Seki with Eyes Question 2
Here's an interesting seki that showed up in a game one night. I've simplified the shapes of the territories somewhat, but Black's false eye position and the corner are exact.
This is a zero score under Japanese rules. Note that under area scoring rules, however, Black has at least one more eye than White. (If White can win a ko, I think, then Black's false eye in the corner can be filled.)
I would welcome scoring analysis from some of the experts. -- Thomas Bushnell, BSG
- (Copied from Seki): I think it's interesting enough to have its own page. See also Seki with Eyes Question 1. Shall we organize a seki path?
It seems to me that Black has to fill the ko in order to keep the seki. If not, White takes the ko, ignores the threat (it would have to be enormous!) and lives in the corner, killing Black.
Am I right?
-- dougm?
TakeNGive: Yes, when White makes atari at a, Black will have to fill the ko at b to preserve the seki. But, White can't really start the attack without a killer ko threat:
TnG: Now the board looks as below, and it's Black's turn; and Black is free to retake the ko at b. So, White shouldn't play this without a large un-removable ko threat or some kind of double ko situation to use as a threat; and when White does initiate this, Black should just fill the ko instead of tenuki.
Ah, yes, I had overlooked that White must fill an own liberty to start the ko. Your explanation makes perfect sense. -- dougm?
See also Seki with Eyes Question 1 and the pages in the Eyes Collection.