Kaisuj: This problem contains an error. It moves my stones like a few diffrenet paths were mixed. After descending to B1, my B1 stone is killed which is impossible!
caranthir: Seems to work ok to me. I'll resolve this question for now. Will get back to it if anyone else notices the same issue.
Константин: Why with P16-R19-S19-N19O19 is seki? White has one more liberty at T19, and black can't T19 first because of self-atari. So white can Q19 or R18.... And it's not a seki, there are two eyes
Sadaharu: The variation you mentioned is already inside
caranthir: To nate2: the sequence you mentioned shows a suboptimal response from the opponent, and in that case we should indeed live with points and not have seki.
nate2: With the sequence P16, R19, S19, N19, the only accepted last move is R18, but O19 is Seki. Obviously Seki is a worse result, but the instructions say that Seki is a success. Maybe at the top it should say No Seki next to No Ko
Ivan Detkov: Seki is a success indeed. I do not see a variant allowing to live without seki with the best play from both sides. Do you?
posivb: 1)
C19G19F19B19A19 is wrong. It's a ko. The problem is "White to live. (No Ko)"
2)
E16B19C19G19F19 seems to work too.
Farkas: I disagree with your comment. Actually A19 is a hanami ko, which force the opponent to waste a ko-threat. Even after your opponent take it back, you can still connect and live.
Seems to work ok to me. I'll resolve this question for now. Will get back to it if anyone else notices the same issue.