Lithel: If white responds at a, then threatens to kill the lower right group. White can again respond at b, c or d.
If at c, then at d and reduces white to 1 eye. If at d, at c and also reduces white to 1 eye.
Lithel: This pattern makes a and b miai for the kill again. If at a, black still plays and now 4 and b and miai for the kill.
Seems to me that a and b are miai here. --erislover
Is there a better play for ?
erislover: It seems that black can play at a directly as well. I don't know if it is better or not... in any case white is dead, and there are still threats to live that could come up in a ko. But it seems to me that capturing with in the diagram got black four points. If a ko did come up and black felt it was better to ignore this white group living, at least he didn't lose any extra stones. What do you think?
The book solution is at a.
a is not White sente to live. If Black does not respond, White can not live by playing b.
d is White sente to live. If Black responds, 4 white stones are captured rather than 2.
a is White sente to live. If Black does not respond, White will live at c.
c is White sente to live. If Black does not respond, White will live at a. After this, White has e as sente to live , as well.
So it seems that White gets two sente moves by playing c first, then e, whereas in the Book Solution, White gets only one sente move.
erislover: Well I can disagree with that. is gote regardless of where it is played above. Taking four points and surely keeping two stones means if a larger ko than the value of this position came up, black could ignore it and still have gotten a bit of profit out of it, while in the book solution, black only minimized ko threats according to you. But it seems to me that white can still get two ko threats. White b above (in book solution) is sente to live. After black captures, white can still play inside the eye black just made for another threat, just like my suggested . Hmm...
Florian: IMHO should also kill.