Volume 3 - Problem 56  

Black to play. Correct Answer is B1. The answer explains: "Capping the four white stones with B1 is the most important move on the board. (...)"

Assumed Continuation  

I am not sure how I could actually kill the white stones. Would something like the sequence to B5 work? It seems Black still has many weak spots. --- (Sebastian)

DJ: Hi Sebastian! Why do you want to kill? The sequence you have shown may not be best, but it is a good approach to the idea of winning a game by attacking and threatening to kill: White has to find a way to live (small, moreover), and in doing so it will necessarily solidify Black's territory on the top left and top right, and why not, give Black also thickness on the outside, which will give him a lot of advantage in any invasion he may devise on the left and bottom sides.
This should be enough to win, without actually killing the white group...

(Sebastian:) Ciao DJ! Good point. I was looking for a way to kill it because:

  • I'm not sure if I as Black could cover all cutting points and connect my northeast group with the rest.
  • I felt that the move only stands out above all others if it kills the group. If the white group lives anyway, then it seemed to make only a gradual difference how big it would get. But I remember now that it always is a big benefit to attack a weak group, which apparently was the point of the exercise.

Gronk: Think of it this way: B is very happy to get B5 or thereabouts since it makes territory on top. View B1 and B3 as more-or-less free moves since they were forcing and W got little in exchange. Don't worry tremendously about cutting points unless and until they would threaten something big (a big kill or a big territory).

(Sebastian:) Aha! So you're saying that, even if W (after W established life, possibly helped by some mistake by B) manages to cut through, e.g. at a and continue with a finger to b, it doesn't really matter because that area wasn't really B's territory yet anyhow, and the finger helps strengthening my border territories. Correct?

Gronk: I speaking at a slightly higher level in that I can't say exactly what B1 and B3 will do later but only that it is clear (to me) that B1-B5 have helped B more than W. B got to secure some territory with B5 and got some influence with B1 and B3 while W still has a weak group. If W makes a move to cut B1-B3 off from the top, B will have an opportunity to further strengthen the top. Remember, W still needs to make life so cutting B1-B3 is not so worrisome yet. Moreover, B1-B3 may even be discarded later, so long as B gets compensation. Right now their value is rather vague (to me) but since they were free moves, that's okay. Finally, W2 and W4 are no more connected to safe W groups than B1 and B3. So why worry? W is worse off here.

GradedGoProblemsForBeginners/Vol3Prob56 last edited by Gronk on September 14, 2004 - 13:43
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