Keywords: Life & Death, Question

jfc: This is a position from a recent game of mine. While you are free to comment on the game as a whole, the big question mark is:

  • can white capture the black+square black stones on the left. The black+circle black stones on the bottom of the board must remain dead.
  • what are white and black's best moves in this fight.

FYI: the [ext] game was played on DGS.

White to move.  

Solution discussion

My solution  

jfc: I spent a lot of time considering this problem before playing my move. I eventually decided that W1 and W3 here were best for white. Unfortunately I experienced a thinko and played W3 immediately, thinking I had played W1 already. Needless to say I resigned shortly thereafter.

After W3, there are many variations but I believe that white can achieve the goal of capturing the marked stones. Given my assessment of the overall game I considered it a requirement that the black+circle black group at the bottom stayed dead.

anonymous: Are you sure that works? - what is black plays atari connect? i.e. black a, white b, black c

jfc: I considered your sequence and I believe that white can enclose and kill black in the continuation. Please present any variation that demonstrates the contrary.

A and B are miai?  

PatrickB: What about trying for a local seki and then killing the containing stones instead?

jfc: excellent idea! I'm amazed that I missed this possibility. I struggled for hours looking for a line that would avoid seki on the side when I forgot that killing the black stones up by b would break the seki.

black oiotoshi again.  

jfc: I was worried about black connecting his two marked groups as shown in this variation but as unkx80 points out below, if white plays W8, black can't play b for another eye.

PatrickB: I will admit to having missed this line on my initial analysis. Good catch, and interesting problem.

race to capture is key.  

jfc: this race to capture is key. If the black+circle stones have one more liberty then black wins race to capture because the black+square group has more liberties than the white+square group.

Reference: One more liberty, black wins.  

jfc: I've modified the position so that black+circle has one more liberty than in the original diagram. In this position black wins the race to capture.

Show me the eyes?  

unkx80: I think this can be yet another option.

jfc: I'm so glad I asked this question here. Despite the amount of time I put in to this problem there are so many things I missed.

I had looked at this variation and was concerned that black+circle would live here (with a second eye around W5) but I failed to notice the black has a shortage of liberties after W9 and can not make a second eye with a.

Thanks folks!

BQM182 last edited by on January 26, 2015 - 08:16
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