Bob McGuigan / Problem 1 Solution

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Solution to Problem on BobMcGuigan

Black to play, White dies.

[Diagram]
Correct Solution  

This is the printed solution but it seems White can get a ko (see below)

[Diagram]
Variation 1 (part 1) W2 here?  



[Diagram]
Variation 1 (part 2, continuing after pt. 1)  



[Diagram]
Variation 1a  



[Diagram]
Variation 1b  

If White takes one stone at a instead of playing 6, Black plays b.



[Diagram]
Variation 2: W2 here?  

After B9, a and b are miai.



[Diagram]
Variation 3: W2 here?  

After W10, Black gets a nakade with a.



[Diagram]
Variation 4: W4 here?  



[Diagram]
Variation 5: W2 here?  



Black failure diagrams

[Diagram]
Black failure number 1  



[Diagram]
Black failure 1a  



[Diagram]
Black failure 2  

White wins the capturing race



[Diagram]
Black failure 3  

After W2 white is alive


jvt: Beautiful problem. I wonder if White can get a ko like this?

[Diagram]
K1. Solution is ko?  

Starting as in variation 1b, White plays W6 instead of B7.



[Diagram]
K1a. How about this for B7?  

B11 at a. This was suggested by Tsukamoto Chiaki on r.g.g. It is similar to variation 1b above.

[Diagram]
K1b. White still gets a ko  

jvt: After B7 in diag. K1a, White plays W8, then Black can only play the ko at a. No other move will work.


[Diagram]
K2. Solution is ko?  

[Diagram]
 

DaveSigaty: This position comes from game 3 of the 8th Meijin Final between Cho and Otake (Black), 1983-09-28. The black stones in the upper left match the problem but the surrounding stones are different. Cho never tried to kill Black. Did he miss a chance or did he correctly read out that Black lives?




[Diagram]
 



BobMcGuigan: This game has a published commentary by Hane Yasumasa 9p in Go World issue number 34. Hane points out that Black can live unconditionally but only in a way that helps White on the top. Hane felt that Cho missed an opportunity. Without quoting the commentary in detail, Black has to respond to a white attack at white+circle either by a hane at the circle point, which allows White to play at the point marked with a square in sente, or else Black could answer the white attack at B1 in the next diagram.

[Diagram]
 

After W10, Black a, White b, etc. through Black e follow and White has succeeded in playing d in sente; which, according to Hane, will be important later in the game.


BobMcGuigan: I think it is interesting to see how the problem position arose. It started with a very common joseki sequence, as in this diagram, and the position at issue in the Cho-Otake game resulted from natural middle game moves around this shape.

[Diagram]
Joseki position  

Charles A closely related position arose in a game Zhao Wendong?-Xie He (B) 1995-01-12, first from this sort of shape:

[Diagram]
Joseki position plus ...  

and then later fighting to give:

[Diagram]
Endgame position  



I won't give the details (and the players were then strong amateurs), but the interest here became how to handle this in the endgame. Black could still run out at a; meaning that the attack with White at b wasn't going to kill. In the end White did take profit with an attack and send Black out into the centre.

This is somewhat related to connecting along dame and one group wins.


jvt: Do you have a reference to the book / page by Fujisawa Shuko where this problem comes from? I'd like to add a link in Errata In Books.

BobMcGuigan: It is problem number 162 from the book "Shuuko Sousaku Tsumego Kessaku Shuu" by Fujisawa Shuko, published by the Nihon Ki-in in Japan, 1980. The title means "A Collection of Original Tsumego Masterpieces by Shuuko". I can't resist mentioning that the word kessaku (masterpiece in the title) could, in other contexts, mean "blunder".


Bob McGuigan / Problem 1 Solution last edited by 71.192.12.205 on July 31, 2007 - 17:11
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