Re: [gnugo-devel] Patch splee 5.5.1b revised

[Gunnar Farnebäck]

Lee wrote:
> arb:203
> 
> 12 . O . . O . . . O . . O O O O O O . O 12
> 11 O . . . . O . . . . . . . . . O X O . 11
> 10 X O O + O X O O . + . . . . . O X X O 10
>  9 X X O . O X X O . . . . O . O O X . X 9
>  8 . X O O O X . X O O . . O O X O X . X 8
>  7 . X X X X . . X X . O O X X . X . X . 7
>  6 . . . . X X X . . X X X O X X X X O O 6
>  5 . . X . . O . . . . X O O O O O O X . 5
>  4 . . . X . . X . . X . X X X X O X X X 4
>  3 . . . . . X O . X . . X . O O O O X . 3
>  2 . . . . . . X . . O O . X O . O O O X 2
>  1 . . . . . . . . . . . . X O X . O X . 1
>    A B C D E F G H J K L M N O P Q R S T
> 
> This is a complicated situation with up to 6 ko's in the lower right
> corner. I don't think gnugo can really handle this situation until some
> time in the far future. T7 is a good move in that it makes the black
> alive for sure and let white not easy to live. However, black is also
> not dead even playing on N3. For example, B:N3,W:T1,B:T7,W:T3,B:T5. Or
> B:N3,W:P7,B:R7,W:S8,B:T11.

I don't think the life of black is a primary issue here, the question
is how large external ko threats black needs in order to kill white.
In particular N3 totally misses the point. This is not a capturing
race but a question of whether white can make two eyes.

> Both before and after patch, the ko_depth is reached during tactical
> reading (attack n6). Surprisingly, the reading code after patch
> generates less variations in this situation.

Does the result of attack n6 change with the patch? Some reading
results must have changed at least and the interesting question is
whether those make sense.

/Gunnar