Re: [gnugo-devel] 3 ko's and nobody wins?

[Olof Fridh]

Very interesting position and also play by gnugo. After black C12 it only 
considers D15 as an attack on D14 and it thinks the E14 worm is dead and 
ends up playing R19 for white instead. BUT if you input D15 yourself it 
will start the triple ko sequence and then it returns to the board position 
below is suddenly see that D15 is important (which it didn't before, 151.13 
points now, 0 points before ) and continues the triple ko and will most 
likely loop forever (looped through it 3 times before giving up).
Note that this is for 3.5.4 I haven't tried it with the latest patches.

Btw the best move for black here is actually D15 instead of C12. This 
creates a simple ko where black takes first, and as this is a game winning 
ko with no ko threats big enough black will just ignore whatever white 
plays and capture. That way black wins the game instead of getting a no 
result. But as both moves saves the black group it can't really be 
considered wrong.

At 09:26 2004-02-01, you wrote:
> While I played with gnugo until the following situation, it crashed on my 
> windows system, maybe due to some of my earlier tweaks. The situation is 
> more interesting than crash itself. When I reload the game and let gnugo 
> generate the move in CYGWIN, it plays on C12. Now white plays D15, and 
> black plays A12, white plays on C11, etc. So there would be infinite many 
> moves with the three ko's.
>
> Unfortunately, I'm unable to resume this game in any of my clients. I 
> wonder what gnugo would think next. Will it continue to play on the ko's 
> endlessly?
>
> SP Lee
>
>    A B C D E F G H J K L M N O P Q R S T
> 19 . . . . . O O . . . . . . . O . . . . 19
> 18 . . . O O X X O . O . . . O . O X . . 18
> 17 . O . . X . X X O . . . O . O X . . . 17
> 16 . . . X X X . . X X . . O O X X . . . 16
> 15 . X X . X O X X . . X X X O . . X . . 15
> 14 X X O X O O X X X . . . . . . . . . . 14
> 13 O O O O O O O O X O O O O O O X . . . 13
> 12 . O . O X X O X O O X X X O X X . . . 12
> 11 O X . X X O X X O O O O X X O X . X X 11     WHITE (O) has captured 9 
> stones
> 10 X X X X O O X X X X X X X X O X . O O 10     BLACK (X) has captured 6 
> stones
>  9 X O O O O . O X X O O O . X O X O O . 9
>  8 X X O . . O X X O O X O O X O O O X O 8
>  7 . O . O O O O X O . X . X X X O X X . 7
>  6 . O O X X O X O X X X . X O O X X . X 6
>  5 . X O . . X X O O O X X O O O O O X X 5
>  4 . X X X X X . O X X O O O . O + . O O 4
>  3 . . . X . X . O X . X O . O X O O X . 3
>  2 . . . . X O O O X O X X O . X . . . . 2
>  1 . . . . X O X X X O . O . . . . . . . 1
>    A B C D E F G H J K L M N O P Q R S T
>
> _______________________________________________
> gnugo-devel mailing list
> address@hidden
> http://mail.gnu.org/mailman/listinfo/gnugo-devel