Gokyo Shumyo, Section 1, Problem 70 / Discussion

Is White 1 wrong ?  

From Gokyo Shumyo, Section 1, Problem 70. I can't find the refutation for W1, but it is late too. --Dieter

1. The hane

Attempt 1: the hane  

Let us consider this to be the basic variation (involving no ko). We will reconsider B3 and W4. B5 and W6 are miai. B7 is clearly wrong: W8 takes the vital point. If now Black a, White has enough outside liberties to capture Black's bent four. If Black doesn't play a, White a makes seki.

Variation at 7  

B1 here is better: White cannot connect because after B3 either Black a will almost fill with a bulky five or White a dies in gote.

Variation at 7 - White's best try  

This results in ko. W6 in "Attempt 1" is forced (for otherwise Black makes a bent three inside eye). So we look for a variation at w4.

Variation at 4  

This W1 is the first alternative. It looks like White can escape, but up to B10 her position is hopeless.

Variation at 4  

But W3 here is better: a and b are miai: Black a - White b is symmetrical to the first diagram and Black b - White a gives White the time to capture the three stones and make two eyes.

Variation at 4 - Black's best  

B2 assures ko. At the moment I am not able to tell if it will become double ko (which means life) or not. This surely means I don't understand ko.

(Sigh) Let's suppose it is some sort of ko, still worse than unconditional life. Then we must proceed to an alternative for W2 in "Attempt 1".

Variation at 2  

Since W1 was the correct move in Gokyo Shumyo, Section 1, Problem 70 / Solution, chances are that it saves the day again. Given Gokyo Shumyo, Section 1, Problem 70 / Solution, B2 is not the answer, but obviously White at B2 will make two eyes.

2. Playing the vital point

We're back to where we started. The hane is not the solution, because it enables White to grab the vital point again. So, let's have Black play there himself.

Attempt 2: the vital point  

Please do some of the work. I may continue later.

Gokyo Shumyo, Section 1, Problem 70 / Discussion last edited by CharlesMatthews on June 17, 2003 - 11:27
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