Re: [gnugo-devel] bug in gnugo

[Gunnar Farneback]

Evan wrote:
> Loading the attached position and asking gnugo for a move generates an
> illegal move:
> 
>    A B C D E F G H J
>  9 . . . . O O O O X 9
>  8 . . . O O X X X X 8
>  7 . . + O X X O O O 7
>  6 . . O O O X O X . 6
>  5 . . O X X X O X X 5
>  4 . O O O X . O X . 4
>  3 . . O X X X O O X 3
>  2 . . O X . X O X X 2     WHITE (O) has captured 0 stones
>  1 . O . O O X X X X 1     BLACK (X) has captured 0 stones
>    A B C D E F G H J

Caused by filllib. It wants to fill the liberty at E2 but notices that
G7 becomes tactically critical then (was undefendable). To avoid that
it suggests first playing the move attacking G7 after E2 was filled.
Unfortunately that move happens to be C1, which can't be played before
E2. This is not difficult to work around and I have a patch, but
unless someone urgently wants to see it I'll wait until Savannah is
back up to submit it.

/Gunnar