Fruit with and without null move

[geko]

I modified Fruit so that it plays without null move:

source in http://arctrix.com/nas/chess/fruit/ (fruit_21_linux.zip), file: search_full.cpp, line 475:

if (UseNull & & depth> = NullDepth NODE_TYPE & &! = NodePV) {

changed in

if (0) {

so i have 2 engines:
fruit: fruit not modified
fruit_nonull: fruit without null move

in a match between fruit and fruit_nonull the winner is fruit (without null move). WHY ??

Thanks in advance

here the match:

[Event "Arena tournament"]
[Site "HP-Pavilio"]
[Date "2011.08.01"]
[Round "1"]
[White "Fruit"]
[Black "Fruit_nonull"]
[Result "0-1"]
[BlackElo "2200"]
[ECO "A43"]
[Opening "Old Benoni"]
[Time "14:51:22"]
[Variation "2.d5 Nf6 3.Nf3 e6 4.Nc3"]
[WhiteElo "2200"]
[TimeControl "300+0"]
[Termination "normal"]
[PlyCount "141"]
[WhiteType "program"]
[BlackType "program"]

1. Nf3 {(Ng1-f3 Nb8-c6 Nb1-c3 Ng8-f6 e2-e3 d7-d5 Bf1-b5 Qd8-d6 d2-d4 Bc8-f5
O-O Nf6-g4 g2-g3) +0.22/13 6} Nc6 {(Nb8-c6 Nb1-c3 Ng8-f6 d2-d4 e7-e6 e2-e3
Bf8-b4 Bf1-d3 O-O O-O d7-d5) -0.15/11 12} 2. d4 {(d2-d4 Ng8-f6 d4-d5 Nc6-b4
c2-c4 Nb4-a6 Nb1-c3 d7-d6 Bc1-f4 Na6-c5 b2-b4 Nc5-e4) +0.25/13 9} Nf6
{(Ng8-f6 d4-d5 Nc6-b4 c2-c4 c7-c6 Nb1-c3 c6xd5 c4xd5 Qd8-a5 e2-e4 d7-d6
Bf1-b5+ Bc8-d7 Bb5xd7+ Nf6xd7) -0.27/10 9} 3. d5 {(d4-d5 Nc6-b4 c2-c4
Nb4-a6 Nb1-c3 d7-d6 Nf3-d4 h7-h6 Bc1-f4 Na6-c5 e2-e3 e7-e5 d5xe6/ep Bc8xe6
Nd4xe6 f7xe6) +0.30/13 8} Nb4 {(Nc6-b4 c2-c4 Nb4-a6 Nb1-c3 d7-d6 Bc1-e3
c7-c6 Be3-f4 Bc8-f5 Nf3-d4) -0.37/10 7} 4. a3 {(a2-a3 Nb4-a6 Nb1-c3 c7-c6
e2-e4 c6xd5 e4xd5 Na6-c5 Bc1-e3 Nc5-e4 Nc3xe4 Nf6xe4 Nf3-e5 Qd8-c7)
+0.57/12 9} Na6 {(Nb4-a6 Nb1-c3 c7-c6 d5xc6 b7xc6 e2-e4 d7-d6 b2-b4 Nf6-g4
Qd1-d4 Qd8-b6) -0.51/10 11} 5. Nc3 {(Nb1-c3 c7-c6 e2-e4 Na6-c5 Qd1-d4
Qd8-b6 d5xc6 Nc5xe4 c6-c7 Ne4-c5 b2-b4) +0.54/12 8} d6 {(d7-d6 e2-e4 Na6-c5
Bf1-d3 Nc5xd3+ Qd1xd3 c7-c6 O-O Qd8-b6 Nf3-d4 Bc8-g4 Rf1-e1) -0.76/10 11}
6. e4 {(e2-e4 e7-e5 d5xe6/ep Bc8xe6 Nf3-g5 Bf8-e7 Ng5xe6 f7xe6 Bc1-e3 O-O
Bf1-c4 Qd8-c8 O-O Na6-c5) +0.79/12 7} Nc5 {(Na6-c5 e4-e5 Nf6-e4 Nc3xe4
Nc5xe4 Qd1-e2 Bc8-f5 Qe2-b5+ c7-c6 Qb5xb7 d6xe5 Qb7xc6+ Bf5-d7) -0.86/10 7}
7. e5 {(e4-e5 d6xe5 Nf3xe5 a7-a6 Qd1-d4 Nc5-d7 Ne5xd7 Bc8xd7 Bc1-f4 Nf6-h5
Bf4-e3 Nh5-f6 O-O-O) +0.74/11 5} dxe5 {(d6xe5 Nf3xe5 a7-a6 Bc1-e3 Nc5-d7
Ne5xd7 Qd8xd7 Bf1-e2 e7-e6 d5xe6 Qd7xd1+ Ra1xd1 Bc8xe6) -0.73/9 8} 8. Nxe5
{(Nf3xe5 a7-a6 Bc1-e3 Nc5-d7 Ne5xd7 Qd8xd7 Bf1-c4 Qd7-g4 Qd1xg4 Nf6xg4
Be3-f4 Bc8-f5 h2-h3) +0.80/10 4} a6 {(a7-a6 Bc1-e3 e7-e6 d5xe6 Bc8xe6
Qd1-f3 Qd8-d6 Ne5-d3 Qd6-b6 Nd3xc5 Bf8xc5 Be3xc5 Qb6xc5 Qf3xb7) -0.72/9 10}
9. Qd4 {(Qd1-d4 Nc5-d7 Ne5xd7 Bc8xd7 Bc1-f4 Nf6-h5 Bf4-e5 f7-f6 Bf1-e2
g7-g6 Be2xh5 g6xh5) +0.72/10 6} Ncd7 {(Nc5-d7 Bc1-f4 Nd7xe5 Qd4xe5 e7-e6
d5xe6 Bc8xe6 Qe5xc7 Qd8xc7 Bf4xc7 Nf6-d5 Nc3xd5 Be6xd5) -0.83/9 9} 10. Bf4
{(Bc1-f4 Nd7xe5 Bf4xe5 e7-e6 Bf1-c4 b7-b5 Bc4-b3 Bc8-b7 d5xe6 f7xe6 Qd4xd8+
Ra8xd8 Be5xc7 Rd8-d4) +0.75/11 12} Nxe5 {(Nd7xe5 Bf4xe5 e7-e6 Bf1-c4 b7-b5
Bc4-b3 Bc8-b7 d5xe6 f7xe6 Qd4xd8+ Ra8xd8 Be5xc7) -0.86/9 7} 11. Bxe5
{(Bf4xe5 e7-e6 Bf1-c4 b7-b5 Bc4-b3 Bc8-b7 O-O-O c7-c5 d5xc6/ep Qd8xd4
Rd1xd4 Bb7xc6) +0.83/10 5} e6 {(e7-e6 Bf1-c4 b7-b5 Bc4-b3 Bc8-b7 d5xe6
f7xe6 Qd4xd8+ Ra8xd8 Be5xc7) -0.86/9 6} 12. Bc4 {(Bf1-c4 b7-b5 Bc4-b3
Bc8-b7 O-O-O c7-c5 d5xc6/ep Qd8xd4 Rd1xd4 Bb7xc6 f2-f3) +0.88/10 4} b5
{(b7-b5 Bc4-b3 Bc8-b7 O-O-O c7-c5 d5xc6/ep Qd8xd4 Rd1xd4 Bb7xc6 f2-f3)
-0.88/9 5} 13. Bb3 {(Bc4-b3 Bc8-b7 d5xe6 f7xe6 Qd4xd8+ Ra8xd8 Bb3xe6 Bf8-d6
Be5xf6 g7xf6 O-O Ke8-e7 Rf1-e1 Bd6-f4) +0.83/11 6} Bb7 {(Bc8-b7 d5xe6 f7xe6
Qd4xd8+ Ra8xd8 Bb3xe6 Bb7xg2 Rh1-g1 Bg2-c6 Be5xc7 Rd8-d4) -0.86/9 7} 14.
dxe6 {(d5xe6 f7xe6 Qd4xd8+ Ra8xd8 Bb3xe6 Bf8-d6 Be5xf6 g7xf6 O-O Bd6-e5
Rf1-e1 Rd8-d2 Be6-f5) +0.72/11 6} fxe6 {(f7xe6 Qd4xd8+ Ra8xd8 Bb3xe6 Bf8-d6
Be5xf6 g7xf6 O-O Bd6-e5 Rf1-e1 Rd8-d2 Be6-f5) -0.72/9 5} 15. Qxd8+
{(Qd4xd8+ Ra8xd8 O-O Ke8-d7 Rf1-e1 Rd8-e8 Ra1-d1+ Bf8-d6 Rd1-d4 Rh8-f8
a3-a4 Bb7-c6 Re1-d1 Nf6-d5 Be5xd6 Kd7xd6 Nc3xd5 e6xd5 Bb3xd5 Bc6xd5 Rd4xd5+
Kd6-c6) +0.93/11 7} Rxd8 {(Ra8xd8 O-O Ke8-d7 Rf1-e1 Rd8-e8 Ra1-d1+ Bf8-d6
Rd1-d4 Rh8-f8 Re1-d1 Nf6-d5 Be5xg7 Nd5xc3 b2xc3) -0.85/9 5} 16. O-O {(O-O
Bf8-d6 Ra1-e1 Ke8-e7 Be5xf6+ Ke7xf6 Re1xe6+ Kf6-g5 Nc3-e4+ Bb7xe4 Re6xe4
Rh8-f8 h2-h4+ Kg5-h5 g2-g3 Rf8-f3 Kg1-g2 Rf3-f6) +0.91/12 6} Bd6 {(Bf8-d6
Ra1-e1 Ke8-e7 Be5xf6+ Ke7xf6 Re1xe6+ Kf6-g5 Nc3-e4+ Bb7xe4 Re6xe4 Rh8-f8
h2-h4+ Kg5-h6 Rf1-e1 Bd6-c5) -0.96/9 5} 17. Rfe1 {(Rf1-e1 Ke8-e7 Be5xf6+
Ke7xf6 Re1xe6+ Kf6-f5 Ra1-e1 Rd8-d7 Nc3-e4 Rh8-d8 Ne4xd6+ Rd7xd6 Re6-e7
Rd6-d1 Re1-f1 Rd1xf1+ Kg1xf1 Rd8-d1+ Kf1-e2) +1.09/12 5} Ke7 {(Ke8-e7
Be5xf6+ Ke7xf6 Re1xe6+ Kf6-f5 a3-a4 b5-b4 Nc3-e2 Kf5-g4 Ra1-e1 Bd6-c5
Bb3-c4) -0.73/9 5} 18. Bxf6+ {(Be5xf6+ Ke7xf6 Re1xe6+ Kf6-f5 Ra1-e1 c7-c5
Bb3-d5 Bb7xd5 Nc3xd5 Bd6xh2+ Kg1xh2 Rd8xd5 Re6-e7 Rd5-d2 Re7xg7 Rd2xc2
g2-g4+ Kf5-f4) +0.71/10 3} Kxf6 {(Ke7xf6 Re1xe6+ Kf6-f5 a3-a4 b5-b4 Nc3-e2
Kf5-g4 Ra1-e1 Bd6-c5 Bb3-c4) -0.73/9 5} 19. Rxe6+ {(Re1xe6+ Kf6-f5 Ra1-e1
c7-c5 Nc3-e4 Bb7xe4 Re6xe4 c5-c4 Bb3-a2 Rd8-d7 g2-g4+ Kf5-g5 Kg1-g2)
+0.71/10 4} Kf5 {(Kf6-f5 g2-g3 Rh8-e8 Ra1-e1 Re8xe6 Bb3xe6+ Kf5-g6 Be6-d5
c7-c6 Bd5-e4+ Kg6-h6) -0.73/9 3} 20. Rae1 {(Ra1-e1 c7-c5 Bb3-d5 Bb7xd5
Nc3xd5 Bd6xh2+ Kg1xh2 Rd8xd5 Kh2-g3 Rh8-d8 f2-f4 a6-a5 Re1-e5+ Rd5xe5
Re6xe5+ Kf5-f6 Re5xc5) +0.71/10 5} c5 {(c7-c5 Bb3-d5 Bb7xd5 Nc3xd5 Bd6xh2+
Kg1xh2 Rd8xd5 Kh2-g3 Rh8-d8 f2-f4 a6-a5 Re1-e5+ Rd5xe5 Re6xe5+ Kf5-f6
Re5xc5) -0.71/9 9} 21. Bd5 {(Bb3-d5 Bb7xd5 Nc3xd5 Bd6xh2+ Kg1xh2 Rd8xd5
Kh2-g3 h7-h5 f2-f4 h5-h4+ Kg3-f3 Rh8-d8 Re6xa6 Rd8-d6) +0.74/10 4} Bxd5
{(Bb7xd5 Nc3xd5 Bd6xh2+ Kg1xh2 Rd8xd5 Re6xa6 Rd5-d2 Kh2-g3 Rh8-d8 f2-f4
Rd8-d5 Ra6-b6) -0.78/10 4} 22. Nxd5 {(Nc3xd5 Bd6xh2+ Kg1xh2 Rd8xd5 Re6xa6
Rh8-d8 Kh2-g3 h7-h5 f2-f4 g7-g5 f4xg5 Kf5xg5 a3-a4 h5-h4+ Kg3-h3 b5-b4)
+0.98/11 3} Bxh2+ {(Bd6xh2+ Kg1xh2 Rd8xd5 Re6xa6 Rd5-d2 Kh2-g3 Rh8-d8 f2-f4
Rd8-d5 Ra6-b6 b5-b4) -0.81/9 2} 23. Kxh2 {(Kg1xh2 Rd8xd5 Re6xa6 Rh8-d8
Kh2-g3 h7-h5 Ra6-b6 Rd5-d2 f2-f4 Rd8-d5 Rb6xb5 Rd2xc2 Rb5-b3) +1.04/12 3}
Rxd5 {(Rd8xd5 Kh2-g3 Rh8-d8 f2-f4 Rd8-d6 Re1-e5+ Rd5xe5 Re6xe5+ Kf5-f6
Re5xc5 Rd6-d2 Rc5-c7) -0.82/9 1} 24. Rxa6 {(Re6xa6 Rh8-d8 Kh2-g3 h7-h5
Ra6-b6 Rd5-d2 Rb6xb5 Rd2xc2 b2-b4 Rd8-d5 Re1-e7 g7-g5) +0.99/12 4} Rhd8
{(Rh8-d8 Kh2-g3 h7-h5 f2-f4 g7-g5 f4xg5 Kf5xg5 a3-a4 h5-h4+ Kg3-h3 b5-b4)
-0.98/9 3} 25. Kg3 {(Kh2-g3 h7-h5 Ra6-b6 Rd5-d2 Rb6xb5 Rd2xc2 b2-b4 Rd8-d5
a3-a4 h5-h4+ Kg3xh4 Rd5-d4+ Kh4-g3 Rd4xb4) +0.91/12 4} h5 {(h7-h5 Ra6-b6
Rd5-d2 Rb6xb5 Rd2xc2 b2-b4 Rd8-d5 Re1-e7 g7-g5) -0.99/10 4} 26. Re7
{(Re1-e7 g7-g5 Re7-f7+ Kf5-e5 Ra6-h6 h5-h4+ Kg3-g4 Rd5-d2 Rf7-f5+ Ke5-e4
Rh6-e6+ Ke4-d4 c2-c3+ Kd4-c4 Kg4xg5 Rd8-g8+ Kg5xh4 Rg8xg2 Re6-e4+ Kc4-b3
Rf5xc5 Kb3xb2 Rc5xb5+ Kb2xc3) +1.08/12 4} g5 {(g7-g5 Re7-f7+ Kf5-e5 Ra6-h6
h5-h4+ Kg3-g4 Rd5-d4+ Kg4xg5 Rd8-g8+ Rh6-g6 Rg8xg6+ Kg5xg6 Rd4-g4+ Kg6-h5
Rg4xg2 Kh5xh4) -1.01/9 2} 27. Rf7+ {(Re7-f7+ Kf5-e4 Ra6-h6 h5-h4+ Kg3-g4
Rd5-d2 Rh6-g6 Rd2xc2 Rg6xg5 b5-b4 Rf7-e7+ Ke4-d4 a3xb4 c5xb4) +0.91/10 2}
Ke4 {(Kf5-e4 Ra6-h6 h5-h4+ Kg3-g4 Rd5-d2 Rh6-g6 Rd2xc2 Rg6xg5 b5-b4 Rf7-e7+
Ke4-d4 a3xb4 c5xb4) -0.91/10 7} 28. Rh6 {(Ra6-h6 h5-h4+ Kg3-g4 Rd5-d2
Rh6-g6 Rd2xc2 Rg6xg5 Rd8-d2 Rf7-f4+ Ke4-d3 Rg5-f5 c5-c4 Rf5-d5+ Kd3-e2
Rd5xb5 Rc2xb2 Rb5xb2 Rd2xb2 Rf4xc4 Ke2xf2 Kg4xh4 Kf2xg2) +0.91/11 6} h4+
{(h5-h4+ Kg3-g4 Rd5-d2 Rh6-g6 Rd2xc2 Rg6xg5 b5-b4 Rf7-e7+ Ke4-d3 a3xb4
c5xb4 Re7-e3+ Kd3-d4) -0.91/10 3} 29. Kg4 {(Kg3-g4 Rd5-d2 Kg4xg5 Rd8-g8+
Kg5xh4 Rd2xc2 Rf7-e7+ Ke4-d5 Rh6-h5+ Kd5-d6 Re7-a7 Rg8xg2 Ra7-a6+ Kd6-c7
Rh5-h7+ Kc7-b8 Ra6-b6+ Kb8-c8 Rb6xb5 Rg2xf2) +0.78/12 4} Rd2 {(Rd5-d2
Kg4xg5 Rd8-g8+ Kg5xh4 Rd2xc2 g2-g4 Rc2xb2 f2-f3+ Ke4-d4 Rf7-d7+ Kd4-e5
Kh4-g3) -1.01/10 3} 30. Kxg5 {(Kg4xg5 Rd8-g8+ Kg5xh4 Rd2xc2 g2-g4 Rc2xb2
f2-f3+ Ke4-d4 Rf7-d7+ Kd4-c4 Rh6-e6 Rb2-a2 Re6-e4+ Kc4-c3 Re4-e5 Ra2-h2+
Kh4-g3) +0.87/11 5} Rg8+ {(Rd8-g8+ Kg5xh4 Rd2xc2 g2-g4 Rc2xb2 Kh4-g3 Ke4-d5
Rf7-c7 Kd5-c4 Rh6-h5 Rb2-b3+ f2-f3) -0.92/10 4} 31. Kxh4 {(Kg5xh4 Rd2xc2
g2-g4 Rc2xb2 f2-f3+ Ke4-e3 Kh4-g3 Rg8-e8 Rf7-f5 c5-c4 Rh6-b6 Rb2-a2 Rf5xb5
Ra2xa3) +0.84/12 3} Rxc2 {(Rd2xc2 g2-g4 Rc2xb2 Kh4-g3 Rg8-e8 f2-f3+ Ke4-e3
Rf7-c7 c5-c4 a3-a4 b5xa4 Rc7xc4) -0.89/10 4} 32. g4 {(g2-g4 Rc2xb2 f2-f3+
Ke4-d4 Rf7-d7+ Kd4-c4 Rh6-e6 Rb2-b1 Re6-e2 Rb1-h1+ Kh4-g3 Kc4-c3 Rd7-d6)
+0.90/10 2} Rxb2 {(Rc2xb2 f2-f3+ Ke4-e3 Kh4-g3 Rg8-e8 Rf7-f5 c5-c4 Rh6-b6
Rb2-a2 Rf5xb5 Ra2xa3) -0.84/9 2} 33. f3+ {(f2-f3+ Ke4-d4 Rf7-d7+ Kd4-c4
Rh6-e6 Rg8-a8 Re6-e3 Rb2-a2 Re3-e4+ Kc4-c3 Rd7-d5 Ra8-c8 Re4-e3+ Kc3-c4)
+0.94/11 3} Ke3 {(Ke4-e3 Kh4-g3 c5-c4 Rf7-e7+ Ke3-d4 Rh6-h5 c4-c3 Re7-e4+
Kd4-d3 Rh5-d5+ Kd3-c2 g4-g5 Kc2-b1 Re4-e1+ Kb1-a2 Re1-e3) -0.95/10 3} 34.
Kg3 {(Kh4-g3 c5-c4 Rf7-e7+ Ke3-d4 Re7-e4+ Kd4-d5 Rh6-h5+ Kd5-d6 Re4-d4+
Kd6-e6 a3-a4 b5xa4 Rh5-h6+ Ke6-e7 Rd4xc4 a4-a3 Rc4-c7+ Ke7-d8) +0.97/11 2}
c4 {(c5-c4 Rf7-e7+ Ke3-d4 Re7-e4+ Kd4-c3 Rh6-b6 Rg8-a8 g4-g5 Rb2-b1 Re4-e5
Kc3-d4 Kg3-f4 Ra8-f8+ Rb6-f6) -0.97/10 6} 35. Re7+ {(Rf7-e7+ Ke3-d4 Re7-e4+
Kd4-c3 Rh6-h5 Rg8-d8 Re4-e5 Kc3-d4 Re5xb5 Rb2xb5 Rh5xb5 Rd8-a8 g4-g5
Ra8xa3) +0.87/11 5} Kd4 {(Ke3-d4 Re7-e4+ Kd4-d5 Rh6-h5+ Kd5-d6 Re4-d4+
Kd6-e6 a3-a4 b5xa4 Rh5-h6+ Ke6-e7 Rd4xc4 a4-a3 Rc4-c7+ Ke7-d8) -0.97/10 2}
36. Re4+ {(Re7-e4+ Kd4-c3 Rh6-b6 Rb2-b3 Re4-e5 Kc3-d4 Rb6xb5 Rb3xb5 Re5xb5
Rg8-a8 Kg3-f4 Ra8xa3) +0.87/10 2} Kc3 {(Kd4-c3 Rh6-h5 Rg8-a8 Re4-e5 Ra8xa3
Re5xb5 Rb2xb5 Rh5xb5 Kc3-d4 Kg3-f4) -0.87/10 2} 37. Re3+ {(Re4-e3+ Kc3-d4
Rh6-e6 Rg8-a8 Re6-e4+ Kd4-c5 g4-g5 Rb2-b3 Re4-e5+ Kc5-d4 Re3-e4+ Kd4-c3
g5-g6 Ra8xa3) +0.86/11 3} Kd4 {(Kc3-d4 Rh6-e6 Rg8-a8 g4-g5 Rb2-b3 Re6-e4+
Kd4-c5 Re4-e5+ Kc5-d4 Re3-e4+ Kd4-c3 g5-g6 Ra8xa3) -0.86/10 2} 38. Rhe6
{(Rh6-e6 Rb2-b1 Re6-e4+ Kd4-c5 Re4-e5+ Kc5-b6 Re5-e6+ Kb6-a5 Kg3-f4 Rb1-d1
g4-g5 Rd1-g1 Re6-e5 Rg8-d8) +0.86/11 1} Rb1 {(Rb2-b1 Re6-e4+ Kd4-c5 Re4-e5+
Kc5-c6 Re5-e6+ Kc6-d7 Re6-e7+ Kd7-c6 Re3-e6+ Kc6-d5 Re6-e5+ Kd5-d4 Re5-e4+
Kd4-c5 Re4-e2) -0.86/9 1} 39. R6e4+ {(Re6-e4+ Kd4-c5 Re4-e5+ Kc5-c6 Re5-h5
Rg8-g6 Kg3-f4 Rb1-d1 g4-g5 Kc6-c5 Rh5-h7 Rg6-d6 Re3-e5+ Kc5-c6) +0.86/10 1}
Kc5 {(Kd4-c5 Re4-e5+ Kc5-c6 g4-g5 Rb1-g1+ Kg3-f4 Rg1-g2 Re5-f5 Rg8-d8
Re3-e6+ Kc6-d7 Rf5-d5+ Kd7xe6 Rd5xd8) -0.88/10 2} 40. Re5+ {(Re4-e5+ Kc5-c6
Re5-h5 Rg8-g6 Kg3-f4 Rb1-d1 g4-g5 Rd1-d5 Re3-e8 Kc6-c5 Re8-e7 Rd5-d4+
Kf4-f5) +0.77/10 2} Kc6 {(Kc5-c6 g4-g5 Rb1-g1+ Kg3-f4 Rg1-g2 Re5-f5 Rg8-d8
Re3-e6+ Kc6-d7 Rf5-d5+ Kd7xe6 Rd5xd8) -0.88/9 2} 41. Rh5 {(Re5-h5 Rg8-g6
Kg3-f4 Rb1-d1 g4-g5 Rd1-d5 Re3-e8 Rd5-d3 Kf4-f5 Kc6-d7) +0.83/10 2} Rg6
{(Rg8-g6 Kg3-f4 Rb1-d1 g4-g5 Rd1-d5 Re3-e8 Kc6-d6 Re8-d8+ Kd6-c6 Rd8-c8+
Kc6-d7) -0.79/9 2} 42. a4 {(a3-a4 b5-b4 Rh5-b5 Kc6-d7 Re3-e4 Rg6-c6 Rb5-d5+
Kd7-c8 Rd5-d4 Rb1-c1 Re4-e8+ Kc8-b7 f3-f4 Rc1-g1+ Kg3-f3) +0.74/11 2} b4
{(b5-b4 Rh5-b5 Kc6-d7 Re3-e4 Rg6-c6 Rb5-d5+ Kd7-c7 a4-a5 c4-c3 Re4-e7+
Kc7-c8) -0.83/9 1} 43. Rb5 {(Rh5-b5 Kc6-d7 a4-a5 Rg6-c6 f3-f4 b4-b3 f4-f5
c4-c3 Rb5-d5+ Kd7-c8 Re3-e8+ Kc8-b7 g4-g5) +0.61/11 2} Kd7 {(Kc6-d7 Re3-e4
Rg6-c6 Rb5-d5+ Kd7-c7 Rd5-d4 Rb1-c1 a4-a5 b4-b3 Re4-e7+ Kc7-c8) -0.71/10 2}
44. Re4 {(Re3-e4 Rg6-c6 a4-a5 b4-b3 a5-a6 Rc6xa6 Re4xc4 b3-b2 Kg3-f2 Ra6-d6
Rb5-e5) +0.50/10 2} Rc6 {(Rg6-c6 a4-a5 b4-b3 a5-a6 Rc6xa6 Re4xc4 b3-b2
Kg3-f2 Ra6-d6 Rb5-e5) -0.50/9 2} 45. Rb7+ {(Rb5-b7+ Kd7-d6 Rb7-h7 c4-c3
a4-a5 Rc6-c5 Rh7-h6+ Kd6-d5 a5-a6 Rb1-g1+ Kg3-f2 c3-c2 Rh6-h5+ Kd5-d6 a6-a7
Rg1-a1 Rh5-h6+ Kd6-c7) +0.35/10 2} Kd6 {(Kd7-d6 Re4-f4 Kd6-e6 g4-g5 Rb1-g1+
Kg3-f2 Rg1xg5 Rf4-e4+ Rg5-e5 Re4xe5+ Ke6xe5 Rb7-b5+ Ke5-d4 Rb5xb4) -0.33/10
2} 46. Rf4 {(Re4-f4 Kd6-e6 g4-g5 Rb1-g1+ Kg3-f2 Rg1xg5 Rf4-e4+ Ke6-f6
Rb7xb4 c4-c3 Re4-f4+ Kf6-e6 Rf4-h4) +0.17/11 2} Ke6 {(Kd6-e6 a4-a5 b4-b3
a5-a6 Rc6xa6 Rf4xc4 Ke6-d5 Rc4-c8 b3-b2 Kg3-f4) -0.31/9 1} 47. Rh7 {(Rb7-h7
c4-c3 Rf4-e4+ Ke6-d5 Rh7-h5+ Kd5-d6 a4-a5 Rc6-c5 Rh5-h6+ Kd6-d7 Re4-d4+
Kd7-c7 Rh6-h7+ Kc7-c6 a5-a6 b4-b3) +0.28/10 2} c3 {(c4-c3 Rf4-e4+ Ke6-d6
a4-a5 Rc6-c8 Rh7-h6+ Kd6-d7 Re4-d4+ Kd7-e7 Rh6-h7+ Ke7-e6 a5-a6 c3-c2
Rd4-e4+ Ke6-d5 Rh7-h5+ Kd5-d6) -0.18/9 1} 48. Rh6+ {(Rh7-h6+ Ke6-d7 Rf4-f7+
Kd7-e8 Rh6xc6 Ke8xf7 a4-a5 Kf7-e7 a5-a6 Ke7-d7 Rc6-c4 Rb1-a1 Kg3-f4 Ra1xa6
Rc4xb4) +0.31/11 2} Kd7 {(Ke6-d7 Rf4-f7+ Kd7-e8 Rh6xc6 Ke8xf7 a4-a5 Rb1-a1
a5-a6 Ra1-a2 Kg3-f4) -0.42/9 0} 49. Rh7+ {(Rh6-h7+ Kd7-e6) 0.00/12 2} Ke6
{(Kd7-e6) 0.00/11 1} 50. Re4+ {(Rf4-e4+ Ke6-d5 Rh7-h5+ Kd5-d6 a4-a5 Rc6-c5
Rh5-h6+ Kd6-d7 a5-a6 c3-c2 Rh6-h7+ Kd7-d6 a6-a7 Rb1-a1 Rh7-h6+ Kd6-d5
Rh6-h5+ Kd5-d6) +0.13/9 1} Kd6 {(Ke6-d6 a4-a5 Rc6-c8 Rh7-h6+ Kd6-d7 Rh6-h2
Rc8-a8 Rh2-h7+ Kd7-c6 Rh7-h6+ Kc6-b5 Re4-e5+ Kb5-c4) -0.23/9 1} 51. Kf4
{(Kg3-f4 Rc6-c5 Rh7-h6+ Kd6-d7 Re4-d4+ Kd7-c7 Rh6-h7+ Kc7-c6 Rh7-h6+
Kc6-c7) 0.00/10 3} Rc5 {(Rc6-c5 Rh7-h6+ Kd6-d7 Re4-d4+ Kd7-e7 Rh6-h7+
Ke7-e8 Rd4-e4+ Ke8-d8 Re4-d4+ Kd8-e8) 0.00/9 1} 52. Rh6+ {(Rh7-h6+ Kd6-d7
Re4-d4+ Kd7-c7 Rh6-h7+ Kc7-c6 Rh7-h6+ Kc6-c7) 0.00/11 1} Kd7 {(Kd6-d7
Re4-d4+ Kd7-c7 Rh6-h7+ Kc7-c6 Rh7-d7 Rc5-a5 Rd4-d6+ Kc6-c5 Rd6-d5+ Kc5-b6
Rd5-d6+ Kb6-c5) 0.00/10 2} 53. Rd4+ {(Re4-d4+ Kd7-c7 Rh6-h7+ Kc7-c6 Rh7-h6+
Kc6-c7) 0.00/12 1} Kc7 {(Kd7-c7 Rh6-h7+ Kc7-b6 Rd4-d6+ Rc5-c6 Rd6xc6+
Kb6xc6 Rh7-h8 Kc6-d5 Rh8-c8 Rb1-a1 Rc8-d8+ Kd5-c4 Rd8-c8+ Kc4-b3 Rc8-a8
Ra1xa4 Ra8xa4 Kb3xa4) +0.74/10 3} 54. Rh7+ {(Rh6-h7+ Kc7-c6 Rh7-d7 Rc5-a5
Rd4-d6+ Kc6-c5 Rd6-d5+ Kc5-b6 Rd7-d6+ Kb6-c7 Rd6-d7+ Kc7-c6 Rd7-d6+ Kc6-c7)
0.00/11 1} Kb6 {(Kc7-b6 Rd4-d6+ Rc5-c6 Rd6xc6+ Kb6xc6 Rh7-h8 Kc6-d5 Rh8-c8
Rb1-a1 Rc8-d8+ Kd5-c4 Rd8-c8+ Kc4-b3 Rc8-a8 Ra1xa4 Ra8xa4 Kb3xa4) +0.74/9
1} 55. Rd6+ {(Rd4-d6+ Rc5-c6 a4-a5+ Kb6-c5 Rd6xc6+ Kc5xc6 Rh7-h8 Kc6-b5
Rh8-c8 Kb5xa5 g4-g5 Rb1-g1 Rc8-a8+ Ka5-b5 Ra8-a2) -0.82/10 2} Rc6 {(Rc5-c6
a4-a5+ Kb6-c5 Rd6xc6+ Kc5xc6 Rh7-h8 Kc6-b7 Rh8-h7+ Kb7-a6 Rh7-c7 Ka6xa5
g4-g5 Rb1-e1) +0.79/9 0} 56. a5+ {(a4-a5+ Kb6-c5 Rd6xc6+ Kc5xc6 Rh7-h8
Rb1-a1 g4-g5 Kc6-d7 Rh8-h2 b4-b3 Rh2-h7+ Kd7-c6 Rh7-h6+ Kc6-c5 g5-g6
Ra1-a4+ Kf4-e5 Ra4xa5) -1.15/11 1} Kc5 {(Kb6-c5 Rd6xc6+ Kc5xc6 Rh7-h8
Kc6-b5 Rh8-c8 Kb5xa5 g4-g5 Rb1-g1 Rc8-a8+ Ka5-b5 Ra8-a2) +0.82/10 1} 57.
Rxc6+ {(Rd6xc6+ Kc5xc6 Rh7-h8 Kc6-b5 Rh8-c8 Rb1-g1 Kf4-e4 Rg1-g2 Ke4-d3
Rg2-d2+ Kd3-e4 Kb5xa5 Rc8-a8+ Ka5-b5 g4-g5) -0.97/12 1} Kxc6 {(Kc5xc6
Rh7-h8 Kc6-b7 Rh8-h7+ Kb7-a6 Rh7-c7 Ka6xa5 g4-g5 Ka5-b6 Rc7-c8 Rb1-e1)
+0.94/9 0} 58. Rh8 {(Rh7-h8 Rb1-a1 a5-a6 Kc6-d5 Rh8-d8+ Kd5-c4 Rd8-c8+
Kc4-b3 g4-g5 Ra1xa6 Kf4-e4 c3-c2 Ke4-d3 Ra6-d6+ Kd3-e3) -1.24/11 1} Kd7
{(Kc6-d7 Rh8-h7+ Kd7-d6 Rh7-h6+ Kd6-d5 Rh6-h5+ Kd5-c4 Rh5-h7 c3-c2 Kf4-e4
c2-c1Q Rh7-c7+ Kc4-b5 Rc7xc1 Rb1xc1 g4-g5 Kb5xa5) +3.60/10 1} 59. Rh7+
{(Rh8-h7+ Kd7-d6 Rh7-h6+ Kd6-d5 Rh6-h5+ Kd5-d4 Rh5-h2 b4-b3 Rh2-h8 c3-c2
Rh8-d8+ Kd4-c3 Rd8-c8+ Kc3-b2 g4-g5 c2-c1Q+ Rc8xc1 Rb1xc1 a5-a6 Rc1-c6
Kf4-f5 Rc6xa6 g5-g6) -7.85/15 24} Kd6 {(Kd7-d6 Rh7-h6+ Kd6-d5 Rh6-h5+
Kd5-c4 Rh5-h7 c3-c2 Rh7-c7+ Kc4-d3 Rc7-d7+ Kd3-e2 Rd7-e7+ Ke2-f2 Re7-c7
c2-c1Q+ Rc7xc1 Rb1xc1 Kf4-e4 b4-b3 Ke4-d3 Kf2xf3) +4.56/11 1} 60. Rh6+
{(Rh7-h6+ Kd6-d5 Rh6-h5+ Kd5-c4 Rh5-h7 c3-c2 Rh7-c7+ Kc4-d3 Kf4-g3 c2-c1Q
Rc7-d7+ Kd3-c4 Rd7-c7+ Kc4-b5 Rc7xc1 Rb1xc1 a5-a6 Kb5xa6 g4-g5 b4-b3)
-8.71/14 12} Kd5 {(Kd6-d5 Rh6-h5+ Kd5-c4 Rh5-h7 c3-c2 Rh7-c7+ Kc4-d3
Rc7-d7+ Kd3-e2 Rd7-e7+ Ke2-f2 Re7-c7 c2-c1Q+ Rc7xc1 Rb1xc1 a5-a6 b4-b3
a6-a7 Rc1-c4+ Kf4-e5 Rc4-c8) +5.93/11 1} 61. Rh5+ {(Rh6-h5+ Kd5-c4 Rh5-h7
c3-c2 Rh7-c7+ Kc4-d3 Kf4-g3 c2-c1Q Rc7-d7+ Kd3-c4 Rd7-c7+ Kc4-b5 Rc7xc1
Rb1xc1 a5-a6 Kb5xa6 g4-g5 b4-b3) -8.71/13 6} Kc4 {(Kd5-c4 Rh5-h7 c3-c2
Rh7-c7+ Kc4-d3 Rc7-d7+ Kd3-e2 Rd7-e7+ Ke2-f2 Re7-c7 c2-c1Q+ Rc7xc1 Rb1xc1
a5-a6 b4-b3 a6-a7 Rc1-c4+ Kf4-e5 Rc4-c8) +5.93/11 1} 62. Rh7 {(Rh5-h7 c3-c2
Rh7-c7+ Kc4-d3 Kf4-g3 c2-c1Q Rc7-d7+ Kd3-c4 Rd7-c7+ Kc4-b5 Rc7xc1 Rb1xc1
a5-a6 Kb5xa6 g4-g5 b4-b3) -8.71/12 3} c2 {(c3-c2 Rh7-c7+ Kc4-d3 Kf4-g3
c2-c1Q Rc7-d7+ Kd3-e3 Rd7-e7+ Ke3-d4 a5-a6 Qc1-g1+ Kg3-f4 Qg1-h2+ Kf4-f5
b4-b3) +8.04/9 0} 63. Rc7+ {(Rh7-c7+ Kc4-d3 Kf4-g3 c2-c1Q Rc7-d7+ Kd3-e2
Rd7-e7+ Ke2-f1 Re7-e5 Qc1-c7 f3-f4 Rb1-b3+ Kg3-h4 Rb3-a3 g4-g5 Ra3xa5)
-8.69/11 1} Kd3 {(Kc4-d3 Kf4-g3 c2-c1Q Rc7-d7+ Kd3-e2 Rd7-e7+ Ke2-f1 Re7-h7
Qc1-e1+ Kg3-f4 Kf1-g2 g4-g5 Qe1-g3+ Kf4-f5 Kg2xf3) +8.61/11 1} 64. Kg3
{(Kf4-g3 c2-c1Q Rc7-d7+ Kd3-e3 Rd7-e7+ Ke3-d4 a5-a6 Qc1-g1+ Kg3-f4 Qg1-h2+
Kf4-f5 b4-b3 g4-g5 Qh2-c2+ Re7-e4+ Kd4-d5) -7.80/9 0} c1=Q {(c2-c1Q Rc7-d7+
Kd3-e2 Rd7-e7+ Ke2-f1 a5-a6 Rb1-b2 Re7-e6 Rb2-g2+ Kg3-h3 Kf1-f2 Re6-e2+
Kf2xe2 Kh3xg2) +9.05/9 0} 65. Rd7+ {(Rc7-d7+ Kd3-e3 Rd7-e7+ Ke3-d4 a5-a6
Qc1-g1+ Kg3-f4 Qg1-h2+ Kf4-f5 b4-b3 g4-g5 Qh2-c2+ Re7-e4+ Kd4-d5) -7.80/8
0} Ke2 {(Kd3-e2 Rd7-e7+ Ke2-f1 a5-a6 Rb1-b2 Re7-e6 Rb2-g2+ Kg3-h3 Kf1-f2
Re6-e2+ Kf2xe2 Kh3xg2) +9.05/9 1} 66. Re7+ {(Rd7-e7+ Ke2-d2 Re7-d7+ Kd2-e3
Rd7-e7+ Ke3-d4 Re7-d7+ Kd4-e5 Rd7-e7+ Ke5-d6 Re7-e2 Qc1-g1+ Kg3-f4) -7.72/7
0} Kf1 {(Ke2-f1 Re7-e4 Rb1-b2 f3-f4 Qc1-c2 Kg3-h4 Qc2xe4 Kh4-g5 Qe4-d5+
f4-f5 Qd5xa5) +13.42/9 1} 67. Re5 {(Re7-e5 Qc1-c7 f3-f4 Rb1-b3+ Kg3-h4
Rb3-a3 Kh4-g5 Ra3xa5) -9.08/7 0} Rb2 {(Rb1-b2 Re5-e6 Rb2-g2+ Kg3-h4 Qc1-f4
Kh4-h5 Rg2-h2+ Kh5-g6 Rh2-h6+ Kg6-g7 Qf4-g5+ Kg7-f8 Rh6-h8+ Kf8-f7 Rh8-h7+
Kf7-f8 Qg5-f4+ Re6-f6 Qf4-b8+) +M10/8 1} 68. f4 {(f3-f4 Qc1-c6 Re5-e1+
Kf1xe1 f4-f5 Rb2-f2 a5-a6 Qc6-d6+ Kg3-h4 Rf2-h2+ Kh4-g5 Qd6-h6+) -M6/9 0}
Qc6 {(Qc1-c6 f4-f5 Rb2-b3+ Re5-e3 Rb3xe3+ Kg3-f4 Qc6-h6+ g4-g5 Qh6-h3 a5-a6
Qh3-f3+) +M6/9 0} 69. f5 {(f4-f5 Rb2-b3+ Re5-e3 Rb3xe3+ Kg3-f4 Qc6-h6+
g4-g5 Qh6-h3 a5-a6 Qh3-g3+) -M5/6 0} Rb3+ {(Rb2-b3+ Re5-e3 Rb3xe3+ Kg3-f4
Qc6-h6+ g4-g5 Qh6-h3 a5-a6 Qh3-g3+) +M5/18 0} 70. Re3 {(Re5-e3 Rb3xe3+
Kg3-f4 Qc6-h6+ g4-g5 Qh6-h3 a5-a6 Qh3-g3+) -M4/6 0} Rxe3+ {(Rb3xe3+ Kg3-f4
Qc6-h6+ g4-g5 Qh6-h3 a5-a6 Qh3-g3+) +M4/36 1} 71. Kf4 {(Kg3-f4 Qc6-h6+
g4-g5 Qh6-h3 a5-a6 Qh3-g3+) -M3/4 0 White resigns} 0-1

[DaveD]

I modified Fruit so that it plays without null move:

source in http://arctrix.com/nas/chess/fruit/ (fruit_21_linux.zip), file: search_full.cpp, line 475:

if (UseNull & & depth> = NullDepth NODE_TYPE & &! = NodePV) {

changed in

if (0) {

so i have 2 engines:
fruit: fruit not modified
fruit_nonull: fruit without null move

in a match between fruit and fruit_nonull the winner is fruit (without null move). WHY ??

Thanks in advance

here the match:

That is only one 5 minute game, not a "match".

[hyatt]

The expected loss is in the 80-160 Elo range. one game is about like tossing a coin.

[wgarvin]

It takes a lot of games--hundreds, at least--to measure whether a change is better or not with any confidence. The smaller the difference, the more games you have to play. Small changes in strength (e.g. 10 elo) can only be measured by playing thousands or even tens of thousands of games.

Here's a thread about number of games needed for testing. There's a program called BayesElo that can be used to calculate a relative rating from a bunch of PGN games.. I don't know much about it, but I believe it can calculate how likely it is that one program is stronger than another when you feed it the results of those hundreds (or thousands) of games.

[geko]

for this purpose I wrote a script to play 2 engines using a file containing the initial positions. The script runs N xboard (in parallel)
http://code.google.com/p/butterfly-ches ... testscript


To use wac.epd file is a good idea?

thank
g.

[hyatt]

WAC is not a particularly good starting point. Most positions (295+) are trivially won by one side.

if you go to ftp.cis.uab.edu/pub/hyatt and probe around, there is a file named something like "openings.epd" that has a good set of epd positions to play games from. These are pretty balanced and none are outright won or lost from the get-go...

[mjlef]

First, you need not modify Fruit if you wish to have it not use Null move pruning. There is a parameter for that.
Second, one game is meanlingless. Give us a few thousand.

[mjlef]

I ran a quick match of 100 games:


-----------------Fruit_21-----------------
Fruit_21 - Fruit_21 no null : 76.0/100 64-12-24 (101101111=11111==111=111111=11=11010=111=11=11==11===000=11=10111111111=1=110110=111=11=0=111110==11?) 76% +200
-----------------Fruit_21 no null-----------------
Fruit_21 no null - Fruit_21 : 24.0/100 12-64-24 (010010000=00000==000=000000=00=00101=000=00=00==00===111=00=01000000000=0=001001=000=00=1=000001==00?) 24% -200

The null move version did quite a bit better. For more accuracy of what it is worth you should run thousands of games.