
no 15 4240 -135 318017 g3 Kd5 h4 Ke6
no 16 8910 -115 604914 h4
no 16 9310 -135 633470 h4 Kd5 g3 Ke6
yes 17 20470 -115 1535012 f4 Kd5 f5
yes 17 20600 -136 1546196 f4 Kd5 f5
yes 18 27810 -116 1978645 f4
yes 18 33670 -136 2418869 f4 Kd5 f5 Ra3 Kf6 Ra6+ Kg7
yes 19 38440 -116 2772110 f4
yes 19 45240 -96 3199966 f4
yes 19 60130 -56 4308679 f4
yes 19 75780 -30 5508877 f4 Kd5 f5 Ra3 Kf6 Ra6+ Kg7
yes 20 77770 -30 5655694 f4 Kd5 f5 Ra3 Kf6 Ra6+ Kg7
yes 21 84520 -30 6131478 f4 Kd5 f5 Ra3 Kf6 Ra6+ Kg7
yes 22 93300 -30 6700343 f4 Kd5 f5 Ra3 Kf6 Ra6+ Kg7 Ke5 g4 Rc6 Kf7
Rb6 Kg7 Rd6 Kf7
yes 23 104390 -30 7395631 f4 Kd5 f5 Ra3 Kf6 Ra6+ Kg7
Even with EGTBs is difficult?

Gaviota with GTBs sticks to f4. I will let it run more but I doubt it will reach to a 0.00 score.

Miguel

Code: Select all

         8   1       0.0    -0.65  1.f4 Ra6+ 2.Kg5
        50   2       0.0    -1.04  1.f4 Ra2
       499   3       0.0    -1.00  1.f4 Ra6+ 2.Kg5 Ra2
      2914   4       0.0    -0.73  1.f4 Ra3 2.Kh5 Kd4
      4045   5       0.0      :-(  1.f4
     33805   5       0.1    -1.17  1.f4 Ra3 2.g4 Rxh3 3.f5 Rh2
     35930   5       0.1    -1.15  1.g4 Ra6+ 2.Kg7 Ra3 3.h4 Rf3 4.g5 Rxf2
    109192   6       0.3    -1.10  1.g4 Ra6+ 2.Kh5 Rf6 3.g5 Rf5 4.h4 Kd4
                                   5.Kg4 Rxf2
    167791   6       0.4      :-)  1.f4
    168413   6       0.4    -0.74  1.f4 Ra3 2.g4 Rxh3 3.f5 Rg3 4.g5 Rg2
    170940   6:      0.4    -0.74  1.f4 Ra3 2.g4 Rxh3 3.f5 Rg3 4.g5 Rg2
    408144   7       0.9    -0.50  1.f4 Kd5 2.f5 Ra3 3.g4 Rxh3 4.g5
    448588   7:      1.2    -0.50  1.f4 Kd5 2.f5 Ra3 3.g4 Rxh3 4.g5
    928877   8       2.0    -0.43  1.f4 Kc5 2.f5 Ra3 3.g4 Rxh3 4.g5 Rh2
                                   5.f6 Rg2
   1372118   8:      3.1    -0.43  1.f4 Kc5 2.f5 Ra3 3.g4 Rxh3 4.g5 Rh2
                                   5.f6 Rg2
   4972549   9       8.9    -0.39  1.f4 Ra6+ 2.Kg5 Ra8 3.g3 Kd4 4.Kg4 Rg8+
                                   5.Kf3 Rc8 6.f5 Ke5 7.g4 Rc3+ 8.Kg2
   6359916   9:     11.8    -0.39  1.f4 Ra6+ 2.Kg5 Ra8 3.g3 Kd4 4.Kg4 Rg8+
                                   5.Kf3 Rc8 6.f5 Ke5 7.g4 Rc3+ 8.Kg2
  15402455  10      20.7    -0.20  1.f4 Ra6+ 2.Kg5 Ra8 3.f5 Kd5 4.g4 Ke5
                                   5.Kg6 Kf4 6.f6 Kg3 7.g5 Kxh3
  17619846  10:     23.4    -0.20  1.f4 Ra6+ 2.Kg5 Ra8 3.f5 Kd5 4.g4 Ke5
                                   5.Kg6 Kf4 6.f6 Kg3 7.g5 Kxh3
 187799747  11     138.8    -0.38  1.f4 Ra6+ 2.Kg5 Kd4 3.h4 Ra5+ 4.Kg4 Ke3
                                   5.h5 Kf2 6.h6 Kxg2 7.h7 Ra8
 630909231  11:    424.9    -0.38  1.f4 Ra6+ 2.Kg5 Kd4 3.h4 Ra5+ 4.Kg4 Ke3
                                   5.h5 Kf2 6.h6 Kxg2 7.h7 Ra8
 926670236  12     616.5    -0.74  1.f4 Kd5 2.f5 Ra6+ 3.Kf7 Ke5 4.g4 Rf6+
                                   5.Kg8 Rh6 6.Kg7 Rc6 7.Kf7 Kf4 8.Ke7 Rc3
                                   9.f6 Rxh3
Well... it sees +0.00 with the wrong move... It must see a losing position (in the last two plies) with positive score that cuts the rests. Nice position to investigate.
Miguel

Code: Select all

 630909231  11:    424.9    -0.38  1.f4 Ra6+ 2.Kg5 Kd4 3.h4 Ra5+ 4.Kg4 Ke3
                                   5.h5 Kf2 6.h6 Kxg2 7.h7 Ra8
 926670236  12     616.5    -0.74  1.f4 Kd5 2.f5 Ra6+ 3.Kf7 Ke5 4.g4 Rf6+
                                   5.Kg8 Rh6 6.Kg7 Rc6 7.Kf7 Kf4 8.Ke7 Rc3
                                   9.f6 Rxh3
4268903771  12    2923.9    +0.00  1.h4 Ra6+ 2.Kf5 Ra8 3.g4 Rg8 4.g5 Rf8+
                                   5.Ke5 Rxf2 <=TABLE
4269149150  12:   2924.3    +0.00  1.h4 Ra6+ 2.Kf5 Ra8 3.g4 Rg8 4.g5 Rf8+
                                   5.Ke5 Rxf2 <=TABLE
4473015685  13    3058.7    +0.00  1.h4 Ra6+ 2.Kf5 Ra8 3.g4 Rg8 4.g5 Rf8+
                                   5.Ke5 Rxf2 <=TABLE
4474212016  13:   3060.1    +0.00  1.h4 Ra6+ 2.Kf5 Ra8 3.g4 Rg8 4.g5 Rf8+
                                   5.Ke5 Rxf2 <=TABLE
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michiguel
Posts: 6401
Joined: Thu Mar 09, 2006 8:30 pm
Location: Chicago, Illinois, USA

Re: tricky endgame

Post by michiguel »

michiguel wrote:
michiguel wrote:
jdart wrote:This is one of the trickier 6-piece endgames:

[d] 8/8/6K1/8/r1k5/7P/5PP1/8 w - -

f4 here draws - other moves lose. Rybka 3 does really well on this - see output below - but many other engines find it difficult.

Fen: 8/8/6K1/8/r1k5/7P/5PP1/8 w - - 0 1
Bm: f4

no 2 0 -185 256 g4
no 3 20 -175 540 g4
no 4 20 -188 907 g4
no 5 20 -195 1509 g4 Kd3
yes 5 30 -168 2273 f4
yes 5 30 -154 2718 f4 Kd5
yes 6 30 -162 3776 f4 Kd5 f5
yes 7 50 -142 4925 f4
yes 7 60 -136 5718 f4 Kd5 f5 Ra6+ Kg5
yes 8 110 -147 8846 f4 Kd5 f5 Ra6+ Kg5 Ke5 g4 Ra8
yes 9 200 -147 17943 f4 Kd5 f5 Ra6+ Kg5 Ke5 g4 Rf6
no 10 500 -153 44652 h4 Kd3 g3 Ra6+ Kg5 Ke2 h5 Kxf2
no 11 860 -135 75731 h4 Kd5 g3 Ke6 f3 Ra8 g4 Rg8+ Kh7 Rf8 h5
Rxf3 Kg6 Rf6+ Kg7 Rf7+ Kg6 Rf4 g5
no 12 1170 -135 96444 h4 Kd5 g3 Ke6 f3 Ra8 g4 Rg8+ Kh7 Rf8 h5
Rxf3 Kg6 Rf6+ Kg7 Rf7+ Kg6 Rf4 g5
no 13 1560 -148 124458 g3 Ra6+ Kg5 Ra5+ Kg6 Ra2 f4
no 14 1940 -147 149393 g3 Ra6+ Kg5 Ra5+ Kg6 Ra2 g4
no 15 4240 -135 318017 g3 Kd5 h4 Ke6
no 16 8910 -115 604914 h4
no 16 9310 -135 633470 h4 Kd5 g3 Ke6
yes 17 20470 -115 1535012 f4 Kd5 f5
yes 17 20600 -136 1546196 f4 Kd5 f5
yes 18 27810 -116 1978645 f4
yes 18 33670 -136 2418869 f4 Kd5 f5 Ra3 Kf6 Ra6+ Kg7
yes 19 38440 -116 2772110 f4
yes 19 45240 -96 3199966 f4
yes 19 60130 -56 4308679 f4
yes 19 75780 -30 5508877 f4 Kd5 f5 Ra3 Kf6 Ra6+ Kg7
yes 20 77770 -30 5655694 f4 Kd5 f5 Ra3 Kf6 Ra6+ Kg7
yes 21 84520 -30 6131478 f4 Kd5 f5 Ra3 Kf6 Ra6+ Kg7
yes 22 93300 -30 6700343 f4 Kd5 f5 Ra3 Kf6 Ra6+ Kg7 Ke5 g4 Rc6 Kf7
Rb6 Kg7 Rd6 Kf7
yes 23 104390 -30 7395631 f4 Kd5 f5 Ra3 Kf6 Ra6+ Kg7
Even with EGTBs is difficult?

Gaviota with GTBs sticks to f4. I will let it run more but I doubt it will reach to a 0.00 score.

Miguel

Code: Select all

         8   1       0.0    -0.65  1.f4 Ra6+ 2.Kg5
        50   2       0.0    -1.04  1.f4 Ra2
       499   3       0.0    -1.00  1.f4 Ra6+ 2.Kg5 Ra2
      2914   4       0.0    -0.73  1.f4 Ra3 2.Kh5 Kd4
      4045   5       0.0      :-(  1.f4
     33805   5       0.1    -1.17  1.f4 Ra3 2.g4 Rxh3 3.f5 Rh2
     35930   5       0.1    -1.15  1.g4 Ra6+ 2.Kg7 Ra3 3.h4 Rf3 4.g5 Rxf2
    109192   6       0.3    -1.10  1.g4 Ra6+ 2.Kh5 Rf6 3.g5 Rf5 4.h4 Kd4
                                   5.Kg4 Rxf2
    167791   6       0.4      :-)  1.f4
    168413   6       0.4    -0.74  1.f4 Ra3 2.g4 Rxh3 3.f5 Rg3 4.g5 Rg2
    170940   6:      0.4    -0.74  1.f4 Ra3 2.g4 Rxh3 3.f5 Rg3 4.g5 Rg2
    408144   7       0.9    -0.50  1.f4 Kd5 2.f5 Ra3 3.g4 Rxh3 4.g5
    448588   7:      1.2    -0.50  1.f4 Kd5 2.f5 Ra3 3.g4 Rxh3 4.g5
    928877   8       2.0    -0.43  1.f4 Kc5 2.f5 Ra3 3.g4 Rxh3 4.g5 Rh2
                                   5.f6 Rg2
   1372118   8:      3.1    -0.43  1.f4 Kc5 2.f5 Ra3 3.g4 Rxh3 4.g5 Rh2
                                   5.f6 Rg2
   4972549   9       8.9    -0.39  1.f4 Ra6+ 2.Kg5 Ra8 3.g3 Kd4 4.Kg4 Rg8+
                                   5.Kf3 Rc8 6.f5 Ke5 7.g4 Rc3+ 8.Kg2
   6359916   9:     11.8    -0.39  1.f4 Ra6+ 2.Kg5 Ra8 3.g3 Kd4 4.Kg4 Rg8+
                                   5.Kf3 Rc8 6.f5 Ke5 7.g4 Rc3+ 8.Kg2
  15402455  10      20.7    -0.20  1.f4 Ra6+ 2.Kg5 Ra8 3.f5 Kd5 4.g4 Ke5
                                   5.Kg6 Kf4 6.f6 Kg3 7.g5 Kxh3
  17619846  10:     23.4    -0.20  1.f4 Ra6+ 2.Kg5 Ra8 3.f5 Kd5 4.g4 Ke5
                                   5.Kg6 Kf4 6.f6 Kg3 7.g5 Kxh3
 187799747  11     138.8    -0.38  1.f4 Ra6+ 2.Kg5 Kd4 3.h4 Ra5+ 4.Kg4 Ke3
                                   5.h5 Kf2 6.h6 Kxg2 7.h7 Ra8
 630909231  11:    424.9    -0.38  1.f4 Ra6+ 2.Kg5 Kd4 3.h4 Ra5+ 4.Kg4 Ke3
                                   5.h5 Kf2 6.h6 Kxg2 7.h7 Ra8
 926670236  12     616.5    -0.74  1.f4 Kd5 2.f5 Ra6+ 3.Kf7 Ke5 4.g4 Rf6+
                                   5.Kg8 Rh6 6.Kg7 Rc6 7.Kf7 Kf4 8.Ke7 Rc3
                                   9.f6 Rxh3
Well... it sees +0.00 with the wrong move... It must see a losing position (in the last two plies) with positive score that cuts the rests. Nice position to investigate.
Miguel

Code: Select all

 630909231  11:    424.9    -0.38  1.f4 Ra6+ 2.Kg5 Kd4 3.h4 Ra5+ 4.Kg4 Ke3
                                   5.h5 Kf2 6.h6 Kxg2 7.h7 Ra8
 926670236  12     616.5    -0.74  1.f4 Kd5 2.f5 Ra6+ 3.Kf7 Ke5 4.g4 Rf6+
                                   5.Kg8 Rh6 6.Kg7 Rc6 7.Kf7 Kf4 8.Ke7 Rc3
                                   9.f6 Rxh3
4268903771  12    2923.9    +0.00  1.h4 Ra6+ 2.Kf5 Ra8 3.g4 Rg8 4.g5 Rf8+
                                   5.Ke5 Rxf2 <=TABLE
4269149150  12:   2924.3    +0.00  1.h4 Ra6+ 2.Kf5 Ra8 3.g4 Rg8 4.g5 Rf8+
                                   5.Ke5 Rxf2 <=TABLE
4473015685  13    3058.7    +0.00  1.h4 Ra6+ 2.Kf5 Ra8 3.g4 Rg8 4.g5 Rf8+
                                   5.Ke5 Rxf2 <=TABLE
4474212016  13:   3060.1    +0.00  1.h4 Ra6+ 2.Kf5 Ra8 3.g4 Rg8 4.g5 Rf8+
                                   5.Ke5 Rxf2 <=TABLE
I was right... two plies of a blindspot

Code: Select all

4998338052  14    3421.7    +0.00  1.h4 Ra6+ 2.Kf5 Ra8 3.g4 Rg8 4.g5 Rf8+
                                   5.Ke5 Rxf2 <=TABLE
5004623743  14:   3428.4    +0.00  1.h4 Ra6+ 2.Kf5 Ra8 3.g4 Rg8 4.g5 Rf8+
                                   5.Ke5 Rxf2 <=TABLE
5983083147  15    4064.8      :-(  1.h4
8629641072  15    5431.2    -0.27  1.f4 Kd5 2.f5 Ra6+ 3.Kf7 Ke4 4.g4 Ke5
                                   5.Kg7 Rb6 6.Kf7 Rc6 7.Kg7 Ra6 8.Kh7 Kf4
                                   9.Kg7 Ra3
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yanquis1972
Posts: 1766
Joined: Wed Jun 03, 2009 12:14 am

Re: tricky endgame

Post by yanquis1972 »

shredder sees that f4 draws when played or in mpv but prunes it out of its single pv search for some reason.
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