[Pachi] Very wierd pachi in winning half eye situation

Petr Baudis pasky at ucw.cz
Tue Aug 7 17:02:58 CEST 2012


On Sat, Jun 23, 2012 at 02:05:08AM +0900, 김민재 wrote:
> Pachi gets very wierd when it is winning only half eye.
> The file that I attatched is a recent pro game sgf file. Choi(w) won a half eye. I let pachi to play more moves after the whole game ended since some dames were unfilled. I saw the GTP shell and the surprizing thing was that even white has already won a half eye with 6.5points komi, the program analyzed white as a losing situation. After some few moves in turn filling dames, white positioned at C2 which is black's eye with no doubt, and eventually resigned itself. I set the komi to 6.5 in the gtp shell myself but the result was same. I did the same test three more times and the result did not change.
> Doing nothing, white was supposed to win, but white analyzed itself losing and gave black a free dead stone and resigned. I believe there should be some mistake in the program. I used "Gogui" for testing in Ubuntu OS. I changed nothing in the code before compiling pachi(version 9.99).

  It seems the culprit is territory vs. area scoring. At that point in
the game, white is to play and an odd number of dame points remains to
be filled, which means that black will get an extra 1 point by the area
scoring. So, Pachi sees that black wins by half a point.

				Petr "Pasky" Baudis

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