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KanazawaProblem20

 

Kanazawa Solution 20
Path: KanazawaSolutions   · Prev: KanazawaSolution19   · Next: KanazawaSolution21
   

[Diagram]
Diag.: Black lives

Starting at the 1-2 point to prevent White from linking up and to simultaneously occupy a VitalPoint, is pretty obvious.


[Diagram]
Diag.: Variation 1

If White takes the other 1-2 point, and destroys the EyeShape with 4, Black 5 makes life. White 6 at A makes a seki in gote.


[Diagram]
Diag.: Variation 2

If White 2 here, Black must resist the temptation to play at 4 but must attach at 3 instead. This is tesuji. If White 4, Black 5 makes seki. If White adds another move at A or B, she almost fills Black's eyespace with one of the bent four shapes that give life.


[Diagram]
Diag.: Variation 3 (Main line in the book)

If White resists with 4, Black sacrifices two stones with 5. This is the continuation of the tesuji. White captures at A ...


[Diagram]
Diag.: Variation 3 (continuation)

... but Black recaptures at 2 !! If White now connects her stones at 3, Black 4 creates damezumari. Note the liberty at the circled point, without which Black would not be able to execute this tesuji, since the move at 4 would place himself in atari.


[Diagram]
Diag.: Variation 4

If White doesn't connect, but tries to make it ko again ...


[Diagram]
Diag.: Variation 4 (cont.)

... Black calmly connects at 2 and will have the time to put all White's stones into atari at A. Again, the circled point is crucial for the tesuji to work.



[Diagram]
Diag.: Mistake at 3

If Black fails to see the tesuji, and falls for the temptation to occupy both 1-2 points instead, White 4 creates a ten thousand year ko. Note: in case the tesuji mentioned above doesn't work, due to the liberty at the circled point being filled, this is Black's best option.



[Diagram]
Diag.: Wrong

The only other option for 1 we have to investigate is Black 1 here: it also prevents White from linking up, and if it worked, it would perhaps make more points than the correct answer.


[Diagram]
Diag.: Wrong (proof)

White 6 makes miai of A and B: B would enable White to almost fill Black's EyeSpace with a bulky five and White A would make an eye inside Black's group. If Black rushes to capture white's stones, he's left with a farmer's hat space inside his group.

Note: In this position, the defects at the circled points may well make the presence of 5 dangerous. But there is no need for Black to look for complications, when simple life is available.



[Diagram]
Diag.: Wrong (proof) - correction

With the clamp at 5, black lives.


[Diagram]
Diag.: Wrong (proof) - correction

If white play at 'a' to prevent a seki, then black plays at 'b' to form a bent four living group.


[Diagram]
Diag.: Wrong (proof) - correction

After 9, white is short of liberties and cannot play at the marked stone to form a bulky five, so black lives.


[Diagram]
Diag.: Wrong (proof) - correction

White 4 here doesn't work... after black 7, white is caught in a conenct-and-die.


[Diagram]
Diag.: Wrong (proof) - correction

Same fate here if black chooses to take the ko at 6 instead.



KarlKnechtel (~14k)

Can't black also live by escaping with a MonkeyJump in this case?

[Diagram]
Diag.: Escape?

[Diagram]
Diag.: Escape?

No escape. --unkx80



[Diagram]
Diag.: Wrong (proof) - correction

So I propose white 2.


[Diagram]
Diag.: Wrong (proof) - correction

This dies easily.


[Diagram]
Diag.: Wrong (proof) - correction

Dead by a bulky five. If black continues by atari at 'a', white simply connects at 5.


[Diagram]
Diag.: Wrong (proof) - correction

After 4, 'a' and 'b' are miai.


[Diagram]
Diag.: Wrong (proof) - correction

Resistance at 3 is useless here.


[Diagram]
Diag.: Wrong (proof) - correction

The black group dies as well, 'a' and 'b' are miai.


[Diagram]
Diag.: Wrong (proof) - correction

The only correct answer for black is at 3. White's correct answer is at 4, and note that white must capture the black stone at 6, resulting in ten thousand year ko. This is the best sequence for both players after black plays at the marked stone.


[Diagram]
Diag.: Wrong (proof) - correction

If white play at 4 here, black lives in a seki.

--unkx80



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