Re: [gnugo-devel] semeai:120

[Arend Bayer]

On Wed, 15 Jun 2005, Gunnar wrote:

> Testcase semeai:120,
> 
>   # A14 is strictly correct since C19 allows W an unfavorable ko.
>   loadsgf games/semeai/semeai19.sgf
>   120 analyze_semeai C18 C19
>   #? [1 1 (A14|C19)]*
> 
> is broken. The most immediate problem is that the proposed move at C19
> is already occupied. Second there's no way to win the semeai (though
> seki is possible). Finally the semeai ought to be C18 vs C17, not C18
> vs C19.

I don't think Black can even achieve seki:
   A B C D E F G H J K L M N O P Q R S T
19 . X O . . . O O . . . . . . . . . . . 19
18 O O X X X X X X O X X . O O . O O X . 18
17 . X O X O O O O O . . O . X O O X . . 17
16 O . O X X O X . . X X O X X X X X . . 16
15 . O O O O X X O O O O X O . . . . . . 15
14 . X O X X X . . . . O X . . . . O . . 14
13 . X X . . . . . . . . X O . . . . . . 13
12 . . . . . . . . . X . . X . . O . . . 12

B A14, W A17, B a15, W b16
Now if B d19, just white f19 wins.
If B f19, W D19, B J19, W H19 reaching:

   A B C D E F G H J K L M N O P Q R S T
19 . X O O . X . O X . . . . . . . . . . 19
18 O O X X X X X X O X X . O O . O O X . 18
17 O . O X O O O O O . . O . X O O X . . 17
16 O O O X X O X . . X X O X X X X X . . 16
15 X O O O O X X O O O O X O . . . . . . 15
14 X X O X X X . . . . O X . . . . O . . 14
13 . X X . . . . . . . . X O . . . . . . 13
12 . . . . . . . . . X . . X . . O . . . 12

And it is still one eye against no eye, and black cannot approach
white fast enough..

> I suspect that the test should be for an earlier position. Dan, do you
> remember how this was intended?
> 
> /Gunnar

Hence I suggest the patch below.

Arend



Index: semeai.tst
===================================================================
RCS file: /cvsroot/gnugo/gnugo/regression/semeai.tst,v
retrieving revision 1.69
diff -u -p -r1.69 semeai.tst
--- semeai.tst  13 Apr 2005 21:19:02 -0000      1.69
+++ semeai.tst  3 Sep 2005 15:10:38 -0000
@@ -439,8 +439,8 @@ play white H2
 
 # A14 is strictly correct since C19 allows W an unfavorable ko.
 loadsgf games/semeai/semeai19.sgf
-120 analyze_semeai C18 C19
-#? [1 1 (A14|C19)]*
+120 analyze_semeai C18 C17
+#? [0 0 PASS]
 
 # There is a complication that B18 and C17 are not amalgamated.
 # If B plays first C19 gives a favorable ko; A15 allows seki.