Hane connect exercise 1

    Keywords: EndGame, Problem
Two stones  

Black and White have weaknesses at b and a respectively, as described on the hane tsugi/discussion page. Can White play the hane at W1? What will be the outcome? Are there other options here ?

Bill: I have added black+circle. Otherwise, White's clamp at c looks good instead of W1, as does White at b.

My analysis:

Ko is dangerous (7 at 1)  

For Black to play the ko in this diagram looks dangerous, as his whole territory will be gone if he loses the ko. Still, if Black is komaster there might be an opportunity here.

Giving way  

Probably Black has to give way at B2. If White continues here, it should be at a; however, there is a good chance that White will play tenuki now, satisfied to have avoided the black hane at b in sente. My impression is therefoer that W1 is a rather small move, but double sente. - Andre Engels

Bill: With the usual assumptions of yose, I get W1 to be a 6 point sente. If Black b, Black a is worth only 4 points (miai).

White continues  

If White does make the next move here, she will play like this.

Bill: This is a one-point gote.

Black's continuation (White 2 tenuki)  

If B1, White will probably not answer. After B3, White can play at W4 or a. Note however that B3 is simply a ko threat: it does not make any points (in theory White could make an approach ko for one point by playing at b, but in practice this is too risky). - Andre Engels
Bill: After B1 the temperature has dropped to 0 (unless White is komaster). If B3 then White a. Or W4 - B3, White b, then Black fills. Normally Black plays first for some ko threats.

Hane connect exercise 1 last edited by Dieter on November 20, 2008 - 11:56
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