[gnugo-devel] Bug in combinaison attacks

[Stéphane Nicolet]

There is probably a problem in the combinaison attack module.

In the following 2 stones game at move 127, gnugo correctly
sees that Black threatens a combinaison attack in the left
territory begining with ataris at J12, G10, E8, B9, C9, but
gives 33 defense points, some of them irrelevant.

Stephane

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./interface/gnugo -l combinaison_blunder.sgf -T -t --quiet --until 227  
--mode ascii


looking for combination attacks ...
The worm B8 can be attacked at C9 after B:J12 W:J13 B:B9 W:A10 B:G10  
W:H12 B:E8 W:F9
The worm G9 can be attacked at F9 after B:J12 W:J13 B:B9 W:A10 B:G10  
W:H12 B:E8 W:D9
The worm G9 can be attacked at F9 after B:J12 W:J13 B:B9 W:A10 B:G10  
W:H12 B:E8 W:C9
The worm B8 can be attacked at C9 after B:J12 W:J13 B:B9 W:A10 B:G10  
W:H11 B:E8 W:F9
The worm G9 can be attacked at F9 after B:J12 W:J13 B:B9 W:A10 B:G10  
W:H11 B:E8 W:D9
The worm G9 can be attacked at F9 after B:J12 W:J13 B:B9 W:A10 B:G10  
W:H11 B:E8 W:C9
L17 deleted defense point, unsafe
Combination attack for black with size 7 found at J12
- defense at K16
- defense at J13
- defense at A12
- defense at H12
- defense at J12
- defense at R12
- defense at S12
- defense at T12
- defense at A11
- defense at B11
- defense at C11
- defense at G11
- defense at H11
- defense at Q11
- defense at R11
- defense at S11
- defense at T11
- defense at A10
- defense at B10
- defense at C10
- defense at F10
- defense at G10
- defense at Q10
- defense at S10
- defense at B9
- defense at C9
- defense at D9
- defense at E9
- defense at F9
- defense at D8
- defense at E8

Looking for additional attack and defense moves. Trying moves ...
H17 H15 A10 B10 C10 B9 C9
Trying to find large scale attack moves.
Trying to upgrade strategical attack and defense moves.

[..]

Top moves:
1. Q10 11.02
2. H12 10.82
3. S10 10.78
4. R12 10.44
5. Q11 10.44
6. J12 10.43
7. G11 10.43
8. B9  10.38
9. K16 10.32
10. E9  10.30
Checking safety of a white move at Q10
Move generation likes Q10 with value 11.02
genmove() recommends Q10 with value 11.02
white (O) move Q10

    White (O) has captured 2 pieces
    Black (X) has captured 4 pieces

    A B C D E F G H J K L M N O P Q R S T
 19 . X . . . . . . X . . . X O O . . . . 19
 18 O X . X . X O O O X X O X X O O O . . 18
 17 O X . X X X O . X O . X . O X X O . . 17
 16 O X X X O O O O O + O X X X X X O . . 16
 15 O O O X O X O . X O O X . . X O . . . 15
 14 O X X X X X O O O X X X . O X O O . . 14
 13 O O X X . X X O . O X . . O X X O . . 13
 12 . O O O X X O . . O X X O O X O . . . 12
 11 . . . . O O . . O X X O O . O . . . . 11
 10 . . . + . . . O O O X . . O .(O)O . O 10
  9 O . . . . . O X X X X O O . O . . O X  9
  8 X O O . . O O O X . X X . O . O O X X  8
  7 X X O O O X X X . X O X X X X O O . X  7
  6 X O O X X . . . X O O O O . X X O O X  6
  5 X X O O X . . . X X O . O X . X O X .  5
  4 . X X X . X . . X O O O X X . X X . X  4
  3 . . . . . . . X . X X O O X . . . X .  3
  2 . . . . . . . X . X O O O O X . . . .  2
  1 . . . . . . . . X O O . O X X . . . .  1
    A B C D E F G H J K L M N O P Q R S T

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combinaison_blunder.sgf
Description: Binary data