BQM 251

black to play and live  

xela: This is problem 334 from volume 4 of Graded Go Problems for Beginners.

solution  

This is the answer given in the book.

can black live unconditionally?  

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.

Ko?  

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)

Ko?  

tderz:

the threat to escape  

tderz: the threat to escape to the center/edge is usually understood as a solution for Life in TsumeGo.

the threat to escape  

HermanHiddema: Does this escape threat actually work? I think black will have to play in the previous diagram one line lower to escape.

Ko?  

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.

Ko?  

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.

Ko?  

tderz: Of course White connects the ko, lives herself and kills white.

ko  

tderz: Concluding from above, it seems that this ko has t be fought.

ko  

tderz: This is a good ko for Black as he took first.

life from here  

tderz: threatening with a only leads to ko b.
Connecting at b lives from here.

This is more complicated.. but also alive  

Herman Hiddema: What if white plays at ?

So then it must be... double ko!  

Alainwettach: in this variation, B seems alive with double ko if he throws in at a after w captures 9.

What about this?  

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: 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.)