BQM 318

19x19 diagram  

W is going to invade the lower side at a.

19x19 diagram  

The invasion begins with . is a light response to . After , white must live quickly.

19x19 diagram  

But, Cho writes, that's completely routine, and this diagram displays a living sequence. My problem is that I don't quite see where two unconditional eyes are to be made, and I would be grateful for any further explanation from anyone to whom this is clear.

Cho makes some comments along the way.

1.) After , Wa followed by Wb and Wc would already make one gote eye. (I suppose W keeps this sequence in reserve so now only one sente eye is necessary?)

2.) If black answered with , then at d would make white safe. (But could black not block at e? Will white necessarily connect out anyhow? Presumably prevents Wd from working, for sure.)

3.) and make the sente eye, after which Wb will initiate a second, gote eye. (But why is sente? If Bf, then are not Bg and Bh miai to kill the middle eye?)

Cho further remarks that these are all perfectly ordinary moves. I probably have some amazing blind spot; I would love to feel completely comfortable with such sequences in my own games. Any enlightenment would be appreciated.

Step 1 and  

White plays at . What happens if Black does not play here? For example, what if Black goes all out and plays a instead of ? How does White take advantage toward the right side?

BTW, This game is analyzed by Sakata Eio in Go World 34. He said, "Black 63 (the marked Black stone)... is clearly a bad move: giving White the easy invasion at 64 must be wrong... When White jumps to 66 (the marked White stone), his group is in no danger of being killed."

Step 2 and  

White plays and B answers at . What happens if Black does not play here? Consider a Black play at a instead. I think it is worth noting that both of the marked Black groups are potentially subject to attack. If Black allows White to drive between them, White will have an easy time.

Step 3 and  

White plays and Black answers with ^[1]. If Black plays a instead, what can White do toward the top? How about if Black plays b instead? It is worth considering what damage Black can do to the marked White stones if Black becomes strong in the center.

Step 4 and  

White plays and Black responds at . What alternatives does Black have? What would White do if Black played at a instead of ? ^[2]

Step 5 and after  

White plays and (in the game) Black turns away. But if Black had tried , how could White respond? ^[3]

If pressing?  

tderz: Anyway, here are professionals at play in a complex situation, perhaps we cannot comprehend everything.

Besides living, also the escape move springs to mind.
(But the Cho book wants to teach shinogi here)

[2]

Note: Comment made before the diagram was corrected.

Step 4 and - analysis  

tderz: I have by no means an idea whether my proposal is correct. However, IMO, if the of the game is not played, White can, should & will move out. - a common good shape - in combination with e.g. h (sometimes in inversed order h-) does this and moves in the direction of , which might be weakened.

[3]

Note: Comment made before the diagram was corrected.

two eyes or link  

tderz: After the exchange -, White could think first of safeguarding the eye at a (it still has the weakness at b.

The lower side allows for one gote eye c through g.

White needs another eye at h by playing eventually at i OR

an escape-link if this can be prevented.

Step 5 and after - analysis  

tderz: Imagine a variant where the lower eye is prevented by a ... after some moves k and L become miai.

These are some of many, many variations.

tderz: Sept. 8: Gosh! 2 stones missing from original problem diagram. This might make all previous considerations superfluous. Reminds me of 26 years ago, when 6d Juergen Mattern and another 3d cried out when I handed in my 'solution' for a problem in a Go-course. Some stones were missing! (which made it worthless in their eyes) At least I was serious and tackled the problem.