My question is: what happens if white plays this way instead?
Now if black plays 'a', white replies at 'b' for ko. If black 'c' instead, then white 'd'. Does black have a better move?
Dieter: I can't refute it.
tderz: at present I see nothing better than a ko.
Sometimes black moves at d gain an edge by hampering white's underneath connection, but white seems to destroy then all the eyes from the left.
This ko - is a very bad ko for Black (White takes first)
Dave: in the previous diagram looks like a mistake to me. Just extending to seems to ensure life for Black.
HermanHiddema: Does this escape threat actually work? I think black will have to play in the previous diagram one line lower to escape.
tderz: If White choses m, Black lives. White can also chose to fight for the ko-connection at n after in the diagram below.
This ko is much better for Black as he took first.
tderz: Alleged internal ko threats black d+e do not seem to work, as White would connect the ko at , then live with f.
Even if this life was not possible black needs too many approach moves (5 = g+h+f+c+i) while Black has only 4 liberties p-q-r-s on top.
tderz: Of course White connects the ko, lives herself and kills white.
tderz: Concluding from above, it seems that this ko has t be fought.
tderz: This is a good ko for Black as he took first.
tderz: threatening with a only leads to ko b.
Connecting at b lives from here.
Alainwettach: Maybe there is one other move to try
Herman Hiddema: What if white plays at ?
Alainwettach: in this variation, B seems alive with double ko if he throws in at a after w captures 9.
unkx80: Looks like a ko to me?
char: Try here =)
Really, I am not joking.
Herman Hiddema: This way, black wins the semeai, so apparently the marked move allows black to escape.
Dave: I think there is no escape for Black here. Black still has only ko although a is now an internal ko threat for Black.
Herman Hiddema: should be at , then black still wins the semeai
Dave: Oops! You are right Herman.
Dave: In theory White can still make ko with . But when White also has to play to stop the escape, Black ends up with a large number of internal ko threats starting with a.
unkx80: To be pedantic, I would even say that Black can live by double ko. After , Black either wins the ko on the left side by capturing at a, or wins the ko on the right side by capturing at b and then c. Also, White d may be answered by Black e. (If at , then Black plays at a for a snapback.)