RTG Problem 77 / Attempts

Sub-page of RTGProblem77

Herman: Black has an obvious gote eye at a, and since there is no way to connect, black will have to find a way to make an eye in sente, the most obvious area being the lower left corner. I think the tesuji of B1 will do the trick


If White attempts to prevent black from making an eye with W2, then B3 will cut off white's stones.

Connecting out  

Although white can live with W4 through W10, black can then cut at a, connecting his group and saving it that way.

unkx80: Isn't it better to play B7 at W8, killing all the white stones?

Herman: You're absolutely right! I thought it led to ko, but it doesn't :)


If white connects with W2 as in this diagram, then with B3 and B5, black makes an eye, and W6 and B7 become miai for the second eye.

This is better for white than the previous diagrams.

unkx80: I expect that the best white move to be W2 at W4, black plays the same W3, then W4 can be played at a.

Herman: Yes, that is better indeed

In-between move  

Bill: How's this?

unkx80: True also, I missed this.

A second question: in typical cases, isn't B7 better directly played at a?

Bill: Yes, you're right. :)

Better, as a rule  

B1 captures white+circle, then White can force up to B7. Later, B9 will normally be sente. Black gets 3 points locally and White gets 1 point at circle.

Not so good  

After B1 White can force up to B5. Later B7 is sente. The net local score is the same, since Black gets 2 points while White does not get 1 point at W8. However, Black no longer has the sente in the center. As against that, circle may not become territory.

BTW, the quick way to see that B1 in the first diagram is at least as good B1 in the second one is the fact that in the second one White can play W2 at 3, forcing B3 at 2 and transposing to the first diagram. :)

RTG Problem 77 / Attempts last edited by Bill on February 20, 2010 - 21:15
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